,transcrib]'s ,notes3 ,und]scores be=e & aft] a ^w or phrase indicate italics 9 ! orig9al text4 ,equal signs be=e & aft] a ^w or phrase indicate bold 9 ! orig9al text4 ,small capitals h be5 conv]t$ to ,,solid capitals4 ,illu/rations h be5 mov$ s !y d n break up p>agraphs4 ,mispr9ts 9 ! table ,,sav+ ,,due ,,to ,,heat+ ,,! ,,fe$ ,,wat]1 ,pg4 #aicf h be5 correct$1 !y are3 ,init4 ,temp4 ,pressure ,old ,value ,new ,value #acj #dj 4#jied 4#jicd #bjj #dj 4#jijj 4#jiii #baj #dj 4#ajjj 4#ajaj #bcj #ajj 4#jaag 4#ajab ,9 ! orig9al text1 !re are two ,fig4 #bgfi's & two ,fig4 #bggj's4 ,! second ( ea* has _h an a suffix add$1 i4e4 #bgfi;a & #bggj;a4 ,on l9e #gcig ! ^w imp$5ce 0 correct$ to imp$ance4 ,sup]scripts are %[n z d & subscripts are %[n z d1 :]e d is an integ]4 ,inconsi/5t spell+ & hyph5ation has be5 left z 9 ! orig9al4 ,,! ,,?\ght ,,is ,,9 ,,! ,,"q ,,! ,,in=mation ,,is ,,9 ,,! ,,answ] ,,hawk9s ,,electrical ,,guide ,,numb] ,,eight ,,que/ions ,,answ]s ,,illu/rations ,a ,,progressive ,,c\rse ,,( ,,/udy ,,= ,,eng9e]s1 ,,electricians1 ,,/ud5ts ,,& ,,^? ,,desir+ ,,to ,,acquire ,a ,,work+ ,,k ,,( ,,electricity ,,& ,,its ,,applications ,a ,,practical ,,treatise by ,,hawk9s ,,& ,,/aff ,,!o ,,audel ,,co4 #gb ,,fif? ,,ave4 ,,new ,,york4 ,,copyright$1 #aiae1 ,,by ,,!o4 ,,audel ,,co41 ,,new ,,york4 ,pr9t$ 9 ! ,unit$ ,/ates4 ,,table ,,( ,,cont5ts ,,guide ,no4 #h ,,wave ,,=m ,,measurem5t #a1hci to #a1hfh ,importance ( wave =m measurem5t--me?ods3 /ep by /ep2 con/antly record+--classes ( app>atus3 wave indication2 oscillographs--/ep by /ep me?ods--,j\b]t's2 f\r "p commutator2 modifi$ f\r "p commutator2 balli/ic galvanomet]2 z]o2 ,hospitali] ondograph--con/antly record+ me?ods3 ca?ode ray2 gl[ light2 mov+ iron2 mov+ coil2 hot wire--oscillographs--mov+ coil type2 con/ruction & op]ation2 production ( ! "t scale2 oscillograms--fall+ plate cam]a2 its use4 ,,swit*bo>ds #a1hfi to #a1hhd ,g5]al pr9ciples3 diagram--small plant a4c4 swit*bo>d--swit*bo>d panels2 g5]ator panel2 diagram ( connections--simple me?od ( det]m9+ bus b> capacity--fe$] panel--diagrams ( connection = two phase & ?ree phase in/allations4 ,,alt]nat+ ,,curr5t ,,wir+ #a1hhe to #a1iad ,effects to be consid]$ 9 mak+ calculations--induction2 self- & mutual2 mutual induction1 h[ caus$--transpositions--inductance p] mile ( ?ree phase circuit1 table--capacity2 table--frequ5cy--sk9 effect2 calculation2 table--corona effect2 its manife/ation2 critical voltage2 spac+ ( wires--resi/ance ( wires--imp$ance--p[] factor2 app>5t curr5t2 usual p[] factors enc\nt]$2 example--wire calculations--sizes ( wire--table ( ! prop]ty ( copp] wire--drop2 example--curr5t--example cov]+ horse p[]1 watts1 app>5t load1 curr5t1 size ( wire1 drop1 voltage at ! alt]nator1 & electrical horse p[]4 ,,p[] ,,/ations #a1iae to #a1ihh ,classification--c5tral /ations2 types3 a4c41 d4c41 & a4c4 & d4c42 reciprocat+ eng9e vs4 turb9e--location ( c5tral /ations2 price ( l&2 tr\ble aft] erection2 wat] supply2 s]vice requir+ direct curr5t--size ( plant2 nature ( load2 peak load2 load factor2 ma*9]y requir$2 example2 factors ( evaporation2 grate surface p] horse p[]--g5]al arrangem5t ( /ation2 belt drive ) c\nt] %aft2 desirable features ( belt drive2 conditions1 suitable = c\nt] %aft drive2 location ( eng9e & boil]s2 ! /eam pipe2 pip+ betwe5 eng9e & cond5s]2 numb] & type ( eng9e2 sup]heat$ /eam2 swit*bo>d location2 individual belt drive2 direct drive--/ation con/ruction--f\ndations--walls-- ro(s--floors--*imneys2 co/ ( *imneys & me*anical draft2 high *imneys ill advis$--/eam turb9e2 types3 impulse & reaction2 :y high vacuum is necess>y2 ! work+ pressure--hydro-electric plants--wat] turb9es2 types3 impulse1 reaction--isolat$ plants--sub-/ations2 arrangem5t2 ?ree phase in/allations2 reactance coils 9 sub-/ations2 portable sub-/ations4 ,,managem5t #a1ihi to #b1aad ,! t]m managem5t--selection2 g5]al consid]ations--selection ( g5]ators2 effici5cy ( g5]ators2 size & numb]2 regulation--in/allation2 precautions2 h&l+ ( armatures2 assembl+ a ma*9e2 spe$ ( g5]ators2 calculation ( pulley sizes2 ge> :eels--belts2 v>i\s belt drives2 horse p[] transmitt$ by belts2 velocity ( belt2 endless belts--swit*bo>ds2 ess5tial po9ts ( diff]5ce betwe5 s+le phase & ?ree phase swit*bo>d wir+2 assembl+ a swit*bo>d2 usual equipm5t4 ,op]ation ( ,alt]nators--alt]nators 9 p>allel2 syn*roniz+2 lamp me?ods2 action ( amortisseur w9d+2 syn*roniz+ ?ree phase alt]nators2 disadvantage ( lamp me?od--cutt+ out alt]nator2 precautions2 hunt+--alt]nators 9 s]ies4 ,trans=m]s2 selection2 effici5cy2 k9d ( oil us$2 detection ( moi/ure2 dry+ oil2 regulation2 trans=m]s 9 p>allel2 pol>ity te/--motor g5]ators2 v>i\s types & conditions requir+ same--dynamotors2 precautions--rot>y conv]t]s2 objections to s+le phase type2 op]ation :5 driv5 by direct curr5t1 by alt]nat+ curr5t2 mo/ tr\blesome "p2 effici5cy2 ov]load2 />t+2 />t+ curr5t4 ,electrical measur+ in/rum5ts2 location2 read+s2 /ation voltmet]s2 po9ts relat+ to ammet]s2 att5tion necess>y2 usual rem$ies to correct voltmet]--h[ to te/ g5]ators2 comm]cial effici5cy2 v>i\s te/s4 ,/ation ,te/+3 resi/ance measurem5t by drop me?od--me?ods ( connect+ ammet] voltmet] & wattmet] = measurem5t ( p[]--motor te/+3 s+le phase motor--?ree phase motor1 voltmet] & ammet] me?od2 two wattmet] me?od2 polyphase wattmet] me?od2 "o wattmet] me?od2 "o wattmet] & ,y box me?od--?ree phase motor ) neutral br\ght out2 s+le wattmet] me?od--temp]ature te/1 ?ree phase induction motor--?ree phase alt]nator te/+3 excitation or magnetization curve te/--syn*ron\s imp$ance te/--load te/--?ree phase alt]nator or syn*ron\s motor temp]ature te/--direct curr5t motor or g5]ator te/+3 magnetization curve--7%unt7 ext]nal *>act]i/ic--direct curr5t motor te/+2 load & spe$ te/s--temp]ature te/1 load+ back me?od--comp\nd dynamo te/+3 ext]nal *>act]i/ic1 adju/able load--trans=m] te/+3 ext]nal *>act]i/ic1 adju/able load--trans=m] te/+3 core loss & leakage or excit+ curr5t te/--copp] loss--copp] loss by wattmet] measurem5t & imp$ance--temp]ature--insulation--int]na l insulation--insulation resi/ance--pol>ity--w9d+ or ratio te/s4 ,,*apt] ,,lxiii ,,wave ,,=m ,,measurem5t ,! great importance ( ! wave =m 9 alt]nat+ curr5t "w is nev] d5i$1 ?\gh x has sometimes be5 ov]look$4 ,! application ( l>ge gas eng9es to ! driv+ ( alt]nators op]at$ 9 p>allel requires an accurate k ( ! wave =m1 & a close con=mation to a s9e wave if p>allel op]ation is to be satisfactory4 ,x is also important t ! fluctuations 9 magnetism ( ! field poles %\ld be kn[n1 especially if solid /eel pole faces be us$4 ,if an alt]nator armature w9d+ be connect$ 9 delta1 ! pres5ce ( a ?ird h>monic becomes objectionable1 z x gives rise to circulat+ curr5ts 9 ! w9d+ itself1 :i* increase ! heat+ & l[]s ! effici5cy ( ! ma*9e4 ,t ! importance ( hav+ a good wave =m is be+ realiz$1 is prov$ by ! increas+ preval5ce 9 alt]nator specifications ( a clause specify+ ! maximum div]g5ce all[able f a true s9e wave4 ,x is h[ev] p]haps n always realiz$ t an alt]nator :i* gives a good pressure wave on no load may give a v bad "o "u c]ta9 loads1 & ! ability ( ! ma*9e to ma9ta9 a good wave =m "u sev]e conditions ( load is a bett] crit]ion ( its good design ?an is ! %ape ( its wave at no load4 ,! "q ( wave =m is ( special int]e/ to ! p[] /ation eng9e]4 ,^u x dep5ds ! answ] to ! que/ions3 :e!r he may gr\nd 8 neutral wires )\t gett+ l>ge circulat+ curr5ts2 :e!r he may safely run any comb9ation ( 8 alt]nators 9 p>allel2 :e!r ! con/ants ( 8 di/ribut+ circuit are ( an ord] liable to cause dang]\s voltage surges due to resonance ) ! h>monics ( 8 pressure wave2 :at /resses he is gett+ 9 8 insulation due to voltage surges :5 swit*+ on or (f1 etc4 ,x has be5 %[n by ,rossl] & ,weld+ t ! lum9\s effici5cy ( ! alt]nat+ curr5t arc may be #dd p] c5t4 high] ) a flat topp$ ?an ) a peak$ pressure wave1 :ile on ! o!r h& x is well kn[n t trans=m]s are m effici5t on a peak$ wave4 ,also ! accuracy ( _m alt]nat+ curr5t in/rum5ts dep5ds ^u ! wave %ape4 ,9 mak+ insulation breakd[n te/s on cables1 insulators1 or ma*9]y1 l>ge errors may be introduc$ unless ! wave =m at ! "t ( ! te/ be kn[n4 ,x is n suffici5t ev5 to "k t ! te/+ alt]nator gives a close approximation to a s9e wave at no load2 s9ce if ! capacity curr5t ( ! app>atus "u te/ be mod]ately l>ge comp>$ ) ! full load curr5t ( ! te/+ alt]nator1 ! *>g+ curr5t tak5 may be suffici5t to di/ort ! wave =m consid]ably1 ?us giv+ wrong results to ! disadvantage ( ei!r ! manufactur] or pur*as]4 ,illu/ration3 ,,fig4 #b1ehc4--;,g5]al ,electric simultane\s record ( ?ree waves ) common z]o4 ,! desirability ( a complete k ( ! mann] 9 :i* ! pressure & curr5t v>ies dur+ ! cycle1 has result$ 9 v>i\s me?ods & app>atus be+ devis$ = obta9+ ?is k4 ,! app>atus 9 use = su* purpose may be divid$ into two g5]al classes1 #a4 ,wave indicators2 #b4 ,oscillographs4 & ! me?ods employ$ ) ^! two species ( app>atus may be describ$ respectively z1 #a4 ,/ep by /ep2 #b4 ,con/antly record+4 t is to say1 9 ! fir/ in/ance1 a numb] ( in/antane\s values are obta9$ at v>i\s po9ts ( ! cycle1 :i* are plott$ & a curve trac$ ?r\gh ! sev]al po9ts ?us obta9$4 ,a con/antly record+ me?od is "o 9 :i* an inf9ite numb] ( values are det]m9$ & record$ by ! ma*9e1 ?us giv+ a complete record ( ! cycle1 leav+ no portion ( ! wave to be fill$ 94 ,illu/ration3 ,,fig4 #b1ehd4--;,g5]al ,electric simultane\s record ( ?ree waves ) sep>ate z]os4 ,illu/ration3 ,figs4 #b1ehe & #b1ehf4--,oscillograms 7f pap] by ,morris & ,catt]son-,smi?1 ,proc4 ,i4 ,e4 ,e41 ,vol4 ,,xxxiii1 page #a1jbc71 %[+ h[ ! curr5t v>ies 9 "o ( ! armature coils ( a direct curr5t motor4 ,fig4 #b1ehe 0 obta9$ ) ! bru%es 9 ! neutral position1 & fig4 #b1ehf ) ! bru%es %ift$ =w>d4 ,! v>i\s me?ods ( det]m9+ ! wave =m may be fur!r classifi$ z3 ,j\b]t's me?od2 ,f\r "p commutator me?od2 ,modifi$ f\r "p commutator me?od2 #a4 ,/ep by /ep ,balli/ic galvanomet] me?od2 ,z]o me?od2 ,by ,hospitali] ondograph4 ,illu/ration3 ,,fig4 #b1ehg4--,oscillogram by ,bailey & ,cleghorne 7,proc4 ,i4,e4,e41 ,vol4 ,,xxxviii71 %[+ ! sp>k+ pressure or pressure betwe5 ! bru% & ! commutator segm5t at ! mom5t ( sep>ation4 ,! waves fall into gr\ps ( ?ree ow+ to ! fact t !re 7 ?ree armature coils 9 ea* slot4 ca?ode ray2 by use ( v>i\s types gl[ light2 #b4 con/antly record+ ( oscillograph1 mov+ iron2 su* z mov+ coil2 hot wire4 ,illu/ration3 ,,fig4 #b1ehh4--,v>i\s wave =ms4 ,! s9e wave repres5ts a curr5t or pressure :i* v>ies accord+ to ! s9e law4 ,a di/ort$ wave is due to ! prop]ties ( ! circuit1 = in/ance1 ! effect ( hy/]esis 9 an iron core introduc$ into a coil is to di/ort ! curr5t wave by add+ h>monics s t ! asc5d+ & desc5d+ portions may n be symmetrical4 ,a peak$ wave has a l>ge maximum z comp>$ ) its virtual value4 ,a peak$ wave is produc$ by a ma*9e ) conc5trat$ w9d+4 ,j\b]t's ,me?od4--,! app>atus requir$ = det]m9+ ! wave =m by ?is /ep by /ep me?od1 consi/s ( a galvanomet]1 cond5s]1 two1 two way swit*es1 resi/ance & adju/able contact mak]1 z %[n 9 fig4 #b1ehi4 ,! contact mak] is atta*$ to ! alt]nator %aft s t x w rotate syn*ron\sly ) ! latt]4 ,by means ( ! adju/able contact1 ! in/ant ( mak+ t is1 ( clos+ ! te/+ circuit may be v>i$1 & ! angul> position ( ! armature1 at :i* ! te/+ circuit is clos$1 det]m9$ f ! scale1 :i* is divid$ into degrees4 ,a resi/ance is plac$ 9 s]ies ) "o ( ! alt]nator leads1 su* t ! drop across x1 gives suffici5t pressure = te/+4 ,ques4 ,describe ! me?od ( mak+ ! te/4 ,illu/ration3 ,,fig4 #b1ehi4--;,diagram illu/rat+ ,j\b]t's /ep by /ep me?od ( wave =m measurem5t4 ,ans4 ,= curr5t wave measurem5t swit* ,no4 #a is plac$ on contact ,f1 & = pressure wave measurem5t1 on contact ,g1 swit* ,no4 #b is n[ turn$ to ,m & ! drop across ! resi/ance 7assum+ swit* ,no4 #a to be turn$ to contact ,f7 measur$ by *>g+ ! cond5s]1 & !n dis*>g+ x ?r\gh ! galvanomet] by turn+ ! swit* to ,s4 ,?is is repeat$ = a numb] ( positions ( ! contact mak]1 not+ ea* "t ! galvanomet] read+ & position ( ! contact mak]4 ,by plott+ ! positions ( contact mak] z absciss1 & ! galvanomet] read+s z ord9ates1 ! curve drawn ?r\gh !m w repres5t ! wave =m4 ,illu/ration3 ,,fig4 #b1eij4--;,f\r "p commutator me?od ( wave =m measurem5t4 ,! contact device consi/s ( two slip r+s & a f\r "p commutator4 ,"o slip r+ is connect$ to "o t]m9al ( ! s\rce1 ! o!r to ! voltmet]1 & ! commutator to ! cond5s]4 ,by adju/+ ,r :5 a kn[n direct curr5t pressure is impress$ across ! t]m9als1 ! voltmet] c be r5d]$ direct read+4 ,illu/ration3 ,,fig4 #b1eia4--,modifi$ f\r "p commutator me?od ( wave =m measurem5t 7,duncan's modification74 ,by ?is me?od "o contact mak] c be us$ = any numb] ( waves hav+ ! same frequ5cy4 ,electro-dynamomet]s are us$ & ! connections are made z "h %[n4 ,! mov+ coils are connect$ 9 s]ies to ! contact mak]1 & ! fix$ coils are connect$ to ! v>i\s s\rces to be inve/igat$1 !n ! deflection w be /eady & by calibration ) direct curr5t c be made to read directly 9 volts4 ,! app>atus is calibrat$ by pass+ a kn[n con/ant curr5t ?r\gh ! resi/ance4 ,illu/ration3 ,,fig4 #b1eib4--;,diagram illu/rat+ ! balli/ic galvanomet] me?od ( wave =m measurem5t4 ,! te/ may be made z describ$ 9 ! accompany+ text1 or 9 case ! contact break] is belt$ in/ead ( atta*$ rigidly to ! %aft1 x c\ld be arrang$ to run slightly out ( syn*ronism1 !n by tak+ read+s at regul> int]vals1 po9ts w be obta9$ along ! curve )\t mov+ ! contact break]4 ,if ?is me?od be us$1 a non-adju/able contact break] suffices4 ,9 arrang+ ! belt drive s z to run slightly out ( syn*ronism1 if ! pulleys be ( ! same size1 ! desir$ result is obta9$ by pa/+ a ?9 /rip ( pap] ar\nd ! face ( "o ( ! pulleys ?us alt]+ ! velocity ratio ( ! drive slightly f unity4 ,balli/ic ,galvanomet] ,me?od4--,?is me?od1 :i* is due to ,kubb]1 employs a contact break] in/ead ( a contact mak]4 ,! di/9ction betwe5 ^! two devices %\ld be not$3 ,a contact mak] keeps ! circuit clos$ dur+ ea* revolution = a %ort int]val only1 :]eas1 a contact break] keeps ! circuit op5 = a %ort int]val only4 ,fig4 #b1eib1 %[s ! necess>y app>atus & connections = apply+ ! balli/ic galvanomet] me?od4 ,! contact break] consi/s ( a commutator hav+ an ebonite or insulat+ segm5t & two bru%es4 ,9 op]ation ! contact break] keeps ! circuit clos$ dur+ all ( ea* revolution1 except ! brief int]val 9 :i* ! bru%es pass ov] ! ebonite segm5t4 ,! contact break] is adju/able & has a scale enabl+ its v>i\s positions ( adju/m5t to be not$4 ,ques4 ,describe ! te/4 ,illu/ration3 ,,figs44 #b1eic & #b1eid4--,two curves repres5t+ pressure & curr5t respectively ( a rot>y conv]t]4 ,fig4 #b1eic1 pressure wave ,v1 fig4 #b1eid curr5t wave ,c4 ,^! waves 7 obta9$ f a conv]t] :i* 0 be+ driv5 by an alt]nator by means ( an indep5d5t motor4 ,! rot>y conv]t] 0 supply+ idle curr5t to "s unload$ trans=m]s & ! ripples cle>ly visible 9 ! pressure wave ,v1 correspond to ! numb] ( tee? 9 ! armature ( ! rot>y conv]t]4 ,ans4 ,! contact break] is plac$ 9 successive positions & galvanomet] read+s tak51 ! swit* be+ turn$ to ,f1 fig4 #b1eib1 9 measur+ ! curr5t wave1 & to ,g 9 measur+ ! pressure wave4 ,! results ?us obta9$ are plott$ giv+ respectively curr5t & pressure waves4 ,ques4 ,h[ is ! app>atus calibrat$8 ,ans4 ,by s5d+ a con/ant curr5t ( kn[n value ?r\gh ! resi/ance ,r4 ,z]o ,me?od4--,9 electrical measurem5ts1 a z]o me?od is "o 9 :i* ! arrangem5t ( ! te/+ devices is su* t ! value ( ! quantity be+ measur$ is %[n :5 ! galvanomet] ne$le po9ts to z]o4 ,9 ! z]o me?od ei!r a contact mak] or contact break] may be us$ 9 connection ) a galvanomet] & slide wire bridge1 z %[n 9 figs4 #b1eie & #b1eif4 ,illu/ration3 ,,fig4 #b1eie4--;,diagram illu/rat+ z]o me?od ( wave measurem5t ) contact mak]4 ,! voltage ( ! batt]y mu/ be at lea/ z great z ! maximum pressure to be measur$ & mu/ be kept con/ant4 ,ques4 ,:at capacity ( batt]y %\ld be us$8 ,ans4 ,its voltage %\ld be z great z ! maximum pressure to be measur$4 ,ques4 ,:at necess>y condition mu/ be ma9ta9$ 9 ! batt]y8 ,ans4 ,its pressure mu/ be kept con/ant4 ,ques4 ,h[ are in/antane\s values measur$8 ,ans4 ,! bridge contact ,a is adju/$ till ! galvanomet] %[s no deflection1 !n ! l5g? ,,z is a measure ( ! pressure4 ,! drop betwe5 ^! po9ts c be directly measur$ ) a voltmet] if desir$4 ,ques4 ,h[ did ,m]%on modify ! te/8 ,ans4 ,he us$ a telephone in/ead ( ! galvanomet] to det]m9e ! correct placem5t ( ! bridge contact ,a4 ,illu/ration3 ,,fig4 #b1eif4--;,diagram illu/rat+ z]o me?od ( wave measurem5t ) contact break]4 ,! voltage ( ! batt]y mu/ be at lea/ z great z ! maximum pressure to be measur$ & mu/ be kept con/ant4 ,ques4 ,h[ c ! in/antane\s values be record$8 ,ans4 ,by atta*+ to ! contact ,a1 a p5cil controll$ by an electro-magnet arrang$ to /rike a revolv+ pap] c>d at ! in/ant ( no deflection1 ! pap] be+ c>ri$ on a drum4 ,hospitali] ,ondograph4--,! device kn[n by ?is "n is a developm5t ( ! ,j\b]t /ep by /ep me?od ( wave =m measurem5t1 t is to say1 ! pr9ciple on :i* its action is bas$1 consi/s 9 automatically *>g+ a cond5s] f ea* #ajj? wave1 & dis*>g+ x ?r\gh a record+ galvanomet]1 ea* successive *>ge ( ! cond5s] be+ automatically tak5 f a po9t a little f>!r along ! wave4 ,illu/ration3 ,,fig4 #b1eig4--;,diagram ( ,hospitali] ondograph %[+ me*anism & connections4 ,x repres5ts a developm5t ( ,j\b]t's /ep by /ep me?od ( wave =m measurem5t4 ,z %[n 9 ! diagram1 fig4 #b1eig1 ! ondograph consi/s ( a syn*ron\s motor ,a1 op]at$ f ! s\rce ( ! wave =m to be measur$1 connect$ by ge>s ,b to a commutator ,d1 9 su* a mann] t :ile ! motor makes a c]ta9 numb] ( revolutions1 ! commutator makes a l numb] dim9i%$ by unity2 t is to say1 if ! spe$ ( ! motor be #ijj revolutions p] m9ute1 ! commutator w h a spe$ ( #hii4 ,! commutator has ?ree contacts1 arrang$ to automatically *>ge ! cond5s] cc' f ! l9e1 & dis*>ge x ?r\gh ! galvanomet] ,e1 ! deflection ( :i* w be proportional to ! pressure at any p>ticul> in/ant :5 contact is made4 ,9 fig4 #b1eig1 ,,gg' are ! motor t]m9als1 ,,hh' are connect$ to ! cond5s] cc' ?r\gh a resi/ance 7to prev5t sp>k+ at ! commutator7 & ,i1 ,i' are ! connections to ! s]vice to be measur$4 ,a p]man5t magnet type ( record+ galvanomet] is employ$4 ,its mov+ coil ,e receives ! dis*>ges ( ! cond5s] 9 rapid succession & turns sl[ly f "o side to ! o!r4 ,illu/ration3 ,,fig4 #b1eih4--,view ( ,hospitali] ondograph4 ,9 op]ation1 a long pivot$ po9t] c>ry+ a p5 & actuat$ by electro-magnets1 records on a revolv+ drum a wave =m repres5t+ ! alt]nat+ curr5t1 pressure or curr5t wave4 ,! movable "p op]ates a long ne$le 7sep>ately m\nt$7 c>ry+ a p5 ,f1 :i* traces ! curve on ! rotat+ cyl9d] ,c4 ,?is cyl9d] is ge>$ to ! syn*ron\s motor to run at su* a spe$ z to regi/] ?ree complete waves ^u its circumf]5ce4 ,by sub/itut+ an electromagnetic galvanomet] = ! p]man5t magnet galvanomet]1 & by us+ ! magnet coils z curr5t coils & ! mov+ coil z ! volt coil1 ! in/rum5t c be made to draw watt curves4 ,fig4 #b1eih %[s ! g5]al appe>ance ( ! ondograph4 ,ca?ode ,ray ,oscillograph4--,?is type ( app>atus = measur+ wave =m 0 devis$ by ,braun1 & consi/s ( a ca?ode ray tube hav+ a fluoresc5t scre5 at "o end1 a small diaphragm ) a hole 9 x at its middle1 & two coils ( a few turns ea*1 plac$ outside x at "r angles to "o ano!r4 ,^! coils c>ry curr5ts proportional to ! pressure & curr5t respectively ( ! circuit "u obs]vation4 ,illu/ration3 ,,fig4 #b1eii4--;,g5]al ,electric mov+ coil oscillograph complete ) trac+ table4 ,! trac+ table is employ$ = obs]v+ ! waves1 & by us+ a piece ( transp>5t pap]1 ! waves "u obs]vation appe> z a cont9u\s b& ( light :i* c be trac$1 ?us mak+ a p]man5t record4 ,?is is n1 h[ev]1 to be reg>d$ z a record+ atta*m5t1 & c n be us$ :]e in/antane\s ph5om5a are be+ inve/igat$4 ,! syn*ron\s motor = op]at+ ! syn*ron\s mirror 9 connection ) trac+ & view+ atta*m5t is w\nd = #ajj to #aae volts1 #be to #abe cycles1 & %\ld1 ( c\rse1 be run f ! same ma*9e :i* furni%es p[] to ! circuit "u obs]vation4 ,a rheo/at = /eady+ & adju/+ ! curr5t %\ld be connect$ 9 s]ies ) ! motor4 ,! beam f ! vibrator mirrors /rik+ ?is syn*ron\s mirror moves back & =? ov] ! curv$ glass1 & gives ! l5g? ( ! wave2 ! movem5t ( ! vibrator mirror gives ! amplitude1 & ! comb9ation gives ! wave complete4 ,an arc lamp or projection lant]n produces ! image reflect$ by ! mirrors ^u ! film1 trac+ table or scre54 ,= ! rotation ( ! photographic film1 a small direct curr5t %unt w\nd motor is ord9>ily us$4 ,! ray !n moves s z to produce an en]gy diagram on ! fluoresc5t scre54 ,illu/ration3 ,,fig4 #b1fjj4--;,g5]al ,electric mov+ coil oscillograph4 ,! mov+ elem5ts consi/ ( s+le loops ( flat wire c>ry+ a small mirror & held 9 t5sion by small spiral spr+s4 ,! curr5t pass+ d[n "o side & up ! o!r1 =ces "o side =w>d & ! o!r backw>d1 ?us caus+ ! mirror to vibrate on a v]tical axis4 ,! vibrator elem5ts fit into *amb]s betwe5 ! poles ( electro-magnets1 & are adju/able1 s z to move ! beam f ! mirror1 bo? v]tically & horizontally4 ,a s5sitiz$ photographic film is wrapp$ ar\nd a drum & held by spr+ clamps4 ,! drum1 ) film1 is plac$ 9 a case & a cap !n plac$ ov] ! end1 mak+ ! case light1 :5 ! index is ei!r up or d[n4 ,! load+ is done 9 a d>k room4 ,a driv+ dog is screw$ into ! drum %aft1 & :i*1 :5 ! drum & case are 9 place1 revolves ! film pa/ a slot4 ,:5 an exposure is to be made1 ! index is mov$ f ! clos$ position1 ?us op5+ ! slot 9 ! case & expos+ ! film to ! beam ( light f ! vibrat+ mirrors :5 ! electrically op]at$ %utt] is op54 ,! slot is !n clos$ by mov+ ! index to ,expos$4 ,a slide ) gr\nd glass c be ins]t$ 9 place ( ! film case or roll hold] to arrange ! optical sy/em :5 mak+ adju/m5ts4 ,! %utt] op]at+ me*anism is arrang$ s z to hold ! %utt] op5 dur+ exactly "o revolution ( ! film drum4 ,!re are two devices connect$ to ! %utt] op]at+ me*anism2 "o op5s ! %utt] at ! in/ant ! end ( ! film passes ! slot2 ! o!r op5s imm$iately1 at any "p ( ! film1 & bo? give exposure dur+ "o revolution4 ,! fir/ is useful :5 mak+ inve/igations 9 :i* ! ev5ts are ei!r recurr+1 or _! beg9n+s kn[n or "u control1 & ! second :5 ! "t ( ! ev5t is n "u control1 su* z ! bl[+ ( fuses or op5+ ( circuit break]s4 ,! in/rum5t is mu* us$ 9 wireless telegraphy1 z x is capable ( %[+ ! *>act]i/ics ( curr5ts ( v high frequ5cy4 ,illu/ration3 ,,fig4 #b1fja4--;,g5]al ,electric mov+ coil oscillograph ) case remov$1 %[+ int]ior con/ruction & arrangem5t ( p>ts4 ,! oscillograph is furni%$ complete ) a ?ree elem5t electro-magnet galvanomet]1 optical sy/em1 %utt] & %utt] op]at+ me*anism1 film driv+ motor & cone pulleys1 photographic & trac+ atta*m5ts1 #f film hold]s1 & ! foll[+ repair p>ts1 = vibrators3 #f extra susp5sion /rips2 #f vibrator mirrors2 #a box gold leaf fuses2 #a bottle mirror cem5t2 #a bottle damp+ liquid4 ,illu/ration3 ,,fig4 #b1fjb4--,oscillogram %[+ ! direct curr5t pressure ( a #be cycle rot>y conv]t] 7bel[71 & 7above7 ! pressure wave tak5 betwe5 "o collector r+ & "o commutator bru%4 ,! #ab ripples p] cycles 9 ! direct curr5t voltage are due to a #ac? h>monic 9 ! alt]nat+ curr5t supply4 ,gl[ ,light ,oscillograph4--,?is device consi/s ( two alum9um rods 9 a p>tially evacuat$ tube1 _! ends be+ ab\t two millimet]s ap>t4 ,:5 an alt]nat+ curr5t ( any frequ5cy passes betwe5 !m a %ea? ( violet light =ms on "o ( ! electrodes1 pass+ ov] to ! o!r :5 ! curr5t rev]ses dur+ ea* cycle4 ,! ph5om5on may be obs]v$ or photograph$ by means ( a revolv+ mirror4 ,illu/ration3 ,,fig4 #b1fjc4--;,curves by ,morris1 illu/rat+ ! dang]\s ru% ( curr5t :i* may occur :5 swit*+ on a trans=m]4 ,! circuit 0 brok5 at ,f & made aga9 at ,g4 ,! curr5t 0 s great z to c>ry ! spot ( light "r (f ! photographic plate due to ! fact t a residual field 0 left 9 ! core aft] swit*+ (f1 & on clos+ ! swit* aga9 ! direction ( ! curr5t 0 su* z to t5d to build up ! full flux 9 ! same direction z ?is residual flux4 ,! dott$ l9es h be5 drawn 9 to %[ h[ ! actual waves 7 di/ort$ f ! normal4 ,mov+ ,iron ,oscillograph4--,?is type is due to ,blondel1 to :om belongs ! cr$it ( work+ out & describ+ 9 consid]able detail ! pr9ciples und]ly+ ! con/ruction ( oscillographs4 ,! mov+ iron type ( oscillograph consi/s ( a v ?9 vane ( iron susp5d$ 9 a p[]ful magnetic field1 ?us =m+ a pol>iz$ magnet4 ,ne> ?is /rip are plac$ two small coils :i* c>ry ! curr5t ^: wave =m is to be measur$4 ,! mov+ iron vane has a v %ort p]iod ( vibration & c !re=e foll[ e v>iation 9 ! curr5t4 ,illu/ration3 ,,fig4 #b1fjd4--,siem5s-,blondel mov+ coil type oscillograph4 ,! coil is 9 ! %ape ( a loop ( ?9 wire1 :i* is susp5d$ 9 ! field ( an electro-magnet excit$ by cont9u\s curr5t4 ,! curr5t to be inve/igat$ is s5t ?r\gh ?is loop1 :i* 9 consequ5ce ( ! int]action ( curr5t & magnetic field1 beg9s to vibrate4 ,! oscillations are r5d]$ visible by direct+ a beam ( light f a cont9u\s curr5t arc lamp onto a small mirror fix$ to ! loop4 ,! light reflect$ by ! mirror is 9 ! =m ( a light /rip1 b by suitable means ?is is drawn out 9 respect ( "t1 s t a curve truly repres5t+ ! curr5t is obta9$4 ,! loop ( f9e wire is /ret*$ betwe5 two supports & is kept 9 t5sion by a spr+4 ,z ! spr+ t5sion is consid]able1 ! directive =ce ( ! vibrat+ sy/em is l>ge1 & its natural p]iodicity v high4 ,! mirror is fix$ 9 ! c5t] ( ! loop1 & has an area ( #a squ>e mm4 ,9 ord] to protect ! loops f me*anical injury !y are built into special frames4 ,! mirrors are ( v>i\s sizes1 ! loop = demon/ration purposes 7projection device7 be+ provid$ ) ! l>ge/ mirror & ! mo/ s5sitive loop ) a mirror ( ! smalle/ dim5sions4 ,atta*$ to ! vane is a small mirror :i* reflects a beam ( light ^u "s type ( receiv+ device4 ,! ,siem5s-,blondel oscillograph %[n 9 fig4 #b1fjd1 is ( ! mov+ coil type1 be+ a developm5t ( ! mov+ iron pr9ciple4 ,mov+ ,coil ,oscillograph4--,! op]ation ( ?is =m ( oscillograph is bas$ on ! behavi\r ( a movable coil 9 a magnetic field4 ,illu/ration3 ,,figs4 #b1fje & #b1fjf4--,oscillograms reproduc$ f a pap] by ,m4 ,b4 ,field on ,a ,/udy ( ! ,ph5om5a ( ,resonance by ! ,aid ( ,oscillograms 7,j\rnal ( ,e4 ,e41 ,vol4 ,,xxxii74 ,! effect ( resonance on ! wave =ms ( alt]nators has be5 ! subject ( mu* inve/igation & discussion2 x is a matt] ( vital importance to ! eng9e] 9 *>ge ( a l>ge alt]nat+ curr5t p[] di/ribution sy/em4 ,fig4 #b1fje %[s ! pressure curve ( an alt]nator runn+ on a l5g? ( unload$ cable1 ! #aa? h>monic be+ v prom95t4 ,fig4 #b1fjf %[s ! /rik+ alt]ation produc$ by r$uc+ ! l5g? ( cable 9 ! circuit & ?us caus+ resonance ) ! #ac? h>monic4 ,x consi/s ess5tially ( a modifi$ mov+ coil galvanomet] comb9$ ) a rotat+ or vibrat+ mirror1 a mov+ photographic film1 or a fall+ photographic plate4 ,! galvanomet] portion ( ! outfit is usually ref]r$ to z ! oscillograph z illu/rat$ 9 figs4 #b1fjh to #b1fab1 repres5t+ diagrammatically ! mov+ sy/em4 ,9 ! n>r[ gap betwe5 ! poles ,s1 ,s ( a p[]ful magnet are /ret*$ two p>allel conductors =m$ by b5d+ a ?9 /rip ( phosphor bronze back on itself ov] an ivory pulley ,p4 ,a spiral spr+ atta*$ to ?is pulley s]ves to keep a uni=m t5sion on ! /rips1 & a guide piece ,l limits ! l5g? ( ! vibrat+ portion to ! "p actually 9 ! magnetic field4 ,a small mirror ,m bridges across ! two /rips z %[n4 ,! effect ( pass+ a curr5t ?r\gh su* a vibrator is to cause "o ( ! /rips to advance :ile ! o!r rec$es1 & ! mirror is ?us turn$ ab\t a v]tical axis4 ,illu/ration3 ,,fig4 #b1fjg4--;,g5]al view ( electro-magnet =m ( ,duddell mov+ coil oscillograph1 %[+ oil ba? & electro-magnet4 ,?is in/rum5t is specially design$ to h a v high natural p]iod ( vibration 7ab\t #a_/aj1jjj ( a second7 s z to be suitable = accurate rese>* "w4 ,x is q accurate = frequ5cies up to #cjj p] second4 ,9 ! figure1 ,a is ! brass oil ba? 9 :i* two vibrators are fix$2 ,b1 core ( electro-magnet :i* is excit$ by two coils1 "o ( :i*1 ,c1 is se54 ,! ends ( ^! two coils are br\ght out to f\r t]m9als at ,d1 s t ! coils may be connect$ 9 s]ies = #bjj volt1 or 9 p>allel = #ajj volt circuits4 ,! bolts1 ,e1,e1 hold ! oil ba? 9 position betwe5 ! poles ( ! magnet4 ,f1,f1,f 7"o n se571 are levell+ screws2 ,g1,g1 t]m9als ( "o vibrator2 ,h1 fuse2 ,k1 !rmomet] ) bulb 9 c5t] ( oil ba?4 ,illu/ration3 ,,figs4 #b1fjh to #b1fab4--,vibrator ( ,duddell mov+ coil oscillograph & section ?r\gh oil ba? ( electro-magnet oscillograph4 ,! vibrator consi/s ( a brass frame ,w1 :i* supports two s(t iron pole pieces ,p1,p4 ,betwe5 ^!1 a long n>r[ groove is divid$ into two p>ts by a ?9 s(t iron p>tition1 :i* runs up ! c5t]4 ,! curr5t be+ l$ 9 by ! brass wire ,u1 passes f an insulat$ brass plate to ! /rip1 :i* is l$ ov] an ivory guide block1 d[n "o ( ! n>r[ grooves & ov] ano!r guide block1 ! loops r\nd ! ivory pulley ,o1 :i* puts t5sion on ! /rip by ! spr+ ,n1 back to ! guide block aga91 up ! o!r n>r[ groove1 & out by way ( ! insulat$ brass plate & lead ,u4 ,halfway up ! grooves ! c5t] iron p>tition ,r is p>tially cut away to p]mit ( a small mirror ,m1 bridg+ across f "o /rip to ! o!r1 be+ /uck to ! /rips by a dot ( %ellac at ea* corn]4 ,! figure illu/rates "o type ( vibrator 9 :i* ,p is removable f ,w = ease 9 repair+4 ,9 type #a1 ^! pole pieces ,p1,p are n removable4 ,! vibrators are plac$ side by side 9 ! gap betwe5 ! poles ,s1,s ( ! electro-magnet1 see fig4 #b1faj4 ,ea* vibrator is pivot$ ab\t v]tical c5t]s1 ! bottom c5t] fitt+ 9 ! base ( ! oil ba?1 & ! "o at ! top be+ =m$ by a screw 9 ! cock piece ,y4 ,x c ?us be easily turn$ 9 azimu?1 its position be+ fix$ by ! adju/+ screw ,l1 a spiral spr+ s]v+ to keep ! vibrator always 9 contact ) ?is screw4 ,s9ce ea* cock piece c be indep5d5tly mov$ =w>d or backw>d1 ea* vibrator c be tipp$ slightly 9 ei!r ( ^! directions s t complete control ov] ! mirrors is obta9$ & reflect$ spots ( light may be made to co9cide ) t reflect$ f ! fix$ z]o mirror1 :i* latt] is fix$ to a brass tongue 9 betwe5 ! two vibrators4 ,a plano-convex l5s ( #ej cm4 focal l5g? is fix$ on ! oil ba? 9 front ( ! vibrator mirrors to conv]ge ! reflect$ beams ( light4 ,x w be notic$ t ?is l5s is slightly incl9$ s t no tr\ble w be giv5 by reflections f its own surface4 ,! normal di/ance f ! vibrator mirrors to ! scale ( photographic plate is #ej cm41 & at ?is di/ance1 a conv5i5t work+ deflection on ea* side ( ! z]o l9e is #c to #d cm4 ,?is is obta9$ ) a ,r4,m4,s4 curr5t ?r\gh ! /rips ( f 4#je to 4#a ( an amp]e accord+ to wave =m1 etc4 ,! maximum deflection on ea* side ( ! z]o l9e %\ld n exce$ #e cm4 :ile ! maximum ,r4,m4,s4 curr5t ?r\gh ! /rips %\ld 9 no case exce$ 4#a amp]e4 ,ea* /rip ( ! loop passes ?r\gh a sep>ate gap 7n %[n 9 ! figure74 ,! :ole ( ! vibrator1 z ?is "p ( ! in/rum5t is call$1 is imm]s$ 9 an oil ba?1 ! object ( ! oil be+ to damp ! movem5t ( ! /rips1 & make ! in/rum5t dead beat4 ,x also has ! additional advantage ( increas+ by refraction ! movem5t ( ! spot ( light reflect$ f ! vibrat+ mirrors4 ,! beam ( light reflect$ f ! mirror ,m is receiv$ on a scre5 or photographic plate1 ! in/antane\s value ( ! curr5t be+ proportional to ! l9e> displacem5t ( ! spot ( light s =m$4 ,) alt]nat+ curr5ts1 ! spot ( light oscillates to & fro z ! curr5t v>ies & w\ld ?us trace a /raight l9e4 ,to obta9 an image ( ! wave =m1 x is necess>y to trav]se ! photographic plate or film 9 a direction at "r angles to ! direction ( ! movem5t ( ! spot ( light4 ,illu/ration3 ,,fig4 #b1fac4--;,duddell mov+ coil oscillograph ) projection & trac+ desk outfit4 ,! outfit is design$ = tea*+ & lecture purposes4 ,9 op]ation1 aft] ! beam ( light f ! arc lamp has be5 reflect$ f ! oscillograph mirrors1 x falls on a vibrat+ mirror :i* gives x a deflection proportional to "t 9 a direction at "r angles to ! deflection x already has & :i* is proportional to ! curr5t pass+ ?r\gh ! oscillograph4 ,x is !re=e only necess>y to place a scre5 9 ! pa? ( ! reflect$ beam ( light to obta9 a trace ( ! wave =m4 ,s9ce ! vibrat+ mirror is vibrat$ by means ( a cam on ! %aft ( a syn*ron\s motor1 :i* motor is driv5 f1 or syn*ron\sly )1 ! s\rce ( supply ^: wave =m is be+ inve/igat$1 ! wave =m is repeat$ "t aft] "t 9 ! same place on ! scre51 & ow+ to ! p]si/5ce ( vision1 ! :ole wave appe>s /ation>y on ! scre54 ,! syn*ron\s motor ) its vibrat+ mirror1 m5tion$ above1 is locat$ und]nea? ! trac+ desk4 ,:5 us$ 9 ?is position a wave a few c5timet]s 9 amplitude is se5 ?r\gh a %eet ( trac+ pap] :i* is b5t r\nd a curv$ %eet ( glass4 ,a p]man5t record ( ! wave =m c ?us easily be trac$ on ! pap]4 ,a d>k box :i* is design$ to hold a %eet ( s5sitiz$ pap] 9 place ( ! trac+ pap]1 c be fitt$ 9 place ( ! trac+ desk4 ,?us an actual photographic record ( ! wave =m is obta9$4 ,if ! syn*ron\s motor be transf]r$ f its position und]nea? ! trac+ desk to ! space res]v$ = x close to ! oscillograph1 ! beam ( light is !n receiv$ on a l>ge mirror :i* is plac$ at an angle ( ab\t #de degrees to ! horizontal & s projects ! wave =m onto a l>ge v]tical scre5 :i* %\ld be fix$ ab\t two & a half met]s di/ant4 ,"u ^! conditions a wave =m ( amplitude #ej cm4 ea* side ! z]o l9e may be obta9$ :i* is !re=e visible to a l>ge audi5ce4 ,ques4 ,h[ are ! oscillograms obta9$ 9 ! ,duddell mov+ coil oscillograph8 ,ans4 ,9 all cases ! oscillograms are obta9$ by a spot ( light trac+ out ! curve connect+ curr5t or voltage ) "t4 ,! s\rce ( light is an arc lamp1 ! light f :i* passes fir/ ?r\gh a l5s1 & !n1 except+ :5 project+ on a scre51 ?r\gh a rectangul> slit ab\t #aj mm4 long by #a mm4 wide4 ,! position ( ! lamp f ! l5s is adju/$ till an image ( ! arc is obta9$ cov]+ ! ?ree 7two mov+1 "o fix$7 small oscillograph mirrors4 ,! light is reflect$ back f ^! mirrors &1 be+ cond5s$ by a l5s :i* is imm$iately 9 front ( !m1 x conv]ges till an image ( ! slit is =m$ on ! surface :]e ! record is desir$4 ,all t is necess>y n[ to obta9 a bright spot ( light in/ead ( ?is l9e image is to introduce 9 ! pa? ( ! beam ( light a cyl9drical l5s ( %ort focal l5g?4 ,illu/ration3 ,,figs4 #b1fad & #b1fae4--,sectional view ( p]man5t magnet =m ( ,duddell mov+ coil oscillograph4 ,?is in/rum5t has a l[] natural p]iod ( vibration 7#a_/cjjj second7 ?an ! type %[n 9 fig4 #b1fab1 & !re=e is n capable ( accurately foll[+ wave =ms ( su* high frequ5cy1 b x is suffici5tly quick act+ to foll[ wave =ms ( all ord9>y frequ5cies ) p]fect accuracy4 ,x is easi] to repair1 & m portable ow+ to ! fact t ! magnetic field is produc$ by a p]man5t magnet in/ead ( an electro-magnet4 ,?is also r5d]s ! in/rum5t suitable = use on high t5sion circuits )\t e>? connection1 z1 ow+ to ! fact t no direct curr5t excitation is requir$1 ! in/rum5t is m easily insulat$ ?an o!r types4 ,ques4 ,:at is ! function ( ! mirrors on ! vibrat+ vane8 ,illu/ration3 ,,fig4 #b1faf4--;,diagram ( connections ( ,duddell oscillograph to high pressure circuit4 ,! modification necess>y = high pressure circuit only applies to ! vibrator :i* gives ! pressure wave & consi/s 9 add+ two m resi/ances1 ,r#d & ,r#e4 ,ref]r+ to fig4 #b1fag1 x w be se5 t 9 case fuse f#b bl[s1 or ! vibrator be accid5tally brok51 ! full supply voltage is imm$iately ?r[n on ! in/rum5t itself4 ,?is is n p]missible 9 high voltage "w & !re=e ! resi/ance ,r#e is introduc$ z a p]man5t %unt to ! oscillograph vibrator4 ,! resi/ance ,r#d is an exact duplicate ( ,r#b be+ a #ba ohm plug resi/ance box = adju/+ ! s5sitivity ( ! vibrator to an ev5 figure4 ,9 practice ,r#e is usually a "p ( ,r#a1 & 9 mo/ ( ! high voltage resi/ances1 two taps are br\ght out ne> "o end to s]ve z ,r#e4 ,"o ( ^! taps is usually #ej ohms di/ant f ! end t]m9al & ! o!r only #e ohms f ! end4 ,! use ( ^! taps is z foll[s3 ,! l>ge resi/ance consi/+ ( ,r#a ,r#e is s *os5 ) respect to ! voltage ( ! circuit "u inve/igation t ! curr5t ?r\gh ,r#a is ab\t 4#a amp]e4 ,x %\ld nev] be m ?an ?is cont9u\sly4 ,!n ,r#d is connect$ to ! #ej ohm tap1 & s9ce ! resi/ance ( ! oscillograph vibrator circuit is v>iable f ab\t #e to #bf ohms by means ( ,r#d1 ! curr5t c be controll$ ?r\gh ! oscillograph f ab\t 4#jff to 4#jia ( an amp]e1 enabl+ an op5 wave =m to a conv5i5t scale to be obta9$4 ,if x n[ be desir$ to record l>ge rises ( pressure1 su* z may occur 9 cases ( resonance1 ! height ( ! wave mu/ be r$uc$ 9 ord] to keep ^! rises on ! plate4 ,?is is accompli%$ by disconnect+ ,r#d f ! #ej ohm tap & connect+ x to ! #e ohm tap1 :5 ! curr5t ?r\gh ! vibrator w be f 4#je to 4#jaf ( an amp]e accord+ to :e!r ! resi/ance ,r#d is 9 or out ( circuit4 ,:51 in/ead ( us+ ! fall+ plate1 ! c9ematograph cam]a is be+ us$1 x becomes necess>y always to "w on ! #e ohm tap s9ce ! wid? ( ! film is mu* less ?an t ( ! plate1 & ! curr5t mu/ !re=e be less4 ,9 exp]im5ts :]e sudd5 rises ( voltage are expect$ x is (t5 advisable to keep ,r#a z great z possible4 ,t end ( ! resi/ance ,r#a ref]r$ to z ,r#e 9 ! diagram %\ld be securely connect$ to ! supply ma9 & no swit* or fuse us$4 ,a swit* may1 if desir$1 be us$ 9 s]ies ) ,r#a1 provid$ x be ins]t$ at ! po9t :]e ,r#a jo9s ! supply ma9 remote f ,r#e4 ,x w be se5 t fuses f#a & f#b are %[n4 ,provid$ t ! connections are always made 9 accordance ) ! diagram1 & ! vibrators are always %unt$ by ,r#e or ,r#c respectively1 !re is n mu* objection to ! use ( ^! fuses1 b on g5]al pr9ciples x is wise to avoid fuses 9 high t5sion "w & accord+ly ) ea* p]man5t magnet oscillograph1 dummy fuses are suppli$1 :i* c be ins]t$ 9 place ( ! ord9>y fuses :5 desir$4 ,! rem>k previ\sly made ab\t keep+ bo? vibrators & ! frame ( ! in/rum5t at approximately ! same pressure applies ) additional emphasis 9 high pressure "w4 ,ans4 ,!y simply control ! direction ( a beam ( light 9 a horizontal plane 9 su* a mann] t its deflection f a z]o position dep5ds on ! curr5t pass+ ?r\gh ! in/rum5t1 & x is !re=e evid5t t ! oscillograph is n complete )\t means ( produc+ a "t scale4 ,illu/ration3 ,,fig4 #b1fag4--;,diagram ( connections ( ,duddell oscillograph to l[ pressure circuit1 ,r#a is a high non-inductive resi/ance connect$ across ! ma9s 9 s]ies ) "o ( ! vibrators4 ,s#b is a swit*1 & f#b1 ! fuse 7on ! oscillograph 9 ?is circuit74 ,! resi/ance ( ,r#a 9 ohms %\ld be r m ?an t5 times ! voltage ( ! circuit1 s t a curr5t ( a little less ?an 4#a ( an amp]e w pass ?r\gh x4 ,! vibrator w !n give ! curve ( ! circuit on an op5 scale4 7,= ! projection oscillograph1 ! resi/ance ,r#a %\ld be only twice ! supply voltage1 s9ce 4#e ( an amp]e is requir$ to give full scale deflection on a l>ge scre547 ,to obta9 ! curr5t wave =m1 ! %unt ,r#c is connect$ 9 s]ies ) ! circuit "u inve/igation & ! second vibrator is connect$ across ?is %unt4 ,"h also f#a is a fuse1 ,s#a a swit*1 & ,r#b an adju/able resi/ance box4 ,! swit* ,s#a is h[ev] unnecess>y if ! plug resi/ance box suppli$ = ,r#b be us$1 s9ce an inf9ity plug is includ$ 9 ?is box4 ,! %unt ,r#c %\ld h a drop ( ab\t #a volt across x 9 ord] to give a suitable work+ curr5t ?r\gh ! vibrator4 ,! resi/ance ,r#b is n absolutely ess5tial1 b x is a great conv5i5ce 9 adju/+ ! curr5t ?r\gh ! vibrator4 ,x is a plug resi/ance box1 ! smalle/ coil be+ 4#jd ( an ohm & ! total #ba ohms4 ,be+ design$ to c>ry 4#e amp]e cont9u\sly x c be us$ ) any o!r type ( ,duddell oscillograph1 & by its use ! s5sitiv5ess ( ! vibrator c be adju/$ s t a r\nd numb] ( amp]es 9 ! %unt gives #a mm4 deflection4 ,?is adju/m5t is be/ made ) direct curr5t4 ,x %\ld be not$ 9 connect+ ! oscillograph 9 circuit1 t ! two vibrators %\ld be s connect$ to ! circuit t x is impossible t a high] pressure diff]5ce ?an #ej volts %\ld exi/ betwe5 "o vibrator & ! o!r1 or betwe5 ei!r vibrator & ! frame4 ,to ensure att5tion to ?is important po9t1 a brass /rap is provid$ :i* connects ! two vibrators toge!r & to ! frame ( ! in/rum5t4 ,?is does n mean t ?is po9t mu/ necess>ily be e>!d s9ce ! frame ( ! in/rum5t is insulat$ f ! e>?4 ,x is advisable1 h[ev]1 to e>? x :5 possible4 ,illu/ration3 ,,figs4 #b1fah & #b1fai4--,two curves obta9$ ) ! fall+ plate cam]a & illu/rat+ ! dis*>ge ( a cond5s] ?r\gh an inductive circuit4 ,:5 tak+ curve ,a ! resi/ance 9 ! circuit 0 v small comp>$ to ! inductance1 :ile be=e tak+ curve ,b an additional non-inductive resi/ance 0 ins]t$ 9 ! circuit s t ! oscillations 7 damp$ out mu* m rapidly al?\gh ! p]iodic "t rema9$ approximately con/ant4 ,ques4 ,h[ is ! "t scale produc$8 ,ans4 ,ei!r ! surface on :i* ! beam ( light falls may be caus$ to move 9 a v]tical plane ) a c]ta9 velocity1 s t ! int]section ( ! beam & ! plane surface traces out a curve connect+ curr5t ) "t 7a curve :i* becomes a p]man5t record if a s5sitiz$ surface be us$72 or1 ! surface may rema9 /ation>y & 9 ! pa? ( ! horizontally vibrat+ beam may be introduc$ a mirror :i* rotates or vibrates ab\t a horizontal axis1 ?us sup]pos+ a v]tical motion proportional to "t on ! horizontal vibration :i* is proportional to curr5t1 & caus+ ! beam ( light to trace out a curve connect+ curr5t & "t on ! /ation>y surface4 ,ques4 ,:at k9d ( record+ app>atus is us$ ) ! ,duddell oscillograph8 ,ans4 ,a fall+ plate cam]a1 or a c9ematograph film cam]a4 ,illu/ration3 ,,fig4 #b1fbj4--,syn*ron\s motor ) vibrat+ mirror z us$ ) ,duddell mov+ coil oscillograph4 ,s9ce ! motor mu/ run syn*ron\sly ) ! wave =m x is requir$ to inve/igate1 x %\ld be suppli$ ) curr5t f ! same s\rce4 ,! motor c be us$ ov] a wide range ( frequ5cies 7f #bj to #abj74 ,:5 work+ at frequ5cies bel[ #dj1 x is advisable to increase ! mom5t ( in]tia ( ! armature1 & = ?is purpose a suitable brass disc is us$4 ,! armature c>ries a sector1 :i* cuts (f ! light f ! arc lamp dur+ a fraction ( ea* revolution1 & a cam :i* rocks ! vibrat+ mirror4 ,x makes "o revolution dur+ two complete p]iods1 & ! cam & sector are s arrang$ t dur+ #a p]iods1 ! mirror is turn+ ) uni=m angul> velocity1 :ile dur+ ! rema9+ half p]iod1 ! mirror is br\ght back quickly to its angul> position1 ! light be+ cut (f by ! sector dur+ ?is half p]iod4 ,ques4 ,expla9 ! op]ation ( ! fall+ plate cam]a4 ,ans4 ,9 ?is arrangem5t a photographic plate is all[$ to fall freely by ! =ce ( gravity d[n a d>k slide4 ,at a c]ta9 po9t 9 its fall x passes a horizontal slit ?r\gh :i* ! beams ( light f ! oscillograph pass1 trac+ out ! curves on ! plate z x falls4 ,illu/ration3 ,,figs4 #b1fba to #b1fbc4--;,int]ior ( c9ematograph cam]a z us$ on ,duddell mov+ coil oscillograph = obta9+ long records4 ,! loose side ( case is %[n remov$ & "o ( ! reels :i* c>ry ! film ly+ 9 front4 ,! spool ( film :i* is plac$ on ! loose reel ,a1 passes ov] ! guide pulley ,b1 !n v]tically d[nw>d betwe5 ! brass gate ,d 7%[n op5 9 ! figure71 & ! brass plate ,c4 ,! exposure ap]ture is 9 ! plate ,c & c be op5$ or clos$ by a %utt] controll$ by ! lev] ,m4 ,! groove 9 ! plate ,c1 & ! spr+s :i* press ! gate ,d flat on ! plate ,c1 prev5t ! film hav+ any b a v]tical motion z x passes ! exposure slit4 ,e is ! sprocket driv+ pulley :i* engages ) ! p]=ations on ! film & unw9ds x f ! reel ,a to reel ,h4 ,outside ! case on ! f> side ( x is secur$ to ! axle ,g a ?ree spe$ cone pulley4 ,?is is driv5 by a motor ( ab\t #a_/g horse p[]1 :i* also drives1 ?r\gh ! ge>s %[n1 ! sprocket pulley ,e4 ,close to ! groov$ cone pulley is a lev] c>ry+ a jockey pulley ,l1 & a brake1 :i* latt] is normally held onto ! cone pulley by a spr+ & s causes ! loose belt to slip4 ,by press+ a lev] :i* is atta*$ to ! fall+ plate cam]a case1 ! brake c be sudd5ly releas$ & at ! same "t ! jockey pulley caus$ to tight5 ! belt onto ! groov$ cone pulley1 s t ! />t+ & /opp+ ( ! film is controll$ indep5d5tly ( ! driv+ motor1 & be+ quickly accompli%$ avoids wa/e ( film4 ,bo? reels are alike & ea* is made 9 two pieces4 ,! upp] reel is loose on its axle & its motion is ret>d$ slightly by a friction brake4 ,! l[] reel is also loose on its axle1 b x is driv5 by means ( a friction clut*1 ! clut* always rotat+ fa/] ?an ! reel s t ! us$ film deliv]$ by ! sprocket pulley ,e is w\nd up z fa/ z deliv]$4 ,k is ! front face ( "o reel1 ! boss on x pu%es into ! tube on ! o!r half ,h1 :i* s]ves n only to unite ! two halves1 b also to secure ! end ( ! film :i* is d\bl$ ?r\gh ,j4 ,! mean spe$ ( ! plate at ! mom5t ( exposure is ab\t #ac feet p] second4 ,?is spe$ is v suitable = use ) frequ5cies ( f #dj to #fj p]iods p] second4 ,a clo? bag is us$ to introduce ! plate to ! slide4 ,a cat* holds ! plate until x is desir$ to let x fall4 ,inside ! case1 is a small motor1 #ajj or #bjj volts direct curr5t1 driv+ f\r mirrors :i* are fix$ ab\t a common axis ) _! planes p>allel to x4 ,illu/ration3 ,,fig4 #b1fbd4--,portion ( oscillograph record tak5 ) c9ematograph film cam]a1 %[+ ! ru% ( curr5t & sudd5 rise ( voltage at ! mom5t ( swit*+ on a high pressure fe$]4 ,by look+ ?r\gh a small slot 9 ! end ( ! cam]a into ^! rotat+ mirrors1 ! obs]v] sees ! wave =m :i* ! oscillograph is trac+ out & is ?us able to make sure t he is obta9+ ! p>ticul> wave =m or o!r curve desir$ be=e expos+ ! plate4 ,illu/ration3 ,,fig4 #b1fbe4--,portion ( oscillograph record tak5 ) a c9ematograph film cam]a %[+ ! effect ( swit*+ (f a high pressure fe$] & illu/rat+ ! viol5t fluctuations produc$ by sp>k+ at ! swit* contacts4 ,! plate falls into a second r$ clo? bag :i* is plac$ on ! bottom ( ! slide4 ,! plates us$ are /]eoscopic size1 #f #c 7#ag4a #h4c cm474 ,ques4 ,= :at use is ! c9ematograph cam]a adapt$8 ,ans4 ,= long records4 ,= in/ance1 9 inve/igations1 su* z obs]vation on ! p>allel+ ( alt]nators1 ! runn+ up to spe$ ( motors1 & ! surges :i* may occur 9 swit*+ on & (f cable1 etc4 ,! c9ematograph cam]a fits on to ! fall+ plate case & by means ( :i* a roll ( c9ematograph film c be driv5 at a uni=m spe$ pa/ ! exposure ap]ture1 enabl+ records up to #ej metres 9 l5g? to be obta9$4 ,an int]ior view ( ! c9ematograph cam]a is %[n 9 fig4 #b1fba4 ,illu/ration3 ,,fig4 #b1fbf4--;,curves reproduc$ f an article by ,j4 ,t4 ,morris 9 ! ,electrician4 ,on record+ transitory ph5om5a by ! oscillograph4 ,illu/ration3 ,,fig4 #b1fbg4--;,fir/ ru% ( curr5t f an alt]nator :5 %ort circuit$1 %[+ unsymmetrical initial wave ( curr5t1 becom+ symmetrical aft] a few cycles4 #be cycles4 ,illu/ration3 ,,fig4 #b1fbh4--,pressure wave obta9$ f n>r[ explor+ coil on alt]nator armature1 indicat+ di/ribution ( field flux4 ,! t]m9al voltage ( ! alt]nator is v ne>ly a s9e wave1 #fj cycles2 ab\t #ag volts4 ,,"s ,,oscillograph ,,records ,illu/ration3 ,,fig4 #b1fbi4--,! waves ( voltage & curr5t ( an alt]nat+ arc4 ,a1 voltage wave2 ,b1 curr5t wave %[+ l[ p[] factor ( ! arc )\t app>5t phase displacem5t4 #fj cycles4 ,illu/ration3 ,,fig4 #b1fcj4--,ruptur+ #fej volt circuit4 ,a1 curr5t wave2 ,b1 #be cycle wave to m>k "t scale4 ,illu/ration3 ,,fig4 #b1fca4--;,fir/ ru% ( curr5t f alt]nator :5 %ort circuit$1 %[+ unsymmetrical curr5t wave1 also wave ( field curr5t caus$ by %ort circuit curr5t 9 armature4 ,upp] curve1 armature curr5t2 l[] curve1 field curr5t4 ,illu/ration3 ,,fig4 #b1fcb4--,mazda 7tung/57 lamp1 %[+ rapid decrease to normal curr5t z filam5t heats up4 #be cycles4 ,illu/ration3 ,,fig4 #b1fcc4--;,curr5t wave 9 telephone l9e correspond+ to su/a9$ v[el s\nd i1 z 9 ma*9e2 voice pit*$ at ,a #aaj4 ,illu/ration3 ,,fig4 #b1fcd4--;,c>bon lamp1 %[+ rapid increase to normal curr5t z filam5t heats up4 #be cycles4 ,illu/ration3 ,,fig4 #b1fce4--,%ort circuit curr5t on direct curr5t end ( rot>y conv]t]1 #ba1ejj amp]es maximum4 ,upp] curve1 direct curr5t voltage2 l[] curve1 direct curr5t amp]age4 ,duration ( %ort circuit ab\t 4#a second4 ,,*apt] ,,lxiv ,,swit*bo>ds ,g5]al ,pr9ciples ( ,swit*bo>d ,connections4--,! int]connection ( g5]ators1 trans=m]s1 l9es1 bus b>s1 & swit*es ) _! relays1 9 mod]n swit*bo>d practice is %[n by ! diagrams1 figs4 #b1fcf to #b1fde4 ,! figures be+ lett]$ ,a to ,j = simplicity1 ! g5]ators are indicat$ by black discs1 & ! swit*es by op5 circles1 :ile ea* heavy l9e repres5ts a set ( bus b>s consi/+ ( two or m bus b>s accord+ to ! sy/em ( di/ribution4 ,x w be und]/ood1 also1 9 ?is connection1 t ! numb] ( pole ( ! swit*es & ! type ( swit* w dep5d ^u ! p>ticul> sy/em ( di/ribution employ$4 ,diagram ,a1 %[s ! simple/ sy/em1 or "o 9 :i* a s+le g5]ator fe$s directly into ! l9e4 ,!re are no trans=m]s or bus b>s & only "o swit* is suffici5t4 ,9 ,b1 a s+le g5]ator supplies two or m fe$]s ?r\gh a s+le set ( bus b>s1 requir+ a swit* = ea* fe$]1 & a s+le g5]ator swit*4 ,9 ,c1 two g5]ators are employ$ & requir$ & ! addition ( a bus section swit*4 ,d1 repres5ts a numb] ( g5]ators supply+ two indep5d5t circuits4 ,! additional set ( bus b>s employ$ = ?is purpose necessitates an additional bus section swit*1 & also additional selector swit*es = bo? fe$]s & g5]ators4 ,e1 %[s a /&>d sy/em ( connection = a city /reet railway sy/em hav+ a l>ge numb] ( fe$]s4 ,illu/ration3 ,,figs4 #b1fde & #b1fdf4--;,diagrams illu/rat+ g5]al pr9ciples ( swit*bo>d connections4 ,?is arrangem5t all[s any gr\p ( fe$]s to be suppli$ f any gr\p ( g5]ators4 ,illu/ration3 ,,fig4 #b1fdf4--;,=t ,wayne swit*bo>d panel = "o alt]nator & "o transf] circuit4 ,diagram giv+ dim5sions1 arrangem5t ( in/rum5ts ( bo>d1 & me?od ( wir+4 ,! diff]5t =ms ( /&>d alt]nat+ curr5t swit*bo>d panels = s+le phase circuits made by ! ,=t ,wayne ,electric ,works are design$ to fulfill all ! usual requirem5ts ( swit*bo>ds = ?is class ( "w4 ,! l9e includes panels equipp$ = a s+le g5]ator2 = "o g5]ator & two circuits2 "o g5]ator & "o transf] circuit2 "o g5]ator1 an inc&esc5t & an arc light+ circuit2 & also fe$] panels ( diff]5t k9ds4 ,x also p]mits ! addition ( a g5]ator swit* = ea* g5]ator4 ,f1 repres5ts ! simple/ sy/em ) trans=m]s4 ,x requires a s+le g5]ator trans=m] bank1 swit* & l9e4 ,! arrangem5t z %[ at ,f is us$ :]e a numb] ( plants supply ! same sy/em4 ,g1 repres5ts a sy/em hav+ m ?an "o l9e4 ,9 ?is case a bus b> & trans=m] swit* is us$ on ! high t5sion side4 ,h1 %[s a numb] ( g5]ators connect$ to a set ( l[ t5sion bus b>s ?r\gh g5]ator swit*es1 & employ+ a l[ t5sion trans=m] swit*4 ,i1 %[s ! connections ( a sy/em hav+ a l>ge numb] ( fe$]s suppli$ by sev]al small g5]ators4 ,9 ?is case1 ! plant is divid$ into two p>ts1 ea* ( :i* may be op]at$ indep5d5tly4 ,illu/ration3 ,,fig4 #b1fdg4--;,g5]al ,electric small plant alt]nat+ curr5t swit*bo>d1 design$ = use 9 small c5tral /ations & isolat$ plants4 ,!y are = use ) "o set ( bus b>s1 to :i* all g5]ators & fe$]s are connect$ by means ( s+le ?r[ lev] swit*es or circuit break]s1 suitable provision be+ made = ! p>allel op]ation ( ! g5]ators4 ,j1 repres5ts ! arrangem5t usually employ$ 9 mod]n plants :]e ! g5]ator capacity is l>ge en\gh to p]mit ( a g5]ator trans=m] unit comb9ation ) two outgo+ l9es4 ,by op]at+ 9 p>allel on ! high t5sion side only1 any g5]ator c be run ) any trans=m]4 ,! :ole plant c be run 9 p>allel1 or ! two p>ts c be run sep>ately4 ,illu/ration3 ,,fig4 #b1fdh4--;,cr\se-,h9ds voltmet] & gr\nd detector radial swit*1 arrang$ = m\nt+ on ! swit*bo>d4 ,! swit* prop] is plac$ on ! re> ( ! bo>d ) h& :eel1 dial1 & indicator only on ! front side4 ,! curr5t c>ry+ p>ts are ( h>d brass1 ) contact surfaces ma*9$ aft] assembl+4 ,! contact p>ts are ( ! plung] spr+ type1 & ! cross b> has fuse connections4 ,gr\nd detector circuits are m>k$ ,g & ,g- = two wire sy/em1 & ,g1 ,g-1 ,,gn & ,,gn- = ?ree wire sy/em4 ,:5 ! voltmet] swit* is to be us$ z a gr\nd detector1 two circuits are requir$ = a two wire sy/em1 & f\r circuits = a ?ree wire sy/em1 t is1 a six circuit voltmet] & gr\nd detector swit* = use on a two wire sy/em has two circuits = gr\nd detector & f\r circuits = voltmet] read+s4 ,a six circuit voltmet] & gr\nd detector swit*1 = use on a ?ree wire sy/em1 has f\r circuits = gr\nd detector & two circuits = voltmet] read+s4 ,swit*bo>d ,panels4--,! t]m panel means ! slab ( m>ble or slate ^u :i* is m\nt$ ! swit*es1 & ! indicat+ & controll+ devices4 ,!re are usually sev]al panels compris+ swit*bo>ds ( mod]ate or l>ge size1 ^! panels be+ classifi$ accord+ to ! division ( ! sy/em t !y control1 z = in/ance3 #a4 ,g5]ator panel2 #b4 ,fe$] panel2 #c4 ,regulator panel1 etc4 ,9 con/ruction1 ! m>ble or slate %\ld be free f metallic ve9s1 & = pressures above1 say1 #fjj volts1 live connections1 t]m9als1 etc41 %\ld pref]ably be insulat$ f ! panels by ebonite1 mica1 or remov$ f !m altoge!r1 z is g5]ally ! case ) ! alt]nat+ ge> :]e ! swit*es are ( ! oil type4 ,illu/ration3 ,,figs4 #b1fdi & #b1fej1--,wir+ diagrams ( ,cr\se-,h9ds voltmet] & gr\nd detector swit*es4 ,fig4 #b1fdi voltmet] swit*2 fig4 #b1fej voltmet] & gr\nd detector swit*4 ,a view ( ! swit* is %[n 9 fig4 #b1fdh2 x is design$ = use on two or ?ree wire sy/ems up to #cjj volts4 ,! bus b>s & connections %\ld be support$ by ! framework at ! back ( ! bo>d1 or 9 sep>ate cells1 & ! in/rum5ts %\ld be op]at$ at l[ pressure ?r\gh in/rum5t trans=m]s4 ,! panels are g5]ally held 9 position by bolt+ !m to an angle iron1 or a /rip iron framework beh9d !m4 ,g5]ator ,panel4--,?is section ( a swit*bo>d c>ries ! in/rum5ts & app>atus = measur+ & electrically controll+ ! g5]ators4 ,on a well design$ swit*bo>d ea* g5]ator has1 z a rule1 its own panel4 ,illu/ration3 ,,figs4 #b1fea to #b1fec4--;,diagrams ( connections = g5]ator panels4 ,key to symbols3 ,a1 ammet]2 ,a4,s41 ammet] swit*2 ,c4,t41 curr5t trans=m]2 ,f41 fuse2 ,f4,a41 direct curr5t field ammet]2 ,f4,s41 field swit*2 ,g4,c4,s41 gov]nor control swit*2 ,l4,s41 limit swit* 7includ$ ) gov]nor motor72 ,o4,s41 oil swit*2 ,p4,i4,w41 polyphase indicat+ wattmet]2 ,p4,w4,m41 polyphase wat?\r met]2 ,p4,r41 pressure receptacle2 ,p4,p41 pressure plug2 ,rheo41 rheo/at2 ,s41 %unt2 ,s4,r41 syn*roniz+ receptacle2 ,s4,p41 syn*roniz+ plugs2 ,t4,b41 t]m9al bo>d = in/rum5t leads2 ,v1 alt]nat+ curr5t voltmet]4 ,illu/ration3 ,,figs4 #b1fed & #b1fee4--;,diagrams illu/rat+ a simple me?od ( det]m9+ bus capacity z sugge/$ by ! ,g5]al ,electric ,co4 ,fig4 #b1fed relates to any panel2 ! me?od is z foll[s3 #a4 ,make a r\gh plan ( ! entire bo>d1 reg>dless ( ! numb] ( panels to be ord]$4 ,! ord] ( panels %[n is recomm5d$1 x be+ mo/ economical ( copp] & be/ adapt$ to future ext5sions4 #b4 ,to avoid confusion keep on "o side ( bo>d ev]y?+ p]ta9+ to excit] buses1 & on o!r side ev]y?+ p]ta9+ to ,a4 ,c4 buses4 #c4 ,) s+le l9es repres5t ! excit] & ,a4 ,c4 buses across su* panels z !y actually ext5d & by means ( arr[s indicate t portion ( ea* bus :i* is connect$ to fe$]s & t portion :i* is connect$ to g5]ators4 ,rememb] t ,g5]ator & ,fe$] arr[s mu/ always po9t t[>d ea* o!r1 o!rwise ! rules giv5 bel[ d n hold4 ,note also t ! field circuits ( alt]nator panels are treat$ z ,d4 ,c4 fe$]s = ! excit] bus4 #d4 ,on ea* panel m>k its amp]e rat+1 t is1 ! maximum curr5t x supplies to or takes f ! bus4 ,= ,a4 ,c4 alt]nator panels ! ,d4 ,c4 rat+ is ! excitation ( ! ma*9es4 #e4 ,apply ! foll[+ rules consecutively1 & note _! application 9 fig4 #b1fed4 7,= ! sake ( cle>ness amp]e rat+s are %[n 9 light face type & bus capacities 9 l>ge type47 ,a4 ,always beg9 ) ! tail ( ! arr[ & treat g5]ator & fe$] sections ( ! bus sep>ately4 ,b4 ,bus capacity = fir/ panel amp]e rat+ ( panel4 ,c4 ,bus capacity = ea* succe$+ panel amp]e rat+ ( panel plus bus capacity = prec$+ panel4 7,see sums m>k$ above ! buses 9 fig4 #b1fed47 ,d4 ,= a panel n connect$ to a bus ext5d+ across x1 use ! small] value ( ! bus capacities already obta9$ = ! two adjo9+ panels4 7,see excit] bus = panel ,c47 ,e4 ,! bus capacity = any fe$] panel ne$ n exce$ ! maximum = ! g5]ator panels 7see ,a4 ,c4 bus = panel ,g7 & vice v]sa 7see excit] bus = panel ,b74 ,h5ce ! corrections made 9 values obta9$ by apply+ rules ,b & ,c4 ,! arrangem5t ( panels %[n 9 fig4 #b1fed is ! "o :i* is mo/ly us$4 ,! above me?od may1 h[ev]1 be appli$ to o!r arrangem5ts1 "o ( :i* is %[n 9 fig4 #b1fee4 ,"h ! g5]ators mu/ fe$ bo? ways to ! fe$]s at ei!r end ( ! bo>d s t 9 det]m9+ ,a4 ,c4 bus capacities x is necess>y to fir/ consid] ! g5]ators ) ! fe$]s at "o end1 & !n ) ! fe$]s at ! o!r end z %[n by ! dott$ ,a4 ,c4 buses4 ,! requir$ bus capacities are !n obta9$ by tak+ ! maximum values = ! two cases4 ,illu/ration3 ,,fig4 #b1fef4--;,end view %[+ g5]al arrangem5t ( swit*bo>ds = #bdj1 #dhj1 & #fjj volt alt]nat+ curr5t4 ,! cut %[s a s+le ?r[ oil swit* m\nt$ on ! panel4 ,9 ! case ( a dynamo1 a good repres5tative panel w\ld h m\nt$ ^u x a rev]se curr5t circuit break]1 an ammet]1 a d\ble pole ma9 swit* 7or p]haps a s+le pole swit*1 s9ce ! circuit break] c\ld also be us$ z a swit*7 a d\ble pole socket into :i* a plug c\ld be ins]t$ to make connection ) a voltmet] m\nt$ on a sw++ bracket at ! end ( ! bo>d2 a rheo/at h&le1 ! sp9dle ( :i* op]ates ! %unt rheo/at ( ! ma*9e1 ! rheo/at be+ plac$ ei!r directly beh9d ! sp9dle1 if ( small size1 or l[] d[n ) *a9 drive f ! h& :eel sp9dle1 if ( l>g] size1 a field dis*>ge swit* & resi/ance1 a lamp ne> ! top ( ! panel = illum9at+ purposes1 a fuse = ! voltmet] socket1 &1 if desir$1 a wat?\r met]4 ,if ! dynamo be comp\nd w\nd1 ! equaliz+ swit* w g5]ally be m\nt$ on ! frame ( ! ma*9e1 & 9 "s cases ! field rheo/at w be op]at$ f a pill> m\nt$ 9 front ( ! swit*bo>d gall]y4 ,if ! g5]ator be = traction purposes1 ! circuit break] is m (t5 ( ! maximum curr5t type1 & a lightn+ arre/] is (t5 add$1 )\t a *oke coil1 ! latt] z well z fur!r lightn+ arre/]s be+ m\nt$ on ! fe$] panels4 ,illu/ration3 ,,figs4 #b1feg & #b1feh4--,two views ( a fe$] panel1 %[+ g5]al arrangem5t ( ! devices assembl$ !reon4 ,a1 circuit break]2 ,b1 ammet]2 ,c1 voltmet]2 ,d1 swit*es4 ,9 ! case ( a high pressure alt]nat+ curr5t plant ( consid]able size1 ! bus b>s oil swit*es1 & ! curr5t & pressure trans=m]s are g5]ally m\nt$ ei!r 9 /onew>e cells1 or built on a framework 9 a space gu>d$ by exp&$ metal walls1 & no high pressure app>atus ( any sort is br\ght on to ! panels !mselves4 ,illu/ration3 ,,figs4 #b1fei to #b1fff4--;,diagram ( connections = ?ree phase fe$] panels4 ,key to symbols3 ,a1 ammet]2 ,a4,s41 ?ree way ammet] swit*2 ,b4,a4,s41 bell al>m swit*2 ,c4,t41 curr5t trans=m]2 ,f1 fuse2 ,o4,s41 oil swit*2 ,p4,i4,w41 polyphase indicat+ wattmet]2 ,p4,w4,m41 polyphase wat?\r met]2 ,t4,b41 t]m9al bo>d2 ,t4,c41 trip coils = oil swit*4 ,fe$] ,panel4--,! indicat+ & control app>atus = a fe$] circuit is assembl$ on a panel call$ ! fe$] panel4 ,! mo/ common equipm5t 9 ! case ( a direct curr5t fe$] panel comprises an ammet]1 a d\ble pole swit*1 & d\ble pole fuses or in/ead ( ! fuses1 a circuit break] on "o or bo? poles2 9 ! case ( a traction fe$] a *oke coil & a lightn+ arre/] are (t5 add$4 ,illu/ration3 ,,figs4 #b1ffg & #b1ffh4--;,diagrams ( connections = two phase & ?ree phase in/allations3 ,a & ,a#a1 ammet]2 ,c4,c41 con/ant curr5t trans=m]2 ,c4,t41 curr5t trans=m]2 ,d4,r41 dis*>ge resi/ance2 ,f1 fuse2 ,f4,s41 field swit*2 ,l4,a41 lightn+ arre/]2 ,o4,s41 oil swit*2 ,p4,p41 pressure plug2 ,p4,r41 pressure receptacle2 ,p4,t41 pressure trans=m]2 ,s & ,s#a1 plug swit*es2 ,t4,c41 oil swit* trip coil2 ,v1 voltmet]4 ,! equipm5t ( a typical high pressure ?ree phase fe$] panel is an ammet] 7sometimes ?ree ammet]s1 "o 9 ea* phase7 op]at$ by a curr5t trans=m]1 & oil break swit* ) two ov]load release coils1 or ?ree if ! neutral ( ! circuit be e>!d1 ! releases be+ op]at$ by curr5t trans=m]s4 ,illu/ration3 ,,fig4 #b1ffi4--;,cr\se-,h9ds radial ammet] swit*1 arrang$ = m\nt+ directly on ! swit*bo>d4 ,x is design$ = use ) ext]nal %unt ammet]s ( any make or capacity1 & 9 connection ) ! requir$ numb] ( %unts1 makes possible ! tak+ ( curr5t read+s ( a correspond+ numb] ( circuits by means ( "o ammet]4 ,! wir+ diagram is %[n 9 fig4 #b1fgj4 ,! swit* :5 on a l>ge sy/em is (t5 9 a cell "s di/ance beh9d ! panel1 & is !n controll$ by a sy/em ( lev]s1 or by a small motor :i* is />t$ & /opp$ by a ?r[ ov] swit* on ! panel1 9 :i* case !re is g5]ally a lamp or lamps on ! panel to %[ :e!r ! swit* is op5 or clos$4 ,air brake swit*es or l9ks are plac$ betwe5 ! bus b>s & ! oil swit* to all[ ( ! latt] be+ isolat$ = inspection purposes1 & z a g5]al rule no app>atus c>ry+ high pressure curr5t is all[$ on ! front ( ! panel4 ,) bo? direct & alt]nat+ curr5t fe$]s1 a wat?\r met] is (t5 add$ to %[ ! total consumption ( ! circuit4 ,illu/ration3 ,,fig4 #b1fgj4--,wir+ diagram = ,cr\se-,h9ds radial ammet] swit* z illu/rat$ 9 fig4 #b1ffi4 ,! swit* prop] is on ! re> ( ! swit*bo>d1 & ! h& :eel dial & indicator on ! front4 ,a typical ?ree phase g5]ator panel is provid$ ) ?ree ammet]s1 "o 9 ea* phase1 op]at$ f ?ree curr5t trans=m]s1 "o to ea* ammet]1 a volt met]1 a p[] factor indicator1 & an indicat+ wat?\r met]1 all op]at$ f "o or m pressure trans=m]s1 & ! necess>y curr5t trans=m]s1 ! op]at+ h&le ( ! oil swit*1 :i* is connect$ to ! swit* itself by means ( rods1 two maximum releases op]at$ by curr5t trans=m]s1 or a rev]se relay = automatically tripp+ ! swit*1 lamps = indicat+ :5 ! swit* is tripp$1 a socket = tak+ ! plug :i* makes connection betwe5 ! second>y ( a pressure trans=m] & ! syn*roniz] on ! syn*roniz+ panel1 & a lamp = illum9at+ purposes1 :ile on ! base ( ! panel or on a pill> at ! front ( ! gall]y is m\nt$ ! ge> = ! field circuit4 ,?is consi/s ( a d\ble pole field swit* & a dis*>ge resi/ance1 an ammet]1 a h&le = ! rheo/at 9 ! g5]ator field1 & 7if ea* alt]nator h its own direct c\pl$ excit]7 possibly also a small rheo/at = ! excit] field4 ,,note4--,9 "s cases :]e ! capacity ( ! plant is n v great1 ! oil swit* is m\nt$ on ! back ( ! panel1 & ! bus b>s1 curr5t trans=m]s1 c41 on ! framework1 also j at ! back ( ! panel1 b "u no circum/ances1 9 good mod]n practice1 is high pressure app>atus p]mitt$ on ! front ( ! bo>d4 ,:]e ! capacity ( ! plant is v l>ge1 ! oil swit*es are op]at$ electrically by means ( small motors1 & 9 ?is case ! small swit* ge> = />t+ & /opp+ ?is motor is m\nt$ on ! g5]ator panel1 also ! lamp or lamps to indicate :5 ! swit* is op51 & :5 clos$4 ,,*apt] ,,lxv ,,alt]nat+ ,,curr5t ,,wir+ ,9 ! case ( alt]nat+ curr5t1 because ( its peculi> behavi\r1 !re are sev]al effects :i* mu/ be consid]$ 9 mak+ wir+ calculations1 :i* d n ent] into ! problem ) direct curr5t4 ,accord+ly1 9 det]m9+ ! size ( wires1 all[ance mu/ be made = #a4 ,self-induction2 #b4 ,mutual-induction2 #c4 ,p[] factor2 #d4 ,sk9 effect2 #e4 ,corona effect2 #f4 ,frequ5cy2 #g4 ,resi/ance4 ,mo/ ( ^! items h already be5 expla9$ at su* l5g?1 t only a brief summ>y ( facts ne$ be add$1 to po9t out _! connection & importance ) alt]nat+ curr5t wir+4 ,induction4--,! effect ( induction1 :e!r self-induction or mutual induction1 is to set up a back pressure ( spuri\s resi/ance1 :i* mu/ be consid]$1 z x sometimes mat]ially affects ! calculation ( circuits ev5 9 int]ior wir+4 ,self-induction is ! effect produc$ by ! action ( ! electric curr5t ^u itself dur+ v>iations 9 /r5g?4 ,ques4 ,:at conditions besides v>iations ( curr5t /r5g? gov]ns ! am\nt ( self-induction 9 a circuit8 ,ans4 ,! %ape ( ! circuit1 & ! "* ( ! surr\nd+ m$ium4 ,if ! circuit be /raight1 !re w be little self-induction1 b if coil$1 ! effect w become pron\nc$4 ,if ! surr\nd+ m$ium be air1 ! self-induction is small1 b if x be iron1 ! self-induction is consid]able4 ,illu/ration3 ,,figs4 #b1fga to #b1fgf4--,! effect ( self-induction4 ,9 a non-inductive circuit1 z 9 fig4 #b1fgb1 ! :ole ( ! virtual pressure is available to cause curr5t to fl[ ?r\gh ! lamp filam5t1 h5ce x w gl[ ) maximum brilliancy4 ,if an inductive coil be ins]t$ 9 ! circuit z 9 fig4 #b1fgd1 ! rev]se pressure due to self-induction w oppose ! virtual pressure1 h5ce ! effective pressure 7:i* is ! diff]5ce betwe5 ! virtual & rev]se pressures71 w be r$uc$ & ! curr5t fl[ ?r\gh ! lamp dim9i%$1 ?us r$uc+ ! brilliancy ( ! illum9ation4 ,! effect may be int5sifi$ to su* degree by int]pos+ an iron core 9 ! coil z 9 fig4 #b1fgf1 z to ext+ui% ! lamp4 ,ques4 ,) respect to self-induction1 :at me?od %\ld be foll[$ 9 wir+8 ,ans4 ,:5 iron conduits are us$1 ! wires ( ea* circuit %\ld n be in/all$ 9 sep>ate conduits1 because su* arrangem5t w cause excessive self-induction4 ,! importance ( ?is may be se5 f ! exp]i5ce ( "o contractor1 :o in/all$ fe$]s & ma9s 9 sep>ate iron pipes4 ,:5 ! curr5t 0 turn$ on1 x 0 f\nd t ! self-induction 0 s great z to r$uce ! pressure to su* an ext5t t ! lamps1 in/ead ( giv+ full c&le p[]1 7 b>ely r$4 ,?is necessitat$ ! removal ( ! fe$]s & ma9 & re-in/all+ !m1 s t ^? ( ! same circuit 7 9 ! same pipe4 ,ques4 ,:at is mutual induction8 ,ans4 ,mutual induction is ! effect ( "o alt]nat+ curr5t circuit ^u ano!r4 ,illu/ration3 ,,fig4 #b1fgg4--,measurem5t ( self induction :5 ! frequ5cy is kn[n4 ,! app>atus requir$ consi/s ( a high resi/ance or electro/atic a4c4 voltmet]1 d4c4 ammet]1 & a non-inductive resi/ance4 ,connect ! inductive resi/ance to be measur$ z %[n1 & close swit* ,m1 %ort circuit+ ! ammet]4 ,connect alt]nator 9 circuit & measure drop across ,r & across ,xi4 ,disconnect alt]nator & connect batt]y 9 circuit1 !n op5 swit* ,m & v>y ! cont9u\s curr5t until ! drop across ,r is ! same z ) ! alt]nat+ curr5t1 bo? measurem5ts be+ made ) ! same voltmet]2 read ammet]1 & measure drop across ,xi4 ,call ! drop across ,xi ) alt]nat+ curr5t ,e1 & ) direct curr5t ,ei1 & ! read+ ( ! ammet] ,j4 ,!n ,l ,e#b ,ei#b #b f ,i4 ,if ! resi/ance ,xi be kn[n1 & ! ammet] be suitable = use ) alt]nat+ curr5t1 ! swit* & ,r may be disp5s$ )4 ,!n ,l ,e#b - ,xi#b ,ii#b #b f ,i1 :]e ,ii is ! value ( ! alt]nat+ curr5t4 ,! resi/ance ( ! voltmet] %\ld be high en\gh to r5d] its curr5t negligible z comp>$ ) t ?r\gh ,xi4 ,ques4 ,h[ is x caus$8 ,ans4 ,x is due to ! magnetic field surr\nd+ a conductor cutt+ adjac5t conductors & induc+ back pressures !re94 ,?is effect z a rule 9 ord9>y in/allations is negligible4 ,transpositions4--,! effect ( mutual induction betwe5 two circuits is proportional to ! int]-l9kage ( ! magnetic fluxes ( ! two l9es4 ,?is 9 turn dep5ds ^u ! proximity ( ! l9es & ^u ! g5]al relative arrangem5t ( ! conductors4 ,illu/ration3 ,,fig4 #b1fgh4--,transposition diagram = two p>allel l9es consi/+ ( two wires ea*4 ,illu/ration3 ,,fig4 #b1fgi4--,transposition diagram = ?ree phase1 ?ree wire l9e1 transpos+ at ! v]tices ( an equilat]al triangle4 ,! l9e is orig9ally balanc$ & becomes unbalanc$ on transpos+1 a proc$ure :i* %\ld be resort$ to only to prev5t mutual induction4 ,illu/ration3 ,,fig4 #b1fhj4--,transposition diagram ( ?ree phase1 ?ree wire l9e1 ) c5t] arrang$ 9 a /raight l9e4 ,! inductive effect ( "o l9e ^u ano!r is equal to ! algebraic sum ( ! fluxes due to ! diff]5t conductors ( ! fir/ l9e1 consid]$ sep>ately1 :i* l9k ! second>y l9e4 ,! effect ( mutual induction is to induce surges 9 ! l9e :]e a diff]5ce ( frequ5cy exi/s betwe5 ! two curr5ts1 & to induce high electro/atic *>ges 9 l9es c>ry+ little or no curr5t1 su* z telephone l9es4 ,,inductance ,,p] ,,mile ,,( ,,?ree ,,phase ,,circuit -------------------------------------- ,diam4 ,di/ance ,self ,size 9 d 9 ,inductance ,b4 ,s4 in*4 in*es4 ,l h5rys4 -------------------------------------- #jjjj 4#df #ab 4#jjbcd #ah 4#jjbef #bd 4#jjbgj #dh 4#jjcab #jjj 4#da #ab 4#jjbda #ah 4#jjbfb #bd 4#jjbgg #dh 4#jjcah #jj 4#cfe #ab 4#jjbdh #ah 4#jjbfi #bd 4#jjbhe #dh 4#jjccj #j 4#cbe #ab 4#jjbed #ah 4#jjbgf #bd 4#jjbic #dh 4#jjcca #a 4#bhi #ab 4#jjbfj #ah 4#jjbha #bd 4#jjcjh #dh 4#jjcch #b 4#beh #ab 4#jjbfg #ah 4#jjbhh #bd 4#jjcjd #dh 4#jjcad #c 4#bbi #ab 4#jjbgd #ah 4#jjbid #bd 4#jjcaj #dh 4#jjcea #d 4#bjd #ab 4#jjbhj #ah 4#jjcjj #bd 4#jjcae #dh 4#jjceh #e 4#ahb #ab 4#jjbhf #ah 4#jjcjg #bd 4#jjcbc #dh 4#jjcef #f 4#afb #ab 4#jjbia #ah 4#jjcac #bd 4#jjcbi #dh 4#jjcfi #g 4#add #ab 4#jjbih #ah 4#jjcaj #bd 4#jjccf #dh 4#jjcgg #h 4#abh #ab 4#jjcjc #ah 4#jjcbe #bd 4#jjcda #dh 4#jjchd #i 4#aad #ab 4#jjcaj #ah 4#jjccb #bd 4#jjcdh #dh 4#jjchi #aj 4#ajb #ab 4#jjcah #ah 4#jjcdj #bd 4#jjcee #dh 4#jjcif -------------------------------------- ,?is effect may be nullifi$ by sep>at+ ! l9es & by transpos+ ! wires ( "o ( ! l9es s t ! effect produc$ 9 "o section is oppos$ by t 9 ano!r4 ,( two p>allel l9es consi/+ ( two wires ea*1 "o may be transpos$ to neutralize ! mutual inductance4 ,fig4 #b1fgh %[s ?is me?od4 ,! l5g? ,l' %\ld be an ev5 factor ( ,l s t to e section ( ! l9e transpos$ !re corresponds an oppos+ section4 ,illu/ration3 ,,fig4 #b1fha4--;,capacity effect 9 s+le phase transmission l9e4 ,! effect is ! same z w\ld be produc$ by %unt+ across ! l9e at ea* po9t an inf9itesimal cond5s] hav+ a capacity equal to t ( an inf9itesimal l5g? ( circuit4 ,= ! purpose ( calculat+ ! *>g+ curr5t1 a v simple & suffici5tly accurate me?od is to det]m9e ! curr5t tak5 by a cond5s] hav+ a capacity equal to t ( ! entire l9e :5 *>g$ to ! pressure on ! l9e at ! g5]at+ end4 ,! effect ( capacity ( ! l9e is to r$uce ! pressure drop1 t is1 improve ! regulation1 & to decrease or increase ! p[] loss dep5d+ on ! load & p[] factor ( ! receiv]4 ,illu/ration3 ,,fig4 #b1fhb4--;,capacity effect 9 a ?ree phase transmission l9e4 ,x is ! same z w\ld be produc$ by %unt+ ! l9e at ea* po9t by ?ree inf9itesimal cond5s]s connect$ 9 /> ) ! neutral po9t gr\nd$1 ! capacity ( ea* cond5s] be+ twice t ( a cond5s] ( inf9itesimal l5g? =m$ by any two ( ! wires4 ,! effect ( capacity on ! regulation & effici5cy ( ! l9e c be det]m9$ ) suffici5t accuracy 9 mo/ cases by consid]+ ! l9e %unt$ at ea* end by ?ree cond5s]s connect$ 9 />1 ! capacity ( ea* cond5s] be+ equal to t =m$ by any two wires ( ! l9e4 ,an approximate value = ! *>g+ curr5t p] wire is ! curr5t requir$ to *>ge a cond5s]1 equal 9 capacity to t ( any two ( ! wires1 to ! pressure at ! g5]at+ end ( ! l9e betwe5 any "o wire & ! neutral po9t4 ,! self inductance ( l9es is readily calculat$ f ! foll[+ =mula3 ,l 4#jjjeeh #b4cjc log 7#b;,a d7 4#be p] mile ( circuit :]e ,l inductance ( a loop ( a ?ree phase circuit 9 h5rys4 ,note4--,! inductance ( a complete s+le phase circuit ,l #b #c4 ,a di/ance betwe5 wires2 d diamet] ( wire4 ,,capacity ,,9 ,,micro-,,f>ads ,,p] ,,mile ,,( ,,circuit ,,= ,,?ree ,,phase ,,sy/em ---------------------------------------- ,diam4 ,di/ance ,capacity ,size 9 ,a 9 ,c 9 ,b4 ,s4 in*4 in*es4 micro-f>ads ---------------------------------------- #jjjj 4#df #ab 4#jbbf #ah 4#jbjd #bd 4#jaibb #dh 4#jadgd #jjj 4#da #ab 4#jbah #ah 4#jaiib #bd 4#jahgf #dh 4#jafch #jj 4#cfe #ab 4#jabd #ah 4#jaidf #bd 4#jahcb #dh 4#jafjd #j 4#cbe #ab 4#jbjgh #ah 4#jahih #bd 4#jafdb #dh 4#jaegj #a 4#bhi #ab 4#jbjbb #ah 4#jaieb #bd 4#jagdh #dh 4#jaed #b 4#beh #ab 4#jaigb #ah 4#jahah #bd 4#jagaj #dh 4#jaeaj #c 4#bbi #ab 4#jaich #ah 4#jagff #bd 4#jafgb #dh 4#jadhj #d 4#bjd #ab 4#jahgd #ah 4#jagbf #bd 4#jafcf #dh 4#jadeb #e 4#ahb #ab 4#jahcj #ah 4#jafij #bd 4#jafjb #dh 4#jadbf #f 4#afb #ab 4#jaghh #ah 4#jafed #bd 4#jaefj #dh 4#jadj #g 4#add #ab 4#jagdf #ah 4#jafah #bd 4#jaech #dh 4#jacgd #h 4#abh #ab 4#jagjh #ah 4#jaehf #bd 4#jaejh #dh 4#jacej #i 4#aad #ab 4#jaffj #ah 4#jaeeb #bd 4#jadgh #dh 4#jacbf #aj 4#ajb #ab 4#jafcf #ah 4#jaebb #bd 4#jadeb #dh 4#jacjd ---------------------------------------- ,capacity4--,9 any giv5 sy/em ( electrical conductors1 a pressure diff]5ce betwe5 two ( !m corresponds to ! pres5ce ( a quantity ( electricity on ea*4 ,) ! same *>ges1 ! diff]5ce ( pressure may be v>i$ by v>y+ ! geometrical arrangem5t & magnitudes & also by introduc+ v>i\s dielectrics4 ,! con/ant connect+ ! *>ge & ! result+ pressure is call$ ! capacity ( ! sy/em4 ,all circuits h a c]ta9 capacity1 because ea* conductor acts l ! plate ( a cond5s]1 & ! insulat+ m$ium1 acts z ! dielectric4 ,! capacity dep5ds ^u ! insulation4 ,= a giv5 grade ( insulation1 ! capacity is proportional to ! surface ( ! conductors1 & univ]sally to ! di/ance betwe5 !m4 ,a ?ree phase ?ree wire transmission l9e spac$ at ! corn]s ( an equilat]al triangle z reg>ds capacity acts precisely z ?\gh ! neutral l9e 7 situat$ at ! c5t] ( ! triangle4 ,! capacity ( circuits is readily calculat$ by apply+ ! foll[+ =mulae3 ,c #ch4hc sc #aj-c _/ log 7,d d7 p] mile1 insulat$ cable ) lead %ea?2 ,c #ch4hc #aj-c _/ log 7#d;h d7 p] mile1 s+le conductor ) e>? return2 ,c #ai4db #aj-c _/ log 7#b;,a d7 p] mile ( p>allel conductors =m+ metallic circuit2 9 :i* ,c ,capacity 9 micro-f>ads2 = a metallic circuit1 ,c capacity betwe5 wires2 sc ,specific inductive capacity ( insulat+ mat]ial2 #a = air1 & #b4be to #c4g = rubb]2 ,d ,inside diamet] ( lead %ea?2 d ,diamet] ( conductor2 h ,di/ance ( conductors above gr\nd2 ,a ,di/ance betwe5 wires4 ,frequ5cy4--,! numb] ( cycles p] second1 or ! frequ5cy1 has a direct effect ^u ! inductance reactance 9 an alt]nat+ curr5t circuit1 z is pla9ly se5 f ! =mula4 ,xi #b;f,l ,9 ! case ( a transmission l9e alone2 ! l[] frequ5cies are ! m desirable1 9 t !y t5d to r$uce ! inductance drop & *>g+ curr5t4 ,! inductance drop is proportional to ! frequ5cy4 ,! natural p]iod ( a l9e1 ) di/ribut$ inductance & capacity1 is approximately giv5 by ,p #g1ijj _/ ,,lc :]e ,l is ! total inductance 9 millih5rys1 & ,c1 ! total capacity 9 micro-f>ads4 ,accord+ly "s l[] odd h>monic ( ! impress$ frequ5cy may be pres5t :i* corresponds ) ! natural p]iod ( ! l9e4 ,:5 ?is obta9s1 oscillations ( dang]\s magnitude may occur4 ,su* co9cid5ces are less likely ) ! l[] h>monics ?an ) ! high]4 ,sk9 ,effect4--,! t5d5cy ( alt]nat+ curr5t to conf9e itself to ! out] portions ( a conductor1 in/ead ( pass+ uni=mly ?r\gh ! cross section1 is call$ sk9 effect4 ,! effect is proportional to ! size ( ! conductor & ! frequ5cy4 ,ques4 ,:at effect has sk9 effect on ! curr5t8 ,ans4 ,x is equival5t to an increase ( ohmic resi/ance & !re=e opposes ! curr5t4 ,illu/ration3 ,,figs4 #b1fhc to #b1fhg4--,sk9 effect & %ield effect4 ,fig4 #b1fhc1 section ( conductor illu/rat+ sk9 effect or t5d5cy ( ! alt]nat+ curr5t to di/ribute itself unequally ?r\gh ! cross section ( a conductor z %[n by ! v>i$ %ad+1 :i* repres5ts ! curr5t fl[+ mo/ /rongly 9 ! out] portions ( ! conductor4 ,= ?is reason x has be5 propos$ to use holl[ or flat in/ead ( solid r\nd conductors2 h[ev]1 ) frequ5cy n exce$+ #ajj1 ! sk9 effect is negligibly small 9 copp] conductors ( ! sizes usually employ$4 ,9 figs4 #b1fhd & #b1fhe1 or #b1fhf & #b1fhg1 if two adjac5t conductors be c>ry+ curr5t 9 ! same direction1 conc5tration w occur on ^? p>ts ( ! two conductors remote f "o ano!r1 & ! ne>] p>ts w h less curr5t1 t is to say1 !y w be %ield$4 ,9 ?is case1 ! induction due to "o conductor w ex]t its oppos+ effect to ! greate/ ext5t on ^? p>ts ( ! o!r conductor ne>e/ to x2 ?is effect decreas+ ! deep] ! latt] is p5etrat$4 ,aft] cross+ ! curr5t axis1 ! induction w /ill decrease 9 magnitude1 b w n[ aid ! curr5t 9 ! conductor4 ,h5ce1 ! effect ( ^! two conductors on "o ano!r w make ! curr5t d5sity m uni=m ?an is ! case :]e ! two conductors adjac5t to "o ano!r are c>ry+ curr5t 9 opposite directions1 z 9 figs4 #b1fhe & #b1fhf1 !re=e1 ! resi/ance & ! heat+ = a giv5 curr5t w be small]4 ,if ! two return conductors be situat$ on ! l9e pass+ ?r\gh ! c5t] ( ! conductors j consid]$1 ! effect w be to /ill fur!r conc5trate ! curr5t2 ! di/ribution symmetry w be fur!r di/urb$1 & ! resi/ance ( ! conductor sy/em increas$4 ,x is !re=e difficult to say :i* ( ! two cases consid]$ holds ! advantage s f> z increas+ ! resi/ance is conc]n$4 ,! case1 h[ev]1 9 :i* ! phases are mix$ has mu* ! small] reactive drop4 ,if ! conductor be l>ge1 or ! frequ5cy high1 ! c5tral portion ( ! conductor c>ries little if any curr5t1 h5ce ! resi/ance is !re=e great] = alt]nat+ curr5t ?an = direct curr5t4 ,ques4 ,= :at condition may sk9 effect be neglect$8 ,ans4 ,= frequ5cies ( #fj or less1 ) conductors hav+ a diamet] n great] ?an #jjjj ,b4 ,s4 gauge4 ,ques4 ,h[ is ! sk9 effect calculat$ = a giv5 wire8 ,ans4 ,its area 9 circul> mils multipli$ by ! frequ5cy1 gives ! ratio ( ! wire's ohmic resi/ance to its comb9$ resi/ance4 ,t is to say1 ! factor ?us obta9$ multipli$ by ! resi/ance ( ! wire to direct curr5t w give its comb9$ resi/ance or resi/ance to alt]nat+ curr5t4 ,! foll[+ table gives ^! ratio factors = l>ge conductors4 ,,ratio ,,factor ,,= ,,comb9$ ,,resi/ance ---------------------------------------- -------- ,cir4 mils4 ,ratio ,cir4 mils4 ,ratio frequ5cy factor frequ5cy factor ---------------------------------------- -------- #aj1jjj1jjj #a4jj #gj1jjj1jjj #a4ac #bj1jjj1jjj #a4ja #hj1jjj1jjj #a4ag #cj1jjj1jjj #a4jc #ij1jjj1jjj #a4bj #dj1jjj1jjj #a4je #ajj1jjj1jjj #a4be #ej1jjj1jjj #a4jh #abe1jjj1jjj #a4cd #fj1jjj1jjj #a4aj #aej1jjj1jjj #a4dc ---------------------------------------- -------- ,corona ,effect4--,:5 two wires1 hav+ a great diff]5ce ( pressure are plac$ ne> ea* o!r1 a c]ta9 ph5om5on occurs1 :i* is call$ corona effect4 ,:5 ! spac+ or di/ance betwe5 ! wires is small & ! diff]5ce ( pressure 9 ! wires v great1 a cont9u\s passage ( en]gy takes place ?r\gh ! dielectric or atmosph]e1 ! am\nt ( ?is en]gy may be an appreciable p]c5tage ( ! p[] transmitt$4 ,!re=e 9 lay+ out high pressure transmission l9es1 ?is effect mu/ be consid]$ 9 ! spac+ ( ! wires4 ,ques4 ,h[ does ! corona effect manife/ itself8 ,ans4 ,x is visible at night z a blui% lum9\s envelope & audible z a hiss+ s\nd4 ,ques4 ,:at is ! critical voltage8 ,ans4 ,! voltage at :i* ! corona effect loss takes place4 ,ques4 ,^u :at does ! critical voltage dep5d8 ,ans4 ,^u ! radius ( ! wires1 ! spac+1 & ! atmosph]ic conditions4 ,illu/ration3 ,,fig4 #b1fhh4--;,electromagnetic & electro/atic fields surr\nd+ ! conductors ( a transmission l9e4 ,! electromagnetic field is repres5t$ by l9es ( magnetic =ce t surr\nd ! conductors 9 circles1 7! solid l9es71 & ! electro/atic field by 7dott$7 circles pass+ f conductor to conductor across at "r angles to ! magnetic circles4 ,= any giv5 size ( wire & di/ance ap>t ( wires !re is a c]ta9 voltage at :i* ! critical d5sity or critical gradi5t is rea*$1 :]e ! air breaks d[n & lum9osity beg9s--! critical voltage :]e corona manife/s itself4 ,at /ill high] voltages corona spreads to fur!r di/ances f ! conductor & a great] volume ( air becomes lum9\s4 ,incid5tally1 x produces noise4 ,n[ to produce light requires p[] & to produce noise requires p[]4 ,air is brok5 d[n & is heat$ 9 break+ d[n1 & to heat also requires p[]2 !re=e1 z soon z corona =ms1 p[] is consum$ or dissipat$ 9 its =mation4 ,:5 ?is ph5om5on occurs on ! conductors ( an alt]nat+ curr5t circuit a *ange takes place 9 relation to curr5t & voltage4 ,on ! wires ( an alt]nat+ curr5t transmission l9e1 at a voltage bel[ t :]e corona =ms--at a voltage :]e wires are n lum9\s--consid]able curr5t1 m or less dep5d+ on voltage & l5g? ( wire1 fl[s into ! circuit z capacity curr5t or *>g+ curr5t4 ,! critical voltage increases ) bo? ! diamet] ( ! wires1 & ! spac+4 ,! losses due to corona effect increase v rapidly ) increas+ pressure beyond ! critical voltage4 ,! magnitude ( ! losses z well z ! critical voltage is affect$1 by atmosph]ic conditions1 h5ce !y probably v>y ) ! p>ticul> locality1 & ! season ( ! ye>4 ,!re=e1 = a giv5 locality1 a voltage :i* is normally bel[ ! critical po9t1 may at times be above x1 dep5d+ ^u *anges 9 ! wea!r4 ,su* elem5ts z smoke1 fog1 moi/ure1 or o!r p>ticles 7du/1 sn[1 etc47 float+ 9 ! air1 increase ! losses2 ra91 h[ev]1 app>5tly has no appreciable effect ^u ! losses4 ,x foll[s !n t 9 ! design ( a transmission l9e1 ! atmosph]ic conditions ( ! p>ticul> locality ?r\gh :i* ! l9e passes %\ld be consid]$4 ,ques4 ,h[ %\ld live wires be spac$8 ,ans4 ,!y %\ld be s spac$ z to less5 ! t5d5cy to leakage & to prev5t ! wires sw++ toge!r or aga9/ t[]s4 ,! spac+ %\ld be only suffici5t = safety1 s9ce increas$ spac+ increases ! self-induction ( ! l9e1 & :ile x less5s ! capacity1 x does s only 9 a slight degree4 ,! foll[+ spac+ is 9 accordance ) av]age practice4 ,,spac+ ,,= ,,v>i\s ,,voltages ------------------- ,volts ,spac+ ------------------- #e1jjj #bh ins4 #ae1jjj #dj ins4 #cj1jjj #dh ins4 #de1jjj #fj ins4 #fj1jjj #fj ins4 #ge1jjj #hd ins4 #ij1jjj #if ins4 #aje1jjj #ajh ins4 #abj1jjj #abj ins4 ------------------- ,resi/ance ( ,wires4--,= quick calculation ! foll[+ me?od ( obta9+ ! resi/ance 7approximately7 ( wires w be f\nd conv5i5t3 #a1jjj feet ,no4 #aj ,b4 ,s4 wire1 :i* is ab\t 4#a in* 9 diamet] 74#ajai71 has a resi/ance ( "o ohm1 at a temp]ature ( #fh ,f4 & weighs #ca4d p\nds4 ,a wire ?ree sizes l>g]1 t is ,no4 #g1 has twice ! cross section & !re=e "o-half ! resi/ance4 ,a wire ?ree sizes small] ?an ,no4 #aj1 t is ,no4 #ac1 has "o-half ! cross section & !re=e twice ! resi/ance4 ,?us1 />t+ ) ,no4 #aj1 any numb] ?ree sizes l>g] w d\ble ! cross sectional area & any wire ?ree sizes small] w halve ! cross sectional area ( ! prec$+ wire4 ,?is is true to ! extreme limits ( ! table1 s t ! area1 weight & resi/ance ( any wire may be at once calculat$ to a close approximation f ?is rule1 int]m$iate sizes be+ obta9$ by int]polation4 ,= alt]nat+ curr5t1 ! comb9$ resi/ance1 t is1 ! total resi/ance1 includ+ sk9 effect1 is obta9$ by multiply+ ! resi/ance1 z f\nd above by ! ratio factor 7see table page #a1hid74 ,illu/ration3 ,,figs4 #b1fhi to #b1fib4--,triangles = obta9+ graphically1 imp$ance1 impress$ pressure1 etc41 9 alt]nat+ curr5t circuits4 ,= a full explanation ( ?is me?od ! read] is ref]r$ to ,guide #e1 ,*apt] ,,xlvii on ,alt]nat+ ,curr5t ,diagrams4 ,a ?or\gh /udy ( ?is *apt] is recomm5d$4 ,imp$ance4--,! total opposition to ! fl[ ( electricity 9 an alt]nat+ curr5t circuit1 or ! imp$ance may be resolv$ into two compon5ts repres5t+ ! ohmic resi/ance & ! spuri\s resi/ance2 ^! compon5ts h a phase diff]5ce ( #ij1 & !y may be repres5t$ graphically by ! two legs ( a "r angle triangle1 ( :i* ! hypo!nuse repres5ts ! imp$ance4 ,simil>ly1 ! volts lo/ or drop 9 an alt]nat+ circuit may be resolv$ into two compon5ts repres5t+ respectively #a4 ,! loss due to resi/ance4 #b4 ,! loss due to reactance4 ,^! compon5ts h a phase diff]5ce ( #ij & are repres5t$ graphically simil> to ! imp$ance compon5ts4 ,?is has be5 expla9$ at consid]able l5g? 9 ,*apt] ,,xlvii 7,guide ,v74 ,illu/ration3 ,,fig4 #b1fic4--,me*anical analogy ( p[] factor1 z exemplifi$ by a locomotive pol+ a c> (f a sid+4 ,! c> & locomotive are %[n mov+ 9 p>allel directions1 & ! pole ,,ab1 incl9$ at an angle 4 ,n[1 if ! l5g? ( ,,ab be tak5 to repres5t ! pressure ex]t$ on ! pole by ! locomotive1 !n ! imag9>y l9es ,,ac & ,,bc1 drawn respectively p>allel & at "r angles to ! direction ( motion w repres5t respectively ! useful & no en]gy 7wattless7 compon5ts2 t is to say1 if ! pressure ,,ab be appli$ to ! c> at an angle 1 only "p ( x1 ,,ac1 is useful 9 propell+ ! c>1 ! o!r compon5t1 ,,bc1 be+ wa/$ 9 t5d+ to pu% ! c> (f ! track at "r angles to ! rails1 be+ resi/$ by ! flanges ( ! out] :eels4 ,p[] ,factor4--,:5 ! curr5t falls out ( /ep ) ! pressure1 z on inductive loads1 ! p[] factor becomes less ?an unity1 & ! effect is to increase ! curr5t requir$ = a giv5 load4 ,accord+ly1 ?is mu/ be consid]$ 9 calculat+ ! size ( ! wires4 ,z has be5 expla9$1 ! curr5t fl[+ 9 an alt]nat+ curr5t circuit1 z measur$ by an ammet]1 c be resolv$ into two compon5ts1 repres5t+ respectively ! active compon5t & ! wattless compon5t or idle curr5t4 ,^! are graphically repres5t$ by ! two legs ( a "r triangle1 ( :i* ! hypo!nuse repres5ts ! curr5t measur$ by ! ammet]4 ,?is app>5t curr5t1 z is evid5t f ! triangle1 exce$s ! active curr5t & lags beh9d ! pressure by an am\nt repres5t$ by ! angle betwe5 ! hypo!nuse & leg repres5t+ ! en]gy curr5t z %[n 9 fig4 #b1fid4 ,illu/ration3 ,,fig4 #b1fid4--;,diagram %[+ t ! app>5t curr5t is m ?an ! active curr5t1 ! excess dep5d+ ^u ! angle ( phase diff]5ce4 ,illu/ration3 ,,fig4 #b1fie4--;,diagram %[+ compon5ts ( imp$ance volts4 ,comp>e ?is diagram ) figs4 #b1fhi & #b1fga1 & note t ! t]m reactance is ! diff]5ce betwe5 ! inductance drop & ! capacity drop if ! circuit conta9 capacity1 = in/ance1 if inductance drop be #aj volts & capacity drop be #g volts !n reactance #aj-g #c volts4 ,ques4 ,:at det]m9es ! heat+ ( ! wires on alt]nat+ curr5t circuits ) inductive loads8 ,ans4 ,! app>5t curr5t1 z repres5t$ by ! hypo!nuse ( ! triangle 9 fig4 #b1fid4 ,ques4 ,h[ is ! app>5t curr5t obta9$8 ,ans4 ,divide ! true watts by ! product ( ! p[] factor multipli$ by ! voltage4 ,example4--,a c]ta9 circuit supplies #bj kw4 to motors at #bbj volts & 4#h p[] factor4 ,:at is ! app>5t curr5t8 true watts #bj1jjj ,app>5t ,curr5t -------------------- -------- #aac4f amp]es p[] factor volts 4#h #bbj ,ques4 ,:at else1 besides p[] factor1 %\ld be consid]$ 9 mak+ wire calculations = motor circuits8 ,ans4 ,! effici5cy ( ! motor1 & ! heavy />t+ curr5t4 ,! product ( ! effici5cy ( ! motor multipli$ by ! p[] factor gives ! app>5t effici5cy1 :i* gov]ns ! size ( ! wires1 app>atus1 etc41 necess>y to fe$ ! motors4 ,all[ance %\ld be made = ! heavy />t+ curr5t requir$ = "s motors to avoid undue drop4 ,,table ,,( ,,approximate ,,amp]es ,,p] ,,t]m9al ,,= ,,induction ,,motors ,column head+s3 ,a-#aaj volts ,b-#bbj volts ,c-#ddj volts ,d-#eej volts ---------------------------------------- ----------------------- ,two phase ,?ree phase ,horse ,s+le phase f\r wire ?ree wire p[]------------------------------------- -------------- ,a ,b ,c ,a ,b ,c ,a ,b ,c ,d ---------------------------------------- ---------------- 4#e #f4f #c4d #a4h #c4c #a4g 4#i #c4g #a4h #a #a #ad #g #c4e #f4d #c4b #a4f #g4d #c4g #a4i #b #bd #ab #f #aa #e4g #b4i #ac #f4f #c4c #b4e #c #cd #ag #h4e #af #h4a #d4a #ai #i4c #d4g #c4e #d #eb #bf #ac #bf #ac #f4e #cj #ae #g4e #f #e #gd #cg #ah4e #ch #ai #i4e #dd #bb #aa #i #aj #id #dg #bc4e #dd #bb #aa #ej #be #ab4e #aa #ae #ff #cc #af4e #gf #ch #ai #af #bj #hh #dd #bb #ajb #ea #be4e #bb #be #aaa #ee #bh #abi #fd #cb #be #cj #acd #fg #cc4e #aed #gg #ch4e #cb #dj #agh #hi #dd4e #bjd #ajg #ec4e #dd #ej #bjd #ajb #ea #bcf #aah #ei #eb #ge #cjh #aed #gg #cef #agh #hi #gg #ajj #djh #bjd #ajb #dgb #bcf #aah #ajj ---------------------------------------- ---------------- ,ques4 ,:at are ! usual p[] factors enc\nt]$ on comm]cial circuits8 ,ans4 ,a mix$ load ( inc&esc5t lamps & induction motors w h a p[] factor ( f 4#h to 4#he2 induction motors above 4#h to 4#he2 inc&esc5t & ,n]n/ lamps 4#ih2 arc lamps1 4#he4 ,wire ,calculations4--,9 ! calculation ( alt]nat+ curr5t circuits1 ! two *ief factors :i* make ! computation diff]5t f t = direct curr5t circuits1 is induction & p[] factor4 ,! fir/ dep5ds on ! frequ5cy1 & physical condition ( ! circuit1 & ! second ^u ! "* ( ! load4 ,ques4 ,"u :at conditions may inductance be neglect$8 ,illu/ration3 ,,figs4 #b1fif to #b1fih4--;,example ( wir+ %[+ :]e inductance is negligible1 & :]e x mu/ be consid]$ 9 wire calculations4 ,ans4 ,9 cases :]e ! wires ( a circuit are n spac$ ov] an in* ap>t1 or 9 conduit "w1 :]e bo? wires are 9 ! same conduit4 ,"u ^! conditions ! calculation is ! same z = direct curr5t aft] mak+ prop] all[ance = p[] factor4 ,ques4 ,"u :at conditions mu/ induction be consid]$8 ,ans4 ,on expos$ circuits ) wires sep>at$ sev]al in*es1 p>ticul>ly 9 ! case ( l>ge wires4 ,sizes ( ,wire4--,! size ( wire = any alt]nat+ circuit may be det]m9$ by slightly modify+ ! =mula us$ 9 direct curr5t "w1 & :i*1 z d]iv$ 9 ,guide ,no4 #d1 page #gdh1 is amp]es feet #ba4f circul> mils --------------------- 7#a7 drop ,! quantity #ba4f1 is twice ! resi/ance 7#aj4h7 ( a foot ( copp] wire "o mil 9 diamet] 7mil foot74 ,?is resi/ance 7#aj4h7 is multipli$ by #b1 giv+ ! quantity #ba4f1 because ! l5g? ( a circuit1 or feet 9 ! =mula1 is giv5 z ! run or di/ance "o way1 t is1 "o-half ! total l5g? ( wire 9 ! circuit1 mu/ be multipli$ by #b to get ! total drop1 viz43 amp]es feet #aj4h #b amp]es feet #ba4f circul> mils ------------------------- --------------------- drop drop ,x is sometimes h[ev] conv5i5t to make ! calculation 9 t]ms ( watts4 ,=mula 7#a7 may be modifi$ = su* calculation4 ,9 modify+ ! =mula1 ! drop %\ld be express$ 9 p]c5tage in/ead ( actual volts lo/1 t is1 in/ead ( ! diff]5ce 9 pressure betwe5 ! beg9n+ & ! end ( ! circuit4 ,9 any circuit ! loss 9 p]c5tage1 or drop loss ------------------ #ajj impress$ pressure f :i* loss impress$ pressure drop --------------------------- 7#b7 #ajj ,sub/itut+ equation 7#b7 9 equation 7#a7 amp]es feet #ba4f circul> mils ----------------------------- loss imp4 pressure ------------------------ #ajj amp]es feet #b1afj -------------------------- 7#c7 loss imp4 pressure ,equation 7#c7 is modifi$ = calculation 9 t]ms ( watts z foll[s3 ,! p[] 9 watts is equal to ! appli$ voltage multipli$ by ! curr5t1 t is to say1 ! p[] is equal to ! volts at ! consum]'s end ( ! circuit multipli$ by ! curr5t1 or simply watts volts amp]es f :i* watts amp]es ----- 7#d7 volts ,illu/ration3 ,,figs4 #b1fii to #b1gjc4--,/r&$ copp] cables4 ,= conductors ( l>ge areas & 9 ! small] sizes :]e extra flexibility is requir$ x becomes necess>y to employ /r&$ cables made by gr\p+ a numb] ( wires toge!r 9 ei!r conc5tric or rope =m4 ,! conc5tric cable z "h illu/rat$ is =m$ by gr\p+ six wires ar\nd a c5tral wire !reby =m+ a sev5 wire cable4 ,! next /ep is ! application 9 a rev]se direction ( ano!r lay] ( #ab wires & a n9ete5 wire cable is produc$4 ,?is is aga9 increas$ by a ?ird lay] ( eighte5 wires = a #cg wire cable & a f\r? lay] ( #bd wires = a #fa wire cable4 ,successive lay]s1 ea* conta9+ #f m wires ?an t prec$+1 may be appli$ until ! desir$ capacity is obta9$4 ,! cuts %[ sectional views ( conc5tric cables ea* =m$ f ,no4 #aj ,b4 ,s4 gauge wires4 ,sub/itut+ ?is value = ! curr5t 9 equation 7#c7 & rememb]+ t ! pressure tak5 is ! volts at ! consum]'s end ( ! l9e watts ----- feet #b1afj volts circul> mils --------------------- loss volts watts feet #b1afj -------------------- 7#e7 loss volts#b ,?is =mula 7#e7 applies to a direct curr5t two wire circuit1 & to adapt x to any alt]nat+ curr5t circuit x is only necess>y to use ! lett] ,m in/ead ( ! numb] #b1afj1 ?us watts feet ,m circul> mils ------------------ 7#f7 loss volts#b 9 :i* ,m is a coeffici5t :i* has v>i\s values accord+ to ! k9d ( circuit & value ( ! p[] factor4 ,^! values are giv5 9 ! foll[+ table3 ,,values ,,( ,m ---------------------------------------- --------------------------- ,,p[] ,,factor ,,sy/em ---------------------------------------- ---------- #a4jj 4#ih 4#ie 4#ij 4#he 4#hj 4#ge 4#gj 4#fe 4#fj ---------------------------------------- ------------------ ,s+le #b1afjb1bdib1djjb1ffjc1jjjc1chjc1hdjd1dj je1aabf1jjj phase ---------------------------------------- ------------------ ,two #a1jhja1abea1bjja1ccja1ejja1fija1ibjb1bj jb1eefc1jjj phase 7#d wire7 ---------------------------------------- ------------------ ,?ree #a1jhja1abea1bjja1ccja1ejja1fija1ibjb1bj jb1eefc1jjj phase 7#c wire7 ---------------------------------------- ------------------ ,,note4--,! above table is calculat$ z foll[s3 ,= s+le phase ,m #b1afj p[] factor#b #ajj2 = two phase f\r wire1 or ?ree phase ?ree wire1 ,m 7#b1afj p[] factor#b7 #ajj4 ,?us ! value ( ,m = a s+le phase l9e ) p[] factor 4#ie #b1afj 4#ieb #ajj #b1djj4 ,x mu/ be evid5t t :5 #b1afj is tak5 z ! value ( ,m1 =mula 7#f7 applies to a two wire direct curr5t circuit & also to a s+le phase alt]nat+ curr5t circuit :5 ! p[] factor is unity4 ,9 ! table ! value ( ,m = any p>ticul> p[] factor is f\nd by divid+ #b1afj by ! squ>e ( t p[] factor = s+le phase & twice ! squ>e ( ! p[] factor = two phase & ?ree phase4 ,ques4 ,= a giv5 load & voltage h[ d ! wires ( a s+le & two phase sy/em comp>e 9 size & weight1 ! p[] factor be+ ! same 9 ea* case8 ,ans4 ,s9ce ! two phase sy/em is virtually two s+le phase sy/ems1 ! f\r wires ( ! two phase sy/ems are half ! size ( ! two wires ( ! s+le phase sy/em1 & accord+ly1 ! weight is ! same = ei!r sy/em4 ,,values ,,( ,t ---------------------------------------- ----------------------- ,,p[] ,,factor ,,sy/em ---------------------------------------- #a4jj 4#ih 4#ij 4#hj 4#gj ---------------------------------------- ------------------- ,s+le phase #a4jj 4#ih 4#ij 4#hj 4#gj ---------------------------------------- ------------------- ,two phase1 #d wire #b4jj #a4if #a4hj #a4fj #a4dj ---------------------------------------- ------------------- ,?ree phase1 #c wire #a4gc #a4gj #a4ee #a4ch #a4ba ---------------------------------------- ------------------- ,,note4--,?is table is = f9d+ ! value ( ! curr5t 9 l9e1 us+ ! =mula ,i ,w 7,e ,t71 9 :i* ,i curr5t 9 l9e2 ,e voltage betwe5 ma9 conductors at receiv+ or consum]s' end2 ,w watts4 ,= in/ance1 :at is ! curr5t 9 a two phase l9e transmitt+ #a1jjj watts at #eej volts1 p[] factor 4#hj8 ,i #a1jjj 7#eej #a4fj7 #a4ac4 ,ques4 ,s9ce !re is no sav+ 9 copp] 9 us+ two phases1 :at advantage has ! two phase sy/em ov] ! "o phase sy/em8 ,ans4 ,x is m desirable on p[] circuits1 because two phase motors are self-/>t+4 ,t is to say1 ! rotat+ magnetic field t c be produc$ by a two phase curr5t1 p]mits an induction motor to />t )\t be+ equipp$ ) any special phase splitt+ devices :i* are necess>y on s+le phase motors1 because ! oscillat+ field produc$ by a s+le phase curr5t does n produce any torque on a squirrel cage armature at re/4 ,ques4 ,= equal work+ conditions1 :at is ! comp>ison betwe5 ! s+le1 two & ?ree phase sy/em z to size & weight ( wires8 ,ans4 ,ea* wire ( ! ?ree phase sy/em is half ! size ( "o ( ! wires ( ! s+le phase sy/em1 h5ce ! weight ( copp] requir$ = ! ?ree phase sy/em is #ge ( t requir$ = ! s+le phase sy/em4 ,s9ce 9 ! two phase sy/em half ( ! load is c>ri$ by ea* phase1 ea* wire ( ! ?ree phase sy/em is ! same size z "o ( ! wires ( ! two phase sy/em1 h5ce1 ! copp] requir$ by ! ?ree phase sy/em is #ge ( t requir$ by ! two phase sy/em4 ,,miscellane\s ,,=mul ,,= ,,copp] ,,wires ,diamet] squ>$ circul> mils ,circul> mils 4#ghed squ>e mils 4#jjjjjcjbg circul> mils p\nds p] foot 4#jjcjbg circul> mils p\nds p] #a1jjj feet 4#jaeihdg circul> mils p\nds p] mile 4#jjchgi squ>e mils p\nds p] #a1jjj feet 4#ccjcc circul> mils feet p] p\nd 4#jjjjjjbibd circul> mils p\nds p] ohm 4#cdb circul> mils ohms p] p\nd 4#jifehe circul> mils feet p] ohm #aj4cecefh circul> mils ohms p] foot ,break+ weight ( wire area break+ weight p] squ>e in*4 ,break+ weight p] squ>e in* area break+ weight ( wire4 ,! weight ( copp] wire is #a-a_/g times ! weight ( iron wire ( same diamet]4 ,,example4--,:at size wires mu/ be us$ on a s+le phase circuit #b1jjj feet 9 l5g? to supply #cj kw4 at #bbj volts ) loss ( #d1 ! p[] factor be+ 4#i8 ,! =mula = circul> mils is watts feet ,m circul> mils ------------------ 7#a7 loss volts#b ,sub/itut+ ! giv5 values & ! prop] value ( ,m f ! table1 9 7#a7 #cj1jjj #b1jjj #b1ffj circul> mils ---------------------- #hb1dch #d #bbjb ,ref]r+ to ! accompany+ table ( ! prop]ties ( copp] wire1 ! ne>e/ l>g] size wire is ,no4 #a ,b4 ,s4 gauge hav+ an area ( #hc1fij circul> mils4 ,,table ,,( ,,! ,,prop]ties ,,( ,,copp] ,,wire ,giv+ weights1 l5g? & resi/ances ( wires ( ,mat?iess5's ,/&>d ,conductivity = bo? ,b4 ,s4 ,g4 7,br[n ,%>pe ,gauge7 & ,b4 ,w4 ,g4 7,birm+ham ,wire ,gauge7 f ,transactions ,octob] #aijc1 ( ! ,am]ican ,in/itute ( ,electrical ,eng9e]s4 ,gauges4 ,to ! ne>e/ f\r? ,l5g?4,resi/ance4 significant digit4 ,weight4 ,diamet]4 ,area4 ,lbs4 ,feet ,ohms p] p] p] lb4#a1jjj ft4 #a1jjj feet4 ,circul> ,b4 ,s4 ,b4,w4,g4 ,in*es4 mils4 #fh ,f4 #jjjj #j4dfj #baa1fjj #fdj4e #a4efa 4#jdhic #jjjj #j4ded #bjf1ajj #fbc4i #a4fjc 4#jejbc #jjj #j4dbe #ahj1fjj #edf4h #a4hbi 4#jegcb #jjj #j4djif #afg1hjj #ejh4j #a4ifi 4#jfagj #jj #j4chj #add1djj #dcg4a #b4bhh 4#jgagj #jj #j4cfdh #acc1ajj #djb4h #b4dhb 4#jgghj #j #j4cdj #aae1fjj #cdi4i #b4heh 4#jhieg #j #j4cbdi #aje1ejj #cai4e #c4acj 4#jihaa #a #j4cjjj #ij1jjj #bgb4d #c4fga 4#aaej #a #j4bhic #hc1fij #bec4c #c4idg 4#abcg #b #j4bhdj #hj1ffj #bdd4a #d4jif 4#abhd #c #j4beij #fg1jhj #bjc4a #d4ibe 4#aedc #b #j4begf #ff1cgj #bjj4i #d4igg 4#aefj #d #j4bchj #ef1fdj #aga4e #e4hcb 4#ahbh #c #j4bbid #eb1fcj #aei4c #f4bgf 4#aifg #e #j4bbjj #dh1djj #adf4e #f4hbf 4#baci #d #j4bjdc #da1gdj #abf4d #g4iad 4#bdhj #f #j4bjcj #da1baj #abd4g #h4jag 4#beac #e #j4ahai #cc1ajj #ajj4b #i4ih 4#cabh #g #j4ahjj #cb1djj #ih4jh #aj4bj 4#caif #h #j4afej #bg1bcj #hb4da #ab4ac 4#chjc #f #j4afbj #bf1bej #gi4df #ab4eh 4#cidd #i #j4adhj #ba1ijj #ff4cj #ae4jh 4#dgbg #g #j4addc #bj1hbj #fc4jb #ae4hg 4#digc #aj #j4acdj #ag1ifj #ed4ce #ah4dj 4#egff #h #j4abhe #af1eaj #di4ih #bj4ja 4#fbga #aa #j4abjj #ad1djj #dc4ei #bb4id 4#gaij #i #j4aadd #ac1jij #ci4fc #be4bc 4#gijh #ab #j4ajij #aa1hhj #ce4if #bg4ha 4#hgae #aj #j4ajai #aj1chj #ca4dc #ca4hb 4#iigb #ac #j4jiej #i1jbe #bg4cb #cf4fj #a4adg #aa #j4jijgd #h1bcd #bd4ic #dj4ab #a4beg #ad #j4jhcjj #f1hhi #bj4he #dg4ie #a4ejc #ab #j4jhjha #f1ecj #ai4gg #ej4ei #a4ehf #ae #j4jgbjj #e1ahd #ae4fi #fc4gc #a4iig #ac #j4jgaif #e1agh #ae4fh #fc4gi #a4iii #af #j4jfejj #d1bbe #ab4gi #gh4ai #b4dea #ad #j4jfdjh #d1ajg #ab4dc #hj4dd #b4eba #ag #j4jehj #c1cfd #aj4ah #ih4bc #c4jgh #ae #j4jegjg #c1beg #i4heh #aja4d #c4agi #af #j4jejhb #b1ehc #g4hah #abg4i #d4jji #ah #j4jdijj #b1dja #g4bfh #acg4f #d4cab #ag #j4jdebfj #b1jdh #f4bjj #afa4c #e4jee #ai #j4jdbjjj #a1gfd #e4cdj #ahg4c #e4hgj #ah #j4jdjcjj #a1fbd #d4iag #bjc4d #f4cgd #ai #j4jcehij #a1bhh #c4hii #bef4e #h4jch #bj #j4jcejjj #a1bbe #c4gjh #bfi4g #h4deb #ba #j4jcbjjj #a1jbd #c4ajj #cbb4f #aj4aa #bj #j4jcaifj #a1jbb #c4jib #cbc4d #aj4ad #ba #j4jbhdfj #haj4a #b4deb #djg4h #ab4gh #bb #j4jbhjjj #ghd4j #b4cgc #dba4d #ac4ba #bb #j4jbecej #fdb4d #a4ide #ead4b #af4ab #bc #j4jbejjj #fbe4j #a4hib #ebh4f #af4eg #bc #j4jbbegj #eji4e #a4edb #fdh4d #bj4cb #bd #j4jbbjjj #dhd4j #a4dfe #fhb4f #ba4ci #bd #j4jbjajj #djd4j #a4bbc #hag4f #be4fc #be #j4jbjjjj #djj4j #a4baa #hbe4i #be4hh #bf #j4jahjjj #cbd4j 4#ihjh #a1jbj #ca4if #be #j4jagijj #cbj4d 4#ifii #a1jca #cb4ca #bg #j4jafjjj #bef4j 4#ggdi #a1bij #dj4de #bf #j4jaeidj #bed4a 4#gfib #a1cjj #dj4ge #bg #j4jadbjj #bja4e 4#fajj #a1fci #ea4ch #bh #j4jadjjj #aif4j 4#eicc #a1fhe #eb4hc #bi #j4jacjjj #afi4j 4#eaaf #a1iee #fa4bg #bh #j4jabfdj #aei4h 4#dhcg #b1jfg #fd4gi #cj #j4jabjjj #add4j 4#dcei #b1bid #ga4ij #bi #j4jaabfj #abf4g 4#chcf #b1fjg #ha4gj #cj #j4jajjcj #ajj4e 4#cjdb #c1bhg #ajc4j #ca #j4jajjjj #ajj4j 4#cjbg #c1cjd #ajc4e #cb #j4jjijjj #ha4j 4#bdeb #d1jgh #abg4h #ca #j4jjhibh #gi4gj 4#bdac #d1ade #abi4i #cc #j4jjhjjj #fd4j 4#aicg #e1afb #afa4h #cb #j4jjgiej #fc4ba 4#aiac #e1bbg #afc4h #cc #j4jjgjhj #ej4ac 4#aeag #f1eia #bjf4f #cd #j4jjgjjj #di4j 4#adhc #f1gdb #baa4c #cd #j4jjfcje #ci4ge 4#abjc #h1caa #bfj4e #ce #j4jjefae #ca4eb 4#jiedc #aj1dhj #cbh4d #cf #ce #j4jjejjj #be4j 4#jgefh #ac1baj #dad4b #cg #j4jjddec #ai4hc 4#jfjja #af1ffj #ebb4b #cf #j4jjdjjj #af4 4#jdhdc #bj1fej #fdg4a #ch #j4jjcife #ae4gb 4#jdgei #ba1jaj #feh4e #ci #j4jjceca #ab4dg 4#jcggd #bf1ejj #hcj4d #dj #j4jjcade #i4hhh 4#jbiic #cc1daj #ajdg4 ---------------------------------------- ---------------------------- ,drop4--,9 ord] to det]m9e ! drop or volts lo/ 9 ! l9e1 ! foll[+ =mula may be us$ drop 77 loss volts7 _/ #ajj7 ,s 7#a7 9 :i* ! loss is a p]c5tage ( ! appli$ p[]1 t is1 ! p[] deliv]$ to ! consum] & n a p]c5tage ( ! p[] at ! alt]nator4 ,volts is ! pressure at ! consum]'s end ( ! circuit4 ,,value ,,( ,s ,,= #fj ,,cycles ---------------------------------------- ------------------------- 4#ih p[] factor 4#ij p[] factor ---------------------------------------- ------------------------ ,size ( ,area ,spac+ ( ,spac+ ( wire 9 conductors conductors ,b4,s4 circul> gauge mils4 ---------------------------------------- #a #c #f #ab #bd #a #c #f #ab #bd ---------------------------------------- ---------------- #ejj1jjj #ejj1jjj #a4baa4dea4faa4gga4iba4cba4hjb4aab4ddb4g e #cjj1jjj #cjj1jjj #a4aea4bia4cha4dha4ega4aia4dga4ffa4hdb4j b #j1jjj #baa1fjj #a4aba4bba4bha4cda4daa4aca4cca4dea4eha4f c #jjj #afg1hjj #a4jia4aha4bba4bha4bia4jha4bca4cca4dda4e c #jj #acc1ajj #a4jga4ada4aha4baa4bea4jca4afa4bda4cba4d j #j #aje1ejj #a4jea4aja4ada4aga4bja4jja4jia4afa4bba4b h #a #hc1fij #a4jda4jha4aja4aca4aea4jja4jea4jia4ada4a i #b #ff1cgj #a4jba4jea4jha4aja4aba4jja4jja4jda4jha4a b #c #eb1fcj #a4jba4jda4jfa4jga4jia4jja4jja4jja4jca4j f #d #da1gdja4jja4jba4jca4jda4jga4jja4jja4jja 4jja4jj #e #cc1ajj #f #bf1beja4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #g #bj1hbj #h #af1eaj #i #ac1jija4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #aj #aj1chj ---------------------------------------- ---------------- ---------------------------------------- ---------------- ,size 4#hj p[] factor 4#gj p[] factor ( ,area ---------------------------------------- -------- wire 9 ,spac+ ( ,spac+ ( ,b4,s4 circul> conductors conductors gauge mils4 ---------------------------------------- #a #c #f #ab #bd #a #c #f #ab #bd ---------------------------------------- ---------------- #ejj1jjj #ejj1jjja4bga4hib4beb4fdc4jca4ada4gbb4ab b4ecb4ib #cjj1jjj #cjj1jjja4aaa4dfa4fha4ijb4aba4jja4cca4ef a4ghb4ja #j1jjj #baa1fjja4jca4bga4dca4eha4gea4jja4ada4bi a4dea4fi #jjj #afg1hjja4jja4afa4bha4daa4eca4jja4jba4ae a4bha4ej #jj #acc1ajja4jja4jga4aea4bba4jja4jja4jja4jc a4aca4ba #j #aje1ejja4jja4jja4jga4aea4jja4jja4jja4jj a4jaa4ji #a #hc1fija4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #b #ff1cgja4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #c #eb1fcja4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #d #da1gdj #e #cc1ajja4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #f #bf1bej #g #bj1hbj #h #af1eaj #i #ac1jija4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #aj #aj1chj ---------------------------------------- ---------------- ,! coeffici5t ,s has v>i\s values z giv5 9 ! accompany+ tables4 ,z w be se5 f ! table1 ! value ( ,s to be us$ dep5ds ^u ! size ( wire1 spac+1 p[] factor & frequ5cy4 ,^! values are accurate en\gh = all practical purposes1 & may be us$ = di/ances ( #bj miles or less & = voltages up to #be1jjj4 ,! capacity effect on v long high voltage l9es1 makes ?is me?od ( det]m9+ ! drop some:at inaccurate beyond ! limits above m5tion$4 ,,value ,,( ,s ,,= #be ,,cycles ---------------------------------------- ------------------------- ,size 4#ih p[] factor 4#ij p[] factor ( ,area ---------------------------------------- -------- wire 9 ,spac+ ( ,spac+ ( ,b4,s4 circul> conductors conductors gauge mils4 ---------------------------------------- #a #b #f #ab #bd #a #c #f #ab #bd ---------------------------------------- ----------------- #ejj1jjj #ejj1jjj #a4jaa4aga4bca4bia4cfa4jba4bba4cea4dca4f a #cjj1jjj #cjj1jjj #a4jda4aja4aca4aha4baa4jja4jha4afa4bea4c a #j1jjj #baa1fjj #a4jca4jga4jia4aaa4ada4jja4jba4jga4aca4a e #jjj #afg1hjj #a4jja4jea4jfa4jia4aja4jja4jja4jba4jga4a a #jj #acc1ajj #a4jja4jca4jea4jfa4jha4jja4jja4jja4jba4j e #j #aje1ejj #a4jja4jaa4jba4jca4jda4jja4jja4jja4jja4j j #a #hc1fij #b #ff1cgja4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #c #eb1fcj #d #da1gdj #e #cc1ajja4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #f #bf1bej #g #bj1hbj #h #af1eaj #i #ac1jija4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #aj #aj1chj ---------------------------------------- ----------------- ,size 4#hj p[] factor 4#gj p[] factor ( ,area ---------------------------------------- -------- wire 9 ,spac+ ( ,spac+ ( ,b4,s4 circul> conductors conductors gauge mils4 ---------------------------------------- #a #c #f #ab #bd #a #c #f #ab #bd ---------------------------------------- ----------------- #ejj1jjj #ejj1jjja4jja4aea4cja4dga4fba4jja4jja4af a4cca4di #cjj1jjj #cjj1jjja4jja4jja4jia4afa4bea4jja4jja4jj a4jba4ab #j1jjj #baa1fjja4jja4jja4jja4jca4aja4jja4jja4jj a4jja4jj #jjj #afg1hjja4jja4jja4jja4jja4jaa4jja4jja4jj a4jja4jj #jj #acc1ajja4jja4jja4jja4jja4jja4jja4jja4jj a4jja4jj #j #aje1ejja4jja4jja4jja4jja4jja4jja4jja4jj a4jja4jj #a #hc1fij #b #ff1cgja4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #c #eb1fcj #d #da1gdj #e #cc1ajja4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #f #bf1bej #g #bj1hbj #h #af1eaj #i #ac1jija4jja4jja4jja4jja4jja4jja4jja4jja 4jja4jj #aj #aj1chj ---------------------------------------- ----------------- ,,example4--,a circuit supply+ curr5t at #ddj volts1 #fj frequ5cy1 ) #e loss & 4#h p[] factor is compos$ ( ,no4 #b ,b4 ,s4 gauge wires spac$ "o foot ap>t4 ,:at is ! drop 9 ! l9e8 ,accord+ to ! =mula loss volts drop -------------- ,s #ajj ,sub/itut+ ! giv5 values1 & value ( ,s z obta9$ f ! table = frequ5cy #fj #e #ddj drop ------- #a #bb volts #ajj ,curr5t4--,z has be5 /at$1 ! effect ( p[] factor less ?an unity1 is to increase ! curr5t2 h5ce1 9 inductive circuit calculations1 ! fir/ /ep is to det]m9e ! curr5t fl[+ 9 a circuit4 ,?is is done z foll[s3 app>5t load curr5t ------------- 7#a7 volts & watts app>5t load ------------ 7#b7 p[] factor ,sub/itut+ 7#b7 9 7#a7 watts ------------ p[] factor watts curr5t ------------ --------------------- 7#c7 volts p[] factor volts ,illu/ration3 ,,fig4 #b1gjd4--,rope type ( /r&$ copp] cable :i* is us$ :5 a high degree ( flexibility is requir$4 ,! con/ruction ( ?is cable is ! /r&+ toge!r ( sev5 gr\ps1 ea* conta9+ sev5 wires & produc+ a total ( #di wires4 ,9 cases :5 a great] c>ry+ capacity is desir$ ?an c be obta9$ ?r\gh ! use ( ! #g #g or #di wire cable1 ! numb] ( gr\ps is increas$ to n9ete5 !reby mak+ a total ( #acc wires 7#ai #g74 ,,example4--,a #ej horse p[] #ddj volt motor has a full load effici5cy ( 4#i & p[] factor ( 4#h4 ,h[ mu* curr5t is requir$8 ,s9ce ! brake horse p[] ( ! motor is giv51 x is necess>y to obta9 ! electrical horse p[]1 ?us brake horse p[] #ej ,e4,h4,p4 ----------------- -- #ee4e effici5cy 4#i :i* 9 watts is #ee4e #gdf #da1djc :i* is ! actual load1 & f :i* actual load #da1djc app>5t load ------------ ------ #ea1ged p[] factor 4#h ,! curr5t !re=e at #ddj volts is app>5t load #ea1ged ------------- ------ #aag4f amp]es volts #ddj ,,example4--,a #ej horse p[] s+le phase #ddj volt motor1 hav+ a full load effici5cy ( 4#ib & p[] factor ( 4#h1 is to be op]at$ at a di/ance ( #a1jjj feet f ! alt]nator4 ,! wires are to be spac$ #f in*es ap>t & ! frequ5cy is #fj1 & loss #e4 ,det]m9e3 ,a1 electrical horse p[]2 ,b1 watts2 ,c1 app>5t load2 ,d1 curr5t2 ,e1 size ( wires2 ,f1 drop2 ,g1 voltage at ! alt]nator4 ,a4 ,electrical horse p[] brake horse p[] #ej ,e4 ,h4 ,p4 ----------------- --- #ed4c effici5cy 4#ib or1 #ed4c #gdf #dj1ejh watts ,,table ,,( ,,wire ,,equival5ts 7,br[n & ,%>pe gauge7 ---------------------------------------- ----------------- #jjjj #b #j #d #c #h #f #af #i #cb #ab #fd #ae #jjj #b #a #d #d #h #g #af #aj #cb #ac #fd #af #jj #b #b #d #e #h #h #af #aa #cb #ad #fd #ag #j #b #c #d #f #h #i #af #ab #cb #ae #fd #ah #a #b #d #d #g #h #aj #af #ac #cb #af #fd #ai #b #b #e #d #h #h #aa #af #ad #cb #ag #fd #bj #c #b #f #d #i #h #ab #af #ae #cb #ah #fd #ba #d #b #g #d #aj #h #ac #af #af #cb #ai #fd #bb #e #b #h #d #aa #h #ad #af #ag #cb #bj #fd #bc #f #b #i #d #ab #h #ae #af #ah #cb #ba #fd #bd #g #b #aj #d #ac #h #af #af #ai #cb #bb #fd #be #h #b #aa #d #ad #h #ag #af #bj #cb #bc #fd #bf #i #b #ab #d #ae #h #ah #af #ba #cb #bd #fd #bg #aj #b #ac #d #af #h #ai #af #bb #cb #be #fd #bh #aa #b #ad #d #ag #h #bj #af #bc #cb #bf #fd #bi #ab #b #ae #d #ah #h #ba #af #bd #cb #bg #fd #cj #ac #b #af #d #ai #h #bb #af #be #cb #bh #ad #b #ag #d #bj #h #bc #af #bf #cb #bi #ae #b #ah #d #ba #h #bd #af #bg #cb #cj #af #b #ai #d #bb #h #be #af #bh #ag #b #bj #d #bc #h #bf #af #bi #ah #b #ba #d #bd #h #bg #af #cj #ai #b #bb #d #be #h #bh #bj #b #bc #d #bf #h #bi #ba #b #bd #d #bg #h #cj ---------------------------------------- ----------------- ,b4 ,watts watts ,e4,h4,p4 #gdf #ed4c #gdf #dj1ejh ,c4 ,app>5t load app>5t load or kva 7actual load or watts p[] factor7 #dj1ejh 4#h #ej1fce ,d4 ,curr5t curr5t 7app>5t load or kva volts7 #ej1fce #ddj #aae amp]es ,e4 ,size ( wires cir4 mils 7watts feet ,m7 7 loss volts#b7 7#dj1ejh #a1jjj #c1chj7 7#e #ddjb7 #ada1ddc ,f table page #a1ijg1 ne>e/ size l>g] wire is ,no4 #jj ,b4,s4 gauge4 ,f4 ,drop drop 77 loss volts7 #ajj7 ,s 77#e #ddj7 #ajj7 #a4ag #be4gd volts ,,note4--,values ( ,s are giv5 on page #aiaj4 ,g4 ,voltage at alt]nator alt]nator pressure 7volts at motor drop7 #ddj #be4gd #dfe4g volts4 ,,*apt] ,,lxvi ,,p[] ,,/ations ,! t]m p[] /ation is usually appli$ to any build+ conta9+ an in/allation ( ma*9]y = ! conv]sion ( en]gy f "o =m into ano!r =m4 ,!re are ?ree g5]al classes ( /ation3 #a4 ,c5tral /ations2 #b4 ,sub-/ations2 #c4 ,isolat$ plants4 ,^! may also be classifi$ ) respect to _! function z #a4 ,g5]at+ /ations2 #b4 ,di/ribut+ /ations2 #c4 ,conv]t+ /ations4 & ) respect to ! =m ( p[] us$ 9 g5]at+ ! electric curr5t1 g5]at+ /ations may be class$ z #a4 ,/eam electric2 #b4 ,hydro-electric2 #c4 ,gas electric1 etc4 ,c5tral ,/ations4--,x mu/ be evid5t t ! g5]al type ( c5tral /ation to be adapt$ to a giv5 case1 t is to say1 ! g5]al "* ( ! ma*9]y to be in/all$ dep5ds ^u ! k9d ( natural en]gy available = conv]sion into electrical en]gy1 & ! "* ( ! electrical en]gy requir$ by ! consum]s4 ,?is gives rise to a fur!r classification1 z #a4 ,alt]nat+ curr5t /ations2 #b4 ,direct curr5t /ations2 #c4 ,alt]nat+ & direct curr5t /ations4 ,! alt]nators or dynamos may be driv5 by /eam or wat] turb9es1 reciprocat+ eng9es1 or gas eng9es1 accord+ to ! "* ( ! natural en]gy available4 ,illu/ration3 ,,fig4 #b1gje4--;,elevation ( small /ation ) direct drive1 %[+ arrangem5t ( ! boil] & eng9e1 pip+1 etc4 ,ques4 ,:y is ! reciprocat+ eng9e be+ l>gely replac$ by ! /eam turb9e1 especially = l>ge units8 ,ans4 ,because ( its high] rotative spe$1 & abs5ce ( a multiplicity ( be>+s :i* 9 ! case ( a high spe$1 reciprocat+ eng9e mu/ be ma9ta9$ 9 close adju/m5t = ! prop] op]ation ( ! eng9e4 ,! high] spe$ ( rotation results 9 a m compact unit1 desirable = driv+ high frequ5cy alt]nators4 ,ques4 ,is ! /eam turb9e m economical ?an a high duty reciprocat+ eng9e8 ,ans4 ,no4 ,location ( ,c5tral ,/ations4--,z a rule1 c5tral /ations %\ld be s locat$ t ! av]age loss ( voltage 9 ov]com+ ! resi/ance ( ! l9es is a m9imum1 & ?is po9t is locat$ at ! c5t] ( gravity ( ! sy/em4 ,9 fig4 #b1gjf is %[n a graphical me?od ( locat+ ?is important spot4 ,illu/ration3 ,fig4 #b1gjf4--;,diagram illu/rat+ graphical me?od ( det]m9+ ! c5t] ( gravity ( a sy/em 9 locat+ ! c5tral /ation4 ,suppose a r\gh canvass ( prospective consum]s 9 a di/rict to be suppli$ ) electric light or p[] %[s ! pr9cipal loads to be locat$ at ,a1 ,b1 ,c1 ,d1 ,e1 etc41 & = simplicity assume t ^! loads w be approximately equal1 s t ea* may be d5ot$ by #a = example3 ,! relative locations ( ,a1 ,b1 ,c1 ,d1 ,e1 etc41 %\ld be drawn to scale 7say #a in* to ! #a1jjj feet7 aft] :i* ! problem resolves itself into f9d+ ! location ( ! /ation ) respect to ?is scale4 ,illu/ration3 ,,fig4 #b1gjg4--;,ext]ior ( c5tral /ation at ,lewis1 ,ia42 example ( v small /ation locat$ 9 ! pr9cipal bus9ess section ( a t[n4 ,x also illu/rates ! use ( a direct connect$ gasol9e electric set4 ,! c5tral /ation is locat$ on ,ma9 ,/reet1 :i* is ! pr9cipal ?or\ghf>e1 & is in/all$ 9 a l[ "o /ory build+ = :i* a m]e nom9al r5tal *>ge is paid1 ! company hav+ ! option to buy ! prop]ty lat] at ! value ( ! l& plus ! co/ ( ! improvem5ts & simple int]e/ on ! same4 ,to ! front ( an old frame build+ ab\t #af feet by #bh feet has be5 built a neat1 well light$ concrete block room1 ab\t #af feet by #af feet1 c>ry+ ! build+ to ! lot l9e & af=d+ ample space = ! g5]at+ set & swit*bo>ds1 & su* desk room z is ne$$ = ! ord9>y (fice bus9ess ( ! company4 ,9 ?is room1 :i* is f9i%$ 9 natural p9e ) pla/]$ walls1 has be5 in/all$ a /&>d ,g5]al ,electric #be kw4 gasol9e electric g5]at+ set consi/+ ( a f\r cyl9d]1 f\r cycle1 v]tical wat] cool$1 #dc-ed ,h4,p4 gasol9e eng9e1 direct connect$ to a ?ree phase1 #b1cjj volt1 #fjj ,r4,p4,m4 alt]nator ) a #abe volt excit] m\nt$ on ! same %aft & 9 ! same frame4 ,) ! g5]at+ set is a slate swit*bo>d panel equipp$ ) ?ree ammet]s1 "o voltmet]1 an in/rum5t plug swit* = voltage indication1 "o s+le pole c>bon break swit*1 "o automatic oil circuit break] l9e swit* & rheo/ats4 ,in/rum5t trans=m]s are m\nt$ above & back ( ! bo>d4 ,= /reet light+ s]vice a #d kw4 con/ant curr5t trans=m] has be5 in/all$1 & ) x a gray m>ble swit*bo>d panel m\nt$ on iron frames & c>ry+ an ammet] & a f\r po9t plug swit*4 ,on a bo>d ne> ! g5]ator set are m\nt$ 9 conv5i5t rea* suitable wr5*es1 spann]s1 & repair p>ts & tools4 ,to cool ! eng9e cyl9d]s five #f #h /eel tanks h be5 in/all$ 9 ! old build+1 a pump on eng9e giv+ =c$ circulation4 ,! solution consi/s 9 fir/ f9d+ ! c5t] ( gravity ( any two ( ! loads1 su* z ^? at ,a & ,b4 ,s9ce ea* ( ^! is #a1 !y w toge!r h ! same effect on ! sy/em z ! resultant load ( #a & #a1 or #b1 locat$ at _! c5t] ( gravity1 ?is po9t be+ s *os5 t ! product ( ! loads by _! respective di/ances f ?is po9t w 9 bo? cases be equal4 ,! loads be+ equal 9 ?is case ! di/ances mu/ be equal 9 ord] t ! products be ! same1 s t ! c5t] ( gravity ( ,a ,b is at ,g1 :i* po9t is midway betwe5 ,a & ,b4 ,consid]+1 next1 ! resultant load ( #b at ,g & ! load ( #a at ,c1 ! resultant load at ! c5t] or gravity ( ^! w be #c1 & ?is mu/ be situat$ at a di/ance ( two units f ,c & "o unit f ,g s t ! di/ance #b times ! load #a at ,c equals ! di/ance #a times ! load #b at ,g4 ,hav+ ?us locat$ ! load #c at ,h1 ! same me?od is foll[$ 9 f9d+ ! load #d at ,i4 ,!n 9 l mann] ! resultant load #d & ! load #a at ,e gives a load #e at ,s4 ,! po9t ,s be+ ! la/ to be det]m9$ repres5ts1 !re=e1 ! position ( ! c5t] ( gravity ( ! entire sy/em1 & consequ5tly ! prop] position ( ! plant 9 ord] to give ! m9imum loss ( voltage on ! l9es4 ,ques4 ,is ! c5t] ( gravity ( ! sy/em1 z obta9$ 9 fig4 #b1gjf1 ! prop] location = ! c5tral /ation8 ,ans4 ,x is v r>ely ! be/ location4 ,ques4 ,:y8 ,ans4 ,o!r conditions1 su* z ! price ( l&1 difficulty ( obta9+ wat]1 facilities = deliv]y ( coal & removal ( a%es1 etc41 may m ?an (fset ! m9imum l9e losses & copp] co/ due to locat+ ! /ation at ! c5t] ( gravity ( ! sy/em4 ,illu/ration3 ,,fig4 #b1gjh4--,map ( ,cia ,docas de ,santos hydro-electric sy/em2 an example ( /ation location remote f ! c5t] ( di/ribution4 ,9 ! figure ,a is ! intake2 ,b1 flume2 ,c1 =ebay2 ,d1 p5/ocks2 ,e1 p[] h\se2 ,f1 n>r[ gauge railway2 ,g1 g5]al /ore2 ,h1 po9t ( deb>kation2 ,i1 transmission l9e2 ,j1 dead ends2 ,k1 sub-/ation4 ,santos1 9 ! republic ( ,brazil1 is "o ( ! great c(fee %ipp+ ports ( ! _w1 & = ! developm5t ( its wat] front has requir$ an elaborate sy/em ( quays4 ,^! h be5 develop$ by ! ,santos ,dock ,company1 :i* holds a concession = ! :ole wat] front4 ,! company1 ne$+ electric p[] = its own use1 has develop$ a sy/em d]iv+ its p[] f a po9t ab\t ?irty miles f ! city1 :]e a small /ream plunges d[n ! sea coa/ f ! m\nta9 range t runs along x4 ,! eng9e]s h e/imat$ t #ajj1jjj horse p[] c be obta9$ f ?is s\rce4 ,ques4 ,h[ !n %\ld ! /ation be locat$8 ,ans4 ,! m practical exp]i5ce ! design] has _h1 & ! m common s5se he possesses1 ! bett] is he equipp$ to h&le ! problem1 z ! solution is g5]ally su* t x _c be work$ out by any rule ( ?umb me?od4 ,illu/ration3 ,,fig4 #b1gji4--,/ation location4 ,! figure %[s two di/ribution c5t]s z a t[n ,a & suburb ,b suppli$ ) electricity f "o /ation4 ,= m9imum co/ ( copp] ! location ( ! /ation w\ld be at ,g1 ! c5t] ( gravity4 ,h[ev]1 x is v r>ely t ?is is ! be/ location4 ,= in/ance at ,c1 l& is *eap] ?an at ,g1 & !re is room = future ext5sion to ! /ation1 z %[n by ! dott$ l9es1 :]eas at ,g1 only en\gh l& is available = pres5t requirem5ts4 ,moreov] ,c is ne> ! railroad :]e coal may be obta9$ )\t ! exp5se ( c>tage1 & be+ locat$ at ! riv]1 ! plant may be run cond5s+ ?us effect+ consid]able economy4 ,! conditions may sometimes be su* t any "o ( ! advantages to be secur$ by locat+ ! /ation at ,c may m ?an (fset ! additional co/ ( copp]4 ,ques4 ,:at are ! g5]al consid]ations ) respect to ! price ( l&8 ,ans4 ,! co/ = ! /ation site may be s high z to necessitate build+ or r5t+ room at a consid]able di/ance f ! di/rict to be suppli$4 ,if ! price ( l& select$ = ! /ation be high1 ! runn+ exp5ses w be simil>ly affect$1 inasmu* z m int]e/ mu/ !n be paid on ! capital inve/$4 ,! price or r5t ( real e/ate might also 9 c]ta9 in/ances alt] ! propos$ int]ior arrangem5t ( ! /ation1 p>ticul>ly s 9 ! case ( a company ) small capital op]at+ 9 a city :]e high prices prevail4 ,9 g5]al1 h[ev]1 x may be /at$ t :atev] effect ! price ( real e/ate w\ld h ^u ! arrangem5t1 op]ation & location ( a c5tral /ation x c q readily & accurately be det]m9$ 9 advance4 ,ques4 ,) respect to ! co/ ( ! l& :at %\ld be especially consid]$8 ,ans4 ,room = ! future ext5sion ( ! plant4 ,al?\gh su* additional space ne$ n be pur*as$ at ! "t ( ! orig9al in/allation x is well1 if possible1 to make provision :]eby x c be obta9$ at a reasonable figure :5 desir$4 ,! prelim9>y canvass ( consum]s w aid 9 decid+ ! am\nt ( space advisable to all[ = future ext5sions2 z a rule1 h[ev]1 x is wise to c\nt on ! plant enl>g+ to n less ?an twice its orig9al size1 z (t5 ! dim5sions h to be increas$ f\r & ev5 six times ^? f\nd suffici5t at ! beg9n+4 ,illu/ration3 ,,fig4 #b1gaj4--,section ( ! c5tral /ation or electricity works at ,d]by1 %[+ boil] & eng9e room & arrangem5t ( bunk]s1 conveyor1 a% pit1 grates1 boil]s 7drum1 heat+ surface & sup]heat]71 economiz]1 flue1 turb9es1 cond5s] pumps1 etc42 also location ( swit*bo>d gall]y & sy/em ( pip+4 ,ques4 ,:at tr\ble is likely to be enc\nt]$ ) an illy locat$ plant aft] x is 9 op]ation8 ,ans4 ,x may be consid]$ a nuisance by ^? resid+ 9 ! vic9ity1 occasion+ _m compla9ts4 ,illu/ration3 ,,fig4 #b1gaa4--,view ( old & new ,wat]side /ations4 ,! new /ation at ! "r has an all turb9e equipm5t ( t5 units1 "s ,curtis & "s ,p>sons ma*9es1 two h a capacity ( #ad1jjj kw41 & ! rema9+ eight are ( #ab1jjj kw4 ea*4 ,! old ,riv]side /ation1 se5 at ! left is describ$ on page #aidj4 ,?us1 if ! plant be plac$ 9 a resid5tial section ( ! community ! smoke1 noise & vibration ( ! ma*9es may become a nuisance to ! surr\nd+ inhabitants1 & ev5tually end 9 suits = damage aga9/ ! company responsible = ! same4 ,= ^! & ! o!r reasons j giv5 a company is sometimes =c$ to disreg>d entirely ! location ( a c5tral /ation ne> ! c5t] ( gravity ( ! sy/em1 & build at a consid]able di/ance2 su* a proce$+ w\ld1 if ! di/ance be great1 necessitate ! in/allation ( a high pressure sy/em4 ,!re might1 h[ev]1 be c]ta9 local laws 9 =ce re/rict+ ! use ( high pressure curr5ts on acc\nt ( ! dang] result+ to life1 t w\ld prev5t ?is solution ( ! problem4 ,9 su* cases !re c\ld und\bt$ly be f\nd "s site :]e ! objections previ\sly not$ w\ld be tol]at$2 ?us1 !re w\ld naturally be little objection to locat+ next to a /able1 a brew]y1 or a factory ( any description4 ,ques4 ,:y is ! matt] ( wat] supply important = a c5tral /ation8 ,ans4 ,because1 9 a /eam driv5 plant1 wat] is us$ 9 ! boil]s = ! production ( /eam by boil+1 & if ! eng9es be ( ! cond5s+ type x is also us$ 9 !m = creat+ a vacuum into :i* ! exhau/ /eam passes s z to increase ! effici5cy ( ! eng9e above :at x w\ld be if ! exhau/ /eam 7 oblig$ to dis*>ge into ! comp>atively high pressure ( ! atmosph]e4 ,! =ce ( ?is w be app>5t by consid]+ t ! wat] consumption ( ! eng9e ord9>ily is f #ae to #be lbs4 ( fe$ wat] p] horse p[] p] h\r1 & ! am\nt ( circulat+ wat] requir$ to ma9ta9 ! vacuum is ab\t #be to #cj times ! fe$ wat]1 & 9 ! case ( turb9es ) _! #bh or #bi in* vacuum1 mu* m4 ,= in/ance1 a #a1jjj horse p[] plant runn+ on #ae lbs4 ( fe$ wat] & #cj to #a circulat+ wat] w\ld require 7#a1jjj #ae7 7#cj #a7 #dfe1jjj lbs4 or #ee1hbb gals4 p] h\r at full capacity4 ,ques4 ,besides price :at o!r consid]ations are important ) respect to wat]8 ,ans4 ,its quality & ! possibility ( a sc>city ( supply4 ,x is q necess>y t ! wat] us$ 9 ! boil]s %\ld be z free z possible f impurities1 s z to prev5t ! deposition )9 !m ( any scale or s$im5ts4 ,! quality ( ! wat] us$ = cond5s+ purposes1 h[ev]1 is n q s important1 al?\gh ! pur] x is ! bett]4 ,if ! plant is to be locat$ 9 a city1 ! matt] ( wat] supply ne$ n g5]ally be consid]$1 because1 z a rule1 x c be obta9$ f ! wat]works2 !re w !n1 ( c\rse1 be a wat] tax to consid] & ?is1 if l>ge1 may w>rant an ef=t be+ made to obta9 ! wat] 9 "s o!r way4 ,9 any ev5t1 h[ev]1 ! possibility ( a sc>city 9 ! supply %\ld be r$uc$ to a m9imum4 ,if ! plant be locat$ 9 ! c\ntry1 "s natural s\rce ( wat] w\ld be utiliz$ unless ! place be suppli$ ) wat]works1 :i* is n g5]ally ! case4 ,x is usual1 h[ev]1 to f9d a /ream1 lake or pond 9 ! vic9ity1 b if none su* be conv5i5tly ne>1 an artesian or o!r =m ( well mu/ be sunk4 ,if abundance ( wat] exi/ 9 ! vic9ity ( ! propos$ in/allation1 n only w\ld ! location ( ! plant be gov]n$ !reby1 b ! k9d ( p[] to be us$ = its op]ation w\ld dep5d !reon4 ,?us1 if ! quantity ( ! wat] 7 suffici5t ?r\gh\t ! entire ye> to supply ! necess>y p[]1 wat] :eels might be in/all$ & us$ 9 place ( boil]s & /eam eng9es = driv+ ! g5]ators4 ,! /ation w\ld !n1 ( c\rse1 be situat$ close to ! wat]fall1 reg>dless ( ! c5t] ( gravity ( ! sy/em4 ,illu/ration3 ,,fig4 #b1gab4--,view illu/rat+ ! location ( a /ation z gov]n$ by ! pres5ce ( a wat] falls4 ,9 su* cases ! natural wat] p[] may be at a consid]able di/ance f ! c5t] ( gravity ( ! di/ribution sy/em because ( ! sav+ 9 g5]ation4 ,9 ! case ( long di/ance transmission v high pressure may be us$ & a trans=m] /ep d[n sub-/ation be locat$ at or ne> ! c5t] ( gravity ( ! sy/em1 ?us consid]ably r$uc+ ! co/ ( copp] = ! transmission l9e4 ,ques4 ,:at %\ld be not$ ) respect to ! coal supply8 ,ans4 ,! facility = transport+ ! coal f ! supply po9t to ! boil] room4 ,9 ?is connection1 an admirable location1 o!r conditions p]mitt+1 is adjac5t to a railway l9e or wat] front s t coal deliv]$ by c> or boat may be unload$ directly into ! b9s supply+ ! boil]s4 ,if ! coal be br\ght by tra91 a side or bran* track w usually be f\nd conv5i5t1 & ?is w usually r5d] any c>t+ ( ! fuel entirely unnecess>y4 ,9 :atev] way ! coal is to be suppli$1 ! liability ( a %ortage due to traffic or navigation be+ clos$ at any "t ( ! ye> %\ld be well look$ into1 z %\ld also ! facility = ! removal ( a%es1 be=e decid+ ^u ! f9al location = ! plant4 ,illu/ration3 ,,fig4 #b1gac4--,view ( a /ation admirably locat$ ) respect to transportation ( ! coal supply4 ,z %[n1 ! coal may be obta9$ ei!r by boat or rail1 & ) mod]n ma*9]y = convey+ ! coal to ! int]ior ( ! /ation1 ! transportation co/ is r$uc$ to a m9imum4 ,illu/ration3 ,,fig4 #b1gad4--;,floor plan ( "p ( ! turb9e c5tral /ation erect$ by ! ,bo/on ,edison ,co41 %[+ two #e1jjj kw4 ,curtis /eam turb9es 9 place4 ,! complete in/allation conta9s twelve #e1jjj kw4 ,curtis /eam turb9es1 a sectional elevation be+ %[n 9 fig4 #b1geh1 page #a1iga4 ,*oice ( ,sy/em4--,! *ief consid]ations 9 ! design ( a c5tral /ation are economy & capacity4 ,:5 ! curr5t has to be transmitt$ long di/ances = ei!r light+ or p[] purposes1 economy is atta9able only by r$uc+ ! weight ( ! copp] conductors4 ,?is c be accompli%$ only by ! use ( ! high voltage curr5ts obta9able f alt]nators4 ,aga91 :]e ! consum]s are locat$ )9 a radius ( two miles f ! c5tral /ation1 !reby requir+ a transmission voltage ( #eej volts or less1 dynamos may be employ$ ) great] economy4 ,alt]nat+ curr5t possesses s]i\s disadvantages = c]ta9 important applications4 ,= in/ance1 9 op]at+ electric railways & = light+ x is (t5 necess>y to transmit direct curr5t at #ejj volts a di/ance ( five or t5 miles4 ,9 su* cases1 ! excessive drop _c be economically r$uc$ by increas+ ! sizes ( ! l9e wire1 :ile a suffici5t increase ( ! voltage w\ld cause s]i\s v>iations "u *anges ( load4 ,h5ce1 x is common practice to employ "s =m ( auxili>y g5]ator or boo/]1 :i* :5 connect$ 9 s]ies ) ! fe$]1 automatically ma9ta9s ! requir$ pressure 9 ! mo/ remote di/ricts s long z ! ma9 g5]ators cont9ue to furni% ! normal or work+ voltage4 ,! advantage ( a direct curr5t in/allation 9 su* cases ov] a simil> plant supply+ alt]nat+ curr5t l9e is ! fact t a /orage batt]y may be us$ 9 connection ) ! =m] = tak+ up ! fluctuations ( ! curr5t1 !reby p]mitt+ ! dynamo to run ) a less v>iable load1 & consequ5tly at high] effici5cy4 ,ques4 ,"n "s s]vices requir+ direct curr5t4 ,ans4 ,direct curr5t is requir$ = c]ta9 k9ds ( electrolytic "w1 su* z electro-plat+1 ! electrical sep>ation ( metals1 etc41 also ! *>g+ ( /orage batt]ies = electric automobiles4 ,illu/ration3 ,,fig4 #b1gae4--;,example ( c5tral /ation locat$ remote f ! di/ribut+ c5t] & furni%+ alt]nat+ curr5t at high pressure to a sub-/ation :]e ! curr5t is pass$ ?r\gh /ep d[n trans=m]s & suppli$ at mod]ate pressure to ! di/ribution sy/em4 ,9 "s cases ! sub-/ation conta9s also conv]t]s supply+ direct curr5t = batt]y *>g+1 electro-plat+1 etc4 ,ques4 ,h[ is direct curr5t suppli$8 ,ans4 ,sometimes ! c5tral /ation is equipp$ ) suitable app>atus = supply+ bo? direct & alt]nat+ curr5t4 ,?is may be accompli%$ 9 sev]al diff]5t ways3 ,by in/all+ bo? direct & alt]nat+ curr5t g5]ators 9 ! c5tral /ation2 by ! use ( d\ble curr5t g5]ators or dynamotors1 f :i* direct curr5t may be tak5 f "o side & alt]nat+ curr5t f ! o!r side2 or by in/all+1 9 ! sub-/ation ( an alt]nat+ curr5t c5tral /ation1 9 addition to ! trans=m]s usually plac$ !re91 a rot>y conv]t] = *ang+ or conv]t+ alt]nat+ curr5t into direct curr5t4 ,?us1 x is evid5t t ! "* ( a c5tral /ation w be gov]n$ to a great ext5t by ! class ( s]vices to be suppli$4 ,an exception to ?is is :]e ! entire output has to be transmitt$ a long di/ance to ! po9t ( utilization4 ,9 su* cases a copp] economy dem&s ! use ( high t5sion alt]nat+ curr5t1 & its di/ribution to consum]s may be made directly by means ( /ep d[n trans=m]s m\nt$ ne> by or )9 ! consum]s' premises1 or x may be trans=m$ into l[ voltage alt]nat+ curr5t by a conv5i5tly locat$ sub-/ation4 ,:]e ! curr5t is to be us$ *iefly = light+ & !re are only a few or no motors to be suppli$1 ! *oice betwe5 direct curr5t & alt]nat+ curr5t w dep5d greatly ^u ! size ( ! in/allation1 direct curr5t be+ pref]able = small in/allations & alt]nat+ curr5t = l>ge in/allations4 ,if ! curr5t is to be us$ prim>ily = op]at+ ma*9]y1 su* z elevators1 travell+ cranes1 ma*9e tools & o!r devices ( a simil> "*1 :i* h to be op]at$ int]mitt5tly & at v>y+ spe$s & loads1 direct curr5t is ! m suitable2 b if ! motors p]=m+ su* "w c be op]at$ cont9u\sly = _m h\rs at a "t "u practically con/ant loads1 z1 = in/ance 9 ! g5]al "w ( a pump+ /ation1 alt]nat+ curr5t may be employ$ ) advantage4 ,illu/ration3 ,,fig4 #b1gaf4--;,diagram illu/rat+ div]sity factor4 ,by def9ition div]sity factor comb9$ actual maximum dem& ( a gr\p ( cu/om]s divid$ by ! sum ( _! individual maximum dem&s4 ,example1 a cu/om] has fifty 7#ej7 watt lamps &1 ( c\rse1 ! sum ( ! individual maximum dem&s ( ! lamps is #b4e kw4 watts 7connect$ load74 ,! cu/om]'s maximum dem&1 h[ev]1 is #a4e kw4 ,h5ce1 ! div]sity factor,a ( ! cu/om]'s gr\p ( lamps is #a4e #b4e 4#f4 ,9 ! diagram ! ord9ates ( ! curves %[ ! ratio maximum dem& to connect$ load = v>i\s k9ds ( electric light+ s]vice 9 ,*icago4 ,a ,,note4--,! div]sity factor ( a cu/om]'s gr\p ( lamps1 namely1 ! ratio ( maximum dem& to connect$ load is usually call$ ! dem& factor ( ! cu/om]4 ,size ( ,plant4--,be=e any def9ite calculation c be made1 or plans drawn1 ! eng9e] mu/ det]m9e ! probable load4 ,?is is usually asc]ta9$ 9 t]ms ( ! numb] & di/ances ( lamps t w be requir$1 by mak+ a ?or\gh canvass ( ! city or t[n1 or t portion = :i* electrical en]gy is to be suppli$4 ,! probable load t ! /ation is to c>ry :5 x beg9s op]ation1 ! nature ( ?is load1 & ! probable rate ( increase are matt]s ^u :i* ! design & con/ruction *iefly dep5d4 ,illu/ration3 ,,fig4 #b1gag4--,load curve = "o day4 ,ques4 ,:at is ! nature ( ! load c>ri$ by a c5tral /ation8 ,ans4 ,x fluctuates ) ! "t ( day & also ) ! "t ( ye>4 ,ques4 ,h[ is a fluctuat+ load be/ repres5t$8 ,ans4 ,graphically1 t is to say by means ( a curve plott$ on coord9ate pap] ( :i* ord9ates repres5t load values & ! correspond+ absciss "t values1 z 9 ! accompany+ curves4 ,:at is ! nature ( a p[] load8 ,ans4 ,:]e electricity is suppli$ = p[] purposes to a numb] ( factories1 ! load is fairly /eady1 dropp+1 ( c\rse1 dur+ meal h\rs4 ,9 ! case ( traction1 ! av]age value ( ! load is fairly /eady b !re are mom5t>ily viol5t fluctuations due to />t+ c>s or tra9s4 ,illu/ration3 ,,fig4 #b1gah4--,load curve = "o ye>4 ,ques4 ,:at is ! peak load8 ,ans4 ,! maximum load :i* has to be c>ri$ by ! /ation at any "t ( day or night z %[n by ! highe/ po9t ( ! load curve4 ,ques4 ,def9e ! load factor4 ,ans4 ,! ma*9]y ( ! /ation evid5tly mu/ be l>ge en\gh to c>ry ! peak load1 & !re=e consid]ably 9 excess ( t requir$ = ! av]age dem&4 ,! ratio ( ! av]age to ! maximum load is call$ ! load factor4 ,!re are two k9ds ( load factor3 ! annual1 & ! daily4 ,! annual load factor is obta9$ z a p]c5tage by multiply+ ! numb] ( units sold 7p] ye>7 by #ajj1 & divid+ by ! product ( ! maximum load & ! numb] ( h\rs 9 ! ye>4 ,! daily load factor is obta9$ by tak+ ! figures = #bd h\rs in/ead ( a ye>4 ,illu/ration3 ,,fig4 #b1gai4--,load curve ( plant supply+ p[] = ! op]ation ( motors 9 a manufactur+ di/rict4 ,! horizontal dott$ l9es %[ suitable p[] rat+s4 ,a prop]ly design$ /eam plant has a l>ge ov]load capacity1 a hydraulic plant has a small ov]load capacity1 & a gasol9e eng9e plant has no ov]load capacity4 ,accord+ly1 ! peak ( ! load 7maximum load7 may be #be or #cj p] c5t4 9 excess ( ! rat$ capacity ( a /eam plant1 n m ?an #e or #aj p] c5t4 9 excess ( ! rat$ capacity ( a hydraulic plant1 n at all 9 excess ( ! rat$ capacity ( a gas eng9e plant4 ,ques4 ,:at mu/ be provid$ 9 addition to ! ma*9]y requir$ to supply ! peak load8 ,ans4 ,additional units mu/ be in/all$ = use 9 case ( repairs or break d[n ( "s ( ! o!r units4 ,,example4--,:at w\ld be ! boil] horse p[] requir$ to g5]ate #e1jjj kw4 "u ! foll[+ conditions3 ,effici5cy ( g5]ators #he2 effici5cy ( eng9es #ij2 fe$ wat] ( eng9es & auxili>ies #ae lbs4 p] ,i4 ,h4 ,p42 boil] pressure #age lbs42 temp]ature ( fe$ wat] #aej ,fahr8 ,) a rate ( combu/ion ( #ae lbs4 ( coal p] sq4 foot ( grate p] h\r & an evaporation 7f & at #bab7 ( #h lbs4 ( wat] p] lb4 ( coal1 :at area ( grate w\ld be requir$ & h[ mu* heat+ surface8 #e1jjj kw4 #e1jjj 4#gdf #f1gjb electrical horse p[] ,to obta9 ?is electrical horse p[] ) alt]nators ^: effici5cy is #he requires #f1gjb 4#he #g1hhe brake horse p[] at ! eng9e ,?is1 ) me*anical effici5cy ( #ij is equival5t to #g1hhe 4#i #h1gfa indicat$ horse p[] ,s9ce #ae lbs4 ( fe$ wat] are requir$ = ! eng9es & auxili>ies p] indicat$ horse p[] p] h\r1 ! total fe$ wat] or evaporation requir$ to g5]ate #e1jjj kw4 is #ae #h1gfa #aca1dae lbs4 p] h\r4 t is to say1 ! boil]s mu/ be ( suffici5t capacity to g5]ate #aca1dae lbs4 ( /eam p] h\r f wat] at a temp]ature ( #aej ,fahr4 ,?is mu/ be multipli$ by ! factor ( evaporation = /eam at #age lbs4 pressure f fe$ wat] at a temp]ature ( #aej1 9 ord] to get ! equival5t evaporation f & at #bab4 ,! =mula = ! factor ( evaporation is ,h - h factor ( evaporation ------- 7#a7 #ife4g 9 :i* ,h total heat ( /eam at ! obs]v$ pressure2 h total heat ( fe$ wat] ( ! obs]v$ temp]ature2 #ife4g lat5t heat1 ( /eam at atmosph]ic pressure4 ,sub/itut+ 9 7#a7 values = ! obs]v$ pressure & temp]ature z obta9$ f ! /eam table #a1aig - #aah factor ( evaporation ------------ #a4aag #ife4g = :i* ! equival5t evaporation f & at #bab is #aca1dae #a4aag #adf1gia lbs4 p] h\r ,,factors ,,( ,,evaporation ---------------------------------------- -------------------------- ,temp ( ,,/eam ,,pressure ,,by ,,gauge fe$ wat]4 ---------------------------------------- ----- ,deg4 ,fahr4 #ej #fj #gj #hj #ij #ajj #aaj #abj #acj ---------------------------------------- ------------------ #cb #a4bada4bafa4bbja4bbba4bbea4bbga4bbia4bc aa4bcb #dj #a4bjfa4bjia4baba4bada4bafa4baia4bbja4bb ba4bbd #ej #a4aiea4aiga4bjaa4bjda4bjfa4bjha4baja4ba ba4bad #fj #a4ahea4ahha4aiaa4aica4aifa4aiha4bjja4bj ba4bjc #gj #a4agea4agha4ahja4ahca4ahea4ahga4ahia4ai aa4aic #hj #a4afda4afga4agja4agca4agea4agga4agia4ah aa4ahc #ij #a4aeda4aega4afja4afba4afea4afga4afia4ag ja4agb #ajj #a4adda4adga4aeja4aeba4aeda4aefa4aeha4af ja4afb #aaj #a4acca4acfa4acia4adba4adda4adfa4adha4ae ja4aeb #abj #a4abca4abfa4abia4acaa4acca4acfa4acha4ad ja4ada #acj #a4aaca4aafa4aaha4abaa4abca4abea4abga4ab ia4acj #adj #a4ajba4ajea4ajha4aaja4aaca4aaea4aaga4aa ia4abj #aej #a4jiaa4jiea4jiha4ajja4ajba4ajda4ajfa4aj ha4aaj #afj #a4jhaa4jhda4jhga4jija4jiba4jida4jifa4ji ha4ajj #agj #a4jgja4jgda4jgga4jgia4jhaa4jhca4jhea4jh ga4jhi #ahj #a4jfja4jfca4jffa4jfia4jgaa4jgca4jgea4jg ga4jgi #aij #a4jeja4jeca4jefa4jeha4jfja4jfca4jfea4jf fa4jfh #bjj #a4jcia4jdca4jdea4jdha4jeja4jeba4jeda4je fa4jeh #baj #a4jbia4jcba4jcea4jcga4jdja4jdba4jdda4jd fa4jdg ---------------------------------------- ------------------ ,temp ( ,,/eam ,,pressure ,,by ,,gauge fe$ wat]4 ---------------------------------------- ----- ,deg4 ,fahr4 #adj #aej #afj #agj #ahj #aij #bjj #baj #bbj ---------------------------------------- ------------------ #cb #a4bcda4bcfa4bcga4bcia4bdja4bdaa4bdca4bd da4bde #dj #a4bbfa4bbga4bbia4bcja4bcba4bcca4bcda4bc fa4bcg #ej #a4baea4baga4baha4bbja4bbaa4bbca4bbda4bb ea4bbf #fj #a4bjea4bjga4bjha4baja4baaa4baba4bada4ba ea4baf #gj #a4aida4aifa4aiga4aiia4bjja4bjba4bjca4bj ea4bjf #hj #a4ahda4ahfa4ahga4ahia4aija4aiba4aica4ai da4aie #ij #a4agda4agfa4agga4agia4ahja4ahaa4ahca4ah da4ahe #ajj #a4afda4afea4afga4afha4agja4agaa4agba4ag da4age #aaj #a4aeca4aeea4aefa4aeha4aeia4afja4afba4af ca4afd #abj #a4adca4adea4adfa4adga4adia4aeja4aeaa4ae ca4aed #acj #a4acba4acda4acfa4acga4acha4adja4adaa4ad ba4add #adj #a4abba4abda4abea4abga4abha4abia4acaa4ac ba4acc #aej #a4aaaa4aaca4aaea4aafa4aaha4aaia4abja4ab aa4abc #afj #a4ajaa4ajca4ajda4ajfa4ajga4ajha4aaja4aa aa4aab #agj #a4jiaa4jiba4jida4jiea4jiga4jiha4jiia4aj aa4ajb #ahj #a4jhja4jhba4jhca4jhea4jhfa4jhha4jhia4ji ja4jia #aij #a4jgja4jgaa4jgca4jgda4jgfa4jgga4jgha4jh ja4jha #bjj #a4jeia4jfaa4jfca4jfda4jfea4jfga4jfha4jf ia4jga #baj #a4jdia4jeaa4jeba4jeca4jeea4jefa4jega4je ia4jfj ---------------------------------------- ------------------ ,temp4 ( ,,/eam ,,pressure ,,by ,,gauge fe$ wat]4 ---------------------------------------- ----- ,deg4 ,fahr4 #bcj #bdj #bej #bfj #bgj #bhj #bij #cjj ---------------------------------------- ------------------ #cb #a4bdfa4bdga4bdha4beja4beaa4beba4beca4be d #dj #a4bcha4bcia4bdja4bdaa4bdba4bdca4bdda4bd e #ej #a4bbha4bbia4bcja4bcaa4bcba4bcca4bcda4bc e #fj #a4baga4baha4baia4bbja4bbaa4bbba4bbca4bb d #gj #a4bjga4bjha4bjia4baja4baaa4baba4baca4ba d #hj #a4aifa4aiha4aiia4bjja4bjaa4bjba4bjca4bj d #ij #a4ahfa4ahga4ahha4ahia4aija4aiaa4aiba4ai c #ajj #a4agfa4agga4agha4agia4ahja4ahaa4ahba4ah c #aaj #a4affa4afga4afha4afia4agja4agaa4agba4ag c #abj #a4aeea4aefa4aega4aeha4aeia4afja4afaa4af b #acj #a4adea4adfa4adga4adha4adia4aeja4aeaa4ae b #adj #a4acda4acea4acfa4acga4acha4acia4adja4ad a #aej #a4abda4abea4abfa4abga4abha4abia4acja4ac a #afj #a4aaca4aaea4aafa4aaga4aaha4aaia4abja4ab a #agj #a4ajca4ajda4ajea4ajfa4ajga4ajha4ajia4aa j #ahj #a4jica4jida4jiea4jifa4jiga4jiha4jiia4aj j #aij #a4jhba4jhca4jhda4jhea4jhfa4jhga4jhha4jh i #bjj #a4jgba4jgca4jgda4jgea4jgfa4jgga4jgha4jg i #baj #a4jfaa4jfba4jfca4jfda4jfea4jffa4jfga4jf h ---------------------------------------- ------------- ,"o boil] horse p[] be+ equal to an evaporation ( #cd lbs4 ( wat] f a fe$ wat] temp]ature ( #bab ,fahr41 into /eam at ! same temp]ature1 ! boil] capacity is accord+ly #adh1aje #cd4e #d1bic boil] horse p[]4 ,! rate ( evaporation is giv5 at #h lbs4 ( wat] 7f & at #bab ,fahr471 = :i* ! fuel requir$ is #adh1aje #h #ah1eac lbs4 ( coal p] h\r4 ,= a rate ( combu/ion ( #ae lbs4 ( coal p] h\r p] squ>e foot ( grate1 grate area #ah1eac #ae #a1bcd sq4 ft4 ,= /ation>y boil]s ! usual ratio ( heat+ surface to grate area is #ce3a1 accord+ly ! heat+ surface correspond+ to ?is ratio is #a1bcd #ce #dc1aij sq4ft4 ,! above calculation is bas$ on a rate ( evaporation ( #h lbs4 ( wat] p] lb4 ( coal & a rate ( combu/ion ( #ae lbs4 ( coal p] sq4 ft4 ( grate4 ,= o!r rates ! requir$ grate area may be obta9$ f ! foll[+ table3 ---------------------------------------- ------------------------------ ,,grate ,,surface ,,p] ,,horse ,,p[] 7,,k5t7 ---------------------------------------- --------------------------- ,p\nds ( ,lbs4 ,p\nds ( coal burn$ p] squ>e foot ( wat] ( grate p] h\r f coal------------------------------------ & at p] #bab h4p4 #h #aj #ab #ae #bj #be #cj #ce #dj p] p] p\nd h\r------------------------------------ ( ,squ>e feet grate p] horse p[] coal ---------------------------------------- ------------------- ,good coal #aj #c4de 4#dc4ce 4#bh 4#bc 4#ag 4#ad 4#aa 4#aj 4#ji & boil] #i #c4hc 4#dh 4#ch 4#cb 4#be 4#ai 4#ae 4#ac 4#aa 4#aj ,fair coal #h4fa #d4 4#ej 4#dj 4#cc 4#bf 4#bj 4#af 4#ac 4#ab 4#aj or boil] #h #d4ca 4#ed 4#dc 4#cf 4#bi 4#bb 4#ag 4#ad 4#ac 4#aa #g #d4ic 4#fb 4#di 4#da 4#cc 4#bd 4#bj 4#ag 4#ad 4#ab ,poor coal #f4i #e4 4#fc 4#ej 4#db 4#cd 4#be 4#bj 4#ag 4#ae 4#ac or boil] #f #e4ge 4#gb 4#eh 4#dh 4#ch 4#bi 4#bc 4#ai 4#ag 4#ad #e #f4i 4#hf 4#fi 4#eh 4#df 4#ce 4#bh 4#bc 4#bb 4#ag ,lignite &#c4de #aj4 #a4bea4jj 4#hc 4#fg 4#ej 4#dj 4#cc 4#bi 4#be poor boil] ---------------------------------------- ------------------- ,g5]al ,arrangem5t ( ,/ation4--,9 design+ an electrical /ation1 x is pref]able t :atev] rooms or divisions ( ! int]ior space are desir$ %\ld det]m9e ! total outside dim5sions ( ! plant 9 ! orig9al plans ( ! build+ ?an t ^! latt] dim5sions be fix$ & ! rooms1 etc41 be fitt$ 9 aft]w>d4 ,,sav+ ,,due ,,to ,,heat+ ,,! ,,fe$ ,,wat] ,table %[+ ! p]c5tage ( sav+ = ea* degree ( increase 9 temp]ature ( fe$ wat] heat$ by wa/e /eam4 ---------------------------------------- ------------------------------ ,init ,pressure ( /eam 9 boil]1 lbs4 p] sq4 in* above atmosph]e temp------------------------------------ ----------------------------- ( fe$ #j #bj #dj #fj #hj #ajj #abj #adj #afj #ahj #bjj ---------------------------------------- ------------------- #cb4jhgb4jhfa4jhee4jhea4jhdg4jhdd4jhda4j hci4jhcg4jhce4jhcc #dj 4#jhgh4jhfg4jhfa4jhef4jhec4jhej4jhdg4jhd e4jhdc4jhda4jhci #ej 4#jhhf4jhge4jhfh4jhfd4jhfj4jheg4jhed4jhe b4jhej4jhdh4jhdf #fj 4#jhid4jhhc4jhgf4jhgb4jhfg4jhfd4jhfb4jhe i4jhef4jhee4jhec #gj 4#jijb4jhij4jhhd4jhgi4jhge4jhgb4jhfi4jhf g4jhfd4jhfb4jhfj #hj 4#jiaj4jhih4jhia4jhhg4jhhc4jhgi4jhgg4jhg d4jhgb4jhgj4jhfh #ij 4#jiai4jijg4jijj4jhie4jhhh4jhhg4jhhd4jhh c4jhgi4jhgg4jhge #ajj 4#jibg4jiae4jijh4jijc4jhii4jhie4jhib4jhi j4jhhg4jhhe4jhhc #aaj 4#jicf4jibc4jiaf4jiaa4jijg4jijc4jijj4jhi h4jhie4jhic4jhia #abj 4#jide4jicb4jibe4jiai4jiae4jiaa4jijh4jij f4jijc4jija4jhii #acj 4#jied4jida4jicd4jibh4jibd4jibj4jiag4jia d4jiab4jiji4jijg #adj 4#jifc4jiej4jidc4jicg4jicb4jibi4jibe4jib c4jibj4jiah4jiaf #aej 4#jigc4jiei4jiea4jidf4jida4jicg4jicd4jic a4jibi4jibf4jibd #afj 4#jihb4jifh4jifa4jiee4jiej4jidf4jidc4jid j4jicg4jice4jicc #agj 4#jiib4jigh4jigj4jifd4jiei4jiee4jieb4jid i4jidf4jidd4jida #ahj 4#ajjb4jihh4jiha4jigc4jifi4jife4jifa4jie h4jiee4jiec4jiea #aij 4#ajab4jiih4jihi4jihc4jigh4jigd4jiga4jif h4jifd4jjfb4jifj #bjj 4#ajbb4ajjh4jiii4jiic4jihh4jihd4jihj4jig g4jigd4jigb4jifi #baj 4#ajcc4ajah4ajaj4ajjc4jiih4jiid4jiij4jih g4jihd4jiha4jigi #bbj -- 4#ajbi4ajai4ajac4ajjh4ajjd4ajjj4jiig4jii d4jiia4jihi #bcj -- 4#ajci4ajca4ajbd4ajah4ajab4ajaj4ajjg4ajj c4ajja4jiii #bdj -- 4#ajej4ajda4ajcd4ajbi4ajbd4ajbj4ajag4aja d4ajaa4ajji #bej -- 4#ajfb4ajeb4ajde4ajdj4ajce4ajca4ajbg4ajb e4ajbb4ajai ---------------------------------------- ------------------- ,,note4--,an approximate rule = ! conditions ( ord9>y practice is a sav+ ( #a p] c5t4 made by ea* increase ( #aa 9 ! temp]ature ( ! fe$ wat]4 ,?is corresponds to 4#jiji p] c5t4 p] degree4 ,! calculation ( sav+ is made z foll[s3 ,boil] pressure1 #ajj lbs4 gauge2 total heat 9 /eam above #cb #a1ahe ,b4,t4,u4 fe$ wat]1 orig9al temp]ature #fj1 f9al temp]ature #bji;,f4 ,increase 9 heat units1 #aej4 ,heat units above #cb 9 fe$ wat] ( orig9al temp]ature #bh4 ,heat units 9 /eam above t 9 cold fe$ wat]1 #a1ahe-bh #a1aeg4 ,sav+ by ! fe$ wat] heat] #aej #a1aeg #ab4if p] c5t4 ,! same result is obta9$ by ! use ( ! table4 ,increase 9 temp]ature #aej tabul> figure 4#jhfd #ab4if p] c5t4 ,let total heat ( #a lb4 ( /eam at ! boil] pressure ,h2 total heat ( #a lb4 ( fe$ wat] be=e ent]+ ! heat] h'1 & aft] pass+ ?r\gh ! heat] h''2 !n ! sav+ made by ! heat] is 7h''-h'7 7,h-h'74 ,"u usual conditions ! plans ( an electrical /ation are readily drawn1 z !y are g5]ally ( a simple nature4 ,! eng9es & g5]ators w occupy ! majority ( ! space1 & ^! are usually plac$ 9 "o l>ge room2 9 "s /ations1 h[ev]1 !y are locat$ respectively 9 two adjac5t rooms4 ,! boil]s are g5]ally locat$ 9 a room ap>t f ! eng9es & dynamos1 & 9 "s cases a sep>ate build+ is provid$ = !m2 ! pumps1 etc41 mu/ be in/all$ n f> f ! boil]s1 & space mu/ also be all[$ ne> ! boil]s = coal & a%es4 ,illu/ration3 ,,fig4 #b1gbj4--;,floor plan ( an electrical /ation hav+ a belt$ drive ) c\nt] %aft4 ,fig4 #b1gbj %[s ! floor plan ( an electrical /ation1 9 :i* a c\nt]%aft & belt$ connections are us$ betwe5 ! eng9es & g5]ators4 ,ref]r+ fir/ to ! plan ( ! build+ itself1 ,a repres5ts ! eng9e & dynamo room1 ,b d5otes ! boil] room1 ,c ! (fice1 ,d ! /ore room1 & ,e ! *imney connect$ ) ! boil]s by means ( ! uptake w4 ,ref]r+ next to ! app>atus in/all$1 ,s1 ,s1 ,s1 ,s repres5ts a batt]y ( f\r boil]s2 ^! are connect$ by /eam pip+ ,,vv to ! two /eam eng9es1 ,m & ,m1 :i* are belt$ to ! c\nt]%aft ,o4 ,belt$ to ! c\nt]%aft are ! g5]ators1 ,t1 ,t1 ,t1 ,t1 ! circuits f :i* are controll$ on ! swit*bo>d1 ,h4 ,ques4 ,:at are ! objections to ! arrangem5t %[n 9 fig4 #b1gbj48 ,ans4 ,! l>ge space requir$ by ! belt drive especially 9 locations :]e l& is exp5sive4 ,ano!r objection is ! frictional loss due to ! belt drive ) its c\nt]%aft1 etc4 ,illu/ration3 ,,fig4 #b1gba4--;,elevation ( /ation hav+ a belt$ drive ) c\nt]%aft1 z %[n 9 plan 9 fig4 #b1gbj4 ,ques4 ,:at are ! desirable features ( ! belt drive8 ,ans4 ,high spe$ g5]ators may be us$1 ?us r$uc+ ! fir/ co/1 & ! multiplicity ( spe$s & flexibility ( ! sy/em result+ f ! use ( a friction clut*4 ,?us 9 fig4 #b1gbj1 ea* pulley may be m\nt$ on ! c\nt] %aft ,o ) a friction clut*4 ,a jaw clut* may also be provid$ at ,z1 ?us p]mitt+ ! %aft ,o to be divid$ into two sections4 ,x is !re=e possible by ?is arrangem5t to cause ei!r ( ! eng9es to drive any "o ( ! g5]ators1 or all ( !m1 or bo? ( ! eng9es to drive all ( ! g5]ators simultane\sly4 ,ques4 ,"u :at condition is ! c\nt] %aft belt drive p>ticul>ly valuable8 ,ans4 ,9 case ( a break d[n ( any "o ( ! eng9es or g5]ators1 & also :5 x becomes necess>y to clean !m )\t int]rupt+ ! s]vice4 ,illu/ration3 ,,fig4 #b1gbb4--,plan ( /ation arrang$ = ext5sion4 ,! space requir$ = a c5tral /ation dep5ds ^u ! numb] & k9d ( lights to be suppli$1 & ^u ! "* & arrangem5t ( ! ma*9]y4 ,9 calculat+ ! size ( build+ requir$1 two ?+s mu/ be c>efully consid]$3 fir/1 ! build+ mu/ be adapt$ to ! plant to be in/all$ 9 ! beg9n+2 & second1 x mu/ be arrang$ s t enl>gem5t c be made )\t dis>rang+ or int]f]+ ) ! plant already 9 exi/5ce4 ,?is is usually be/ secur$ by provid+ = expansion 9 "o or two def9ite directions1 ! build+ be+ made l>ge en\gh to accommodate additional units t w be necess>y at "s future "t because ( ! gr[? ( ! community & consequ5t increas$ dem& = electric curr5t4 ,ques4 ,h[ may ! design 9 fig4 #b1gbj be modifi$ = ! in/allation ( a /orage batt]y8 ,ans4 ,if a /orage batt]y be necess>y1 a p>tition may be con/ruct$ across ! room ,a1 z indicat$ by ! dott$ l9es1 & ! batt]y in/all$ 9 ! room ?us =m$4 ,illu/ration3 ,,fig4 #b1gbc4--;,int]ior ( old ,riv]side /ation %[+ at ! "r1 sev5 #f1jjj horse p[] alt]nators driv5 by reciprocat+ eng9es1 & at ! left1 a numb] ( turb9e units aggregat+ #ij1jjj horse p[]4 ,ques4 ,m5tion a few details 9 ! g5]al arrangem5t ( ! build+ fig4 #b1gbj4 ,ans4 ,two doors to ! room ,a may conv5i5tly be provid$ at ,k & ,l1 ! =m] connect+ ) ! boil] room ,b1 & ! latt] s]v+ z ! ma9 entrance to ! /ation4 ,!re is little t ne$ be add$ to :at has already be5 /at$ reg>d+ ! boil] room ,b4 ,! door at ,f provides = ! entrance ( coal & ! removal ( a%es1 :ile at ,p1 ! pump & heat]s may conv5i5tly be locat$4 ,9 ! (fice ,c1 visitors may be receiv$1 ! /ation reports made out1 bullet9s issu$ f "t to "t1 & :atev] eng9e]+ problems arise may "h be solv$ on pap] by ! eng9e] 9 *>ge ( ! plant4 ,! /ore room ,d w be f\nd conv5i5t = v>i\s supplies1 tools & appliances ne$$ 9 ! op]ation ( ! /ation4 ,^! may "h be kept "u lock & key & ! daily wa/e & loss result+ f c>elessness avoid$4 ,ques4 ,:at important po9t %\ld be not$ 9 locat+ ! eng9es & boil]s8 ,ans4 ,!y %\ld be s plac$ t ! pip+ betwe5 !m w be z %ort & direct z possible4 ,ques4 ,:y8 ,ans4 ,! /eam pipe %\ld be %ort to r$uce ! loss ( heat betwe5 eng9e & boil] to a m9imum1 & bo? %ort & direct to avoid undue friction & consequ5t drop 9 pressure ( ! /eam 9 pass+ ?r\gh ! pipe to ! eng9e4 ,entirely too little att5tion is giv5 to ?is matt] on ! "p ( design]s & x _c be too /rongly emphasiz$ t1 = economy1 ! /eam pipe betwe5 an eng9e & boil] %\ld be z %ort & direct z possible1 hav+ reg>d ( c\rse1 = prop] pip+ me?ods4 ,ques4 ,:at %\ld be provid$ = ! /eam pipe8 ,ans4 ,a heavy cov]+ ( approv$ mat]ial %\ld be plac$ ar\nd ! pipe to r$uce ! loss ( heat by radiation4 ,= ?is purpose hair felt1 m9]al wool & asbe/os are us$4 ,illu/ration3 ,,fig4 #b1gbd4--,view ( eng9e & cond5s]1 %[+ h[ to arrange ! pip+ to secure good vacuum4 ,locate ! cond5s] z ne> ! eng9e z possible2 use easy b5ds in/ead ( elb[s2 place ! pump bel[ bottom ( cond5s] s ! wat] w dra9 to pump4 ,at ,a is a relief valve1 = protection 9 case ! cond5s] become flood$ ?r\gh failure ( ! pump1 & at ,b is a gate valve to %ut (f cond5s] 9 case atmosph]ic exhau/ is desir$ to p]mit repairs to be made to cond5s] dur+ op]ation4 ,a wat] seal %\ld be ma9ta9$ on ! relief valve & special att5tion %\ld be giv5 to ! /uff+ box ( ! gate valve to prev5t air leakage4 ,! dis*>ge valve ( ! pump %\ld be wat] seal$4 ,ques4 ,h[ %\ld ! pip+ be arrang$ betwe5 ! eng9e & cond5s]1 & :y8 ,ans4 ,x %\ld be z %ort & direct z possible2 especially %\ld elb[s be avoid$ s t ! back pressure on ! eng9e pi/on w be r$uc$ z ne> z c be to t ( ! cond5s]4 ,t is to say1 9 ord] to get ne>ly ! full effect ( ! vacuum 9 ! cond5s] ! frictional resi/ance ( ! pip+ %\ld be r$uc$ to a m9imum4 ,:]e #ij turns are necess>y1 easy b5ds %\ld be us$ in/ead ( %>p elb[s4 ,! =ce ( ?is argum5t mu/ be app>5t by not+ ! practice ( /eam turb9e build]s ( plac+ ! turb9e "r up aga9/ ! cond5s]1 & rememb]+ t a high vacuum is necess>y to ! economical work+ ( a turb9e4 ,see fig4 #a1dde1 page #a1ahb4 ,ques4 ,:at are ! consid]ations respect+ ! numb] & type ( eng9e to be us$8 ,ans4 ,9 ! illu/ration fig4 #b1gbj1 two eng9es ,m & ,m' are employ$1 "o belt$ to ea* end ( ! c\nt]%aft ,o4 ,^! eng9es %\ld be ( simil> or id5tical patt]n2 = a small output !y may be ei!r simple or comp\nd1 z ! conditions ( fuel exp5diture may dictate1 b if ! output be l>ge1 triple expansion eng9es or turb9es are advisable4 ,illu/ration3 ,,fig4 #b1gbe4--;,dry pipe = horizontal boil]3 x is connect$ to ! ma9 outlet & its upp] surface is p]=at$ ) small holes1 ! f> end be+ clos$4 ,) ?is arrangem5t /eam is tak5 f ! boil] ov] a l>ge area1 s t x w conta9 v little moi/ure4 ,all horizontal boil]s )\t a dome %\ld be fitt$ ) a dry pipe2 mo/ eng9e]s d n realize ! importance ( obta9+ dry /eam = eng9e op]ation4 ,corliss or simil> sl[ spe$ eng9es may advantage\sly be us$ 9 ei!r case4 ,9 all cases ! eng9e %\ld be run cond5s+ unless ! co/ = circulat+ wat] is prohibitive2 ev5 9 su* cases cool+ t[]s may be in/all$ & effect a sav+4 ,9 op]ation1 dur+ ! great] "p ( ! day1 "o eng9e runn+ two or p]haps ?ree ( ! g5]ators1 w c>ry ! load1 b :5 ! load is p>ticul>ly heavy1 z 9 ! morn+ & ev5+1 bo? eng9es & all ! g5]ators may be requir$ to meet ! dem&s4 ,illu/ration3 ,,fig4 #b1gbf4--,me?od ( connect+ a head] to a batt]y ( boil]s4 ,:]e two or m boil]s are connect$ to a s+le head]1 ! use ( a reliable non-return boil] /op valve is necess>y1 & 9 "s c\ntries _! in/allation is compulsory4 ,a non-return boil] /op valve w in/antly close %\ld ! pressure 9 ! boil] to :i* x is atta*$ sudd5ly decrease bel[ t 9 ! head]1 & !reby prev5t ! entrance ( /eam f ! o!r boil]s ( ! batt]y4 ,?is sudd5 decrease 9 pressure may be caus$ by a ruptur$ fitt+ or ! bl[+ out ( a tube1 9 :i* ev5t an ord9>y /op valve tak+ ! place ( a non-return boil] /op valve w\ld be inadequate1 z ! loss ( /eam f ! o!r boil]s ( ! batt]y w\ld be trem5d\s be=e an ord9>y valve c\ld be rea*$ & clos$1 assum+ t x w\ld be possible to d s1 :i* 9 ! majority ( cases x is n4 ,%\ld x be desir$ to cut out a boil] = clean+ or repairs1 ! non-return boil] /op valve w n p]mit /eam to ent] ! boil] f ! head]1 ev5 %\ld ! h&:eel be op]at$ = ?is purpose1 z x _c be op5$ by h&1 b c1 h[ev]1 be clos$4 ,a non-return boil] /op valve %\ld be atta*$ to ea* boil] & connect$ to an angle valve on ! head]4 ,a pipe b5d %\ld be us$ = connect+ ! valves1 z ?is w all[ = expansion & contraction4 ,! pipe %\ld slope a trifle d[nw>d t[>d ! head] & a suitable dra9 provid$4 ,?is dra9 %\ld be op5$ & all wat] p]mitt$ to escape be=e ! angle valve is op5$1 !reby prev5t+ any damage due to wat] hamm]4 ,by ex]cis+ a little +5uity 9 %ift+ ! load on diff]5t ma*9es at diff]5t times1 bo? eng9es & dynamos1 may readily be clean$ & repair$ )\t int]rupt+ ! s]vice4 ,ques4 ,= economy :at k9d ( /eam %\ld be us$8 ,ans4 ,sup]-heat$ /eam4 ,! sav+ due to ! use ( sup]heat$ /eam is ab\t #a = e t5 degrees ,fahr4 ( sup]-heat4 ,x %\ld be us$ 9 all cases4 ,ques4 ,h[ %\ld ! ma*9es be locat$8 ,ans4 ,suffici5t space %\ld be all[$ betwe5 !m t clean+ & repair+ may be done easily1 quickly & effectually4 ,illu/ration3 ,,figs4 #b1gbg & #b1gbh4--,me?od ( prev5t+ vibration & ( support+ pipes4 ,! figures %[ top & side views ( a ma9 head] c>ri$ 9 suitable frames fitt$ ) adju/able roll]4 ,:ile ! pipe is illu/rat$ z re/+ on ! adju/able roll]s1 nev]!less ! roll]s may also be plac$ at ! sides or on top ( ! pipe to prev5t vibration1 or 9 cases :]e ! ?ru/ f a horizontal or v]tical bran* has to be provid$ =4 ,?is arrangem5t w take c>e ( ! vibration )\t 9 any way prev5t+ ! free expansion & contraction ( ! pipe4 ,ques4 ,h[ %\ld ! swit*bo>d be locat$8 ,ans4 ,9 fig4 #b1gbj1 ! swit*bo>d ,h is m\nt$ aga9/ ! wall divid+ ! room ,a f ! room ,b1 & is 9 l9e ) ! ma*9es4 ,! advantages aris+ f a swit*bo>d ?us in/all$ are1 t ! swit*bo>d att5dant work+ !reon c obta9 at any "t an unob/ruct$ view ( ! p]=mance ( ea* individual ma*9e1 & he has 9 consequ5ce a mu* bett] control ( !m2 !n1 too1 :ile he is engag$ at ! eng9es or g5]ators he c also see ! measur+ in/rum5ts on ! swit*bo>d1 & asc]ta9 approximately ! read+s ^u !m4 ,9 cases ( em]g5cy x is sometimes necess>y = ! eng9e] 9 *>ge ( a plant to be 9 sev]al places at ! same "t 9 ord] to prev5t an accid5t1 & t ?is seem+ly impossibility may be approximat$ z ne>ly z possible1 x is ess5tial t ! controll+ devices be locat$ z closely toge!r z is consi/5t1 & t no mov+ belt or pulley int]v5e betwe5 !m4 ,^! conditions are well satisfi$ 9 fig4 #b1gbj1 & ow+ to ! %ort di/ances betwe5 ! g5]ators & ! swit*bo>d ! drop ( voltage 9 ea* ( ! conduct+ wires betwe5 !m w be l[4 ,?is latt] advantage is wor?y ( notice 9 a /ation g5]at+ l>ge curr5ts at a l[ pressure4 ,to (fset ! advantages j m5tion$1 ! location ( ! swit*bo>d 9 l9e ) ! ma*9es introduces an elem5t ( dang] to ! swit*bo>d1 its app>atus1 & ! att5dant1 on acc\nt ( ! possible bur/+ ( a fly:eel or o!r p>ts ( ! ma*9es f c5trifugal =ce4 ,illu/ration3 ,,figs4 #b1gbi & #b1gcj4--,po9ts on plac+ /op valves4 ,! fir/ & mo/ important feature is to asc]ta9 :e!r ! valve w act z a wat] trap = cond5s$ /eam4 ,fig4 #b1gbi illu/rates a common error 9 ! plac+ ( valves1 z ?is arrangem5t p]mits ( an accumulation ( cond5s$ /eam above ! valve :5 clos$1 & %\ld ! eng9e] be c>eless & op5 ! valve sudd5ly1 s]i\s results might foll[ ow+ to wat]-hamm]4 ,fig4 #b1gcj illu/rates ! correct me?od ( plac+ ! valve4 ,x sometimes occurs1 h[ev]1 t x is n conv5i5t to place ! valve z %[n 9 fig4 #b1gcj & t fig4 #b1gbi is ! only mann] 9 :i* ! valve c be plac$4 ,9 su* cases1 ! valve %\ld h a dra91 & ?is dra9 %\ld always be op5$ be=e ! l>ge valve is op5$4 ,if ! swit*bo>d be plac$ 9 ! dott$ position at ,h'1 or1 9 fact1 at ! opposite end ( ! room ,a1 ! damage to life & prop]ty t might result f ! effects ( c5trifugal =ce w\ld be elim9at$1 b 9 place !re( w\ld be ! disadvantages ( an ob/ruct$ view ( ! ma*9es f ! swit*bo>d1 an ob/ruct$ view ( ! swit*bo>d f ! ma*9es1 inaccessibility betwe5 ^! two1 & a great] drop ( voltage 9 ! majority ( ! conduct+ wires betwe5 ! g5]ators & ! swit*bo>d4 ,ques4 ,describe a second arrangem5t ( /ation ) belt drive & comp>e x ) ! design %[n 9 fig4 #b1gbj4 ,illu/ration3 ,,fig4 #b1gca4--,plan ( electrical /ation ) belt drive )\t c\nt] %aft4 ,! in/allation "h repres5t$ consi/s ( two boil]s1 ,s1 etc41 & ?ree sets ( eng9es & g5]ators1 ,t1 ,m1 etc4 ,suffici5t all[ance has be5 made 9 ! plans1 h[ev]1 = future increase ( bus9ess1 z additional space has be5 provid$ = an extra eng9e & g5]ator set1 z indicat$ by ! dott$ l9es4 ,ans4 ,a floor plan some:at diff]5t f t pres5t$ 9 fig4 #b1gbj is %[n 9 fig4 #b1gca4 ,"h a belt drive is employ$1 b no c\nt]%aft is us$4 ,ea* g5]ator1 !re=e1 is dep5d5t ^u its respective eng9e1 & 9 consequ5ce ! flexibility obta9$ by ! use ( a c\nt]%aft is lo/4 ,on ! o!r h&1 !re is less loss ( me*anical p[] betwe5 ! eng9es & g5]ators 9 ! driv+ ( ! latt]1 & less floor space is necess>y 9 ! room ,a4 ,if1 h[ev]1 ! floor area ( ?is room be made ! same z 9 ! previ\s arrangem5t & ! same numb] ( ma*9es are to be in/all$1 !y may be spac$ fur!r ap>t1 af=d+ 9 consequ5ce consid]ably m room = clean+ & repair+ !m4 ,9 op]ation1 ! normal conditions %\ld be su* t any two ( ! eng9e & g5]ator sets may readily c>ry ! av]age load1 ! ?ird set to be us$ only z a res]ve ei!r to aid ! o!r two :5 ! load is unusually heavy or to replace "o ( ! o!r sets :5 x becomes necess>y to clean or repair ! latt]4 ,! swit*bo>d may p]haps be be/ locat$ at ,h1 z a simil> position on ! opposite side ( ! room ,a w\ld br+ x b5ea? "o or m ( ! /eam pipes & ?us endang] x %\ld a possible leakage occur f ^! pipes4 ,if locat$ at ,h1 h[ev]1 x w be 9 l9e ) ! ma*9es1 & !re=e w be subject to ! disadvantages previ\sly m5tion$ = su* cases2 consequ5tly x might be z well to place x at ! fur!r end ( ! room1 ei!r aga9/ ! p>tition 7%[n dott$7 ( ! /orage batt]y room if ?is be built1 or else 7if no /orage batt]y is to be in/all$71 aga9/ ! end wall itself4 ,! ne>] end ( ! room ,a w\ld n be v desirable = ! swit*bo>d in/allation on acc\nt ( be+ s f> remov$ f ! ma*9es1 & !re=e m or less inaccessible f !m4 ,outside ( :at has n[ be5 m5tion$1 ! division ( ! floor plan & ! arrangem5t !re9 is practically ! same z 9 fig4 #b1gbj1 accord+ly :at has already be5 /at$ reg>d+ ! =m] in/allation applies1 !re=e1 ) equal =ce to ! pres5t in/allation4 ,ques4 ,describe a plant ) direct drive4 ,ans4 ,?is type ( drive is %[n 9 fig4 #b1gcb4 ,ea* eng9e is directly connect$ to a g5]ator1 t is1 ! ma9 %afts ( bo? are jo9$ toge!r 9 l9e s t ! g5]ator is driv5 )\t ! aid ( a belt4 ,ques4 ,:at is ! advantage ( direct drive8 ,ans4 ,! great sav+ 9 floor space1 :i* is pla9ly %[n 9 fig4 #b1gcb1 ! portion ,a' repres5t+ ! sav+ :i* results ov] ! in/allations previ\sly illu/rat$ 9 figs4 #b1gbj & #b1gca4 ,ques4 ,h[ c\ld ! floor space be fur!r r$uc$8 ,ans4 ,by employ+ v]tical in/ead ( horizontal eng9es4 ,ques4 ,:at %\ld be done be=e draw+ ! plans = ! /ation8 ,ans4 ,! types ( ! v>i\s ma*9es & app>atus to be in/all$ %\ld1 z ne>ly z possible1 be select$ 9 advance s t _! approximate dim5sions may s]ve z a guide 9 draw+ up ! plans ( ! build+4 ,illu/ration3 ,,fig4 #b1gcb4--,plan ( electrical /ation conta9+ direct connect$ units4 ,z %[n1 space is provid$ = an extra boil] & eng9e & g5]ator set1 z indicat$ by ! dott$ l9es4 ,space also exi/s = a /orage batt]y room if necess>y1 & ! p>tition divid+ ?is room f ! eng9e & dynamo room is %[n by a dott$ l9e z 9 previ\s cases4 ,ow+ to ! great diff]5ce 9 ^! dim5sions = ! v>i\s types1 & 9 fact = ! same types z manufactur$ by diff]5t conc]ns1 no def9ite rules reg>d+ ! necess>y space requir$ c "h be giv54 ,9 a g5]al way1 h[ev]1 ! au?or has endeav\r$ to indicate by ! draw+s ! relative am\nts ( space t ord9>ily w\ld be consid]$ suffici5t4 ,ques4 ,:at is ! disadvantage ( direct drive8 ,ans4 ,a m exp5sive g5]ator is requir$ because x mu/ run at ! same spe$ z ! eng9e1 :i* is relatively l[ z comp>$ ) t ( a belt$ g5]ator4 ,/ation ,con/ruction4--,! con/ruction or re>rangem5t ( ! build+ int5d$ = ! plant is a problem t "u ord9>y conditions w\ld be solv$ by an ar*itect1 or at lea/ by an ar*itect ) ! assi/ance ( an electrical or me*anical eng9e]1 /ill !re are _m in/allations :]e ! electrical eng9e] has be5 compell$ to design ! build+4 ,9 su* in/ances he %\ld be equipp$ ) a g5]al k ( ! con/ruction ( build+s4 ,f\ndations4--,! f\ndation may be ei!r natural or artificial2 t is1 x may be compos$ ( rock or soil suffici5tly solid to s]ve ! purpose unaid$1 or x may be su* z to require /r5g!n+ by means ( wood or iron beams1 etc4 ,9 ei!r case any t5d5cy t[>d a consid]able settl+ or %ift+ ( ! f\ndation due to ! action ( wat]1 fro/1 etc41 aft] ! /ation has be5 complet$ mu/ be well gu>d$ aga9/4 ,to ?is end special att5tion %\ld be giv5 to ! matt] ( dra9age4 ,ques4 ,h[ %\ld ! f\ndation be con/ruct$ = ! ma*9es8 ,ans4 ,! f\ndations con/ruct$ = ! ma*9es %\ld be entirely sep>ate f t built = ! walls ( ! build+1 s t ! vibrations ( ! =m] w n affect ! latt]4 ,if !re be sev]al eng9es & dynamos to be in/all$1 x is be/ to con/ruct two f\ndations1 "o = ! eng9es & "o = ! dynamos4 ,if1 h[ev]1 !re be consid]able di/ance betwe5 ! units1 x may be advisable to build a sep>ate f\ndation = ea* eng9e & = ea* dynamo4 ,! mat]ial ( :i* ^! f\ndations are compos$ %\ld if ! ma*9es be ( #bj horse p[] or ov]1 possess consid]able /r5g? & be imp]vi\s to moi/ure4 ,brick1 /one & concrete are desirable = ! purpose1 & only ! be/ quality ( cem5t mort> %\ld be employ$4 ,c>e mu/ be tak5 t lime mort> is n us$ 9 place ( cem5t mort>1 z ! =m] is n well adapt$ to )/& ! vibrations ( ! ma*9es )\t crumbl+4 ,illu/ration3 ,,fig4 #b1gcc4--;,angle = f\ndation foot+4 ,9 ord9>y practice ! foot+ c\rses ^u :i* ! walls ( ! build+ prop] re/1 consi/ ( blocks or slabs ( /one z l>ge z are available & conv5i5t to h&le4 ,foot+s ( brick or concrete are also us$ 9 v s(t soils2 foot+s consi/+ ( timb] grillage are (t5 employ$4 ,a grillage ( iron or /eel beams has also be5 us$ successfully4 ,! incl9ation ( ! angle 1 ( foot+ %\ld be ab\t z foll[s3 = metal foot+s #ge2 = /one1 #fj2 = concrete1 #de2 = brick1 #cj4 ,damp pro( c\rses ( slate1 or lay] ( asphalt are laid 9 or on ! f\ndations or l[] walls to prev5t moi/ure aris+ or p5etrat+ by capill>y attraction4 ,ques4 ,describe a me?od ( con/ruct+ f\ndations4 ,ans4 ,an excavation is made to ! desir$ dep? & a =m ins]t$ correspond+ to ! desir$ dim5sions = ! f\ndation4 ,a template is plac$ on top locat+ all ! c5t]s1 ) iron pipes susp5d$ f ^! c5t]s1 two or ?ree sizes l>g] ?an ! an*or bolts4 ,at ! l[] end ( ! pipes are core boxes4 ,concrete is p\r$ into ! m\ld ?us =m$1 & :5 h>d1 ! =ms are remov$ ?us leav+ ! solid f\ndation4 ,! an*or bolts are ins]t$ ?r\gh ! pipes & pass$ ?r\gh iron plates at ! l[] end z %[n 9 fig4 #b1gcd1 be+ secur$ by nuts4 ,by us+ pipe ( two or ?ree bolt diamet]s a m>g9 is provid$ = adju/m5t s ! bolts w pass ?r\gh ! holes 9 ! frame ( ! ma*9e ?us all[+ = any slight errors 9 lay+ out ! c5t]s on ! template4 ,illu/ration3 ,,fig4 #b1gcd4--;,concrete f\ndation %[+ me?od ( in/all+ ! an*or bolts4 ,ques4 ,:at is ! object ( ! op5+s 9 ! bottom ( ! f\ndation8 ,ans4 ,9 case ( a defective bolt1 x may be replac$ by a new "o )\t injury to ! f\ndation4 ,walls4--,reg>d+ ! mat]ial = ! walls ( ! /ation iron1 /one1 brick & wood may be consid]$4 ,( ^!1 iron 9 ! =m ( %eets or plates w\ld be entirely firepro(1 b be+ itself a conductor w\ld introduce difficulties 9 ma9ta9+ a high insulation resi/ance ( ! curr5t c>ry+ circuits2 x w\ld also make ! build+ difficult to heat 9 w9t] & to keep cool 9 summ]4 ,/one 9 ! =m ( lime/one1 granite or s&/one1 z a build+ mat]ial is desirable = solidity & attractiv5ess2 x is also firepro( & an insulator1 b ! high co/ ( su* a /ructure = an electrical /ation usually prohibits its use except 9 private plants or 9 electrical /ations locat$ 9 l>ge cities4 ,illu/ration3 ,,fig4 #b1gce4--,view %[+ "p ( template = locat+ an*or bolt c5t]s1 pipes ?r\gh :i* ! bolts pass & bolt boxes at l[] end ( bolts4 ,! complet$ f\ndation is %[n 9 fig4 #b1gcd1 ) template remov$4 ,! template is made ( pla9 bo>ds ^u :i* ! c5t] l9es are drawn1 & bolt c5t] locat$4 ,holes are bor$ at ! bolt c5t]s to p]mit ins]tion ( ! pipes z %[n4 ,brick is a good mat]ial & is readily obta9$ 9 ne>ly all p>ts ( ! c\ntry2 x is comp>atively *eap1 & is also an insulat+ & firepro( mat]ial4 ,! bricks select$ = ?is purpose %\ld possess true %>p edges1 & be h>d burn$4 ,ques4 ,:at are ! features ( wood8 ,ans4 ,wood =ms ! *eape/ mat]ial t c be us$ = ! walls ( electrical /ations1 & x usually af=ds satisfaction1 b has ! disadvantage ( high fire risk4 ,ro(s4--,9 fig4 #b1gcf is %[n "o =m ( con/ruction = ! ro( ( an electrical /ation4 ,! end view "h pres5t$ %[s ! upp] portion ( ! walls at ,b & ,d2 ^! support ! iron trusses ,c1 & ! ro( prop] ,,mn4 ,9 _m /ations !re is provid$ ?r\gh\t ! l5g? ( ! build+1 a monitor or rais$ /ructure on ! peak ( ! ro( = v5tilation & light4 ,! end view ( ! monitor is %[n at ,s 9 ! figure2 its sides %\ld be fitt$ ) w9d[s adju/able f ! floor4 ,illu/ration3 ,,fig4 #b1gcf4--,"o =m ( ro( con/ruction4 ,floors4--,! floor ( ! /ation %\ld be s design$ t x w be capable ( support+ a reasonable weight1 b z ! weights ( ! ma*9es are borne entirely by _! respective f\ndations ! normal weight ^u ! floor w n be great2 = %ort p]iods1 h[ev]1 x may be call$ ^u to support "o or two ma*9es :ile !y are be+ plac$ 9 position or int]*ang$1 & due all[ance mu/ be made = su* occurr5ces4 ,/ation floors = eng9e & dynamo rooms are1 z a rule1 con/ruct$ ( wood4 ,:]e v high curr5ts are g5]at$1 h[ev]1 insulat$ floors ( special con/ruction m\nt$ on glass are necess>y z a protection f injuri\s %ocks4 ,brick1 concrete1 cem5t1 & o!r sub/ances ( a simil> nature are objectionable z a floor mat]ial = eng9e & dynamo rooms on acc\nt ( ! grit f !m1 caus$ by con/ant we>1 be+ liable to get into ! be>+s ( ! ma*9es4 ,:]e !re are no mov+ p>ts1 h[ev]1 z 9 ! boil] room1 ! mat]ials j m5tion$ possess no disadvantages & are pref]able to wood on acc\nt ( be+ firepro(4 ,,!oretical ,,draft ,,pressure ,,9 ,,in*es ,,( ,,wat] ,,9 ,a ,,*imney #ajj ,,feet ,,high 7,= o!r heights ! draft v>ies directly z ! height7 ,temp4 9 ,,temp4 ,,( ,,ext]nal ,,air4 7,,b>omet] #cj ,,in*es7 ,*imney1 ,f4 #j #aj #bj #cj #dj #ej #fj #gj #hj #ij #ajj #bjj 4#dec 4#dai 4#chd 4#cec 4#cba 4#bib 4#bfc 4#bcd 4#bji 4#ahb 4#aeg #bbj 4#dhh 4#dec 4#dai 4#chh 4#cee 4#cbf 4#bih 4#bfi 4#bdd 4#bag 4#aib #bdj 4#ebj 4#dhh 4#dea 4#dba 4#chh 4#cei 4#ccj 4#cja 4#bgf 4#bej 4#bbe #bfj 4#eee 4#ebh 4#dhd 4#dec 4#dbj 4#cib 4#cfc 4#ccd 4#cji 4#bhb 4#beg #bhj 4#ehd 4#edi 4#eae 4#dhb 4#dea 4#dbb 4#cid 4#cfe 4#cdj 4#cac 4#bhh #cjj 4#faa 4#egf 4#eda 4#eaa 4#dgh 4#ddi 4#dbj 4#cib 4#cfg 4#cdj 4#cae #cbj 4#fcg 4#fjc 4#efh 4#ech 4#eje 4#dgf 4#ddg 4#dai 4#cid 4#cfg 4#cdb #cdj 4#ffb 4#fch 4#eic 4#efc 4#ecj 4#eja 4#dgb 4#ddc 4#dai 4#cib 4#cfg #cfj 4#fhg 4#fec 4#fah 4#ehh 4#eee 4#ebf 4#dig 4#dfh 4#ddd 4#dag 4#cib #chj 4#gaj 4#fgf 4#fda 4#faa 4#egh 4#edi 4#ebj 4#dib 4#dfg 4#ddj 4#dae #djj 4#gcb 4#fig 4#ffb 4#fcb 4#eih 4#egj 4#eda 4#eac 4#dhh 4#dfa 4#dcf #dbj 4#gec 4#gah 4#fhd 4#fec 4#fbj 4#eia 4#efc 4#ecd 4#eji 4#dhb 4#deg #ddj 4#ggd 4#gci 4#gje 4#fgd 4#fda 4#fab 4#ehd 4#eee 4#ecj 4#ejc 4#dgh #dfj 4#gic 4#geh 4#gbd 4#fid 4#ffj 4#fcb 4#fjc 4#egd 4#edi 4#ebb 4#dig #dhj 4#haj 4#ggf 4#gda 4#gaj 4#fgh 4#fdi 4#fbj 4#eia 4#eff 4#edj 4#eae #ejj 4#hbi 4#gia 4#gfj 4#gcj 4#fig 4#ffi 4#fci 4#faj 4#ehf 4#eei 4#ecd ,*imneys4--,^! are g5]ally con/ruct$ ( brick & iron1 sometimes ( concrete4 ,iron *imneys co/ less ?an brick *imneys1 necessitate less sub/antial f\ndations1 & are free f ! liability ( crack+4 ,!y mu/ be pa9t$ to prev5t corrosion1 are less sub/antial1 & lose consid]ably m heat by radiation ?an d brick *imneys4 ,illu/ration3 ,,fig4 #b1gcg4--;,an example ( direct connect$ unit ) gas eng9e p[]4 ,! view %[s a ,we/+h\se #bjj kva41 #d1jjj volt1 ?ree phase1 #fj cycle alt]nator direct connect$ to a gas eng9e4 ,illu/ration3 ,,fig4 #b1gch4--;,curves %[+ comp>ative co/s ( *imney & me*anical draft4 ,9 c]ta9 ( ^!1 ! co/ ( ! exi/+ *imney is kn[n1 & t ( ! complete me*anical draft plant is e/imat$1 :ile 9 o!rs1 ! co/ ( me*anical draft in/allation is det]m9$ f ! contract price1 & ! exp5se ( a *imney to produce equival5t results is calculat$4 ,co/s are %[n = bo? s+le1 =c$ & induc$ eng9e driv5 fans & = duplex eng9e driv5 plants1 9 :i* ei!r fan may s]ve z a relay4 ,an app>atus ( ! latt] type is ! mo/ exp5sive1 & f9ds its greate/ use :]e economiz]s are employ$4 ,bo? brick & iron *imneys1 require an inn] wall or l9+ ( brick1 :i* =ms ! flue prop]1 & 9 ord] t ?is wall be n crack$ by sudd5 cool+ an air space is left betwe5 x & ! out] wall4 ,9 a brick *imney ! inn] wall ne$ n ext5d mu* beyond half ! height ( ! *imney1 b :5 iron is us$ x %\ld rea* to ! top4 ,ques4 ,^u :at does ! =ce ( natural draught 9 a *imney dep5d8 ,ans4 ,x dep5ds ^u ! diff]5ce betwe5 ! weight ( ! column ( hot gases inside ! *imney & ! weight ( a l column ( ! cold ext]nal air4 ,illu/ration3 ,,figs4 #b1gci & #b1gdj4--,sub/itut+ me*anical draught 9 place ( *imney4 ,! relative proportions ( a brick *imney1 & ( ! smoke pipe requir$ :5 me*anical draft is introduc$ are =cibly %[n 9 ! illu/rations1 :i* %[ ! works ( ! ,b4,f4 ,/urtevant ,co41 at ,jamaica ,pla91 ,mass4 ,! removal ( ! boil]s to a position too f> di/ant f ! exi/+ *imney to p]mit ( its long] fulfill+ its (fice1 l$ to ! sub/itution ( an induc$ draft fan & ! subsequ5t removal ( ! *imney4 ,! pres5t /ack or smoke pipe1 b>ely visible 9 fig4 #b1gdj1 ext5ds only #ca feet above ! gr\nd1 & no tr\ble is exp]i5c$ f smoke4 ,ques4 ,h[ is ! int5sity ( ! draught express$8 ,ans4 ,9 t]ms ( ! numb] ( in*es ( a wat] column su/a9$ by ! pressure produc$4 ,ques4 ,are high *imneys necess>y8 ,ans4 ,no4 ,*imneys above #aej feet 9 height are v co/ly1 & _! increas$ co/ is n ju/ifi$ by increas$ effici5cy4 ,illu/rations3 ,,figs4 #b1gda to #b1gdd4--;,in/allation ( =c$ draft sy/em to old boil] plant4 ,! figures illu/rate ! simple/ me?od4 ,! fan :i* is ( /eel plate ) direct connect$ d\ble cyl9d] eng9e1 is plac$ imm$iately ov] ! end ( a brick duct into :i* ! air is dis*>g$4 ,?is duct is c>ri$ "u gr\nd across ! front ( ! boil]s1 to ! a% pits ( ea* ( :i* connection is made ?r\gh bran* ducts4 ,ea* bran* duct op5+ is provid$ ) special a% pit damp]1 op]at$ by not*$ h&le b>1 z illu/rat$ 9 ! detail4 ,?is me?od ( introduction s]ves to di/ribute ! air )9 ! a% pit1 & to secure ev5 fl[ ?r\gh ! fuel ^u ! grate above4 ,( c\rse1 ! a% pit doors mu/ rema9 clos$ 9 ord] to br+ ab\t ?is result4 ,a *imney ( suffici5t height to m]ely dis*>ge ! gases above objectionable level is all t is absolutely necess>y ) ?is arrangem5t4 ,al?\gh ! introduction ( a fan 9 an old plant is usually evid5ce ( ! insuffici5cy ( ! exi/+ *imney to meet ! requirem5ts1 su* a *imney1 w1 h[ev]1 usually s]ve z a dis*>ge pipe = ! gases :5 ! fan is employ$4 ,! fan ?us becomes m ?an a m]e auxili>y to ! *imney2 x practically supplants x s f> z ! me?od ( draught production is conc]n$4 ,! late/ *imney practice is to build two or m small *imneys in/ead ( "o l>ge "o4 ,a notable example is ! ,spreckels ,sug> ,ref9]y 9 ,philadelphia1 :]e ?ree sep>ate *imneys are us$ = "o boil] plant ( #g1ejj horse p[]4 ,! ?ree *imneys are said to h co/ sev]al ?\s& doll>s less ?an an equival5t s+le *imney4 ,v tall *imneys h be5 *>act]iz$ by "o writ] z monum5ts to ! folly ( _! build]s4 ,illu/ration3 ,,figs4 #b1gde & #b1gdf4--;,comp>ison ( *imney draft & me*anical draft4 ,! illu/rations %[ a plant ( #b1djj ,h4,p4 ( mod]n wat] tube boil]s1 #ab 9 numb]1 set 9 pairs & equipp$ ) economiz]s4 ,fig4 #b1gde indicates ! location ( a *imney1 #i feet 9 int]nal diamet] by #ahj feet high1 design$ to furni% ! necess>y draft2 fig4 #b1gdf repres5ts ! same plant ) a complete duplex induc$ draught app>atus sub/itut$ = ! *imney1 & plac$ above ! economiz] connections4 ,ea* ( ! two fans is driv5 by a special eng9e1 direct connect$ to ! fan %aft1 & ea* is capable ( produc+ draft = ! entire plant4 ,a %ort /eel plate /ack unites ! two fan outlets & dis*>ges ! gases j above ! boil] h\se ro(4 ,all ( ! room necess>y = ! *imney is sav$1 & no valuable space is requir$ = ! fans4 ,ques4 ,h[ is me*anical draft secur$8 ,ans4 ,9 two ways1 kn[n respectively z induc$ draught & =c$ draught4 ,ques4 ,describe ! me?od ( induc$ draft4 ,ans4 ,a fan is locat$ 9 ! smoke flue1 & :i* 9 op]ation draws ! gases ?r\gh ! furnace & dis*>ges !m into a %ort *imney4 ,ques4 ,describe ! me?od ( =c$ draft4 ,ans4 ,9 ?is me?od1 air is =c$ into ! furnace und]nea? ! grate b>s by means ( a fan or a /eam jet bl[]4 ,illu/ration3 ,,fig4 #b1gdg4--;,=c$ draft plant ) holl[ bridge wall at ! ,cry/al ,wat] ,co41 ,buffalo1 ,n4 ,y4 ,! air is deliv]$ to ! a% pit via ! holl[ bridge wall1 be+ suppli$ "u pressure by ! bl[] se5 at ! side ( ! boil] sett+4 ,z %[n1 ! bl[] is op]at$ by a small reciprocat+ eng9e2 h[ev]1 compact bl[+ units ) /eam turb9e drive c be _h & :i* are design$ to be plac$ 9 ! boil] sett+4 ,ques4 ,:at is ! application ( ! two sy/ems8 ,ans4 ,induc$ draft is in/all$ mo/ly 9 new plants1 :ile =c$ draft is bett] adapt$ to old plants4 ,/eam ,turb9es4--,x is n ! au?or's int5tion to discuss at l5g? ! /eam end ( ! electric plant1 because too mu* space w\ld be requir$1 & also because ! subject belongs prop]ly to ! field ( me*anical eng9e]+ r ?an electrical eng9e]+4 ,h[ev]1 because ( ! rec5t introduction ( ! /eam turb9e = ! direct driv+ ( l>ge g5]ators1 & ! fact t x is n[ almo/ univ]sally us$ 9 l>ge c5tral /ations1 a detail$ explanation ( its pr9ciples & con/ruction may n be out ( place4 ,illu/ration3 ,,fig4 #b1gdh4--,longitud9al section ( elem5t>y ,p>sons type /eam turb9e4 ,! turb9e consi/s ess5tially ( a fix$ cas+1 or cyl9d]1 & a revolv+ sp9dle or drum4 ,! ends ( ! sp9dle are ext5d$ 9 ! =m ( a %aft1 c>ri$ 9 two be>+s ,a & ,b1 &1 except+ ! small p>ts ( ! gov]n+ me*anism & ! oil pump1 ^! be>+s are ! only rubb+ p>ts 9 ! entire turb9e4 ,/eam ent]s f ! /eam pipe at ,c & passes ?r\gh ! ma9 ?rottle or regulat+ valve ,d1 :i*1 z actually con/ruct$1 is a balanc$ valve4 ,?is valve is op]at$ by ! gov]nor ?r\gh suitable controll+ me*anism4 ,! /eam ent]s ! cyl9d] ?r\gh ! passage ,e &1 turn+ to ! left passes ?r\gh alt]nate /ation>y & revolv+ r[s ( blades1 f9ally em]g+ f !m at ,f & fl[+ ?r\gh ! connection ,g to ! cond5s] or to ! atmosph]e1 dep5d+ ^u :e!r ! turb9e is cond5s+ or non-cond5s+4 ,ea* r[ ( blades1 bo? /ation>y & revolv+1 ext5ds completely ar\nd ! turb9e & ! /eam fl[s ?r\gh ! full annulus betwe5 ! sp9dle & ! cyl9d]4 ,9 an ideal turb9e ! l5g?s ( ! blades & ! diamet] ( ! sp9dle :i* c>ries !m w\ld cont9u\sly & gradually increase f ! /eam inlet to ! exhau/4 ,practically1 h[ev]1 ! desir$ effect is produc$ by mak+ ! sp9dle 9 /eps1 !re be+ g5]ally ?ree su* /eps or /ages1 ,h1 ,j & ,k4 ,! blades 9 ea* /ep are arrang$ 9 gr\ps ( increas+ l5g?4 ,at ! beg9n+ ( ea* ( ! l>g] /eps1 ! blades are usually %ort] ?an at ! end ( ! prec$+ small] /ep1 ! *ange be+ made 9 su* a way t ! correct relation ( blade l5g? to sp9dle diamet] is secur$4 ,! /eam1 act+ z previ\sly describ$1 produces a ?ru/ t5d+ to =ce ! sp9dle t[>d ! left1 z se5 9 ! cut4 ,?is ?ru/1 h[ev]1 is c\nt]act$ by ! balance pi/ons1 ,l1 ,m & ,n1 :i* are ( ! necess>y diamet] to neutralize ! ?ru/ on ! sp9dle /eps1 ,h1 ,j & ,k1 respectively4 ,^! elem5ts are call$ pi/ons = conv5i5ce1 al?\gh !y d n come 9 contact ) ! cyl9d]1 b bo? ! pi/ons & ! cyl9d] are provid$ ) alt]nate r+s :i* =m a labyr9? pack+ to ret>d ! leakage ( /eam4 ,9 ord] t ea* balance pi/on may h ! prop] pressure on bo? sides1 equaliz+ passages ,o1 ,p & ,q are provid$ connect+ ! balance pi/ons ) ! correspond+ /ages ( ! blad+4 ,! end ?ru/ be+ ?us practically neutraliz$ by means ( ! balance pi/ons1 ! sp9dle floats s t x c be easily mov$ 9 "o direction or ! o!r4 ,9 ord] to def9itely fix ! position ( ! sp9dle1 a small adju/able coll> be>+ is provid$ at ,r1 inside ! h\s+ ( ! ma9 be>+ ,b4 ,?is coll> be>+ is adju/able s z to locate & hold ! sp9dle 9 su* position s t !re w be su* a cle>ance betwe5 ! r+s ( ! balance pi/on & ^? ( ! cyl9d]1 t ! leakage ( /eam w be r$uc$ to a m9imum &1 at ! same "t1 prev5t actual contact "u v>y+ conditions ( temp]ature4 ,:]e ! %aft passes out ( ! cyl9d]1 at ,s & ,t1 x is necess>y to provide aga9/ 9-leakage ( air or out-leakage ( /eam by means ( gl&s4 ,^! gl&s are made tight by wat] pack+ )\t metallic contact4 ,! %aft ( ! turb9e is ext5d$ at ,u & c\pl$ to ! %aft ( ! alt]nator by means ( a flexible c\pl+4 ,! high pressure turb9es are s proportion$ t1 :5 us+ /eam z previ\sly describ$1 !y h en\gh capacity to take c>e ( ! ord9>y fluctuations ( load :5 controll$ by ! gov]nor ?r\gh ! valve ,d1 ?us insur+ maximum economy ( /eam consumption at approximately ! rat$ load4 ,to provide = ov]loads1 ! valve ,v is suppli$ to admit /eam to an int]m$iate /age ( ! turb9e4 ,?is valve %[n diagrammatically 9 ! illu/ration1 is arrang$ to be op]at$ by ! gov]nor & is1 accord+ to circum/ances1 locat$ ei!r z %[n by ! illu/ration1 or at ano!r /age ( ! turb9e4 ,illu/ration3 ,,fig4 #b1gdi4--;,arrangem5t ( blad+ 9 ,p>sons type turb9e1 consi/+ ( alt]nate mov+ & /ation>y blades4 ,! pa? tak5 by ! /eam is indicat$ by ! arr[s4 ,a turb9e is a ma*9e 9 :i* a rot>y motion is obta9$ by transf]5ce ( ! mom5tum ( a fluid or gas4 ,9 g5]al ! fluid is guid$ by fix$ blades1 atta*$ to a cas+1 &1 imp++ on o!r blades m\nt$ on a drum or %aft1 caus+ ! latt] to revolve4 ,turb9es are class$ 9 v>i\s ways z3 #a1 radial fl[1 :5 ! /eam ent]s ne> ! c5t] & escapes t[>d ! circumf]5ce2 & #b1 p>allel fl[1 :5 ! /eam travels axially or p>allel to ! l5g? ( ! turn+ body4 ,turb9es are commonly1 yet errone\sly class$ z3 #a4 ,impulse2 #b4 ,reaction4 ,ques4 ,:at is ! di/9ction betwe5 ^! two types8 ,ans4 ,9 ! s call$ impulse type1 /eam ent]s & leaves ! passages betwe5 ! vanes at ! same pressure4 ,9 ! s call$ reaction type1 ! pressure is less on ! exit side ( ! vanes ?an on ! entrance side4 ,fig4 #b1gej is a sectional view ( ! ,p>sons-,we/+h\se p>allel fl[ turb9e4 ,/eam f ! boil] ent]s fir/ a receiv] 9 :i* are ! gov]nor controll$ admission valves4 ,^! valves are actuat$ by a c5trifugal gov]nor4 ,illu/ration3 ,,fig4 #b1gej4--,sectional view ( ,p>sons-,we/+h\se turb9e1 %[+ rotor & gov]nor4 ,/eam does n ent] ! turb9e 9 a cont9u\s bla/1 b int]mitt5tly1 or 9 puffs4 ,! spe$ regulation is !re=e accompli%$ by proportion+ ! duration ( ^! puffs to ! load ( ! eng9e1 ?is be+ effect$ by ! gov]nor1 fig4 #b1geb4 ,! gov]nor ( ! turb9e has only to move a small pilot valve1 or slide1 ,e1 :i* admits /eam "u ! pi/on ,f1 & lifts ! ?rottle valve prop] (f its seat4 ,z soon z ! pilot valve closes1 ! spr+ %ifts ! ma9 ?rottle valve4 ,?us1 at light loads1 ! ma9 ?rottle or admission valve is cont9ually op5+ & %utt+ at uni=m int]vals1 ! l5g? ( "t dur+ :i* x rema9s op5 dep5d+ ^u ! load4 ,z ! load increases1 ! duration ( ! valve op5+ also increases1 until at full load ! valve does n rea* its seat at all & ! /eam fl[s /eadily ?r\gh ! turb9e4 ,! /eam ?us admitt$ fl[s into ! annul> passage ,a1 fig4 #b1gej1 by ! op5+ ,s1 & !n pa/ ! blades1 revolv+ ! rotor4 ,:5 ! load increases above ! normal rat$ am\nt a second>y pilot valve is mov$ by ! same means1 ?is 9 turn admitt+ /eam to a pi/on1 simil> to ,f1 :i* lifts ano!r ?rottle valve4 ,?is admits /eam into ! annul> space ,i1 s t x acts ^u ! l>g] diamet] ( ! drum or rotor1 giv+ l>gely increas$ p[] = ! "t be+4 ,! lev]s or arms ( ! gov]nor are m\nt$ ^u knife edges in/ead ( p9s1 mak+ x extremely s5sitive4 ,! t5sion spr+ may be adju/$ by h& :ile ! turb9e is runn+4 ,illu/ration3 ,,fig4 #b1gea4--,sectional view ( a comb9ation impulse & reaction s+le fl[ turb9e4 ,?is is a modification ( ! s+le fl[ type1 9 :i* ! smalle/ b>rel ( reaction blad+ is replac$ by an impulse :eel4 ,/eam is admitt$ to ! nozzle block ,a1 is exp&$ 9 ! nozzles & dis*>g$ aga9/ a portion ( ! p]iph]y ( ! impulse :eel4 ,! int]m$iate & l[ pressure /ages are id5tical ) ! correspond+ /ages 9 ! s+le fl[ type4 ,! sub/itution ( ! impulse elem5t = ! high pressure section ( reaction blad+ has no influ5ce "o way or ano!r on ! effici5cy4 ,t is to say ! effici5cy ( an impulse :eel is ab\t ! same at ! lea/ effici5t section ( reaction blad+4 ,?is design is attractive1 h[ev]1 9 t x %ort5s ! ma*9e mat]ially1 & gives a /iff] design ( rotor4 ,! ent]+ /eam is conf9$ 9 ! nozzle *amb] until its pressure & temp]ature h be5 mat]ially r$uc$ by exp&+ ?r\gh ! nozzles4 ,z ! nozzle *amb] is ca/ sep>ately f ! ma9 cyl9d]1 ! temp]ature & pressure diff]5ces to :i* ! cyl9d] is subject$ are correspond+ly less5$4 ,h[ev]1 probably on acc\nt ( its small diamet] at ! high pressure section1 ! /raight ,p>sons type has always %[n itself to be adequate = all ( ! /eam pressures & temp]atures enc\nt]$ 9 ord9>y practice4 ,! gov]nor does n actually move ! pilot valve1 b %ifts ! po9t ,l 9 fig4 #b1geb4 ,a reciprocat+ motion is giv5 to ! rod ,i by a small ecc5tric on ! gov]nor %aft2 ?is is driv5 by worm ge>+ %[n ne> ,o 9 fig4 #b1gej1 s t ! ecc5tric makes "o revolution to ab\t eight ( ! turb9e4 ,?us1 ) a turb9e runn+ #a1bjj revolutions1 ! rod ,i w\ld be mov$ up & d[n #aej times p] m9ute4 ,z ! po9ts ,a & ,h are fix$1 ! motion is convey$ to ! small pilot valve ,e1 ?us giv+ #aej puffs a m9ute4 ,! gov]nor 9 %ift+ ! po9t ,l br+s ! edge ( ! pilot valve ne>] ! port & s cuts (f ! /eam e>li]4 ,! annul> diamet] or space betwe5 ! rotor & ! /ator is gradually increas$ f inlet to exhau/1 ! blades be+ made long] 9 ea* r+4 ,:5 ! me*anical limit is rea*$1 ! diamet] ( ! rotor is increas$ z at ,i & ,d s z to keep ! l5g? ( blade )9 b\nd4 ,balance pi/ons z at ,b1 ,c1 ,f are atta*$ to ! rotor1 _! (fice be+ to oppose end ?ru/ ^u ^? blades 9 correspond+ diamet] ( ! rotor4 ,communication is e/abli%$ ?r\gh ! passage ,v & pipe ,m betwe5 ! eduction pipe & ! back ( ^! pi/ons1 ?us increas+ ! effici5cy ( _! balanc+ & also tak+ c>e ( any leakage pa/ !m4 ,a small ?ru/ be>+ ,t prev5ts end play ( ! rotor1 & is adju/able to ma9ta9 ! prop] cle>ance betwe5 ! r+s ( blades2 ?is v>ies f in* at ! admission to #a in* at ! exhau/4 ,?is be>+ also takes up any extra unbalanc$ ?ru/4 ,a turb9e %\ld op]ate ) a high vacuum1 because )\t ?is x does n comp>e favorably ) an ord9>y reciprocat+ eng9e f ! po9t ( economy4 ,illu/ration3 ,,fig4 #b1geb4--,sectional view ( gov]nor ( ! ,p>sons-,we/+h\se turb9e4 ,sep>ate air pumps are provid$ to create ! vacuum4 ,:]e ! ord9>y type ( v]tical air pump is employ$1 a boo/] or vacuum increas] is add$1 z no?+ bel[ #bf in*es is advisable1 #bh & #bi in*es be+ always /riv5 =4 ,x is also pref]able to use a c]ta9 am\nt ( sup]-heat ) /eam turb9es4 ,to assi/ 9 produc+ ! high vacuum1 exhau/ passages are made l>ge1 ! eduction passage ,e 9 fig4 #b1gej be+ ne>ly tw5ty-?ree times ! area ( ! /eam pipe4 ,among o!r details1 a notewor?y feature is a small oil pump ,k1 :i* circulates oil ?r\gh be>+s ( ! ma*9]y1 ! oil be+ drawn f ! tank "u ! gov]nor %aft & gravitat+ !re aft] use4 ,no pressure ( oil is employ$4 ,/uff+ r+s prev5t leakage2 ^! consi/ ( alt]nate grooves & coll>s 9 %aft & be>+1 l ! grooves 9 an indicator pi/on4 ,ques4 ,:y is a high vacuum desirable8 ,ans4 ,because ! turb9e is capable ( exp&+ ! /eam to a v l[ t]m9al pressure1 & ?is is necess>y = economy4 ,ques4 ,:at may be said ( ! work+ pressures = turb9es8 ,ans4 ,to meet ! v>i$ conditions ( s]vice1 turb9es are design$ to op]ate )3 #a1 high pressure1 #b1 l[ pressure1 or #c1 mix$ pressure4 ,illu/ration3 ,,fig4 #b1gec4--,sectional view ( a d\ble fl[ turb9e4 ,! maximum economical capacity ( a s+le fl[ turb9e is limit$ by ! rotative spe$4 ,! economical velocity at :i* ! /eam may pass ?r\gh ! blades ( ! turb9e dep5ds on ! velocity ( ! mov+ blades4 ,! capacity ( ! turb9e dep5ds on ! weight ( ! /eam pass$ p] unit ( "t1 :i* 9 turn dep5ds on ! mean velocity & ! height ( ! blades4 ,= a giv5 rotative spe$1 ! mean diamet] ( blade r+ practicable is limit$ by ! all[able /resses due to c5trifugal =ce1 & !re is a practical limit = ! height ( ! blades4 ,n[ if ! rotative spe$ be tak5 only half z great1 ! maximum diamet] ( ! rotor may be d\bl$ &1 )\t increas+ ! height ( ! blades1 ! capacity ( ! turb9e w be d\bl$4 ,s ) ! s+le fl[ /eam turb9e z well z ) ! s+le crank reciprocat+ eng9e1 !re is a practical limit+ economical capacity = any giv5 spe$4 ,if ?is limit be rea*$ ) a s+le crank reciprocat+ eng9e1 a unit ( d\ble ! p[] may be produc$ at ! same spe$ by c\pl+ two s+le crank eng9es to "o %aft4 ,simil> results are secur$ mak+ a d\ble fl[ turb9e :i* is 9 effect1 z w be se5 f ! figure1 two s+le fl[ turb9es made up 9 a s+le rotor 9 a s+le cas+ ) a common inlet & two exhau/s4 ,/eam ent]s ! nozzle block1 acts on ! impulse elem5t1 & !n ! curr5t divides1 "o-half ( ! /eam go+ ?r\gh ! reaction blad+ at ! left ( ! impulse :eel2 ! rema9d] passes ov] ! top ( ! impulse :eel & ?r\gh ! impulse blad+ at ! "r4 ,high pressure turb9es op]ate at ab\t ! same initial pressure z triple expansion eng9es4 ,l[ pressure1 z "h appli$1 means ! exhau/ pressure ( ! reciprocat+ eng9e f :i* ! exhau/ /eam passes ?r\gh ! turb9e be=e ent]+ ! cond5s]4 ,mix$ pressure implies t ! exhau/ /eam is supplem5t$1 = heavy loads1 by ! admission ( live /eam4 ,ques4 ,:at det]m9es ! work+ pressure8 ,ans4 ,:5 all ! p[] is furni%$ by ! turb9e1 x is design$ = high pressure2 :5 op]at$ 9 comb9ation ) a reciprocat+ eng9e1 l[ pressure is us$ = con/ant load1 & mix$ pressure = v>iable load4 ,illu/ration3 ,,fig4 #b1ged4--,sectional view ( a semi-d\ble fl[ turb9e4 ,?is is a modification 9 :i* ! int]m$iate section ( reaction blad+ is s+le fl[1 & ! l[ pressure section only is d\ble fl[4 ,?is w\ld be analog\s to a f\r cyl9d] triple expansion eng9e1 t is1 "o ) "o high pressure1 "o int]m$iate pressure & two l[ pressure cyl9d]s--a design n at all uncommon 9 v l>ge eng9es 9 :i* ! requir$ dim5sions ( a s+le l[ pressure cyl9d] w\ld be prohibitive4 ,su* turb9es are useful = capacities great] ?an is desirable = a s+le fl[ turb9e1 & :i* are /ill bel[ ! maximum possibilities ( a d\ble fl[ turb9e ( ! same spe$4 ,9 su* ma*9es ! be/ effici5cy is secur$ by mak+ ! int]m$iate blad+ 9 a s+le section l>ge en\gh to pass ! entire quantity ( /eam4 ,a dummy simil> to ^? us$ on ! s+le fl[ ,p>sons type1 %[n at ! "r ( ! impulse :eel1 compels all ( ! /eam to pass ?r\gh ! s+le int]m$iate section ( ! reaction blad+1 & balances ! end ?ru/ due to ?is section4 ,:5 ! /eam issues f ! int]m$iate section1 ! curr5t is divid$1 "o-half pass+ directly to ! adjac5t l[ pressure section1 :ile ! o!r half passes ?r\gh ! holes %[n 9 ! p]iph]y ( ! holl[ rotor & ?r\gh ! rotor itself1 beyond ! dummy r+1 into ! o!r l[ pressure section at ! left h& end ( ! turb9e4 ,,note4--,!re are logical eng9e]+ reasons = ! exi/5ce ( ! sev]al types ( turb9e1 viz41 s+le fl[1 d\ble fl[1 & semi-d\ble fl[4 ,! d\ble fl[ turb9e is n inh]5tly sup]ior to ! s+le fl[ design1 b is us$ "u conditions = :i* ! s+le fl[ ma*9e is unsuitable4 ,simil>ly1 ! semi-d\ble fl[ is recomm5d$ only = conditions :i* x c meet m satisfactorily ?an ei!r ( ! o!r types4 ,,note4--,l[ pressure turb9es use exhau/ /eam f non-cond5s+ eng9es & are valuable z an adjunct to exi/+ plants = ! purpose ( increas+ economy & capacity ) a m9imum outlay = new equipm5t4 ,,note4--,ble$] turb9es are = use 9 plants :i* are requir$ to furni%1 n only p[]1 b also consid]able & v>y+ quantities ( l[ pressure /eam = heat+ purposes4 ,9 ^! turb9es a "p ( ! /eam aft] x has done "w 9 ! high pressure /ages may be div]t$ to ! heat+ sy/em1 & ! rema9d] exp&$ ?r\gh ! l[ pressure blad+ & exhau/$ into ! cond5s]4 ,9 ?is way none ( ! en]gy ( ! heat+ /eam1 due to ! diff]5ce ( pressure betwe5 ! boil] & ! heat+ sy/em is wa/$4 ,on ! o!r h& if no /eam is requir$ = heat+ purposes1 ! turb9e op]ates j z effici5tly z ?\gh ! ble$] feature 7 abs5t4 ,illu/ration3 ,,fig4 #b1gee4--,we/+h\se valve ge> ) /eam relay4 ,9 ! small] turb9es1 ! gov]nor acts directly on ! /eam admission valves1 op5+ fir/ ! prim>y valve1 & !n1 if necess>y1 ! second>y valve1 aft] ! prim>y is fully op54 ,9 turb9es ( ! s+le fl[ ,p>sons type1 ! gov]nor actuates two small valves controll+ ports lead+ to /eam relay cyl9d]s :i* op]ate ! admission valves4 ,! little valve controll+ ! relay cyl9d] = ! second>y valve has m lap ?an ! o!r & consequ5tly does n come into action until ! prim>y valve has atta9$ its maximum effective op5+4 ,! figure %[s ! g5]al design ( ?is type ( valve ge>4 ,! ,de ,laval /eam turb9e is t]m$ by its build]s a high spe$ rot>y /eam eng9e4 ,x has b a s+le :eel1 fitt$ ) vanes or buckets ( su* curvature z has be5 f\nd to be be/ adapt$ = receiv+ ! impulse ( ! /eam jet4 ,!re are no /ation>y or guide blades1 ! angul> position ( ! nozzles giv+ direction to ! jet4 ,! nozzles are plac$ at an angle ( #bj degrees to ! plane ( motion ( ! buckets4 ,! be/ en]gy 9 ! /eam is practically devot$ to ! production ( velocity 9 ! exp&+ or div]g5t nozzle1 & ! velocity ?us atta9$ by ! issu+ jet ( /eam is ab\t #d1jjj feet p] second4 ,to atta9 ! maximum effici5cy1 ! buckets atta*$ to ! p]iph]y ( ! :eel aga9/ :i* ?is jet imp+es %\ld h a spe$ ( ab\t #a1ijj feet p] second1 b1 ow+ to ! difficulty ( produc+ a mat]ial = ! :eel /rong en\gh to )/& ! /ra9s induc$ by su* a high spe$1 x has be5 f\nd necess>y to limit ! p]iph]al spe$ to #a1bjj or #a1cjj feet p] second4 ,x is well kn[n t 9 a correctly design$ nozzle ! adiabatic expansion ( ! /eam f maximum to m9imum pressure w conv]t ! entire /atic en]gy ( ! /eam into k9etic en]gy4 ,!oretically ?is is :at occurs 9 ! ,de ,laval nozzle4 ,! exp&+ /eam acquires great velocity1 & ! en]gy ( ! jet ( /eam issu+ f ! nozzle is equal to ! am\nt ( en]gy t w\ld be develop$ if an equal volume ( /eam 7 all[$ to adiabatically exp& beh9d ! pi/on ( a reciprocat+ eng9e1 a condition1 h[ev]1 :i* = obvi\s reasons has nev] yet be5 atta9$ 9 practice ) ! reciprocat+ eng9e4 ,b ) ! div]g5t nozzle ! conditions are diff]5t4 ,! ,curtis turb9e is built by ! ,g5]al ,electric ,company at _! works 9 ,s*5ectady1 ,n4 ,y41 & ,lynn1 ,mass4 ,!y are ( ! horizontal & v]tical types4 ,9 ! v]tical type ! revolv+ p>ts are set ^u a v]tical %aft1 ! diamet] ( ! %aft correspond+ to ! size ( ! ma*9e4 ,! %aft is support$ by & runs ^u a /ep be>+ at ! bottom4 ,?is /ep be>+ consi/s ( two cyl9drical ca/ iron plates be>+ ^u ea* o!r & hav+ a c5tral recess betwe5 !m into :i* lubricat+ oil is =c$ "u pressure by a /eam or electrically driv5 pump1 ! oil pass+ up f b5ea?4 ,illu/ration3 ,,figs4 #b1gef & #b1geg4--,we/+h\se valve ge> ) oil relay4 ,gov]nors = ! l>g] turb9es1 p>ticul>ly ^? ( ! comb9ation impulse & reaction d\ble1 or s+le d\ble fl[ type1 employ an oil relay me*anism1 z %[n 9 ! figure1 = op]at+ ! /eam valves4 ,9 ^! turb9es ! lubricat+ oil circulat+ pump1 ma9ta9s a high] pressure ?an is requir$ = ! lubricat+ sy/em4 ,! gov]nor controls a small relay valve ,a :i* admits pressure oil to1 or exhau/s x f ! op]at+ cyl9d]4 ,:5 oil is admitt$ to ! op]at+ cyl9d] rais+ ! pi/on1 ! lev] ,c lifts ! prim>y valve ,e4 ,! lev] ,d moves simultane\sly ) ,c1 b on acc\nt ( ! slott$ connection ) ! /em ( ! second>y valve ,f1 ! latt] does n beg9 to lift until ! prim>y valve is rais$ to ! po9t at :i* its effective op5+ ceases to be increas$ by fur!r upw>d travel4 ,9 ! ,we/+h\se designs1 ! op]at+ valve1 ,a is connect$ n only to ! gov]nor1 b also to a vibrator1 :i* gives x a slight b cont9u\s reciprocat+ motion1 :ile ! gov]nor controls its mean position4 ,! effect ( ?is is manife/$ 9 a slight pulsation ?r\gh\t ! entire relay sy/em1 :i*1 s to speak1 keeps x alive & ready to respond in/antly1 to ! smalle/ *ange 9 ! position ( ! gov]nor4 ,! oil relay c be made suffici5tly p[]ful to op]ate valves ( any size1 & x is also 9 effect a safety device 9 t any failure ( ! lubricat+ oil supply w automatically & imm$iately %ut (f ! /eam & /op ! turb9e4 ,a weight$ accumulator is sometimes in/all$ 9 connection ) ! oil pipe z a conv5i5t device = gov]n+ ! /ep be>+ pumps1 & also z a safety device 9 case ! pumps %\ld fail1 b x is seldom requir$ = ! latt] purpose1 z ! /ep be>+ pumps h prov5 aft] a long s]vice 9 a numb] ( cases1 to be reliable4 ,! v]tical %aft is also held 9 place & kept /eady by ?ree sleeve be>+s "o j above ! /ep1 "o betwe5 ! turb9e & g5]ator1 & ! o!r ne> ! top4 ,illu/ration3 ,,fig4 #b1geh4--;,elevation ( new turb9e c5tral /ation erect$ by ! ,bo/on ,edison ,co4 ,! turb9e room is #fh feet1 #d in*es wide & #fej feet long f outside to outside ( ! walls4 ,! boil] room is #adi feet1 #f in*es by #fdj feet & equipp$ ) twelve gr\ps ( boil]1 "o gr\p consi/+ ( eight #eab ,h4,p4 boil]s = ea* turb9e4 ,! swit*+ arrangem5ts are locat$ 9 a sep>ate build+ z %[n 9 ! elevation4 ,! total floor space cov]$ by boil] room1 turb9e room & swit*bo>d room is #b4fd squ>e feet p] kw4 ,! boil]s are all on ! gr\nd floor4 ,see fig4 #b1gad = plan4 ,^! guide be>+s are lubricat$ by a /&>d gravity fe$ sy/em4 ,x is app>5t t ! am\nt ( friction 9 ! ma*9e is v small1 & z !re is no end ?ru/ caus$ by ! action ( ! /eam1 ! relation betwe5 ! revolv+ & /ation>y blades may be ma9ta9$ accurately4 ,z a consequ5ce1 !re=e1 ! cle>ances are r$uc$ to ! m9imum4 ,! ,curtis turb9e is divid$ into two or m /ages1 & ea* /age has "o1 two or m sets ( revolv+ blades bolt$ ^u ! p]iph]ies ( :eels key$ to ! %aft4 ,!re are also ! correspond+ sets ( /ation>y blades bolt$ to ! inn] walls ( ! cyl9d] or cas+4 ,! gov]n+ ( spe$ is accompli%$ 9 ! fir/ set ( nozzles & ! control ( ! admission valves "h is effect$ by means ( a c5trifugal gov]nor atta*$ to ! top end ( ! %aft4 ,?is gov]nor1 by a v slight movem5t1 imp>ts motion to lev]s1 :i* 9 turn "w ! valve me*anism4 ,! admission ( /eam to ! nozzles is controll$ by pi/on valves :i* are actuat$ by /eam f small pilot valves :i* are 9 turn "u ! control ( ! gov]nor4 ,illu/ration3 ,,fig4 #b1gei4--;,illu/ration ( a weir4 ,to make a weir1 place a bo>d across ! /ream at "s po9t :i* w all[ a pond to =m above4 ,! bo>d %\ld h a not* cut 9 x ) bo? side edges & ! bottom %>ply bevel$ t[>d ! intake1 z %[n 9 ! above cut4 ,! bottom ( ! not*1 :i* is call$ ! cre/ ( ! weir1 %\ld be p]fectly level & ! sides v]tical4 ,9 ! pond back ( ! weir1 at a di/ance n less ?an ! l5g? ( ! not*1 drive a /ake ne> ! bank1 ) its top precisely level ) ! cre/4 ,by means ( a rule1 or a graduat$ /ake z %[n1 measure ! dep? ( wat] ov] ! top ( /ake1 mak+ all[ance = capill>y attraction ( ! wat] aga9/ ! sides ( ! weir4 ,= extreme accuracy ?is dep? may be measur$ to ?\s&?s ( a foot by means ( a hook gauge1 famili> to all eng9e]s4 ,hav+ asc]ta9$ ! dep? ( wat] ov] ! /ake1 ref] to ! accompany+ table1 f :i* may be calculat$ ! am\nt ( wat] fl[+ ov] ! weir4 ,!re are c]ta9 proportions :i* mu/ be obs]v$ 9 ! dim5sions ( ?is not*4 ,its l5g?1 or wid?1 %\ld be betwe5 f\r & eight times ! dep? ( wat] fl[+ ov] ! cre/ ( ! weir4 ,! pond back ( ! weir %\ld be at lea/ fifty p] c5t4 wid] ?an ! not* & ( suffici5t wid? & dep? t ! velocity ( fl[ or approa* be n ov] "o foot p] second4 ,9 ord] to obta9 ^! results x is advisable to exp]im5t to "s ext5t4 ,spe$ regulation is effect$ by v>y+ ! numb] ( nozzles 9 fl[1 t is1 = light loads few] nozzles are op5 & a small] volume ( /eam is admitt$ to ! turb9e :eel1 b ! /eam t is admitt$ imp+es aga9/ ! mov+ blades ) ! same velocity always1 no matt] :e!r ! volume be l>ge or small4 ,) a full load & all ! nozzle sections 9 fl[1 ! /eam passes to ! :eel 9 a broad belt & /eady fl[4 ,,weir ,,table giv+ cubic feet ( wat] p] m9ute t w fl[ ov] a weir "o in* wide & f to #bj in*es deep4 ---------------------------------------- ---------------- ,dep? in*es ---------------------------------------- ---------------- #j 4#jj 4#ja 4#je 4#ji 4#ad 4#ai 4#bf 4#cb #a 4#dj 4#dg 4#ee 4#fd 4#gc 4#hb 4#ib #a4jb #b #a4ac #a4bc #a4ce #a4cf #a4eh #a4gj #a4hb #a4ie #c #b4jg #b4ba #b4cd #b4dh #b4fa #b4gf #b4ij #c4je #d #c4bj #c4ce #c4ej #c4ff #c4ha #c4ig #d4ad #d4cj #e #d4dg #d4fd #d4ha #d4ih #e4ae #e4cc #e4ea #e4fi #f #e4hg #f4jf #f4be #f4dd #f4fb #f4hb #g4ja #g4ba #g #g4dj #g4fj #g4hj #h4ja #h4ba #h4db #h4fc #h4hc #h #i4je #i4bf #i4dg #i4fi #i4ia #aj4ac #aj4ce #aj4eg #i #aj4hj #aa4jb #aa4be #aa4dh #aa4ga #aa4id #ab4ag #ab4da #aj #ab4fd #ab4hh #ac4ab #ac4cf #ac4fj #ac4he #ad4ji #ad4cd #aa #ad4ei #ad4hd #ae4ji #ae4cd #ae4ei #ae4he #af4aa #af4cf #ab #af4fb #af4hh #ag4ae #ag4da #ag4fg #ag4id #ah4ba #ah4dg #ac #ah4gd #ai4ja #ai4bi #ai4ef #ai4hd #bj4aa #bj4ci #bj4fg #ad #bj4ie #ba4bc #ba4ea #ba4hj #bb4jh #bb4cg #bb4fe #bb4id #ae #bc4bc #bc4eb #bc4hb #bd4aa #bd4dj #bd4gj #be4jj #be4cj #af #be4fj #be4ij #bf4bj #bf4ej #bf4hj #bg4aa #bg4db #bg4gb #ag #bh4jc #bh4cd #bh4fe #bh4ig #bi4bh #bi4ei #bi4ia #cj4bb #ah #cj4ed #cj4hf #ca4ah #ca4ej #ca4hb #cb4ae #cb4dg #cb4hj #ai #cc4ab #cc4de #cc4gh #cd4aa #cd4dd #cd4gg #ce4aj #ce4dd #bj #ce4gg #cf4aa #cf4de #cf4gh #cg4ab #cg4df #cg4hj #ch4ae ---------------------------------------- ---------------- ,,note4--,! weir table on ?is page conta9s figures #a1 #b1 #c1 etc41 9 ! fir/ v]tical column :i* indicates ! in*es dep? ( wat] runn+ ov] weir bo>d not*es4 ,frequ5tly ! dep?s measur$ repres5t also fractional in*es1 betwe5 #a & #b1 #b & #c1 etc4 ,! horizontal l9e ( fraction at ! top repres5ts ^! fractional p>ts1 & c be appli$ betwe5 any ( ! numb]s ( in*es dep?1 f #a to #be4 ,! body ( ! table %[s ! cubic feet1 & ! fractional p>ts ( a cubic foot1 :i* w pass ea* m9ute = ea* in* 9 dep?1 & = ea* fractional "p ( an in* by eigh?s = all dep?s f #a to #be in*es4 ,ea* ( ^! results is = only "o in* wid? ( weir4 ,to e/imate = any wid? ( weir ! result obta9$ = "o in* wid? mu/ be multipli$ by ! numb] ( in*es con/itut+ ! :ole horizontal l5g? ( weir4 ,illu/ration3 ,,figs4 #b1gfj & #b1gfa4--,samson v]tical runn] & %aft1 & complete ,samson v]tical turb9e4 ,! runn] is compos$ ( two sep>ate & di/9ct types ( :eel1 hav+ !reby also two diamet]s4 ,ea* :eel or set ( buckets receives its sep>ate quantity ( wat] f "o & ! same set ( guides1 b ea* set acts only once & s+ly ^u ! wat] us$1 & ! wat] does n act twice ^u ! comb9$ :eel1 z "s suppose4 ,9 con/ruction1 ! l[] or ma9 set ( buckets is made ( flang$ plate /eel1 & ca/ solidly into a heavy r+ surr\nd+ ! out] & l[] edges1 & into a heavy diaphragm1 sep>at+ ! two sets ( buckets4 ,illu/ration3 ,,fig4 #b1gfb4--,wat] dis*>g+ f a ne$le nozzle due to a pressure ( #afi lbs4 p] sq4 94 ,hydro-,electric ,plants4--,! economy ) :i* electricity c be transmitt$ long di/ances by high t5sion alt]nat+ curr5ts1 has l$ to ! developm5t ( a l>ge numb] ( wat] p[]s 9 m or less remote regions4 ,illu/ration3 ,,fig4 #b1gfc4--,photograph ( an op]at+ tang5tial wat] :eel equipp$ ) ,pelton buckets4 ,?is economy is possible by ! facility ) :i* alt]nat+ curr5t c be trans=m$ up & d[n4 ,?us at ! hydro-electro plant1 ! curr5t g5]at$ by ! wat] :eel driv5 alt]nator is trans=m$ to v high pressure & transmitt$ ) economy a long di/ance to ! di/ribut+ po9t :]e x is trans=m$ d[n to ! prop] pressure = di/ribution4 ,a wat] :eel or turb9e is a ma*9e 9 :i* a rot>y motion is obta9$ by transf]5ce ( ! mom5tum ( wat]2 broadly speak+1 ! fluid is guid$ by fix$ blades1 atta*$ ) a cas+1 & imp++ on o!r blades m\nt$ on a drum or %aft1 caus+ ! latt] to revolve4 ,!re are two g5]al classes ( turb9e3 #a4 ,impulse turb9es2 #b4 ,reaction turb9es4 ,illu/ration3 ,,fig4 #b1gfd4--,sectional elevation ( "o ( ! #e1jjj horse p[] v]tical ,pelton-,francis turb9es directly connect$ to g5]ator1 z in/all$ = ! ,s*5ectady ,p[] ,co4 ,ques4 ,:at is an impulse turb9e8 ,ans4 ,"o 9 :i* ! fluid is direct$ by means ( a s]ies ( nozzles aga9/ vanes :i* x drives4 ,ques4 ,:at is a reaction turb9e8 ,ans4 ,"o 9 :i* ! pressure or head ( ! wat] is employ$ r ?an its velocity4 ,! curr5t is deflect$ ^u ! :eel by ! action ( suitably dispos$ guide blades1 ! passages be+ full ( wat]4 ,rot>y motion is obta9$ by ! *ange 9 ! direction & mom5tum ( ! fluid4 ,illu/ration3 ,figs4 #b1gfe to #b1gfh4--;,cross sections ( ,l[el dam p[] h\se1 & :eel pits conta9+ sixte5 ,samson turb9es3 ,! section ,c-,d gives an end view ( ! g5]ator room %[+ ! locations ( ! g5]ators bel[ ! head level wat]4 ,!y are secure aga9/ flood wat]1 or leakage1 by well con/ruct$ /uff+ boxes 9 ! iron bulkheads1 ?r\gh :i* ! turb9e :eel %afts pass & connect to ! g5]ators4 ,section ,e-,f gives an end view ( "o ( ^! :eel rooms or p5/ocks1 & %[s ! ext5sion ( ! draft tube f :eel case into tail wat]4 ,! section ,a-,b %[s ! sub-/ructure ( gravel & macadam "u ! controll+ gates1 ?is =m+ also a portion or ext5sion ( ! dam prop]4 ,^! gates turn on an axis made ( two #ae in* ,i beams securely rivet$ toge!r ) plates & angle irons to :i* ! wood5 frame is atta*$4 ,! radius ( ! gates is #ad feet4 ,!y are design$ to all[ ! wat] to pass und]nea? ! gate1 ?us controll+ any height ( head wat]4 ,!y are int5d$ to take c>e ( an excess ( wat] at unusual /ages ( ! riv]4 ,! :ole affair has be5 well design$ & execut$4 ,?is plant furni%es a good example ( a secure1 & level f\ndation1 s9ce ! :eel h\ses & g5]ator room are imm$iately on ! rock4 ,x is necess>y 9 all t&em plants to provide a v secure1 sub/antial sup]-/ructure s t ! long l9e ( turb9es & %aft w always rema9 /raight & 9 prop] alignm5t ) ! g5]ator & ! turb9e cases4 ,us]s _c be rem9d$ ( ?is too (t54 ,ques4 ,"n ?ree classes ( reaction turb9es4 ,ans4 ,p>allel fl[1 inw>d fl[1 & outw>d fl[4 ,p>allel fl[ turb9es h an effici5cy ( ab\t #gj & are suit$ = l[ falls n ov] #cj feet4 ,inw>d & outw>d fl[ turb9es h an effici5cy ( ab\t #he4 ,impulse turb9es are suitable = high heads4 ,illu/ration3 ,,figs4 #b1gfi & #b1ggj4--;,ext]ior & int]ior ( hydro-electric plant at ,h>risburg1 ,va4 ,x is locat$ on ! s\? =k ( ! ,%5&oah ,riv]1 twelve & "o-half miles di/ant4 ,a dam #gbj feet long & #ae feet high 0 built on a lime/one l$ge runn+ across ! riv]2 :i* ) a fall ( #e feet f ! dam to ! p[] h\se1 a qu>t] ( a mile di/ant1 secur$ an effective head pressure ( #bj feet4 ,! p[] h\se1 compris+ ! g5]ator room & ! :eel room1 also ! ma*9]y room1 are "h %[n4 ,! :eel room1 :i* is #bj #dj feet1 ext5ds across ! head race1 & re/s ^u solid concrete walls1 =m+ ! sides & ends ( ! :eel pits4 ,! end wall is #f feet ?ick at ! bottom1 & #d feet at ! top4 ,x has ?ree ar*$ op5+s1 ea* #h feet wide & #i feet high1 ?r\gh :i* ! wat] escapes aft] leav+ ! turb9es4 ,! intake is protect$ by a wr\ght iron rack #dj feet long4 ,! p[] is obta9$ by ?ree #ej in* v]tical %aft ,samson turb9es1 ) a #bj in* ,samson = an excit]4 ,! ?ree l>ge turb9es h a rat+ ( #a1cej horse p[]2 & are connect$ to ! ma9 horizontal l9e %aft by bevel mortise ge>s #g feet diamet] & #ae in*es face4 ,! c\pl+s on ! ma9 %aft h #dh in* friction clut* hubs1 p]mitt+ ei!r or ea* turb9e be+ op]at$1 or %ut d[n indep5d5tly ( ! o!rs4 ,! ma9 %aft is #he feet long & #f in*es diamet]2 mak+ #bhj revolutions4 ,?is %aft c>ries two pulleys #gj in*es diamet] & #ch in*es face = driv+ ! g5]ators4 ,! accompany+ illu/ration %[s ! h>ness "w1 ge>s1 pulleys1 etc41 furni%$ ) ! turb9es4 ,! #bj in* horizontal %aft ,samson turb9e ( #gb horse p[] is direct connect$ to an excit] g5]ator ( #bj kw41 runn+ #gjj rev4 p] m94 ,! two l>ge g5]ators are driv5 #dej revolutions p] m9ute by belts produc+ a ?ree phase curr5t ( #fj cycles ( #aa1ejj volts = ! twelve & "o-half miles transmission4 ,! l9e consi/s ( ?ree /r&s ( ,no4 #d b>e copp] wire4 ,?is curr5t is us$ = light+ & p[] purposes1 & ! plant is ( ! late/ improv$ design & con/ruction4 ,isolat$ ,plants4--,:5 electric p[] transmission f c5tral /ations fir/ came into comm]cial use1 ! di/ance f ! /ation at :i* curr5t c\ld be obta9$ at a reasonable co/ 0 exce$+ly limit$4 ,illu/ration3 ,,fig4 #b1gfi;a4--,triumph direct curr5t g5]ator set ) upright slide valve eng9e4 ,illu/ration3 ,,fig4 #b1ggj;a4--,murray alt]nat+ curr5t direct connect$ unit ) high spe$ ,corliss eng9e & belt driv5 excit]1 #ej1 #ge & #ajj kva4 alt]nator & #aej ,r4,p4,m4 eng9e4 ,illu/ration3 ,,fig4 #b1gga4--;,direct connect$ direct curr5t unit ) ,ridgway high spe$ f\r valve eng9e4 ,illu/ration3 ,,fig4 #b1ggb4--;,buckeye mobile1 or self conta9$ unit consi/+ ( comp\nd cond5s+ eng9e1 boil]1 sup]heat]1 reheat]1 fe$ & air pumps2 x produces "o horse p[] on #a lbs4 ( coal1 built 9 sizes f #ge to #fjj horse p[]4 ,illu/ration3 ,,fig4 #b1ggc4--,we/+h\se ?ree cyl9d] gas eng9e1 direct connect$ to dynamo1 %[+ application ( gas eng9e drive = small direct connect$ units4 ,consequ5tly1 p]sons desir+ electrical p[] 7 9 ! majority ( cases =c$ to in/all _! own app>atus = produc+ x1 ?is be+ ! orig9 ( isolat$ plants4 ,f ! nature ( ! case x is evid5t t an isolat$ plant is z a rule small] & m simple 9 con/ruction ?an a c5tral /ation1 & 9 consequ5ce mu* m readily op]at$ & manag$4 ,x is g5]ally own$ by a private individual or a corporation & op]at$ 9 conjunction ) o!r affairs ( a simil> "*4 ,a basem5t or o!r portion ( a build+ is usually set aside 9 :i* ! necess>y app>atus is in/all$4 ,illu/ration3 ,,fig4 #b1ggd4--;,g5]al ,electric #be kw41 gasol9e electric g5]at+ set = light+ & p[]4 ,! eng9e has f\r cyl9d]s #g #g1 & runs at a spe$ ( #efj revolutions p] m9ute4 ,! total c&le p[] capacity 9 ,mazda lamps is #bj1jjj4 ,! ignition is by l[ t5sion magneto1 coil & batt]y4 ,c>burett] is ( ! con/ant level type to :i* gasol9e is deliv]$ by a pump driv5 by ! eng9e4 ,=c$ lubrication2 five crank %aft be>+s babbitt$2 valves 9 side2 ov]all dim5sions #if #cd #fj high2 weight #e1jjj4 ,al?\gh electricity is n[ transmitt$ economically to great di/ances f c5tral /ations1 !re is /ill a field = ! isolat$ plant4 ,! av]age type ( isolat$ plant has enl>g$ f a small dynamo driv5 by a little slide valve eng9e locat$ 9 an out ( ! way corn] to direct connect$ g5]ators & eng9es ( hundr$s & ev5 ?\s&s ( horse p[] assembl$ 9 a l>ge room specially adapt$ to ! purpose4 ,9 ! m mod]n ( ^!1 ! electrical outputs are ea* frequ5tly equal to t ( a t[n c5tral /ation ( respectable size1 & ! auxili>y equipm5ts are simil> 9 e p>ticul>4 ,z a matt] ( fact1 9 c]ta9 mod]n isolat$ plants ! only feature t di/+ui%es !m f c5tral /ations is t 9 ! =m] case ! own] ( ! plant repres5ts ! sole consum] & conducts o!r bus9ess 9 connection ) x1 :]eas 9 ! latt] case !re are a l>ge numb] ( consum]s un9t]e/$ f9ancially 9 ! ent]prise1 :i* is itself g5]ally own$ & op]at$ by a company conduct+ no o!r bus9ess4 ,illu/ration3 ,,fig4 #b1gge4--,plan ( sub-/ation ) air bla/ trans=m]s & motor op]at$ oil swit*es & und]gr\nd #aa1jjj or #ac1bjj volt high t5sion l9es4 ,sub-,/ations4--,accord+ to ! usual mean+ ( ! t]m1 a sub-/ation is a build+ provid$ ) app>atus = *ang+ high pressure alt]nat+ curr5t receiv$ f ! c5tral /ation into direct curr5t ( ! requisite pressure1 :i* 9 ! case ( railways is #eej to #fjj volts4 ,:]e traffic is heavy & ! railway sy/em ( consid]able di/ance1 sub-/ations are provid$ at int]vals along ! l9e1 ea* receiv+ high pressure curr5t f "o l>ge c5tral /ation & conv]t+ x into mod]ate pressure direct curr5t = _! di/ricts4 ,ques4 ,^u :at does ! arrangem5t ( ! sub-/ation dep5d8 ,ans4 ,^u ! "* ( ! "w & ! type ( app>atus employ$ = conv]t+ ! high pressure alt]nat+ curr5t into direct curr5t4 ,illu/ration3 ,,fig4 #b1ggf4--,plan ( small sub-/ation ) s+le phase oil insulat$ self-cool+ trans=m]s & h& op]at$ oil swit*es #aa1jjj or #ac1bjj volts1 ov]head high t5sion l9es4 ,9 g5]al x %\ld be sub/antial1 conv5i5t to in/all or replace ! heavy ma*9es1 & ! lay\t arrang$ s t ! app>atus c be readily op]at$ by ^? 9 att5dance4 ,an ov]head travel+ crane is ! mo/ conv5i5t me?od ( h&l+ ! heavy ma*9]y1 & is frequ5tly us$ 9 l>ge sub-/ations4 ,fig4 #b1ggf %[s a sectional view1 & fig4 #b1ggg1 a plan = a small sub-/ation conta9+ two rot>y conv]t]s & two banks ( ?ree s+le phase /atic trans=m]s op]at+ on a ?ree phase sy/em at #aa1jjj or #ac1bjj volts1 toge!r ) ! auxili>y app>atus4 ,illu/ration3 ,,fig4 #b1ggg4--;,elevation ( small sub-/ation1 z %[n 9 plan 9 ,fig4 #b1ggf4 ,ques4 ,= ?ree phase in/allations1 :at are ! m]its ( sep>ate & comb9$ trans=m]s8 ,ans4 ,) sep>ate trans=m] = ea* phase1 repairs are m readily made 9 case ( accid5t or burn\ts 9 ! coils4 ,! ?ree phase units h ! advantage ( l[ fir/ co/4 ,sub-/ation trans=m]s produce consid]able heat1 due to ! hy/]esis & eddy curr5ts1 & x is necess>y to get rid ( x4 ,small trans=m]s radiate ! heat f ! %ell & ! m$ium sizes h corrugat$ %ells :i* increase ! surface & provide m rapid radiation4 ,l>ge trans=m]s are cool$ by an air bla/ suppli$ by motor driv5 bl[]s or by wat] pump$ ?r\gh a coil ( pipe :i* is imm]s$ 9 ! insulat+ oil ( ! trans=m]4 ,! l>ge size oil insulat$1 wat] cool$ trans=m]s are us$ on circuits ( #cc1jjj volts or m4 ,9 wat] turb9e plants1 ! wat] may be pip$ to ! trans=m] "u pressure & ! pump omitt$ :i* cuts d[n ! co/ ( op]at+4 ,air bla/ trans=m]s usually h a damp] or %utt] = air control4 ,illu/ration3 ,,fig4 #b1ggh4--,m>9e portable trans=m] /ation on ,los ,angeles ,aqu$uct4 ,! view %[s ?ree #bj kva4 ,we/+h\se out door trans=m]s in/all$ on a float1 #cc1jjj volts high pressure2 #ddj volts l[ pressure2 #ej cycles4 ,ques4 ,expla9 ! use ( reactance coils 9 sub-/ations4 ,ans4 ,9 ord] t ! direct curr5t voltage ( ! ord9>y rot>y may be regulat$ by a field rheo/at1 :i* calls = a correspond+ *ange 9 ! alt]nat+ curr5t voltage1 a reactance coil is provid$ betwe5 ! l[ t5sion w9d+ & ! conv]t]4 ,)\t su* a reactance ! ma9t5ance ( ! same voltage at full load z at no load involves excessive lead+ & lagg+ curr5ts & consequ5tly excessive heat+ 9 ! armature inductors1 unless ! resi/ance drop f ! s\rce ( con/ant pressure is small1 or ! natural reactance ( ! circuit high4 ,ques4 ,:at is ! effect ( weak5+ ! conv]t] field8 ,ans4 ,a lagg+ curr5t is set up :i* causes a drop 9 ! reactance coil4 ,illu/ration3 ,,fig4 #b1ggi4--,sectional elevation ( portable outdoor trans=m] type sub-/ation4 ,! high voltage swit*+ & protective app>atus is m\nt$1 out ( ! way1 on ! ro( ( ! c>1 b is op]at$ f ! swit*bo>d ) a /&>d remote control h&le4 ,! trans=m] is c>ri$ directly ov] ! truck at ! uncov]$ end ( ! c> & ! l[-t5sion leads f x run 9 conduit b5ea? ! floor & up into ! cab1 7:i* conta9s ! conv]t] & swit*bo>d7 to ! conv]t]4 ,! positive lead runs ?r\gh a conduit & ends 9 a t]m9al on ! ro(4 ,! en]gy ?us makes a complete circuit ( ! c> leav+ at a po9t close to t at :i* x ent]$4 ,! l[ pressure alt]nat+ curr5t z well z ! direct curr5t positive leads are c>ri$ bel[ ! c> floor 9 iron conduit support$ f ! *annel frame4 ,! field wires are c>ri$ ?r\gh ?is conduit to ! rheo/at4 ,wir+ = ! lights is arrang$ to supply two1 #e light clu/]s4 ,"o is f$ ) ! #fjj volt direct curr5t & ! o!r ) #dbj volt alt]nat+ curr5t4 ,all light+ conductors are c>ri$ 9 metal m\ld+ c>ri$ betwe5 ! flanges ( ! *annel iron ribs4 ,high wir+ is c>ri$ entirely on ! ro( ( ! c> :]e x is entirely out ( ! way & :]e ! op]ator _c come 9 contact ) x4 ,! swit*bo>d %\ld be ( ! utmo/ simplicity4 ,usually ! negative & equaliz] swit*es1 & ! field break-up swit* are m\nt$ on ! frame ( ! conv]t]4 ,! d\ble ?r[ swit* = />t+ & runn+ ! conv]t] c be m\nt$ "u ! floor ( ! c> & op]at$ by h&le at ! swit*bo>d4 ,! rheo/at c be m\nt$ back ( ! swit*bo>d on brackets bolt$ to ! c> sup]-/ructure4 ,! swit*bo>d ne$ only c>ry ! positive knife swit* & circuit break]1 & ! alt]nat+ curr5t ammet]1 voltmet] & p[] factor met]4 ,sometimes a wat?\r met] is add$4 ,! positive lead is br\ght out ?r\gh a conduit on ! ro( ( ! c> & is arrang$ = bolt+ to ! positive fe$]4 ,! negative & equaliz] t]m9als are locat$ at ! cab end ( ! c> & are arrang$ s t connection c be easily made f !m to ! gr\nd &1 if necess>y1 to an equaliz] circuit4 ,!re is usually a slid+ door at ea* end ( ! cab & two w9d[s on ea* side4 ,above ! doors1 transoms1 ext5d+ ! wid? ( ! cab1 are arrang$ to drop s t a curr5t ( air w circulate ?r\gh ! cab "u ! ro(1 c>ry+ out ! heat$ air4 ,!re are also sev]al v5tilat+ holes b5ea? ! conv]t] 9 ! floor ( ! c>4 ,^! provisions insure a con/ant circulation ( air ?r\gh ! c> :i* c>ries away all heat$ air4 ,ques4 ,/ate ! effect ( /r5g!n+ conv]t] field4 ,ans4 ,a lead+ curr5t is set up :i* gives a rise ( voltage 9 ! reactance coil4 ,h5ce :5 a heavy curr5t passes ?r\gh ! s]ies coil ( a comp\nd w\nd conv]t] & t5ds to produce a lead+ curr5t1 ! reactance coil w balance x1 & improve ! p[] factor ( ! :ole l9e4 ,illu/ration3 ,,fig4 #b1ghj4--,we/+h\se #cjj kw4 conv]t] 9 portable sub-/ation4 ,portable ,sub-,/ations4--,a portable sub-/ation con/itutes a sp>e equipm5t = practically any numb] ( p]man5t sub-/ations & r5d]s unnecess>y ! in/allation ( sp>e equipm5t 9 ea*4 ,x c be us$ to increase ! capacity ( a p]man5t sub-/ation :5 ! load is unusually heavy1 or to provide s]vice :ile a p]man5t sub-/ation is be+ ov]haul$ or rebuilt4 ,! trans=m] c be us$ = em]g5cy light+1 ! prim>y be+ connect$ to a high pressure l9e & ! second>y to ! load1 if special provision be made at ! "t ! trans=m] is built to adapt x = ^! applications4 ,illu/ration3 ,,fig4 #b1gha4--,swit*bo>d end ( ,we/+h\se portable sub-/ation4 ,:5 an electric railway has a portable sub-/ation1 direct curr5t c be provid$ at any po9t on ! sy/em :]e !re is track at ! high pressure l9e4 ,! direct curr5t c be made available v quickly z its production involves only ! transf]r+ ( ! sub-/ation1 & its connection to ! high pressure l9e4 ,portable sub-/ations range 9 capacity f #bjj to #ejj kw41 & = all alt]nat+ curr5t voltages up to #ff1jjj1 & frequ5cies ( #be & #fj cycles4 ,al?\gh portable sub-/ations usually mu/ be ( m or less special design to adapt !m to ! conditions "u :i* !y mu/ op]ate1 !re are c]ta9 g5]al features t are common to all4 ,all memb]s are readily accessible & !re are no unnecess>y p>ts4 ,! weight & dim5sions are a m9imum insur+ ease ( transportation4 ,live p>ts are s protect$ t ! dang] ( accid5tal contact ) !m is m9imiz$4 ,illu/ration3 ,,figs4 #b1ghb & #b1ghc4--,views ( levell+ device = ,we/+h\se conv]t]4 ,ques4 ,:at are ! advantages ( us+ outdoor trans=m]s on portable sub-/ations8 ,ans4 ,all high pressure wir+ is kept out ( ! c>4 ,! trans=m] is m effectively cool$ & ! heat dissipat$ by ! trans=m] does n w>m ! int]ior ( ! cab4 ,! trans=m] is mu* m accessible4 ,! c> c be run "u a crane & ! trans=m] coils pull$ out ) a hoi/4 ,taps = diff]5t high & l[ pressure voltages c be readily provid$ at ! "t ! trans=m] is be+ built4 ,,*apt] ,,lxvii ,,managem5t ,! t]m managem5t1 broadly speak+1 includes n only ! actual skill$ att5tion necess>y = ! prop] op]ation ( ! ma*9es1 aft] ! plant is built1 b also o!r duties :i* mu/ be p]=m$ f its inception to completion1 & :i* may be classifi$ z #a4 ,selection2 #b4 ,location2 #c4 ,erection2 #d4 ,te/+2 #e4 ,runn+2 #f4 ,c>e2 #g4 ,repair4 ,t is to say1 someone mu/ select ! ma*9]y1 det]m9e :]e ea* ma*9e is to be locat$1 in/all !m1 & !n att5d to ! runn+ ( ! ma*9es & make any necess>y repairs due to ! ord9>y mi%aps likely to occur 9 op]ation4 ,^! v>i\s duties are usually entru/$ to m ?an "o individual2 ?us1 ! selection & location ( ! ma*9]y is done by ! design] ( ! plant1 & requires = its prop] execution ! s]vices ( an electrical eng9e]1 or "o possess+ m ?an simply a practical k ( p[] plants4 ,! erection ( ! ma*9es is be/ accompli%$ by ^? mak+ a specialty ( ?is l9e ( "w1 :o by ! nature ( ! und]tak+ acquire pr(ici5cy 9 me?ods ( precision & an appreciation ( ! value ( accuracy :i* is s ess5tial 9 ! "w ( align+ ! ma*9es1 & :i* if poorly done w prove a con/ant s\rce ( annoyance aft]w>d4 ,! att5tion requir$ = ! op]ation ( ! ma*9es1 embrac+ ! runn+ c>e & repair1 is left to ! man 9 *>ge1 :o 9 mo/ cases ( small & m$ium size plants is ! *ief /eam eng9e]4 ,he mu/ !re=e1 n only und]/& ! /eam app>atus1 b possess suffici5t k ( electrical ma*9]y to op]ate & ma9ta9 x 9 prop] work+ ord]4 ,! pres5t *apt] deals *iefly ) alt]nat+ curr5t ma*9]y1 ! managem5t ( direct curr5t ma*9es hav+ be5 fully expla9$ 9 ,guide ,no4 #c1 h[ev]1 "s ( ! matt] "h pres5t$ is common to bo? classes ( app>atus4 99 99 99 99 99 ,selection4--,9 ord] to intellig5tly select a ma*9e s t x w prop]ly h>monize ) ! conditions "u :i* x is to op]ate1 !re are sev]al ?+s to be consid]$4 #a4 ,type2 #b4 ,capacity2 #c4 ,effici5cy2 #d4 ,con/ruction4 ,! g5]al type ( ma*9e to be us$ is1 ( c\rse1 dep5d5t on ! sy/em employ$1 t is1 :e!r x be direct or alt]nat+1 s+le or polyphase4 ,?us1 ! voltage 9 mo/ cases is fix$ except on trans=m] sy/ems :]e a *oice ( voltage may be _h by select+ a trans=m] to suit4 ,9 alt]nat+ curr5t con/ant pressure transmission circuits1 an av]age voltage ( #b1bjj volts ) /ep d[n trans=m] ratios ( #a_/aj & #a_/bj is 9 g5]al use1 & is recomm5d$4 ,= long di/ance1 ! foll[+ av]age voltages are recomm5d$ #f1jjj2 #aa1jjj2 #bb1jjj2 #cc1jjj2 #dd1jjj2 #ff1jjj2 #hh1jjj2 & high]1 dep5d+ on ! l5g? ( ! l9e & degree ( economy desir$4 ,9 alt]nat+ circuits ! /&>d frequ5cies are #be1 & #fj cycles4 ,^! frequ5cies are already 9 ext5sive use & x is recomm5d$ to adh]e to !m z closely z possible4 ,illu/ration3 ,,fig4 #b1ghd4--;,diagram ( connections = te/+ to obta9 ! saturation curve ( an alt]nator4 ,! saturation curve %[s ! relation betwe5 ! volts g5]at$ 9 ! armature & ! amp]es ( field curr5t 7or amp]e turns ( ! field7 = a con/ant armature curr5t4 ,! armature curr5t may be z]o1 9 :i* case ! curve is call$ no load saturation curve1 or sometimes ! op5 circuit *>act]i/ic curve4 ,a saturation curve may be tak5 ) full load curr5t 9 ! armature2 b ?is is r>ely done1 except 9 alt]nators ( comp>atively small output4 ,if a full load saturation curve be desir$1 x c be approximately calculat$ f ! no load saturation curve4 ,! figure %[s ! connections4 ,if ! voltage g5]at$ is great] ?an ! capacity ( ! voltmet]1 a multiply+ coil or a /ep d[n pressure trans=m] may be us$1 z %[n4 ,a s]ies ( obs]vations ( ! voltage betwe5 ! t]m9als ( "o ( ! phases1 is made = diff]5t values ( ! field curr5t4 ,eight or n9e po9ts along ! curve are usually suffici5t1 ! s]ies ext5d+ f z]o to ab\t fifty p] c5t4 above normal rat$ voltage4 ,! po9ts %\ld be tak5 m closely toge!r 9 ! vic9ity ( normal voltage ?an at o!r portions ( ! curve4 ,c>e mu/ be tak5 t ! alt]nator is run at its rat$ spe$1 & ?is spe$ mu/ be kept con/ant4 ,deviations f con/ant spe$ may be mo/ easily detect$ by ! use ( a ta*omet]4 ,if ! ma*9e be two phase or ?ree phase1 ! voltmet] may be connect$ to any "o phase ?r\gh\t a complete s]ies ( obs]vations4 ,! voltage ( all ! phases %\ld be obs]v$ = normal full load excitation by connect+ ! voltmet] to ea* phase successively1 keep+ ! field curr5t con/ant at normal voltage4 ,?is is done 9 ord] to see h[ closely ! voltage ( ! diff]5t phases agree4 ,9 fix+ ! capacity ( a ma*9e1 c>eful consid]ation %\ld be giv5 to ! conditions ( op]ation bo? pres5t & future 9 ord] t ! resultant effici5cy may be maximum4 ,mo/ ma*9es %[ ! be/ effici5cy at or ne> full load4 ,if ! load be always con/ant1 z = in/ance1 a pump =c+ wat] to a giv5 head1 x w\ld be a simple matt] to specify ! prop] size ( ma*9e1 b 9 ne>ly all cases1 & especially 9 electrical plants1 ! load v>ies widely1 n only ! daily & h\rly fluctuations1 b ! v>y+ dem&s dep5d+ on ! season ( ! ye> & gr[? ( ! plant's bus9ess4 ,all ( ^! conditions t5d to complicate ! matt]1 s t intellig5t selection ( capacity ( a ma*9e requires n only calculation b mature judgm5t1 :i* is only obta9$ by long exp]i5ce4 ,illu/ration3 ,,fig4 #b1ghe4--,saturation curve tak5 f a #b1jjj kw41 ?ree phase alt]nator ( ! revolv+ field type1 hav+ #af poles1 & g5]at+ #b1jjj volts1 & #egf amp]es p] phase :5 run at #cjj ,r4,p4,m4 ,9 select+ a ma*9e1 or 9 fact any item connect$ ) ! plant its con/ruction %\ld be c>efully consid]$4 ,/&>d con/ruction %\ld be insi/$ ^u s t 9 ! ev5t ( damage a new "p c be obta9$ ) ! lea/ possible delay4 ,! p>ts ( mo/ ma*9es are int]*angeable1 t is to say1 ) ! ref9$ me?ods ( ma*9]y a duplicate "p 7usually c>ri$ 9 /ock7 may be obta9$ at once to replace a defective or brok5 "p1 & made ) su* precision t little or no fitt+ w be requir$4 ,! importance ( /&>d con/ruction _c be bett] illu/rat$ ?an 9 ! matt] ( /eam pip+1 t is1 ! k9d ( fitt+s select$ = a giv5 in/allation4 ,) ! exception ( ! exhau/ l9e f eng9e to cond5s]1 :]e o!r ?an /&>d con/ruction may sometimes be us$ to r$uce ! frictional resi/ance to ! /eam1 ! au?or w\ld adh]e to /&>d con/ruction except 9 v exceptional cases4 ,^? :o h _h practical exp]i5ce 9 pipe fitt+ w appreciate ! wisdom ( ?is4 ,= in/allations 9 places remote f l>ge supply h\ses1 ! m usual =ms ( /&>d fitt+s %\ld be employ$1 su* z ord9>y ,t's1 #de & #ij elb[s1 etc4 ,9 su* locations1 :]e design]s specify ! less usual =ms ( /&>d fitt+s su* z union fitt+s1 (fset r$uc]s1 etc41 or special fitt+s made to sket*1 x simply means1 9 ! fir/ in/ance t !y usually _c be obta9$ ( ! local deal]1 mak+ x necess>y to ord] f "s l>ge supply h\se & result+ 9 vexati\s delays4 ,z a rule1 ^? :o specify special fitt+s h f\nd t _! mak+ requires an unreasonable l5g? ( "t1 & ! co/ to be sev]al times t ( ! equival5t 9 /&>d fitt+s4 ,an exam9ation ( a few in/allations w usually %[ num]\s special & odd %ape fitt+s1 :i* are entirely unnecess>y4 ,moreov]1 a /&>d design1 9 g5]al1 is bett] ?an a special design1 because ! =m] has be5 tri$ out1 & any imp]fection or weakness rem$i$1 & :]e ?\s&s ( ca/+s ( a k9d are turn$ out1 a bett] article is usually ! result z comp>$ ) a special ca/+4 ,9 ! matt] ( con/ruction1 9 addition to ! items j m5tion$1 x %\ld be consid]$ ) respect to #a4 ,quality2 #b4 ,range2 #c4 ,accessibility2 #d4 ,proportion2 #e4 ,lubrication2 #f4 ,adju/m5t4 ,x is poor policy1 except+ 9 v r>e in/ances1 to buy a *eap article1 z1 especially 9 ^! days ( comm]cial gre$1 ! be/ is none too good4 ,illu/ration3 ,,figs4 #b1ghf & #b1ghg4--,:eel & roll] pipe cutt]s illu/rat+ range4 ,! illu/rations %[ ! comp>ative movem5ts necess>y ) ! two types ( cutt] to p]=m _! function4 ,! :eel cutt] requir+ only a small arc ( movem5t w cut a pipe 9 an inaccessible place z %[n1 :i* ) a roll] cutt] w\ld be impossible4 ,accord+ly1 ! :eel cutt] is said to h a great] range ?an ! roll] cutt]4 ,p]haps next 9 importance to quality1 at lea/ 9 mo/ cases1 is range4 ,?is may be def9$ z scope ( op]ation1 effectiv5ess1 or adaptability4 ,! importance ( range is p]haps mo/ pron\nc$ 9 ! selection ( tools1 especially = plants remote f repair %ops4 ,= in/ance1 9 select+ a pipe cutt]1 !re are two g5]al classes3 :eel cutt]s1 & roll] cutt]s4 ,a :eel cutt] has ?ree :eels & a roll] cutt] "o :eel & two roll]s1 ! object ( ! roll]s be+ to keep ! :eel p]p5dicul> to ! pipe 9 />t+ ! cut & to r$uce burn+4 ,x mu/ be evid5t t 9 op]ation1 a roll] cutt] requires suffici5t room ar\nd ! pipe to p]mit mak+ a complete revolution ( ! cutt]1 :]eas1 ) a :eel cutt]1 ! "w may be done by mov+ ! cutt] back & =? ?r\gh a small arc1 z illu/rat$ 9 figs4 #b1ghf & #b1ghg4 ,?us a :eel cutt] has a great] range ?an a roll cutt]4 ,range relates n only to ability to op]ate 9 inaccessible places b to ! v>i\s op]ations t may be p]=m$ by "o tool4 ,,prop]ties ,,( ,,/&>d ,,wr\ght ,,iron ,,pipe ---------------------------------------- --------- ,diamet] ,?ick- ,circumf]5ce4 ness4 ------------------------ ---------------- ,nom9al ,actual ,actual ,ext]nal,int]nal int]nalext]nalint]nal ---------------------------------------- ------ ,in*es ,in*es ,in*es ,in*es ,in*es ,in*es ---------------------------------------- ------ 4#dje 4#bg 4#jfh #a4bgb 4#hdh 4#ed 4#cfd 4#jhh #a4fif #a4add 4#fge 4#did 4#ia #b4aba #a4eeb 4#hd 4#fbc 4#aji #b4fci #a4ieg #a4je 4#hbd 4#aac #c4bii #b4ehi #a #a4cae #a4jdh 4#acd #d4aca #c4bib #a #a4ff #a4ch 4#ad #e4bae #d4cce #a #a4i #a4faa 4#ade #e4ifi #e4jfa #b #b4cge #b4jfg 4#aed #g4dfa #f4did #b #b4hge #b4dfh 4#bjd #i4jcb #g4gec #c #c4e #c4jfg 4#bag #aj4iif #i4fcf #c #d4 #c4edh 4#bbf #ab4eff #aa4adf #d #d4e #d4jbf 4#bcg #ad4acg #ab4fdh #d #e4 #d4ejh 4#bdf #ae4gjh #ad4afb #e #e4efc #e4jde 4#bei #ag4dgg #ae4hdi #f #f4fbe #f4jfe 4#bh #bj4hac #ai4jed #g #g4fbe #g4jbc 4#cja #bc4iee #bb4jfc #h #h4fbe #g4ihb 4#cbb #bg4jif #be4jgf #i #i4fbe #h4icg 4#cdd #cj4bch #bh4jgf #aj #aj4ge #aj4jai 4#cff #cc4ggb #ca4dgg #aa #ab4 #aa4be 4#cge #cg4fii #ce4cdc #ab #ab4ge #ab4 4#cge #dj4jee #cg4g ---------------------------------------- ------ ---------------------------------------- --------------------------- ,l5g? ,l5g? ( pipe ( pipe ,nom9al ,diam4 ,transv]se areas4 p] squ>e conta9-weight ,numb] foot ( + "o p] ( ---------------------------------------- --- cubic foot4 ?read ,nom4 ,ext]nal,int]nal ,metal ,ext'nal,int'nal foot4 p] int]n surfacesurface in* ---------------------------------------- ------------------ ( ,in*es,sq4 ins4,sq4 ins4,sq4ins4 ,feet ,feet ,feet ,p\nds screw ---------------------------------------- ----------------------- 4#abi 4#jegc 4#jgag #i4dd #ad4ae #beac4 4#bda #bg 4#bbi 4#ajda 4#abdi #g4jge #aj4di #achc4c 4#db #ah 4#ceh 4#aiag 4#affc #e4feg #g4gc #gea4b 4#eei #ah 4#eed 4#cjdh 4#bdib #d4edg #f4ac #dgb4d 4#hcg #ad 4#hff 4#eccc 4#ccbg #c4fcg #d4fce #bgj4 #a4aae #ad #a #a4ceh 4#hfbf 4#died #b4ijd #c4fde #aff4i #a4ffh #aa #a #b4afd #a4dif 4#ffh #b4cja #b4gfh #if4be #b4bdd #aa #a #b4hce #b4jch 4#gig #b4ja #b4cga #gj4ff #b4fgh #aa #b #d4dc #c4cef #a4jgd #a4fjh #a4hdh #db4ia #c4fji #aa #b #f4dib #d4ghd #a4gjh #a4cbh #a4edg #cj4a #e4gci #h #c #i4fba #g4chh #b4bdc #a4jia #a4bde #ai4e #g4ecf #h #c #ab4eff #i4hhg #b4fgi 4#iee #a4jgg #ad4eg #i4jja #h #d #ae4ijd #ab4gc #c4agd 4#hdi 4#idi #aa4ca #aj4ffe #h #d #ai4fce #ae4ifa #c4fgd 4#gfd 4#hdh #i4jb #ab4cd #h #e #bd4cjf #ai4ii #d4caf 4#fhg 4#geg #g4b #ad4ejb #h #f #cd4dgb #bh4hhh #e4ehd 4#egg 4#fc #d4ih #ah4gfb #h #g #de4ffd #ch4gch #f4ibf 4#eja 4#edd #c4gb #bc4bga #h #h #eh4dbf #ej4jd #h4chf 4#ddc 4#dgh #b4hh #bh4agg #h #i #gb4gf #fb4gc #aj4jc 4#cig 4#dbg #b4bi #cc4gja #h #aj #ij4gfc #gh4hci #aa4ibd 4#cee 4#chb #a4hb #dj4jfe #h #aa #aac4jih #ii4djb #ac4fif 4#cah 4#cci #a4dejde4ie #h #ab #abg4fgg #aac4jih #ad4egi 4#bii 4#cai #a4bg #dh4ihe #h ---------------------------------------- ---------------------- ,op5 con/ruction %\ld be employ$1 :]ev] possible1 s t all p>ts ( a ma*9e t require att5tion1 or t may become d]ang$ 9 op]ation1 may be accessible = adju/m5t or repair4 ,! design %\ld be su* t !re is ample /r5g?1 & ! be>+s = mov+ p>ts %\ld be ( lib]al proportions to avoid heat+ ) m9imum att5tion4 ,a comp>ison ( ! proportions us$ by diff]5t manufactur]s = a ma*9e ( giv5 size might pr(itably be made be=e a selection is made4 ,! matt] ( lubrication is important4 ,fa/ runn+ ma*9es1 su* z g5]ators & motors1 %\ld be provid$ ) r+ oil]s & oil res]voirs ( ample capacity1 z %[n 9 figs4 #b1ghh to #b1gid4 ,illu/ration3 ,,fig4 #b1ghh4--,sectional view %[+ a r+ oil] or self oil+ be>+4 ,z %[n ! p$e/al or be>+ /&>d is cor$ out to =m a res]voir = ! oil4 ,! r+s are 9 roll+ contact ) ! %aft1 & dip at _! l[] "p into ! oil4 ,9 op]ation1 oil is br\ght up by ! r+s :i* revolve because ( ! frictional contacts ) ! %aft4 ,! oil is 9 ?is way br\ght up to ! top ( ! be>+ & di/ribut$ along ! %aft gradually desc5d+ by gravity to ! res]voir1 be+ ?us us$ ov] & ov]4 ,a dra9 cock1 is provid$ 9 ! base s t ! oil may be p]iodically remov$ f ! res]voir & /ra9$ to remove ! accumulation ( =eign matt]4 ,?is %\ld be frequ5tly done to m9imize ! we> ( ! be>+4 ,all be>+s subject to appreciable we> %\ld be made adju/able s t lo/ motion may be tak5 up f "t to "t & ?us keep ! vibration & noise ( op]ation )9 prop] limits4 ,selection ( ,g5]ators4--,?is is gov]n$ by ! class ( "w to be done & by c]ta9 local conditions :i* are liable to v>y consid]ably = diff]5t /ations4 ,^! v>iable factors det]m9e :e!r ! g5]ators mu/ be ( ! direct or alt]nat+ curr5t type1 :e!r !y mu/ be w\nd to develop a high or a l[ voltage1 & :e!r _! outputs 9 amp]es mu/ be l>ge or small4 ,suffici5t in=mation has already be5 giv5 to cov] ^! v>i\s cases2 !re are1 h[ev]1 c]ta9 g5]al rules t may advantage\sly be obs]v$ 9 ! selection ( g5]ators design$ to fill any ( ! a=em5tion$ conditions1 & x is well to possess c]ta9 facts reg>d+ _! con/ruction4 ,illu/ration3 ,,figs4 #b1ghi to #b1gid4--,self oil+ self align+ be>+ op54 ,views %[+ oil grooves1 r+s1 bolts etc4 ,ques4 ,"n an important po9t to be consid]$ 9 select+ a g5]ator4 ,ans4 ,its effici5cy4 ,ques4 ,:at are ! important po9ts ) respect to effici5cy8 ,ans4 ,a g5]ator possess+ a high effici5cy at ! av]age load is m desirable ?an a g5]ator %[+ a high effici5cy at full load4 ,ques4 ,:y8 ,ans4 ,! reason is t 9 /ation practice ! full load limit is seldom rea*$1 ! usual load c>ri$ by a g5]ator ord9>ily ly+ betwe5 ! "o-half & ?ree-qu>t] load po9ts4 ,ques4 ,h[ d ! effici5cies ( l>ge & small g5]ators comp>e8 ,ans4 ,!re is little diff]5ce4 ,illu/ration3 ,,fig4 #b1gie4--,rotor ( ,we/+h\se type ,t turb9e dynamo set4 ,! dynamo is ( ! commutat+ pole type ei!r %unt or comp\nd w\nd4 ,! turb9e is ( ! s+le :eel impulse type4 ,! :eel is m\nt$ directly on ! end ( ! %aft z %[n4 ,/eam is us$ two or m times on ! :eel to secure effici5cy4 ,a fly ball gov]nor is provid$ ) weights hung on h>d5$ /eel knife edges4 ,9 case ( ov] spe$+1 an automatic safety /op ?rottle valve is tapp$ %utt+ (f ! /eam supply4 ,?is type ( turb9e dynamo set is especially applicable = excit] s]vice 9 mod]n1 sup]heat$ /eam g5]at+ /ations :]e ! /eam pressure exce$s #abe p\nds4 ,we/+h\se ,type ,t turb9es op]ate directly 7t is1 )\t a r$uc+ valve7 on pressures up to #bjj p\nds p] squ>e in* ) /eam sup]heat$ to #aej degrees ,fahr5heit4 ,ques4 ,h[ are ! sizes & numb] ( g5]ator det]m9$8 ,ans4 ,! sizes & numb] ( g5]ator to be in/all$ %\ld be su* z to p]mit ! eng9es op]at+ !m be+ work$ at ne>ly full load1 because ! effici5cies ( ! latt] ma*9es decrease rapidly :5 c>ry+ less ?an ?is am\nt4 ,ques4 ,:at is und]/ood by regulation8 ,ans4 ,! accuracy & reliability ) :i* ! pressure or curr5t develop$ 9 a ma*9e may be controll$4 ,x is g5]ally possible if pur*as+ ( a reputable conc]n1 to obta9 access to record %eets on :i* may be f\nd results ( te/s conduct$ on ! g5]ator 9 "q1 & z ^! are really ! only means ( asc]ta9+ ! values ( effici5cy & regulation1 ! pur*as] has a "r to inspect !m4 ,if1 = "s reason or o!r1 he has n be5 af=d$ ?is privilege1 he %\ld ord] ! ma*9e in/all$ 9 ! /ation on approval1 & te/ its effici5cy & regulation be=e mak+ ! pur*ase4 ,illu/ration3 ,,fig4 #b1gif4--;,cross section ( electrical /ation %[+ small travel+ crane4 ,in/allation4--,! in/allation ( ma*9es & app>atus 9 an electrical /ation is a task :i* increases 9 difficulty ) ! size ( ! plant4 ,:5 ! p>ts are small & comp>atively light !y may readily be plac$ 9 position1 ei!r by h&1 by erect+ tempor>y supports :i* may be mov$ f place to place z desir$1 or by roll+ ! p>ts along on ! floor ^u pieces ( iron pipe4 ,if1 h[ev]1 ! p>ts be l>ge & heavy1 a travel+ crane su* z %[n 9 fig4 #b1gig1 becomes necess>y4 ,ques4 ,:at precaution %\ld be tak5 9 mov+ ! p>ts ( ma*9es8 ,ans4 ,c>e %\ld be tak5 n to injure ! be>+s & %afts1 ! jo9ts 9 magnetic circuits su* z ^? betwe5 frame & pole pieces1 & ! w9d+s on ! field & armature4 ,illu/ration3 ,,fig4 #b1gig4--;,cross section ( electrical /ation %[+ a travel+ crane = ! in/allation or removal ( l>ge & heavy ma*9e p>ts4 ,a travel+ crane consi/s ( an iron beam :i*1 be+ suppli$ ) :eels at ! ends1 c be made to move ei!r me*anically or electrically ^u a track runn+ ! entire l5g? ( ! /ation4 ,?is track is n support$ by ! walls ( ! build+1 b re/s ^u beams specially provid$ = ! purpose4 ,9 addition to ! horizontal motion ?us obta9$1 ano!r horizontal motion at "r angles to ! =m] is af=d$ by means ( ! c>riage :i*1 be+ also m\nt$ on :eels1 runs ^u a track on ! top ( ! beam4 ,electrical p[] is g5]ally us$ to move ! c>riage & also ! revolv+ drums conta9$ !reon1 ! latt] ( :i* give a v]tical motion to ! ma9 hoi/ or ! auxili>y hoi/1 ^! hoi/s be+ us$ respectively = rais+ or l[]+ heavy or light loads4 ,9 ! l>g] sizes ( electric travel+ crane1 a cage is atta*$ to ! beam = ! op]ator1 :o1 by means ( ?ree controll]s m\nt$ 9 ! cage1 c move a load on ei!r ! ma9 or auxili>y hoi/ 9 any direction4 ,! insulations ( ! w9d+s are p]haps ! mo/ vital p>ts ( a g5]ator1 & ! mo/ readily injur$4 ,! prick ( a p9 or tack1 a bruise1 or a b5d+ ( ! wires by re/+ _! weight ^u !m or by _! com+ 9 contact ) "s h>d sub/ance1 w (t5 r5d] a field coil or an armature useless4 ,ow+ to its co/ly con/ruction1 x is advisable :5 transport+ armatures by means ( cranes to use a wood5 spread]1 z %[n 9 fig4 #b1gih to prev5t ! support+ rope bruis+ ! w9d+4 ,illu/ration3 ,,fig4 #b1gih4--,view ( armature 9 transit %[+ use ( a wood5 spread] z a protection4 ,if a *a9 be us$ 9 place ( ! rope1 a padd+ ( clo? %\ld be plac$ ar\nd ! armature %aft & special c>e tak5 t ! *a9 does n scrat* ! commutator4 ,ques4 ,if an armature _c be plac$ at once 9 its f9al position :at %\ld be done8 ,ans4 ,x may be laid tempor>ily ^u ! floor1 if a %eet ( c>dbo>d or clo? be plac$ und]nea? ! armature z a protection = ! w9d+s2 9 case ! armature is n to be us$ = "s "t1 x is bett] practice to place x 9 a horizontal position on two wood5 supports ne> ! %aft ends4 ,ques4 ,:at k9d ( base %\ld be us$ ) a belt driv5 g5]ator or motor8 ,ans4 ,! base %\ld be provid$ ) ,v ways & adju/+ screws = mov+ ! ma*9e horizontally to take up slack 9 ! belt1 z %[n 9 fig4 #b1gii4 ,ow+ to ! normal t5sion on ! belt1 !re is a mom5t ex]t$ equal 9 am\nt to ! di/ance f ! c5t] ( gravity ( ! ma*9e to ! c5t] ( ! belt1 multipli$ by ! effective pull on ! belt4 ,?is =ce t5ds to turn ! ma*9e ab\t its c5t] ( gravity4 ,by plac+ ! screws z %[n1 any turn+ mom5t1 z j m5tion$1 is prev5t$4 ,illu/ration3 ,,fig4 #b1gii4--,plan ( belt drive ma*9e %[+ ,v ways & adju/+ screws = mov+ ! ma*9e =w>d f ! eng9e or c\nt] %aft to take up slack 9 ! belt4 ,ques4 ,h[ %\ld a ma*9e be assembl$8 ,ans4 ,! assembl+ %\ld progress by ! aid ( a blue pr9t1 or by ! in=mation obta9$ f a photograph ( ! complete ma*9e z x appe>s :5 ready = s]vice4 ,ea* "p %\ld be p]fectly clean :5 plac$ 9 position1 especially ^? p>ts betwe5 :i* !re is friction :5 ! ma*9e is 9 op]ation1 or across :i* pass l9es ( magnetic =ce2 9 bo? cases ! surfaces 9 contact mu/ be true & slightly oil$ be=e plac+ 9 position4 ,contact surfaces =m+ "p ( electrical circuits mu/ also be clean & tightly screw$ toge!r4 ,an important po9t to be> 9 m9d :5 assembl+ a ma*9e is1 to s place ! p>ts t x w n be necess>y to remove any "o ( !m 9 ord] to get "s o!r "p 9 its prop] position4 ,by rememb]+ ?is simple rule mu* "t w be sav$1 & 9 ! majority ( in/ances ! p>ts w f9ally be bett] fitt$ toge!r ?an if ! task has to be repeat$ a numb] ( times4 ,:5 !re are two or m p>ts ( ! ma*9e simil>ly %ap$1 x is (t5 difficult to prop]ly locate !m1 b 9 su* cases notice %\ld be tak5 ( ! factory m>ks usually /amp$ ^u su* pieces & _! prop] places det]m9$ f ! in/ructions s5t ) ! ma*9e4 ,illu/ration3 ,,figs4 #b1hjj to #b1hjb4--,/>rett's improv$ spe$ indicator4 ,9 con/ruction1 ! work+ p>ts are enclos$ l a wat*4 ,! graduations %[ e revolution1 & ) two r[s ( figures read bo? "r & left z ! %aft may run4 ,:ile look+ at ! wat*1 ea* hundr$ revolutions may be c\nt$ by all[+ ! oval head$ p9 on ! revolv+ disc to pass "u ! ?umb z ! in/rum5t is press$ to its "w4 ,a late improvem5t 9 ?is indicator consi/s 9 ! rotat+ disc1 :i*1 be+ c>ri$ by friction may be mov$ to ! />t+ po9t :]e ! rais$ knobs co9cide4 ,:5 ! sp9dle is plac$ 9 connection ) ! revolv+ %aft1 press+ ! rais$ knob ) ! ?umb w prev5t ! disc rotat+1 :ile ! h& ( ! wat* gets to ! "r position to take ! "t4 ,by releas+ ! pressure ! disc is lib]at$ = c\nt+ ! revolutions ( ! %aft :5 e #ajj may be not$ by feel+ ! knob pass "u ! ?umb lightly press$ aga9/ x1 ?us reliev+ ! eye1 :i* has only to look on ! wat* to note ! "t4 ,ques4 ,:at %\ld be not$ ) respect to spe$ ( g5]ator8 ,ans4 ,ea* g5]ator is design$ to be run at a c]ta9 spe$ 9 ord] to develop ! voltage at :i* ! ma*9e is rat$4 ,! spe$1 9 revolutions p] m9ute1 ! pressure 9 volts1 & ! capacity or output 9 watts 7volts amp]es7 or 9 kil[atts 7?\s&s ( watts7 are g5]ally /amp$ on a nameplate screw$ to ! ma*9e4 ,?is requirem5t frequ5tly requires calculations to be made by ! erectors to det]m9e ! prop] size pulleys to employ to obta9 ! desir$ spe$4 ,illu/ration3 ,,fig4 #b1hjc4--;,home made belt clamp4 ,x is made ) f\r pieces ( oak ( ample size to firmly grip ! belt ends :]e ! bolts are tight5$4 ,! figure %[s ! clamp complete & 9 position on ! belt & cle>ly illu/rates ! details ( con/ruction4 ,9 mak+ ! long bolts ! ?read %\ld be cut ab\t ?ree-qu>t] l5g? ( bolt & deep en\gh s t ! nuts w easily screw on4 ,example4--,:at diamet] ( eng9e pulley is requir$ to run a dynamo at a spe$ ( #a1dej revolutions p] m9ute ! dynamo pulley be+ #aj in*es 9 diamet] & ! spe$ ( eng9e1 #bge revolutions p] m9ute8 ,! diamet] ( pulley requir$ on eng9e is #aj 7#a1dej #bge7 #ec in*es1 ne>ly4 ,rule4--,to f9d ! diamet] ( ! driv+ pulley1 multiply ! spe$ ( ! driv5 pulley by its diamet]1 divide ! product by ! spe$ ( ! driv] & ! answ] w be ! size ( ! driv] requir$4 ,example4--,if ! spe$ ( an eng9e be #cbe revolutions p] m9ute1 diamet] ( eng9e pulley #db in*es1 & ! spe$ ( ! dynamo #a1djj revolutions p] m9ute1 h[ l>ge a pulley is requir$ on dynamo8 ,! size ( ! dynamo pulley is #db 7#cbe #a1djj7 #i in*es4 ,rule4--,to f9d ! size ( dynamo pulley1 multiply ! spe$ ( eng9e by ! diamet] ( eng9e :eel & divide ! product by ! spe$ ( ! dynamo4 ,illu/ration3 ,,figs4 #b1hjd & #b1hje4--;,a good me?od ( lac+ a belt4 ,! view at ! left %[s out] side ( belt1 & at ! "r1 inn] or pulley side4 ,example4--,if a /eam eng9e1 runn+ #cjj revolutions p] m9ute1 h a belt :eel #dh in*es 9 diamet]1 & be belt$ to a dynamo hav+ a pulley #ab in*es 9 diamet]1 h[ _m revolutions p] m9ute w ! dynamo make8 ,! spe$ ( dynamo w be #cjj 7#dh #ab7 #a1bjj rev4 p] m94 ,rule4--,:5 ! spe$ ( ! driv+ pulley & its diamet] are kn[n1 & ! diamet] ( ! driv5 pulley is kn[n1 ! spe$ ( ! driv5 pulley is f\nd by multiply+ ! spe$ ( ! driv] by its diamet] 9 in*es & divid+ ! product by ! diamet] ( ! driv5 pulley4 ,example4--,:at w be ! requir$ spe$ ( an eng9e hav+ a belt :eel #df in*es 9 diamet] to run a dynamo #a1ejj revolutions p] m9ute1 ! dynamo pulley be+ #aa in*es 9 diamet]8 ,! spe$ ( ! eng9e is #a1ejj 7#aa #df7 #cei rev4 p] m94 ne>ly4 ,illu/ration3 ,,fig4 #b1hjf4--,wir+ diagram & directions = op]at+ ,holz]-,cabot s+le phase self-/>t+ motor4 ,location3 ,! motor %\ld be plac$ 9 z cle> & dry a location z possible1 away f acid or o!r fumes :i* w\ld attack ! metal p>ts or insulation1 & %\ld be locat$ :]e x is easily accessible = clean+ & oil+4 ,erection3 ,! motor %\ld be set s t ! %aft is level & p>allel ) ! %aft x is to drive s t ! belt w run 9 ! middle ( ! pulleys4 ,d n use a belt :i* is too heavy or too tight = ! "w x has to d1 z x w mat]ially r$uce ! output ( ! motor4 ,! belt %\ld be f "o-half to "o in* n>r[] ?an ! pulley4 ,rotation3 ,9 ord] to rev]se ! direction ( rotation1 int]*ange leads ,a & ,b4 ,susp5d$ ,motors3 ,motors ) r+ oil be>+s may be us$ on ! wall or ceil+ by tak+ (f end caps & revolv+ #ij or #ahj degrees until ! oil wells come directly bel[ ! be>+s4 ,/>t+3 ,motors are provid$ ) l9k across two t]m9als on ! upp] "r h& bracket at ! front ( ! motor & ) ?is connection %\ld />t consid]able ov]loads4 ,if ! />t+ curr5t be too great ) ?is connection1 x may be r$uc$ by remov+ ! l9k4 ,temp]atures3 ,at full load ! motor w feel hot to ! h&1 b ?is is f> bel[ ! dang] po9t4 ,if too hot = t\*1 measure temp]ature ) a !rmomet] by plac+ bulb aga9/ field w9d+ = #aj m9utes1 cov]+ !rmomet] ) clo? or wa/e4 ,! temp]ature %\ld n exce$ #ge degrees ,fahr4 above ! surr\nd+ air4 ,oil+3 ,fill ! oil wells to ! ov]fl[ be=e />t+ & keep !m full4 ,see t ! oil r+s turn freely ) %aft4 ,c>e3 ,! motor mu/ be kept clean4 ,smoo? collector r+s ) s&pap] & see t ! bru%es make good contact4 ,:5 bru%es become worn !y may be rev]s$4 ,:5 fitt+ new bru%es or *ang+ !m always s&pap] !m d[n until !y make good contact ) ! collector r+s1 by pass+ a /rip ( s&pap] b5ea? ! bru%4 ,rule4--,to f9d ! spe$ ( eng9e :5 diamet] ( bo? pulleys1 & spe$ ( dynamo are giv51 multiply ! dynamo spe$ by ! diamet] ( its pulley & divide by ! diamet] ( eng9e pulley4 ,ques4 ,h[ are ! diamet]s & spe$s ( ge> :eels figur$8 ,ans4 ,! same z belt$ :eels1 us+ ei!r ! pit* circle diamet]s or numb] ( tee? 9 ea* ge> :eel4 ,illu/ration3 ,,figs4 #b1hjg to #b1hji4--,wir+ diagrams & directions = op]at+ ,holz]-,cabot sl[ spe$ alt]nat+ curr5t motors4 ,erect+3 ,9 in/all+ ! motor1 be sure ! trans=m] & wir+ to ! motor are l>ge en\gh to p]mit ! prop] voltage at ! t]m9als4 ,if too small1 ! voltage w drop & r$uce ! capacity ( ! motor4 ,oil+3 ,ma9ta9 oil 9 wells to ! ov]fl[4 ,/>t+3 ,s+le phase motors are />t$ by fir/ ?r[+ ! />t+ swit* d[n into ! />t+ position1 & :5 ! motor is up to spe$1 ?r[+ x up into ! runn+ position4 ,d n hold ! swit* 9 />t+ position ov] #aj seconds4 ,/>t] = s+le phase motors above ,h4,p4 are arrang$ ) an adju/+ l9k at ! bottom ( ! panel4 ,! l9k is %[n 9 ! position ( lea/ />t+ torque & curr5t4 ,connect f ,w to #b or ,w to #c = />t+ heavi] loads4 ,two or ?ree phase motors are />t$ simply by clos+ ! swit*4 ,^! motors />t full load )\t />t]s4 ,! motor %\ld />t promptly on clos+ ! swit*4 ,x %\ld be />t$ ! fir/ "t )\t be+ c\pl$ to ! l9e %aft4 ,if ! motor />t free1 b w n />t load$1 x %[s ei!r t ! load ^u ! motor is too great1 ! l9e voltage too l[1 or ! frequ5cy too high4 ,! voltage & frequ5cy ) ! motor runn+ %\ld be )9 #e ( ! "n plate rat+ & ! voltage ) #aj to #ae :ile />t+4 ,if ! motor d n />t free1 ei!r x is gett+ no curr5t or some?+ is wrong ) ! motor4 ,9 ei!r case an electrician %\ld be consult$4 ,solution3 ,to rev]se ! direction ( rotation int]*ange ! leads m>k$ ,,xx 9 ! diagrams4 ,temp]ature3 ,at full load ! motor %\ld n heat ov] #ge degrees ,fahr4 above ! temp]ature ( ! surr\nd+ air2 if run 9 a small enclos$ space ) no v5tilation1 ! temp]ature w be some:at high]4 ,ques4 ,:at %\ld be not$ ) respect to g5]ator pulleys8 ,ans4 ,a pulley ( c]ta9 size is usually suppli$ ) ea* g5]ator by its manufactur]1 & x is n g5]ally advisable to dep>t mu* f ! dim5sions ( ?is pulley4 ,accord+ly1 ! solution ( ! pulley problem usually consi/s 9 f9d+ ! necess>y diamet] ( ! driv+ pulley relative to t ( ! pulley on ! g5]ator 9 ord] to furni% ! requir$ spe$4 ,ques4 ,:at is ! *ief objection to belt drive8 ,ans4 ,! l>ge am\nt ( floor space requir$4 ,illu/ration3 ,,fig4 #b1haj4--,t&em drive = economiz+ floor space ) belt transmission4 ,belts ( diff]5t l5g?s are us$1 z %[n1 ea* ( :i* passes ov] ! driv+ :eel d ( ! eng9e1 & !n ov] ! pulley :eel ( "o ( ! g5]ators4 ,9 su* an arrangem5t ! belts w\ld be run l5g?wise ?r\gh ! room 9 :i* ! ma*9es are plac$1 & x is obvi\s t s9ce ! wid? ( ! room w\ld be gov]n$ by ! wid? ( ! ma*9es ?us in/all$1 ?is me?od is a v effici5t "o = accompli%+ ! end 9 view4 ,ques4 ,h[ may ! am\nt ( space t w\ld ord9>ily be requir$ = belt drive1 be r$uc$8 ,ans4 ,by driv+ ma*9es 9 t&em z 9 fig4 #b1haj1 or by ! d\ble pulley drive z 9 fig4 #b1haa4 ,ques4 ,:at is ! objection to ! t&em me?od8 ,ans4 ,! mo/ economical di/ance betwe5 c5t]s _c be employ$ = all ma*9es4 ,ques4 ,:at is ! objectionable t5d5cy 9 resort+ to floor economy me?ods ) belt transmission8 ,ans4 ,! t5d5cy to place ! ma*9es too closely toge!r4 ,?is is poor economy z x makes ! clean+ ( ! ma*9es a difficult & dang]\s task2 x is !re=e advisable to all[ suffici5t room = ?is purpose reg>dless ( ! me?od ( belt+ employ$4 ,illu/ration3 ,,fig4 #b1haa4--;,d\ble pulley drive = economiz+ floor space ) belt transmission4 ,:]e a c5t] crank eng9e is us$ bo? pulleys may be employ$ by belt+ a ma*9e to ea* z %[n4 ,al?\gh consid]able floor space w\ld be sav$ by ! use ( ?is s*eme if ! g5]ators ?us belt$ 7 plac$ at ,m & ,g yet /ill m floor space w\ld be sav$ by hav+ !m occupy ! positions indicat$ at ,m & ,s4 ,ques4 ,:at is ! approv$ location = an alt]nator excit]8 ,ans4 ,to economize floor space ! excit] may be plac$ betwe5 ! alt]nator & eng9e at ,s 9 fig4 #b1haa4 ,belts4--,9 ! selection ( a belt1 ! quality ( ! lea!r %\ld be fir/ "u consid]ation4 ,! lea!r mu/ be firm1 yet pliable1 free f wr9kles on ! gra9 or hair side1 & ( an ev5 ?ickness ?r\gh\t4 ,illu/ration3 ,,fig4 #b1hab4--,sep>ately excit$ belt driv5 alt]nator %[+ approv$ location ( excit]4 ,9 an electrical /ation :]e alt]nat+ curr5t is g5]at$1 ! alt]nators = produc+ ! curr5t g5]ally require sep>ate excitation = _! field w9d+s2 t is1 x is usually necess>y to in/all 9 conjunction ) an alt]nator a small dynamo = supply+ curr5t to ! alt]nator field4 ,! excit] is a comp>atively small ma*9e2 9 fact1 x requires only ab\t #a p] c5t4 ( ! capacity ( ! alt]nator :i* x excites1 & s be+ small is (t5 belt$ to an auxili>y pulley m\nt$ on ! alt]nator %aft4 ,consid]able floor space w\ld be occupi$ by an in/allation ( ?is nature if ! excit] be plac$ at ,m1 & belt$ to ! alt]nator z indicat$ by ! dott$ l9es4 ,by locat+ ! excit] at ,s1 betwe5 ! alt]nator & ! eng9e1 mu* floor space w be sav$ & ! g5]al appe>ance ( ! in/allation improv$4 ,if ! belt be well select$ & prop]ly h&l$1 x %\ld d s]vice = tw5ty ye>s1 & ev5 !n if ! worn "p be cut (f1 ! rema9+ portion may be remade & us$ aga9 z a n>r[] & %ort] belt4 ,besides lea!r belts1 !re are ^? made ( rubb] :i* )/& moi/ure mu* bett] ?an lea!r belts1 & :i* also possess an excell5t grip on ! pulley2 !y are1 h[ev]1 m co/ly & mu* less durable "u normal conditions4 ,9 addition to lea!r & rubb] belts1 !re are belts compos$ ( cotton1 ( a comb9ation ( cotton & lea!r1 & ( rope4 ,! lea!r belt1 h[ev]1 is ! /&>d & is to be recomm5d$4 ,equally important ) ! quality ( a belt is its size 9 ord] to transmit ! necess>y p[]4 ,! av]age /ra9 "u :i* lea!r w break has be5 f\nd by _m exp]im5ts to be #c1bjj p\nds p] squ>e in* ( cross section4 ,a good quality ( lea!r w su/a9 a some:at great] /ra94 ,9 use on ! pulleys1 belts %\ld n be subject$ to a great] /ra9 ?an "o elev5? _! t5sile /r5g?1 or ab\t #bij p\nds to ! squ>e in* or cross section4 ,?is w be ab\t #ee p\nds av]age /ra9 = e in* 9 wid? ( s+le belt ?ree-sixte5?s in* ?ick4 ,! /ra9 all[$ = all wid?s ( belt+--s+le1 light d\ble1 & heavy d\ble--is 9 direct proportion to ! ?ickness ( ! belt4 ,ques4 ,h[ mu* horse p[] w a belt transmit8 ,ans4 ,! capacity ( a belt dep5ds on1 its wid?1 spe$1 & ?ickness4 ,a s+le belt "o in* wide & travell+ #a1jjj feet p] m9ute w transmit "o horse p[]2 a d\ble belt "u ! same conditions1 w transmit two horse p[]4 ,illu/ration3 ,,fig4 #b1hac4--,"o horse p[] transmitt$ by belt to illu/rate ! rule giv5 above4 ,a pulley is driv5 by a belt by means ( ! friction betwe5 ! surfaces 9 contact4 ,let ,t be ! t5sion on ! driv+ side ( ! belt1 & ,t'1 ! t5sion on ! loose side2 !n ! driv+ =ce ,t-,t'4 ,9 ! figure ,t is tak5 at #cd lbs4 & ,t' at #a lb42 h5ce driv+ =ce #cd-a #cc lbs4 ,s9ce ! belt is travell+ at a velocity ( #a1jjj feet p] m9ute ! p[] transmitt$ #cc lbs4 #a1jjj ft4 #cc1jjj ft4 lbs4 p] m9ute #a horse p[]4 ,?is corresponds to a work+ pull ( #cc & #ff lbs4 p] in* ( wid? respectively4 ,example4--,:at wid? d\ble belt w be requir$ to transmit #ej horse p[] travell+ at a spe$ ( #c1jjj feet p] m9ute8 ,! horse p[] transmitt$ by ea* in* wid? ( d\ble belt travell+ at ! /at$ spe$ is #c1jjj #a ----- #b #f1 #a1jjj h5ce ! wid? ( belt requir$ to transmit #ej horse p[] is #ej #f #h4cc1 say #h in*es4 ,ques4 ,at :at velocity %\ld a belt be run8 ,ans4 ,at f #c1jjj to #e1jjj feet p] m9ute4 ,ques4 ,h[ may ! greate/ am\nt ( p[] transmitt+ capacity be obta9$ f belts8 ,ans4 ,by cov]+ ! pulleys ) lea!r4 ,ques4 ,h[ %\ld belts be run8 ,ans4 ,) ! tight side und]nea? z 9 fig4 #b1had4 ,illu/ration3 ,,figs4 #b1had & #b1hae4--,"r & wrong way to run a belt4 ,! tight side %\ld be und]nea? s z to increase ! arc ( contact & consequ5tly ! adhesion1 t is to say1 a bett] grip1 is 9 ?is way obta9$4 ,ques4 ,:at is a good indication ( ! capacity ( a belt 9 op]ation8 ,ans4 ,its appe>ance aft] a few days' run4 ,if ! side ( ! belt com+ 9 contact ) ! pulley assume a mottl$ appe>ance1 x is an indication t ! capacity ( ! belt is consid]ably 9 excess ( ! p[] :i* x is transmitt+1 inasmu* z ! spott$ portions ( ! belt d n t\* ! pulley2 & 9 consequ5ce ( ?is !re is liable to be m or less slipp+4 ,small quantities ( a mixture ( tall[ & fi% oil :i* h previ\sly be5 melt$ toge!r 9 ! proportion ( two ( ! =m] to "o ( ! latt]1 w1 if appli$ to ! belt at frequ5t int]vals1 d mu* t[>d s(t5+ x1 & ?us by p]mitt+ its entire surface to come 9 contact ) ! pulley1 prev5t any t5d5cy t[>d slipp+4 ,! be/ results are obta9$ :5 ! smoo? side ( ! belt is us$ next to ! pulley1 s9ce te/s conduct$ 9 ! pa/ prove t m p[] is ?us transmitt$1 & t ! belt la/s long] :5 us$ 9 ?is way4 ,illu/ration3 ,,fig4 #b1haf4--,! ,hill friction clut* pulley = p[] control4 ,! clut* me*anism w />t a load equival5t to ! d\ble belt capacity ( ! pulley to :i* ! clut* is atta*$4 ,ques4 ,:at is ! comp>ison betwe5 ! s call$ endless belts & lac$ belts8 ,ans4 ,) an endless belt !re is no unev5 or noisy action z ) lac$ belts1 :5 ! lac$ jo9t passes ov] ! pulleys1 & ! =m] is free f ! liability ( breakage at ! jo9t4 ,ques4 ,h[ %\ld a belt be plac$ on ! pulleys8 ,ans4 ,! belt %\ld fir/ be plac$ on ! pulley at re/1 & !n run on ! o!r pulley :ile ! latt] is 9 motion4 ,! be/ results are obta9$1 & ! /ra9 on ! belt is less1 :5 ! spe$ at :i* ! mov+ pulley revolves is comp>atively l[4 ,) heavy belts1 p>ticul> c>e %\ld be tak5 to prev5t any portion ( ! clo?+ be+ caught ei!r by ! mov+ belt or pulleys1 z _m s]i\s accid5ts h result$ 9 ! pa/ f c>elessness 9 reg>d to ?is important detail4 ,! p]son h&l+ ! belt %\ld1 !re=e1 be sure ( a firm foot+1 & :5 x is impossible to secure ?is1 x is advisable to /op ! eng9e & fit ! belt ar\nd ! eng9e pulley z well z possible by ! aid ( a rope loop$ ar\nd ! belt4 ,illu/ration3 ,,fig4 #b1hag--,sectional view ( ,hill clut* me*anism4 ,9 e case ! me*anism hub ,a1 & 9 a clut* c\pl+ ! r+ ,w1 is p]man5tly & rigidly secur$ to ! %aft & ne$ n be di/urb$ :5 remov+ ! we>+ p>ts4 ,:5 erect$1 ! adju/m5t %\ld be v]ifi$1 & always ) ! clut* & r+ engag$ & at re/4 ,if ! jaws d n press equally on ! r+1 or if ! pressure requir$ on ! cone be abnormal1 loos5 ! upp] adju/+ nuts ,t on eye bolts & set up ! l[] adju/+ nuts ,t until ea* set ( jaws is "u ! same pressure4 ,%\ld ! clut* !n slip :5 />t$ x is evid5t t ! jaw pressure is insuffici5t & a fur!r adju/m5t w be necess>y4 ,all clut*es are equipp$ ?r\gh\t ) split lock wa%]s4 ,vibration or %ock w n loos5 ! nuts if prop]ly set up4 ,! jaws c be remov$ p>allel to ! %aft z foll[s3 ,remove ! gibs ,v1 & )draw ! jaw p9s ,p1 !n pull out ! lev]s ,d4 ,d n di/urb ! eye bolt nuts ,t & ,t4 ,! outside jaws ,b c n[ be tak5 out4 ,remove ! bolt nuts ,i all[+ ! fulcrum plates ,r to be tak5 (f4 ,on ! sep>able hub patt]n ! clamp+ bolts mu/ be tak5 out be=e fulcrum plate is remov$4 ,! inside jaws ,c may n[ be )drawn4 ,always set ! clut* op]at+ lev] 9 ! position z %[n 9 fig4 #b1haf to avoid int]f]5ce ) me*anism p>ts4 ,oil ! mov+ p>ts ( ! clut*4 ,keep x clean4 ,exam9e at regul> int]vals4 ,ques4 ,"u :at conditions does a belt drive give ! be/ results8 ,ans4 ,:5 ! two pulleys are at ! same level4 ,if ! belt mu/ occupy an incl9$ position x %\ld n =m a great] angle ?an #de degrees ) ! horizontal4 ,ques4 ,:at is a *>act]i/ic feature 9 ! op]ation ( belts1 & :y8 ,ans4 ,belts 9 motion w always run to ! highe/ side ( a pulley2 ?is is due p>tially to ! great] spe$ 9 feet p] m9ute develop$ at t po9t ow+ to ! great] circumf]5ce ( ! pulley1 & also to ! effects ( c5trifugal =ce4 ,if1 !re=e1 ! highe/ sides ( bo? pulleys be 9 l9e ) ea* o!r1 & ! %afts ( ! respective pulleys be p>allel to ea* o!r1 !re w be no t5d5cy = ! belt to leave ! pulleys :5 once 9 its prop] position4 ,9 ord] t ^! conditions be ma9ta9$1 ! belt %\ld be no m ?an tight en\gh to prev5t slipp+1 & ! di/ance betwe5 ! c5t]s ( ! pulleys %\ld be approximately #c4e times ! diamet] ( ! l>g] "o4 ,illu/ration3 ,,fig4 #b1hah4--;,hill clut* me*anism ,smi? type4 ,! friction surfaces are wood to iron1 ! wood %oes be+ made f maple4 ,all p>ts ( ! toggle ge> are ( /eel & =g+s ) ! exception ( ! connection lev] :i* is ( ca/ iron4 ,ques4 ,:at m9or appurt5ances %\ld be provid$ 9 a /ation8 ,ans4 ,app>atus %\ld be in/all$ z a prev5tion aga9/ accid5ts1 su* z fire1 & protection ( att5dants f dang]4 ,9 e electrical /ation !re %\ld be a pump1 pipes & hose2 ! pump may be ei!r directly connect$ to a small electric motor or belt$ to a c\nt]%aft1 :ile ! pipes & hose %\ld be s plac$ t no wat] c accid5tally rea* ! g5]ators & electrical circuits4 ,a numb] ( fire bucket fill$ ) wat] %\ld be plac$ on brackets ar\nd ! /ation1 & ) ^! !re %\ld be an equal numb] ( bucket conta9+ dry s&1 ! wat] be+ us$ = ext+ui%+ fire occurr+ at a di/ance f ! ma*9es & conductors1 & ! s& = ext+ui%+ fire 9 curr5t c>ry+ circuits :]e wat] w\ld cause m h>m ?an b5efit4 ,to prev5t ! s& be+ bl[n ab\t ! /ation1 ea* s& bucket1 :5 n 9 use1 %\ld be provid$ ) a cov]4 ,neat cans & boxes %\ld be m\nt$ 9 conv5i5t places = greasy rags1 wa/e1 nuts1 screws1 etc41 :i* are us$ cont9ually & :i* !re=e _c be kept 9 ! /or]oom4 ,:ile x is important to gu>d aga9/ fire 9 ! /ation1 x is equally necess>y to provide = p]sonal safety4 ,all passages & d>k pits %\ld !re=e be ?or\ghly light$ bo? day & night1 & ob/acles ( any nature t are n absolutely necess>y 9 ! op]ation ( ! /ation1 %\ld be remov$4 ,mov+ belts1 & especially ^? pass+ ?r\gh ! floor1 %\ld be enclos$ 9 iron rail+s4 ,if high voltages be g5]at$1 x is well to place a rail+ ab\t ! swit*bo>d to prev5t accid5tal contact ) curr5t c>ry+ circuits1 & 9 su* cases x is also advisable to con/ruct an insulat$ plat=m on ! floor 9 front ( ! swit*bo>d4 ,illu/ration3 ,,fig4 #b1hai4--,me?od ( jo9+ adjac5t swit*bo>d panels4 ,swit*bo>ds4--,! plan ( swit*bo>d wir+ = alt]nat+ curr5t "w dep5ds ^u ! sy/em 9 use & ?is latt] may be ei!r ( ! s+le phase1 two phase1 ?ree phase1 or monocyclic types4 ,! g5]al pr9ciples 9 all ^! cases1 h[ev]1 are practically id5tical4 ,fig4 #b1hbj %[s ! swit*bo>d wir+ = a s+le phase alt]nator4 ,z an aid 9 read+ ! diagram1 ! conductors c>ry+ alt]nat+ curr5t are repres5t$ by solid l9es1 & ^? c>ry+ direct curr5t1 by dott$ l9es4 ,illu/ration3 ,,fig4 #b1hbj4--,swit*bo>d wir+ = a s+le phase sep>ately excit$ alt]nator4 ,! direct curr5t circuits are repres5t$ by dott$ l9es1 & ! alt]nat+ curr5t circuit1 by solid l9es4 ,! excit] %[n at ! "r is a %unt w\nd ma*9e4 ,by means ( ! excit] rheo/at1 ! voltage = excit+ ! field w9d+ ( ! alt]nator is v>i$2 ?is1 9 turn1 v>ies ! voltage develop$ 9 ! alt]nator s9ce ! ma9 leads ( ! excit] are connect$ ?r\gh a d\ble pole swit* ,g to ! field w9d+ ( ! alt]nator4 ,illu/ration3 ,,figs4 #b1hba to #b1hbe4--;,g5]al ,electric diagrams ( connections4 ,a1 ammet]2 ,c4,b1 circuit break]2 ,c4,p1 c&le p[]2 ,c4,t1 curr5t trans=m]2 ,d4,r1 dis*>ge resi/ance2 ,f1 fuse2 ,f4,s1 field swit*2 ,l1 lamp2 ,o4,c1 ov]load coil2 ,p4,p1 pressure plug2 ,p4,r1 pressure receptacle2 ,r4,c1 reactance2 rheo1 rheo/at2 ,r4,p1 syn*roniz+ plug1 runn+2 ,r4,s1 resi/ance2 ,s1 swit*2 ,s4,i1 syn*ronism indicator2 ,s4,p1 syn*roniz+ plug1 />t+2 ,s4,r1 syn*roniz+ receptacle2 ,v1 voltmet]4 ,a rheo/at is also introduc$ 9 ! alt]nator field w9d+ circuit to adju/ ! alt]nator pressure4 ,x may seem unnecess>y to employ a rheo/at 9 ea* ( two sep>ate field circuits to regulate ! voltage ( ! alt]nator1 b ^! rheo/ats are n bo? us$ to produce ! same result4 ,:5 a consid]able v>iation ( pressure is requir$1 ! excit] rheo/at is manipulat$1 :]eas = a f9e adju/m5t ( voltage ! alt]nator rheo/at is pref]ably employ$4 ,sometimes a direct curr5t ammet] is introduc$ 9 ! alt]nator's field circuit to aid 9 ! adju/m5t4 ,! ma9 circuit ( alt]nator aft] be+ protect$ on bo? sides by fuses1 runs to ! d\ble pole swit* ,k4 ,^! fuses s]ve z a protection to ! alt]nator 9 case ( a %ort circuit at ! ma9 swit*4 ,x w be notic$ ! fuses are ( ! s+le pole type & are m\nt$ a consid]able di/ance ap>t2 ?is is to prev5t any liability ( a %ort circuit betwe5 !m 9 case ( action4 ,enclos$ fuses are n[ us$ entirely = su* "w1 s9ce 9 ^! !re is no dang] ( heat$ metal be+ ?r[n ab\t & caus+ damage :5 ! fuse wire is melt$4 ,enclos$ fuses are also m readily & quickly replac$ ?an op5 fuses1 ! conta9+ tube ( ea* be+ easy to adju/ 9 circuit1 & :5 ! fuse wire )9 is once melt$ ! tube is disc>d$ = a new "o4 ,! ma9 circuit aft] pass+ ?r\gh ! ma9 swit* is fur!r protect$ on bo? sides by circuit break]s4 ,leav+ ^! protective devices1 ! left h& side ( ! circuit includes ! alt]nat+ curr5t ammet]1 & !n connects ) "o ( ! bus b>s4 ,! "r h& side ( ! circuit runs f ! circuit break] to ! o!r bus b>4 ,z _m fe$] circuits may be connect$ to ! bus b>s & suppli$ ) curr5t by ! alt]nator z ! capacity ( ?is ma*9e w p]mit4 ,if1 h[ev]1 !re be m ?an "o fe$] circuit1 ea* mu/ be wir$ ?r\gh a d\ble pole swit*4 ,9 alt]nat+ curr5t "w ! pressures dealt ) are mu* great] ?an ^? 9 direct curr5t in/allations1 s t proportionate c>e mu/ be tak5 9 ! wir+ to remove all possibility ( gr\nds4 ,to locate su* tr\bles1 h[ev]1 %\ld !y occur1 a gr\nd detector is provid$4 ,= ?is class ( "w ! gr\nd detector mu/ be an in/rum5t especially design$ = high pressure circuits4 ,two ( its t]m9als %\ld be connect$ to ! l9e wires & ! ?ird1 to gr\nd2 9 case ( a leak on ! l9e1 a curr5t w !n fl[ ?r\gh ! detector & by ! position ( ! po9t] ! location & s]i\sness ( ! leak may be judg$4 ,a /ep d[n trans=m] is also r5d]$ necess>y = ! voltmet] & ! pilot lamps1 ow+ to ! high voltage 9 use4 ,! prim>y w9d+ ( ! trans=m] is connect$ across ! ma9 circuit ( ! alt]nator4 ,?is connection %\ld nev] be made s t x w be cut out ( circuit :5 ! ma9 swit* is op51 = x is always advisable to consult ! voltmet] be=e ?r[+ on ! load by clos+ ?is swit*4 ,illu/ration3 ,,figs4 #b1hbf to #b1hbi4--;,g5]al ,electric diagrams ( connections4 ,a1 ammet]2 ,c4,b1 circuit break]2 ,c4,p1 c&le p[]2 ,c4,t1 curr5t trans=m]2 ,d4,r1 dis*>ge resi/ance2 ,f1 fuse2 ,f4,s1 field swit*2 ,l1 lamp2 ,o4,c1 ov]load coil2 ,p4,p1 pressure plug2 ,p4,r1 pressure receptacle2 ,r4,c1 reactance2 rheo1 rheo/at2 ,r4,p1 syn*roniz+ plug1 runn+2 ,r4,s1 resi/ance2 ,s1 swit*2 ,s4,i1 syn*ron\s indicator3 ,s4,p1 syn*roniz+ plug1 />t+2 ,s4,r1 syn*roniz+ receptacle3 ,v1 voltmet]4 ,ques4 ,h[ does ! swit*bo>d wir+ = a two phase sy/em diff] f ! s+le phase arrangem5t %[n 9 fig4 #b1hbj8 ,ans4 ,x is practically ! same1 except = ! introduction ( an extra ammet] & a comp5sator 9 ea* ( ! outside wires1 & 9 ! use ( a f\r pole swit* 9 place ( ! two pole ma9 swit*4 ,! ammet]s1 ( c\rse1 are = measur+ ! alt]nat+ curr5ts 9 ea* ( ! two phases or legs ( ! sy/em1 & ! comp5sators are two trans=m]s ) _! prim>y coils 9 s]ies ) ! outside wires & _! second>y coils 9 s]ies ) ea* o!r across ! outside wires4 ,! trans=m]s ?us connect$ are kn[n z comp5sators or pressure regulators1 & z su* comp5sate = ! drop 9 pressure on ei!r side ( ! sy/em4 ,ques4 ,h[ is ! f\r pole ma9 swit* wir$8 ,ans4 ,its two c5tral t]m9als :i* connect directly ) ! l9e wires1 are jo9$ toge!r by a conductor1 & f ?is po9t "o wire is l$ (f4 ,?is wire1 toge!r ) ! two outside wires1 =m ! fe$]s ( ! sy/em4 ,ques4 ,h[ _m voltmet]s are requir$ = ! two phase sy/em8 ,ans4 ,"o voltmet] is suffici5t on ! bo>d if a prop] swit*+ device be employ$ to %ift its connections across ei!r ( ! two circuits2 o!rwise1 two voltmet]s w be necess>y1 "o bridg$ across ea* ( ^! respective circuits4 ,! same reason+ holds true 9 reg>d to gr\nd detectors1 s t "o or two ( ^! w be requir$1 dep5d+ ^u ! a=em5tion$ conditions4 ,ques4 ,:at are ! ess5tial po9ts ( diff]5ce betwe5 ! s+le phase swit*bo>d wir+ z %[n 9 fig4 #b1hbj1 & t requir$ = a ?ree wire ?ree phase sy/em8 ,ans4 ,! ?ree phase sy/em requires ! use ( a ?ree pole swit* 9 place ( ! two pole swit*2 ! ins]tion ( an ammet]1 a circuit break]1 & a comp5sator 9 ea* ( ! ?ree wires ( ! sy/em2 ! pres5ce ( two gr\nd detectors in/ead ( "o1 & ! addition ( a voltmet] swit* if b "o voltmet] be provid$1 or else ! in/allation ( two voltmet]s1 connect$ ! "o betwe5 ! middle wire & out] "r h& wire1 & ! o!r betwe5 ! middle wire & out] left h& wire4 ,illu/ration3 ,,fig4 #b1hcj4--;,diagram ( swit*bo>d connections = ,g5]al ,electric automatic voltage regulator ) two excit]s & two alt]nators4 ,ques4 ,m5tion a few po9ts relat+ to lightn+ arre/]s4 ,ans4 ,9 mo/ cases :]e direct curr5t is us$ !y are m\nt$ on ! walls ( ! /ation ne> ! place at :i* ! l9e wires ent]4 ,if !y be m\nt$ outside ! /ation at ?is po9t1 special precautions %\ld be tak5 to keep !m free f moi/ure by enclos+ !m 9 iron cases1 b no matt] :]e !y are locat$ x is necess>y t !y be dry 9 ord] to "w prop]ly4 ,illu/ration3 ,,figs4 #b1hca & #b1hcb4--;,g>ton-,daniels alt]nat+ curr5t lightn+ arre/]2 diagram %[+ connections4 ,a lightn+ dis*>ge takes ! pa? indicat$ by ! dott$ l9e1 across ! upp] air gap ,a1 ?r\gh resi/ance rod ,b1 ,c1 ,d1 across copp] /rip ,r on ! base1 !nce fl[+ to gr\nd ?r\gh ! movable plung] ,m1 l[] on gap ,n1 & gr\nd b9d+ po/ ,l4 ,! dis*>ge pa? is practically /raight1 conta9s an air gap1 di/ance ( b #c_/cb in*1 a s]ies resi/ance av]ag+ b #bbe ohms4 ,! lightn+ dis*>ge does n fl[ ?r\gh ! flexible lead connect+ b& ,d on ! l[] end ( ! resi/ance rod ) ! top ( ! movable plung]4 ,^! two po9ts are electrically connect$ by ! heavy copp] /rip ,r1 & lightn+ dis*>ges g5]ally1 if n always1 take ! pa? across ?is copp] /rip 9 pref]5ce to fl[+ ?r\gh ! inductance ( ! "o turn ( flexible cable4 ,:5 a dis*>ge occurs f l9e to gr\nd ?r\gh any lightn+ arre/]1 ! air gaps arc ov]1 & s !re is (f]$ a pa? f l9e to gr\nd = ! l9e curr5t4 ,?is fl[ ( l9e curr5t foll[+ ! lightn+ dis*>ge to gr\nd may v>y any:]e f a small capacity curr5t :]e ! arre/] is in/all$ on an ungr\nd$ circuit1 a mod]ately heavy fl[ on a p>tially gr\nd$ circuit1 to a v heavy fl[ on a gr\nd$ circuit--ei!r a circuit op]at$ z a dead gr\nd$ circuit1 or a circuit :i* has become accid5tally gr\nd$ dur+ a /orm4 ,! pa? tak5 by ?is fl[ ( l9e curr5t f l9e to gr\nd may be trac$ by foll[+ ! pa? %[n by ! da%$ l9e4 ,x1 z se51 crosses upp] air gap ,a1 fl[s ?r\gh section ,b ( ! resi/ance rod to b& ,c4 ,leav+ b& ,c x fl[s ?r\gh ! magnet w9d+ ,h1 !nce to b& ,d on ! resi/ance rod1 ?r\gh flexible lead to upp] end ( movable plung]1 ?r\gh movable plung]1 across l[] air gap ,n1 to gr\nd b9d+ po/ ,l1 !nce to gr\nd4 ,! function ( ! %ort l5g? ( resi/ance rod ,,cd is z foll[s3 ,x has an ohmic resi/ance ( ab\t #cj ohms b is non-inductive4 ,magnet w9d+ ,h1 connect$ to b&s ,c & ,d on ! ends ( ?is %ort l5g? ( rod has an ohmic resi/ance ( #c ohms1 b is highly inductive4 ,lightn+ dis*>ges be+ ( high frequ5cy take ! high] resi/ance b non-inductive pa? ,,cd 9 _! passage f l9e to gr\nd4 ,! fl[ ( normal curr5t f l9e to gr\nd be+ ( a v l[ frequ5cy1 #be or #fj cycles 9 ord9>y alt]nat+ curr5t circuits1 z]o 9 direct curr5t circuits--takes ! l[ resi/ance pa? ?r\gh coil ,h 9 its pa? to gr\nd4 ,section ,,cd ( ! rod is us$ !re=e simply to %unt ! inductance ( w9d+ ,h to high frequ5cy lightn+ dis*>ges1 leav+ ! lightn+ dis*>ge pa? 9 ! arre/] a non-inductive highly effici5t pa?4 ,9 all ,g>ton-,daniels ,a4 ,c4 lightn+ arre/]s op]at+ on non-gr\nd$ or p>tially gr\nd$ circuits1 ! action ( ! air gaps & s]ies resi/ance are toge!r suffici5t to ext+ui% ! fl[ ( normal curr5t to gr\nd at ! z]o po9t ( ! g5]ator voltage wave4 ,if1 h[ev]1 z frequ5tly happ5s1 ! l9e gr\nds accid5tally dur+ a /orm1 !n ! arre/] does n h to dep5d = its prop] op]ation on ! arc ext+ui%+ prop]ties ( ! air gaps & resi/ance1 b ! heavi] fl[ ( l9e curr5t ?r\gh ! arre/] en]gizes ! movable plung]1 :i* raises upw>d 9 ! coil1 op5+ ! circuit betwe5 ! dis*>ge po9t ,m & ! l[] end ( ! plung]4 ,to limit ! fl[ ( l9e curr5t to gr\nd ! resi/ance rod ,b is provid$1 !re be+ approximately #bbe ohms betwe5 ! dis*>ge po9t ,a & clamp ,c 9 ! #b1ejj volt arre/]4 ,?is feature is p>ticul>ly effective :]e ! circuit is tempor>ily or accid5tally gr\nd$4 ,! s]ies resi/ance prev5ts a heavy %ort circuit ?r\gh ! arre/] & limits ! curr5t to a value t is readily brok5 by ! cut out & is n en\gh to imp$e ! passage ( ! dis*>ge4 ,illu/ration3 ,,fig4 #b1hcc4--;,diagram ( swit*bo>d connections = ,g5]al ,electric automatic voltage regulator ) ?ree excit]s & ?ree alt]nators4 ,if possible1 "o place %\ld be set aside = !m & a m>ble or slate panel provid$ on :i* !y may be m\nt$4 ,wood5 supports are undesirable = lightn+ arre/]s on acc\nt ( ! fire risk incurr$2 ?is1 h[ev]1 may be r$uc$ to a m9imum by employ+ skeleton bo>ds & us+ %eets ( asbe/os betwe5 ! arre/]s & ! wood4 ,9 p>ts ( ! c\ntry :]e lightn+ is ( common occurr5ce & :]e ov]head circuits are in/all$ :i* c>ry high pressures1 heavy curr5ts1 & ext5d ov] consid]able t]ritory1 x is advisable to h ! /ation well equipp$ ) lightn+ arre/]s ( ! mo/ improv$ types4 ,9 ea* side ( ! ma9 circuit1 betwe5 ! lightn+ arre/] connections & ! swit*bo>d app>atus !re %\ld be connect$ a *oke coil or else ea* ( ! ma9 conductors at ?is po9t %\ld be tightly coil$ up "p ( its l5g? to answ] ! same purpose4 ,a quick & effective way ( coil+ up a wire consi/s 9 wrapp+ ar\nd a cyl9drical piece ( iron or wood t "p ( ! conductor 9 :i* x is desir$ to h ! coils1 ! desir$ numb] ( times1 & !n )draw+ ! cyl9drical piece4 ,! coils1 ea* ( :i* may conta9 #ej or #bjj turns1 ?us ins]t$ 9 ! ma9 circuit introduce a high resi/ance or reluctance to a lightn+ curr5t1 & ?us prev5t x pass+ to ! g5]ator2 !re w1 h[ev]1 be an easy pa? to e>? af=d$ x ?r\gh ! lightn+ arre/]1 & s no damage w be done4 ,coils ( ! nature j m5tion$ may advantage\sly be introduc$ betwe5 ! g5]ator & swit*bo>d to take up ! reactive curr5t develop$ ^u ! op5+ ( ! circuit1 & 9 ! case ( susp5d$ conductors1 ! coils may be us$ to take up ! slack by ! spr+-l effect produc$ by !m4 ,! safety ( ! op]ator %\ld be especially consid]$ 9 ! design ( high pressure alt]nat+ curr5t swit*bo>ds4 ,su* protection may be secur$ by scre5+ all ! expos$ t]m9als1 or pref]ably by m\nt+ all ! swit* me*anism on ! back ( ! bo>d ) simply ! swit* h&le project+ ?r\gh to ! front2 by pu%+ or pull+ ! swit* h&le1 ! connections c ?us be %ift$ ei!r to "o side ( ! sy/em or to ! o!r4 ,ques4 ,^u :at does ! "w ( assembl+ a swit*bo>d dep5d8 ,ans4 ,x dep5ds almo/ entirely ^u ! size ( ! plant1 v>y+ f ! simple task ( m\nt+ a s+le panel 9 ! case ( an isolat$ plant1 to ! m difficult problem ( support+ a l>ge numb] ( panels 9 a c5tral /ation4 ,ques4 ,:5 ! mat]ial *os5 = a swit*bo>d mu/ be %ipp$ a consid]able di/ance1 :at =m ( bo>d %\ld be us$8 ,ans4 ,! bo>d units or slabs %\ld be ( small dim5sions1 to avoid ! liability ( breakage & exp5se ( r5ewal :5 a unit becomes crack$ or ma*9e injur$4 ,illu/ration3 ,,figs4 #b1hcd & #b1hce4--;,front & re> views %[+ ,g5]al ,electric automatic voltage regulator m\nt$ on swit*bo>d panel4 ,ord9>ily1 swit*bo>ds v>y f five to eight feet 9 height & ! wid?s ( ! panels v>y f five to six feet4 ,9 "s bo>ds ! seams betwe5 ! slabs run v]tically1 & 9 o!rs horizontally4 ,9 ord] to r5d] ! assembl+ ( ! swit*bo>d z simple z possible1 & its appe>ance :5 f9i%$ ! mo/ arti/ic1 ^! seams %\ld run horizontally r ?an v]tically4 ,! edges ( ea* ( ! slabs %\ld also be *amf]$ s t !re w be less dang] ( _! break+ out :5 be+ m\nt$ on ! framework4 ,ques4 ,9 assembl+ a swit*bo>d1 h[ %\ld ! l[] slabs be plac$1 & :y8 ,ans4 ,!y %\ld be susp5d$ a little di/ance f ! floor to prev5t contact ) any oil1 dirt1 wat] or rubbi% t might be on ! floor4 ,ques4 ,h[ are ! slabs or panels support$8 ,ans4 ,!y are c>ri$ on an iron or wood5 framework ) braces to give /ability4 ,! braces %\ld be securely fa/5$ at "o end to ! wall ( ! /ation1 & at ! o!r end to ! framework ( ! bo>d1 z %[n 9 fig4 #b1hcf4 ,to fa/5 ! swit*bo>d end ( ! brace directly to ! slate1 m>ble or o!r mat]ial compos+ ! bo>d is poor practice & %\ld nev] be attempt$4 ,if ! /ation be con/ruct$ ( iron1 ^! swit*bo>d braces mu/ be su* t !y w ?or\ghly insulate ! bo>d & its cont5ts f ! adjo9+ wall4 ,illu/ration3 ,,fig4 #b1hcf4--,me?od ( support+ ! framework ( a swit*bo>d4 ,ques4 ,:at is ! usual equipm5t ( a swit*bo>d8 ,ans4 ,x comprises swit*+ devices1 curr5t or pressure limit+ devices1 indicat+ devices1 & fuses = protect+ ! app>atus & circuits4 ,illu/ration3 ,,fig4 #b1hcg4--;,diagram %[+ elem5t>y connections ( ,g5]al ,electric automatic regulator = direct curr5t4 ,x consi/s ess5tially ( a ma9 control magnet ) two indep5d5t w9d+s & a diff]5tially w\nd relay magnet4 ,"o w9d+1 kn[n z ! pressure w9d+1 ( ! ma9 control magnet is connect$ across ! dynamo t]m9als1 ! o!r across a %unt 9 "o ( ! load ma9s4 ,! latt] is ! comp5sat+ w9d+ & x opposes ! action ( ! pressure w9d+ s t z ! load increases1 a high] pressure at ! dynamo is necess>y to ov] comp\nd = l9e drop4 ,9 ord9>y practice1 ! voltage t]m9als are connect$ to ! bus b>s1 & ! comp5sat+ %unt ins]t$ 9 "o ( ! pr9cipal fe$]s ( ! sy/em4 ,9 op]ation ! %unt circuit across ! dynamo field rheo/at is fir/ op5$ by means ( a swit* provid$ = t purpose on ! base ( ! regulator & ! rheo/at turn$ to a po9t t w r$uce ! g5]ator voltage #ce p] c5t bel[ normal4 ,! ma9 control magnet is at once weak5$ & all[s ! spr+ to pull out ! movable core until ! ma9 contacts are clos$4 ,?is closes ! second circuit ( ! diff]5tial relay1 ?us neutraliz+ its w9d+s4 ,! relay spr+ !n lifts ! armature & closes ! relay contacts4 ,! swit* 9 ! %unt circuit across ! dynamo field rheo/at is n[ clos$1 practically %ort circuit+ ! rheo/at1 & ! dynamo voltage at once rises4 ,z soon z x rea*es ! po9t = :i* ! regulator has be5 adju/$1 ! ma9 control magnet is /r5g!n$1 :i* causes ! ma9 contacts to op51 :i* 9 turn op5 ! relay contacts across ! rheo/at4 ,! rheo/at is n[ 9 ! field circuit1 ! voltage at once falls (f1 ! ma9 contacts are clos$1 & relay armature releas$1 & %unt circuit across ! rheo/at aga9 complet$4 ,! voltage !n />ts to rise & ?is cycle ( op]ation is cont9u$ at a high rate ( vibration1 ma9ta9+ n a con/ant b a /eady voltage at ! bus b>s4 ,:5 nei!r ! comp5sat+ w9d+ nor pressure wires are us$1 !re w be no ov] comp\nd+ effect due to increase ( load & a con/ant voltage w be ma9ta9$ at ! bus b>s4 ,! comp5sat+ w9d+ on ! control magnet1 :i* opposes ! pressure w9d+ is connect$ across an adju/able %unt 9 ! pr9cipal fe$] circuit4 ,z ! load increases ! voltage drop across ! %unt increases & ! effect ( ! comp5sat+ w9d+ becomes great]4 ,?is w require a high] voltage on ! pressure w9d+ to op5 ! ma9 contacts & ! regulator w !re=e cause ! dynamo to comp5sate = l9e drop1 ma9ta9+ at ! bus b>s a /eady voltage )\t fluctuations1 :i* rises & falls ) a load on ! fe$]s1 giv+ a con/ant voltage at ! lamps or c5t] ( di/ribution4 ,! comp5sat+ %unt may be adju/$ s z to comp5sate = any desir$ l9e drop up to #ae p] c5t2 x is pref]ably plac$ 9 ! pr9cipal light+ fe$]1 b may be connect$ to ! bus b>s s t ! total curr5t w pass ?r\gh x4 ,! latt] me?od1 h[ev]1 is sometimes desirable1 z l>ge fluctuat+ p[] loads on sep>ate fe$]s might di/urb ! regulation ( ! light+ fe$]s4 ,adju/m5t is made by slid+ ! movable contact at ! c5t] ( ! %unt4 ,?is contact may be clamp$ at any desir$ po9t & det]m9es ! pressure across ! comp5sat+ w9d+ ( ! regulator's ma9 control magnet4 ,:]e pressure wires are run back to ! c5tral /ation f ! c5t] ( di/ribution !y may be connect$ directly to ! pressure w9d+ ( ! ma9 control magnet1 & x is unnecess>y to use ! comp5sat+ %unt4 ,! pressure wires take ! place ( ! leads f ! control magnet to ! bus b>s & ma9ta9 a con/ant voltage at ! c5t] ( di/ribution4 ,on "s swit*bo>ds are also m\nt$ small trans=m]s = rais+ or l[]+ ! voltages1 & lightn+ arre/]s z a protection f lightn+4 ,9 addition to ! app>atus previ\sly m5tion$ ne>ly all swit*bo>ds c>ry at or ne> _! top two or m inc&esc5t lamps provid$ ) %ades or reflectors1 = light+ ! bo>d4 ,ques4 ,:at %\ld be done be=e wir+ a swit*bo>d8 ,ans4 ,! electrical connections betwe5 ! v>i\s app>atus m\nt$ on ! face or front ( ! bo>d1 are made on ! back ( ! bo>d4 ,x is necess>y t ^! connections be prop]ly made else consid]able electrical p[] w be wa/$ at ?is po9t4 ,! wir+ on ! back ( ! bo>d %\ld !re=e be plann$ out on pap] be=e comm5c+ ! "w4 ,illu/ration3 ,,fig4 #b1hch4--;,diagram %[+ connections ( ,g5]al ,electric automatic voltage regulator = direct curr5t z connect$ = ma9ta9+ balanc$ voltage on bo? sides ( a ?ree wire sy/em us+ a balanc] set4 ,9 op]ation1 %\ld ! voltage on ! upp] bus b>s become great] ?an t on ! l[] ones1 ! middle & upp] contacts on ! regulator w close1 ?us op5+ ! relay contacts to ! left & clos+ ^? to ! "r4 ,?is ins]ts all ! resi/ance 9 ! field ( balanc] ,a1 & %ort circuits ! resi/ance 9 ! field ( balanc] ,b4 ,a w !n be runn+ z a motor1 & ,b z a dynamo1 !reby equaliz+ ! two voltages until t on ! l[] bus b>s becomes great] ?an t ( ! upp] ones2 !n ! regulator contacts op]ate 9 ! opposite direction & balanc] ,a is run z a dynamo1 & balanc] ,b z a motor4 ,?is cycle ( op]ation is repeat$ at ! rate ( f ?ree to f\r hundr$ times p] m9ute1 ?us ma9ta9+ a balanc$ voltage on ! sy/em4 ,9 lay+ out ! plan ( wir+ c>e mu/ be tak5 to all[ suffici5t contact surface at ea* connection2 !re %\ld be n less ?an "o squ>e in* ( contact surface all[$ = ea* #afj amp]es ( curr5t transmitt$4 ,illu/ration3 ,,fig4 #b1hci4--;,diagram ( connections ( ,g5]al ,electric voltage regulators = "o or m alt]nators us+ "o excit]4 ,= ! bus b>s1 :i*1 by ! way are always ( copp]1 "o squ>e in* p] #a1jjj amp]es is ! usual all[ance2 ?is is equal to #a1jjj circul> mils ( cross sectional area p] amp]e4 ,e ef=t %\ld be made to give ! bus b>s ! greate/ am\nt ( radiation consi/5t ) o!r conditions1 9 ord] t _! resi/ances may n become excessive ow+ to ! heat develop$ by ! l>ge curr5ts !y are =c$ to c>ry4 ,suppose1 = in/ance1 ! numb] ( amp]es to be g5]at$ is su* z to require bus b>s hav+ ea* a cross sectional area ( "o squ>e in*4 ,if ! end dim5sions ( ^! b>s 7 ea* #a in* by #a in*1 !re w\ld be less radiat+ surface ?an if _! dim5sions 7 ea* #b in*es by in*4 ,op]ation ( ,alt]nators4--,! op]ation ( an alt]nator :5 run s+ly diff]s b little f t = a dynamo4 ,z to ! prelim9>ies1 ! excit] mu/ fir/ be />t$4 ,?is is done 9 ! same way z = any %unt dynamo4 ,at fir/ only a small curr5t %\ld be s5t ?r\gh ! field w9d+ ( ! alt]nator2 !n1 if ! excit] op]ates satisfactorily & ! field magnetism ( ! op]ator %[ up well1 ! load may gradually be ?r[n on until ! normal curr5t is c>ri$1 ! same me?od ( proc$ure be+ foll[$ z 9 ! simil> case ( a dynamo4 ,illu/ration3 ,,figs4 #b1hdj & #b1hda4--;,g5]al ,electric equaliz] regulator design$ to equalize ! load on two ma*9es1 & diagram ( connections4 ,on load+ an alt]nator1 a noticeable drop 9 voltage occurs across its t]m9als4 ,?is drop 9 voltage is caus$ 9 "p by ! demagnetization ( ! field magnets due to ! armature curr5t1 & s dep5ds 9 a measure ^u ! position & =m ( ! pole pieces z well z ^u ^? ( ! tee? 9 ! armature core4 ,! resi/ance ( ! armature w9d+ also causes a drop 9 voltage "u an increase ( load4 ,ano!r cause :i* may be m5tion$ is ! inductance ( ! armature w9d+1 :i* is 9 turn due to ! positions ( ! armature coils ) respect to ea* o!r & also ) respect to ! field magnets4 ,illu/ration3 ,,fig4 #b1hdb4--;,connection ( ,g5]al ,electric equaliz+ regulator = equaliz+ loads on an eng9e driv5 dynamo & rot>y conv]t] runn+ 9 p>allel4 ,%\ld ! load on ! dynamo become great] ?an t on ! rot>y conv]t]1 ! middle & upp] contacts on ! regulator close1 & ?us by means ( ! relay swit* & control motor1 cause ! fe$] regulator to boo/ ! voltage on ! rot>y until ! loads aga9 become equal4 ,%\ld ! load on ! rot>y conv]t] become great] ?an t on ! g5]ator1 ! regulator contacts op]ate 9 ! rev]se direction & ! fe$] regulator is caus$ to buck ! rot>y voltage4 ,alt]nators 9 ,p>allel4--,:5 ! load on a /ation increases beyond t :i* c conv5i5tly be c>ri$ by "o alt]nator1 x becomes necess>y to connect o!r alt]nators 9 p>allel ) x4 ,to prop]ly swit* 9 a new ma*9e 9 p>allel ) "o already 9 op]ation & c>ry+ load1 requires a complete k ( ! situation on ! "p ( ! att5dant1 & also "s exp]i5ce4 ,! connections = op]at+ alt]nators 9 p>allel are %[n 9 fig4 #b1hdc4 ,9 ! illu/ration ! alt]nator ,a is 9 op]ation & is supply+ curr5t to ! bus b>s4 ,! alt]nator ,b is at re/4 ,! ma9 pole swit* ,b' by means ( :i* ?is ma*9e c be connect$ into circuit is !re=e op54 ,illu/ration3 ,,fig4 #b1hdc4--,me?od ( syn*roniz+ ) "o lamp2 d>k lamp me?od4 ,assum+ ,a to be 9 op]ation1 ,b1 may be br\ght up to approximately ! prop] spe$1 & voltage4 ,!n if ,b1 be run a little sl[] or fa/] ?an ,a1 ! syn*roniz+ lamp w gl[ = "o mom5t & be d>k ! next4 ,at ! in/ant :5 ! pressures are equal & ! ma*9es 9 phase1 ! lamp w become d>k1 b :5 ! phases are 9 quadrature1 ! lamp w gl[ at its maximum brilliancy4 ,s9ce ! flick]+ ( ! lamp is dep5d5t ^u ! diff]5ce 9 frequ5cy1 ! ma*9es %\ld n be ?r[n 9 p>allel :ile ?is flick]+ exi/s4 ,! ne>] alt]nator approa*es syn*ronism1 9 adju/+ its spe$1 ! sl[] ! flick]+1 & :5 ! flick]+ becomes v sl[1 ! incom+ ma*9e may be ?r[n 9 ! mom5t ! lamp is d>k by clos+ ! swit*4 ,! ma*9es are !n 9 phase & t5d to rema9 s1 s9ce if "o sl[ d[n1 ! o!r w drive x z a motor4 ,n[1 if ! load increase to su* ext5t z to require ! s]vice ( ! second alt]nator ,b1 x mu/ be swit*$ 9 p>allel ) ,a4 ,9 ord] t bo? ma*9es may op]ate prop]ly 9 p>allel1 ?ree conditions mu/ be satisfi$ be=e !y are connect$ toge!r1 or else ! "o alt]nator w be %ort circuit$ ?r\gh ! o!r1 & s]i\s results w und\bt$ly foll[4 ,accord+ly be=e clos+ ma9 swit* ,b1 x is necess>y t #a4 ,! frequ5cies ( bo? ma*9es be ! same2 #b4 ,! ma*9es mu/ be 9 syn*ronism2 #c4 ,! voltages mu/ be ! same4 ,ques4 ,h[ are ! frequ5cies made ! same8 ,ans4 ,by spe$+ up ! alt]nator to be cut 91 or *ange ! spe$ ( bo? until frequ5cy ( bo? ma*9es is ! same4 ,illu/ration3 ,,fig4 #b1hdd4--;,diagram ( connections ( ,g5]al ,electric automatic voltage regulator = sev]al alt]nators runn+ 9 p>allel ) excit]s 9 p>allel4 ,ques4 ,h[ are ! alt]nators syn*roniz$ or br\ght 9 phase8 ,ans4 ,! syn*ronism ( ! alt]nators is det]m9$ by employ+ "s =m ( syn*roniz]1 z by ! s+le lamp me?od ( fig4 #b1hdc1 or ! two lamp me?od ( fig4 #b1hde4 ,ques4 ,9 syn*roniz+ by ! "o lamp me?od1 :5 %\ld ! incom+ ma*9e be ?r[n 98 ,ans4 ,x is advisable to close ! swit* :5 ! ma*9es are approa*+ syn*ronism r ?an :5 !y are rec$+ f x1 t is to say1 ! in/ant ! lamp becomes d>k4 ,illu/ration3 ,,fig4 #b1hde4--,me?od ( syn*roniz+ ) two lamps2 d>k lamp me?od4 ,! two syn*roniz+ lamps are connect$ z %[n1 & ea* mu/ be design$ to supply its rat$ c&le p[] at ! normal voltage develop$ by ! alt]nators4 ,n[ s9ce ! alt]nators are bo? runn+ "u normal field excitation ! left h& t]m9als ( ea* ( !m w alt]nately be positive & negative 9 pol>ity1 :ile ! "r h& t]m9als are respectively negative & positive 9 pol>ity4 ,if1 h[ev]1 ! alt]nators be 9 phase ) ea* o!r1 ! left h& t]m9als ( bo? ( !m w be positive :ile ! "r h& t]m9als are negative1 & :5 ! left h& t]m9als ( bo? ma*9es are negative ! "r h& t]m9als w be positive4 ,h5ce1 :5 ! ma*9es are 9 phase !re w be no diff]5ce ( pressure betwe5 ! left h& t]m9als or betwe5 ! "r h& t]m9als ( ! two ma*9es4 ,h5ce1 if ! syn*roniz+ lamps be connect$ z %[n1 bo? w be d>k4 ,! in/ant !re is a diff]5ce ( phase1 bo? lamps w gl[ atta9+ full c&le p[] :5 ! diff]5ce ( phase has rea*$ a maximum4 ,z ! alt]nators cont9ue to come clos] 9 /ep1 ! r$ gl[ w gradually fade away until ! lamps become d>k4 ,!n ! swit* may be clos$1 !reby ?r[+ ! two ma*9es 9 p>allel4 ,if ! int]vals betwe5 ! successive light+ up ( ! lamps are ( %ort duration x is advisable to wait until ^! become long] ev5 ?\gh ! o!r conditions are satisfi$1 because :]e ! phases pass ea* o!r rapidly !re is a great] possibility ( n br++ !m toge!r at ! prop] in/ant4 ,an int]val ( n less ?an five seconds %\ld !re=e be all[$ betwe5 ! successive light+ up ( ! lamps1 be=e clos+ ! swit*4 ,illu/ration3 ,,fig4 #b1hdf4--;,inductor type syn*roscope4 ,?is type is especially applicable :]e pressure trans=m]s are already in/all$ = use ) o!r met]s4 ,z x requires only ab\t t5 app>5t watts x may be us$ on ! same trans=m]s ) o!r met]s4 ,!re are ?ree /ation>y coils1 ,n1 ,m & ,c1 & a mov+ sy/em1 compris+ an iron armature1 ,a1 rigidly atta*$ to a %aft suitably pivot$ & m\nt$ 9 be>+s4 ,a po9t] is also atta*$ to ! %aft4 ,! mov+ sy/em is balanc$ & is n subject$ to any re/ra9+ =ce1 su* z a spr+ or gravity control4 ,! axes ( ! coils ,n & ,m are 9 ! same v]tical plane1 b #ij degrees ap>t1 :ile ! axis ( ,c is 9 a horizontal plane4 ,! coils ,n & ,m are connect$ 9 split phase relation ?r\gh an inductive resi/ance ,p & non-inductive resi/ance ,q1 & ^! two circuits are p>allel across ! bus b> t]m9als #c & #d ( ! syn*roscope4 ,coil ,c is connect$ ?r\gh a non-inductive resi/ance across ! upp] ma*9e t]m9als #a & #b ( ! syn*roscope4 ,9 op]ation1 curr5t 9 ! coil ,c magnetizes ! iron core c>ri$ by ! %aft & ! two projections1 m>k$ ,a & iron armature4 ,!re is h[ev]1 no t5d5cy to rotate ! %aft4 ,if curr5t be pass$ ?r\gh "o ( ! o!r coils1 say ,m1 a magnetic field w be produc$ p>allel ) its axis4 ,?is w act on ! projections ( ! iron armature1 caus+ x to turn s t ! positive & negative projections assume _! appropriate position 9 ! field ( ! coil ,m4 ,a rev]sal ( ! direction 9 bo? coils w obvi\sly n affect ! position ( ! armature1 h5ce alt]nat+ curr5t ( ! same frequ5cy & phase 9 ! coils ,c & ,m cause ! same directional effect ^u ! armature z if direct curr5t 7 pass$ ?r\gh ! coils4 ,if curr5t lagg+ #ij degrees beh9d t 9 ! coils ,m & ,c be pass$ ?r\gh ! coil ,n1 x w cause no rotative effect ^u ! armature1 because ! maximum value ( ! field :i* x produces w occur at ! in/ant :5 ! pole /r5g? ( ! armature is z]o4 ,! two curr5ts 9 ! coils ,m & ,n produce a %ift+ magnetic field :i* rotates ab\t ! %aft z an axis4 ,z all curr5ts are assum$ to be ( ! same frequ5cy1 ! rate ( rotation ( ?is field is su* t its direction corresponds ) t ( ! armature projections at ! in/ant :5 ! poles induc$ 9 !m by ! curr5t 9 ! coil ,c are at maximum value1 & ! field %ifts ?r\gh #ahj degrees 9 ! same int]val z is requir$ = rev]sal ( ! poles4 ,?is is ! ess5tial feature ( ! in/rum5t1 namely1 t ! armature projections take a position 9 ! rotat+ magnetic field :i* corresponds to ! direction ( ! field at ! in/ant :5 ! projections are magnetiz$ to _! maximum /r5g? by _! curr5t 9 ! coil ,c4 ,if ! frequ5cy ( ! curr5ts 9 ! coils :i* produce ! %ift+ field be less ?an t 9 ! coil :i* magnetiz$ ! armature1 !n ! armature mu/ turn 9 ord] t x may be p>allel ) ! field :5 its poles are at maximum /r5g?4 ,ques4 ,:at are ! objections to ! "o lamp me?od8 ,ans4 ,! filam5t ( ! lamp may break1 & cause d>kness1 or ! lamp may be d>k ) consid]able voltage z x takes ov] #bj volts to cause a #ajj volt lamp to gl[4 ,ques4 ,:at capacity ( s+le lamp mu/ be us$8 ,ans4 ,x mu/ be good = twice ! voltage ( ei!r ma*9e4 ,illu/ration3 ,,fig4 #b1hdg4--;,brilliant lamp me?od ( syn*roniz+4 ,! syn*roniz+ lamps are connect$ z %[n1 & mu/ be ( ! alt]nator voltage4 ,:5 ! voltages are equal & ! ma*9es 9 phase1 ! diff]5ce ( pressure betwe5 a & a giv5 po9t is ! same z t betwe5 a' & ! same po9t2 ?is obta9s = b & b'4 ,accord+ly1 a lamp connect$ across a b' w burn ) ! same brilliancy z across a' b2 ! same holds = ! o!r lamp4 ,:5 ! voltages are ! same & ! phase diff]5ce is #ahj ! lamps are d>k1 & z ! phase diff]5ce is decreas$1 ! lamps gl[ ) increas+ brightness until at syn*ronism !y gl[ ) maximum brilliancy4 ,h5ce ! incom+ alt]nator %\ld be ?r[n 9 at ! in/ant ( maximum brilliancy4 ,ques4 ,:at modification ( ! syn*roniz+ me?ods %[n 9 ! accompany+ illu/rations is necess>y :5 high pressure alt]nators are us$8 ,ans4 ,/ep d[n trans=m]s mu/ be us$ betwe5 ! alt]nators & ! lamps to obta9 ! prop] work+ voltages = ! lamps4 ,illu/ration3 ,,fig4 #b1hdh4--,syn*roniz+ ) high pressure alt]nators2 d>k & brilliant lamp me?ods4 ,9 bo? me?ods ! prim>ies ( ! trans=m]s are connect$ 9 ! same way across ! t]m9als ( ! alt]nators z %[n4 ,9 ! d>k lamp me?od1 ! connections betwe5 ! second>y coils ( ! trans=m]s mu/ be made s t :5 ea* is subject$ to ! same conditions ! action ( ! "o coil opposes t ( ! o!r z 9 ! d>k lamp me?od2 !n1 if ! trans=m]s be bo? ( ! same design1 !re w be no voltage across ! lamps :5 ! alt]nators are 9 phase ) ea* o!r4 ,if ! ratio ( ea* trans=m] is su* z to give1 = example1 #ajj volts across its second>y t]m9als1 !n ! two inc&esc5t lamps s9ce !y are jo9$ toge!r 9 s]ies mu/ ea* be design$ = #ajj volts4 ,"o #bjj volt lamp c\ld be us$ 9 ei!r me?od 9 place ( ! two #ajj volt lamps4 ,:51 !re=e1 ! alt]nators are directly opposite 9 phase to ea* o!r1 bo? ! lamps w burn brightly2 z ! alt]nators come toge!r 9 phase ! lamps w produce less & less light1 until :5 ! ma*9es are exactly 9 phase no light w be emitt$ at all1 at :i* in/ant ! incom+ alt]nator %\ld be ?r[n 94 ,x mu/ be evid5t1 if ! trans=m] second>y connections are arrang$ z 9 ! brilliant lamp me?od1 s t !y d n oppose ea* o!r1 ! lamps w be at maximum brilliancy :5 ! alt]nators are 9 phase & d>k :5 ! phase diff]5ce is #ahj1 assum+ ( c\rse equaliz$ voltage4 ,ques4 ,h[ is ! voltage ( an incom+ ma*9e adju/$ s t x w be ! same z ! "o already 9 op]ation8 ,ans4 ,by v>y+ ! field excitation ) a rheo/at 9 ! alt]nator field circuit4 ,ques4 ,h[ may two or m alt]nators be />t$ simultane\sly8 ,ans4 ,aft] br++ ea* ( !m up to its prop] spe$ s z to obta9 equal frequ5cies1 ! ma9 swit*es may be clos$1 !reby jo9+ _! armature circuits 9 p>allel4 ,z yet1 h[ev]1 _! respective field w9d+s h n be5 suppli$ ) curr5t1 s t no h>m c result 9 do+ ?is4 ,! excit]s ( ^! ma*9es aft] be+ jo9$ 9 p>allel1 %\ld !n be made to s5d direct curr5t simultane\sly ?r\gh ! field w9d+s ( ! alt]nators1 & f ?is /age on ! directions previ\sly giv5 may be foll[$ 9 detail4 ,ques4 ,:at are ! conditions :5 two or m alt]nators are directly connect$ toge!r8 ,ans4 ,if rigidly connect$ toge!r1 or directly connect$ to ! same eng9e1 !y mu/ necess>ily run 9 ! same mann] at all times4 ,:5 ma*9es connect$ 9 ?is way are once prop]ly adju/$ s t !y are 9 phase ) ea* o!r1 _! op]ation 9 p>allel is ev5 a simpl] task ?an :5 !y are all />t$ toge!r b are n directly connect$4 ,ques4 ,:5 an alt]nator is driv5 by a gas eng9e1 :at provision is sometimes made to insure successful op]ation 9 p>allel8 ,ans4 ,an amortisseur w9d+ is provid$ to c\nt]act ! t5d5cy to hunt+4 ,illu/ration3 ,,fig4 #b1hdi4--;,diagram ( ,l9coln ,syn*roniz]4 ,9 con/ruction1 a /ation>y coil ,f1 has susp5d$ )9 x a coil ,a1 free to move ab\t an axis 9 ! planes ( bo? coils & includ+ a diamet] ( ea*4 ,if an alt]nat+ curr5t be pass$ ?r\gh bo? coils1 ,a1 w take a position ) its plane p>allel to ,f4 ,if n[ ! curr5ts 9 ,a & ,f be rev]s$ ) respect to ea* o!r1 coil ,a w take up a position #ahj f its =m] position4 ,rev]sal ( ! relative directions ( curr5ts 9 ,a & ,f is equival5t to *ang+ _! phase relation by #ahj1 & !re=e ?is *ange ( #ahj 9 phase relation is foll[$ by a correspond+ *ange ( #ahj 9 _! me*anical relation4 ,suppose n[1 in/ead ( rev]s+ ! relative direction ( curr5ts 9 ,a & ,f1 ! *ange 9 phase relation betwe5 !m be made gradually & )\t di/urb+ ! curr5t /r5g? 9 ei!r coil4 ,x is evid5t t :5 ! phase diff]5ce betwe5 ,a & ,f rea*es #ij1 ! =ce betwe5 ,a & ,f w become r$uc$ to z]o1 & a movable sy/em1 ( :i* ,a may be made a "p1 is 9 condition to take up any position dem&$ by any o!r =ce4 ,let a second numb] ( ?is movable sy/em consi/ ( coil ,b1 :i* may be fa/5$ rigidly to coil ,a1 ) its plane #ij f t ( coil ,a1 & ! axis ( ,a pass+ ?r\gh diamet] ( ,b4 ,fur!r1 suppose a curr5t to circulate ?r\gh ,b1 ^: diff]5ce 9 phase relation to t 9 ,a1 is always #ij4 ,x is evid5t "u ^! conditions t :5 ! diff]5ce 9 phase betwe5 ,a & ,f is #ij1 ! movable sy/em w take up a position1 su* t ,b is p>allel to ,f1 because ! =ce betwe5 ,a & ,f is z]o1 & ! =ce betwe5 ,b & ,f is a maximum2 simil>ly :5 ! diff]5ce 9 phase betwe5 ,b & ,f is #ij1 ,a w be p>allel to ,f4 ,t is1 beg9n+ ) a phase diff]5ce betwe5 ,a & ,f ( z]o a phase *ange ( #ij w be foll[$ by a me*anical *ange on a movable sy/em ( #ij1 & ea* successive *ange ( #ij 9 phase w be foll[$ by a correspond+ me*anical *ange ( #ij4 ,= int]m$iate phase relation1 x c be prov$ t "u c]ta9 conditions ! position ( equilibrium assum$ by ! movable elem5t w exactly repres5t ! phase relations4 ,t is1 ) prop] design1 ! me*anical angle betwe5 ! plane ( ,f & t ( ,a & also betwe5 ! plane ( ,f & t ( ,b1 is always equal to ! phase angle betwe5 ! curr5t fl[+ 9 ,f & ^? 9 ,a & ,b respectively4 ,z comm]cially con/ruct$ coil ,f consi/s ( a small lam9at$ iron field magnet ) a w9d+ ^: t]m9als are connect$ ) b9d+ po/s4 ,! coils ,a & ,b are w9d+s practically #ij ap>t on a lam9at$ iron armature pivot$ betwe5 ! poles ( ! magnet4 ,^! two w9d+s are jo9$1 & a tap f ! junction is br\ght out ?r\gh a slip r+ to "o ( two o!r b9d+ po/s4 ,! two rema9+ ends are br\ght out ?r\gh two m slip r+s1 "o ( :i* is connect$ to ! rema9+ b9d+ po/1 ?r\gh a non-inductive resi/ance1 & ! o!r to ! same b9d+ po/ ?r\gh an inductive resi/ance4 ,a light alum9um h& atta*$ to ! armature %aft m>ks ! position assum$ by ! armature4 ,ques4 ,:at is ! action ( ! amortisseur w9d+8 ,ans4 ,any sudd5 *ange 9 ! spe$ ( ! field1 g5]ates a curr5t 9 ! amortisseur w9d+ :i* resi/s ! *ange ( velocity t caus$ ! curr5t4 ,! appe>ance ( an amortisseur w9d+ is %[n 9 ! cut bel[ 7fig4 #b1hej7 illu/rat+ ! field ( a syn*ron\s cond5s] equipp$ ) amortisseur w9d+4 ,illu/ration3 ,,fig4 #b1hej4--;,g5]al ,electric field ( syn*ron\s cond5s] provid$ ) amortisseur w9d+4 ,hunt+ is accompani$ by a %ift+ ( flux across ! face ( ! pole pieces due to ! v>iation 9 ! effect ( armature reaction on ! ma9 field flux z ! curr5t v>ies & ! angul> displacem5t betwe5 ! field & armature poles is *ang$4 ,copp] %ort circuit$ coll>s plac$ ar\nd ! pole face h curr5ts induc$ 9 !m by ?is %ift+ flux1 :i* h su* a direction z to ex]t a torque t5d+ to oppose any *ange 9 ! relative position ( ! field & armature4 ,?is action is simil> to t ( ! runn+ torque ( an induction motor & ! damp+ device has be5 /ill fur!r develop$ until 9 its be/ =m x resembles ! armature w9d+ ( a squirrel cage induction motor4 ,! pole pieces are 9 ducts1 & l[ resi/ance copp] b>s plac$ 9 !m ) _! ends jo9$ by means ( a cont9u\s %ort circuit+ r+ ext5d+ ar\nd ! field4 ,su* a device has prov5 v effective 9 damp+ out oscillations />t$ f any cause1 ! same w9d+ do+ duty z a damp+ device & to assi/ ! />t+ *>act]i/ics4 ,ques4 ,h[ are ?ree phase alt]nators syn*roniz$8 ,ans4 ,9 a mann] simil> to ! s+le phase me?od4 ,?us ! syn*roniz+ lamps may be arrang$ z 9 fig4 #b1eha1 :i* is simply an ext5sion ( ! s+le phase me?od4 ,ques4 ,are ?ree lamps necess>y8 ,ans4 ,only to insure t ! connections are prop]ly made1 aft] :i* "o lamp is all t is requir$4 ,ques4 ,h[ is x kn[n t ! connections ( fig4 #b1hea are correct8 ,ans4 ,if1 9 op]ation1 ! ?ree lamps become bright or d>k simultane\sly1 ! connections are correct2 if ?is action takes place successively1 ! connections are wrong4 ,if wrong1 transpose ! leads ( "o ma*9e until simultane\s action ( ! lamps is secur$4 ,illu/ration3 ,,fig4 #b1hea4--,me?od ( syn*roniz+ ?ree phase alt]nators )1 ?ree lamps1 be+ an ext5sion ( ! s+le phase me?od4 ,ques4 ,:at is ! disadvantage ( ! lamp me?od ( syn*roniz+8 ,ans4 ,lack ( s5sitiv5ess4 ,ques4 ,:i* is ! accept$ lamp me?od1 d>k or brilliant8 ,ans4 ,9 ! ,unit$ ,/ates x is usual to make ! connections = a d>k lamp at syn*ronism1 :ile 9 ,engl& ! opposite practice obta9s4 ,) ! d>k lamp me?od1 ! break+ ( a filam5t might cause ! ma*9es to be connect$ ) a great phase diff]5ce1 :]eas1 ) ! brilliant lamp x is difficult to det]m9e ! po9t ( maximum brilliancy4 ,?is latt] me?od1 !re=e may be call$ ! saf]4 ,ques4 ,:at may be us$ 9 place ( lamps = syn*roniz+8 ,ans4 ,"s =m ( syn*roscopes1 or syn*roniz]s4 ,ques4 ,h[ does ! ,l9coln syn*roniz] "w8 ,ans4 ,! con/ruction is su* t a h& moves ar\nd a dial s t ! angle betwe5 ! h& & ! v]tical is always ! phase angle betwe5 ! two s\rces ( electric pressure to :i* ! syn*roniz] is connect$4 ,if ! incom+ alt]nator be runn+ too sl[1 ! h& deflects 9 "o direction1 if too fa/1 9 ! o!r direction4 ,:5 ! h& %[s no deflection1 t is1 :5 x /&s v]tical1 ! ma*9es are 9 phase4 ,a complete revolution ( ! h& indicates a ga9 or loss ( "o cycle 9 ! frequ5cy ( ! incom+ ma*9e1 z ref]r$ to ! bus b>s4 ,cutt+ ,out ,alt]nator4--,:5 x is desir$ to cut out ( circuit an alt]nator runn+ 9 p>allel ) o!rs1 ! me?od ( proc$ure is z foll[s3 #a4 ,r$uce driv+ p[] until ! load has be5 transf]r$ to ! o!r alt]nators1 adju/+ field rheo/at to obta9 m9imum curr5t2 #b4 ,op5 ma9 swit*2 #c4 ,op5 field swit*4 ,ques4 ,:at precaution %\ld be tak58 ,ans4 ,nev] op5 field swit* be=e ma9 swit*4 ,illu/ration3 ,,fig4 #b1heb4--;,g5]al ,electric #ejj kw41 horizontal mix$ pressure ,curtis turb9e connect$ to a #ejj kw4 dynamo4 ,9 a ,curtis turb9e x is n necess>y to use ! :ole p]iph]y ( ! fir/ /age = l[ pressure /eam nozzles4 ,a section c be p>tition$ (f & equipp$ ) special exp&+ nozzles to receive /eam at high pressure direct f ! boil]s4 ,su* nozzles deliv] _! /eam aga9/ ! same :eel z d ! l[ pressure nozzles1 b occupy only a small portion ( its p]iph]y4 ,! /eam is exp&$ 9 ^! nozzles f high pressure all ! way d[n to ! normal pressure ( ! fir/ /age1 & 9 su* expansion acquires a high velocity & consequ5tly conta9s a great deal ( en]gy--mu* m ?an does an equal quantity ( l[ pressure /eam4 ,9 consequ5ce ( ?is1 high pressure /eam is us$ ) a f> l[] wat] rate ?an is obta9$ ) l[ pressure /eam1 or ) high pressure /eam r$uc$ to l[ pressure 9 a r$uc+ valve4 ,?is con/ruction is call$ mix$ pressure4 ,its function is ! same z t ( ! r$uc+ valve1 t is1 x makes up = a defici5cy ( l[ pressure /eam by draw+ direct on ! boil]s4 ,) ?is con/ruction1 ! full p[] ( ! turb9e c be develop$ )3 ,all l[-pressure /eam1 all high pressure /eam1 or1 any necess>y proportion ( /eam ( ea* pressure4 ,fur!rmore1 ! transition f all l[ pressure to all high pressure1 ?r\gh all ! conditions int]m$iate betwe5 ^! extremes1 is provid$ = automatically by ! turb9e gov]nor2 a defici5cy ( l[ pressure /eam causes ! high pressure nozzles to op5 automatically4 ,ques4 ,:at is ! ord9>y me?od ( cutt+ out an alt]nator8 ,ans4 ,! ma9 swit* is usually op5$ )\t any prelim9>ies4 ,ques4 ,:at is ! objection to ?is proc$ure8 ,ans4 ,x sudd5ly ?r[s all ! load on ! o!r alt]nators1 & causes hunt+4 ,ques4 ,:at =ms ( drive are especially desirable = runn+ alt]nators 9 p>allel1 & :y8 ,ans4 ,wat] turb9e or /eam turb9e because ( ! uni=m torque1 ?us giv+ uni=m motion ( rotation4 ,) reciprocat+ eng9es1 ! crank effect is v v>iable dur+ ! revolution1 result+ 9 pulsations driv+ ! alt]nator too fa/ or too sl[1 & caus+ cross curr5t betwe5 ! alt]nators4 ,ques4 ,is a sluggi%1 or a too s5sitive gov]nor pref]able on an eng9e driv+ alt]nators 9 p>allel8 ,ans4 ,a sluggi% gov]nor4 ,alt]nators 9 ,s]ies4--,alt]nators are seldom if ev] connect$ 9 s]ies1 = ! reason t ! syn*roniz+ t5d5cy peculi> to ^! ma*9es causes !m to oppose ea* o!r & fall out ( phase :5 !y are jo9$ toge!r 9 ?is way4 ,if1 h[ev]1 !y be directly connect$ to ea* o!r1 or to an eng9e1 s t !y necess>ily keep 9 phase at all times1 & ?us add _! respective voltages in/ead ( c\nt]act+ !m1 s]ies op]ation is possible4 ,,note4--,accord+ to ! practice ( ! ,g5]al ,electric ,co41 #b degrees ( phase diff]5ce f a mean is ! limit all[able 9 ord9>y cases4 ,x w1 9 c]ta9 cases1 be possible to op]ate satisfactorily 9 p>allel1 or to run syn*ron\s app>atus f ma*9es ^: angul> v>iation exce$s ?is am\nt1 & 9 o!r cases x w be easy & desirable to obta9 a bett] spe$ control4 ,! #b degree limit is int5d$ to imply t ! maximum dep>ture f ! mean position dur+ any revolution %all n exce$ #b #cfj ( an angle correspond+ to two poles ( a ma*9e4 ,! angle ( circumf]5ce :i* corresponds to ! #b degree ( phase v>iation c be asc]ta9$ by divid+ #b by ! numb] ( pole2 ?us1 9 a #bj pole ma*9e1 ! all[able angul> v>iation f ! mean w\ld be #b #aj ( "o degree4 ,illu/ration3 ,,fig4 #b1hec4--;,diagram ( connections = syn*roniz+ two comp\nd w\nd ?ree phase alt]nators4 ,a & ,a' are ! armatures ( ! two ma*9es1 ! fields ( :i* are p>tly sep>ately excit$1 ! am\nt ( excitation curr5t be+ controll$ by ! s]ies comp\nd+ rheo/ats ,b & ,b'1 :i* =m a /ation>y %unt4 ,x is assum$ t ! alt]nator ,a is connect$ to ! bus b>s #a1 #b1 & #c1 by ! swit* #a,s4 ,if an increase make x necess>y to introduce ! alt]nator ,a'1 x is fir/ run up to spe$ & excit$ to /&>d pressure by its excit]1 & !n ! d\ble plug swit* #c,s is clos$1 connect+ ! prim>y ( ! /ation trans=m] ,t & ,t' ) ! bus b>s ?r\gh ! second>y coil1 s t ! syn*roniz+ lamps light up :5 ! second>y circuit is clos$ ?r\gh ! s+le pole swit* #d,s4 ,! prim>y ( ! /ation trans=m] ,t is ?us excit$ ?r\gh ! d\ble pole swit* #e,s1 connect+ x ) ! out] t]m9als ( ! armature ,a'4 ,! two alt]nators w n[ "w 9 opposition to ea* o!r ^u ! syn*roniz+ lamps1 ! trans=m] ,t be+ op]at$ by ! new alt]nator ,a' ?r\gh ! swit* #b,s1 & ! trans=m] ,t' be+ op]at$ by ! work+ alt]nator ,a1 f ! bus b>s4 ,if ! new alt]nator be n 9 /ep ) ! work+ alt]nator1 ! syn*roniz+ lamps w gl[1 gr[+ bright] & dimm] alt]nately ) great] or less] rapidity4 ,9 ?is case1 ! armature spe$ ( ! new alt]nator mu/ be controll$ 9 su* a mann] t ! bright5+ & dimm+ w occur m & m sl[ly1 until ! lamps cease to gl[ or rema9 ext+ui%$ = a decid$ int]val ( "t4 ,! ext9ction ( ! light is due to ! disappe>ance ( ! second>y curr5t1 & indicates t ! alt]nators are 9 /ep4 ,! swit* #b,s %\ld n[ be ?r[n1 ?us c\pl+ ! two ma*9es electrically1 & bo? ( !m w cont9ue to op]ate 9 /ep4 ,! d\ble pole equaliz] swit* #f,s %\ld n[ be clos$1 connect+ ! two field w9d+s 9 p>allel & equaliz+ ! comp\nd+1 s t any v>iations ( load w affect ! two alt]nators equally4 ,aft] ! alt]nators h be5 connect$ 9 p>allel1 ! swit*es #d,s & #e,s1 may be op5$ leav+ ! swit* #c,s clos$1 to op]ate ! swit*bo>d lamps ,k1 ,k1 z pilot lights f ! bus b>s4 ,trans=m]s4--,^!1 z a :ole1 are simple 9 con/ruction1 high 9 effici5cy1 & comp>atively inexp5sive4 ,_! pr9ciples ( op]ation are also readily und]/ood4 ,! effici5cy ( a trans=m]1 t is1 ! ratio betwe5 full load prim>y & full load second>y is greate/ :5 ! load on x is su* t ! sum ( ! con/ant losses equals ! sum ( ! v>iable losses4 ,9 g5]al1 trans=m]s design$ = high frequ5cies & l>ge capacities are m effici5t ?an ^? design$ = l[ frequ5cies & small capacities4 ,z a :ole1 h[ev]1 a trans=m] leaves b little to be desir$ z reg>ds effici5cy1 a mod]n #fj cycle trans=m] ( #ej kil[atts capacity or m possesses an effici5cy ( approximately #ih p] c5t4 at full load & an effici5cy ( ab\t #ig p] c5t4 at half load4 ,ques4 ,h[ %\ld a trans=m] be select$1 ) respect to effici5cy8 ,ans4 ,"o %\ld be *os51 ^: p>ts are s proportion$ t ! po9t ( maximum effici5cy occurs at t load :i* ! trans=m] usually c>ries 9 s]vice4 ,9 _m alt]nat+ curr5t in/allations1 comp>atively light loads are c>ri$ ! great] "p ( ! "t1 ! rat$ full load or an ov]load be+ occurr5ces ( %ort durations4 ,= su* purposes special att5tion %\ld be giv5 to ! design+ or select+ ( trans=m]s hav+ l[ core losses r ?an l[ resi/ance losses1 because ! latt] are !n ( relatively small importance4 ,ques4 ,:at k9d ( effici5cy is ! /ation manag] int]e/$ 98 ,ans4 ,! all day effici5cy4 ,?is expression1 z commonly met ) 9 practice1 d5otes ! p]c5tage t ! am\nt ( en]gy actually us$ by ! consum] is ( ! total en]gy suppli$ to 8 trans=m] dur+ #bd h\rs4 ,! =mula = calculat+ ! all day effici5cy ( a trans=m] is bas$ ^u ! supposition t ! am\nt ( en]gy us$ by ! consum] dur+ #bd h\rs is equival5t to full load on 8 trans=m] dur+ five h\rs & is z foll[s3 #ew ,e ------------- #bd;c #er #ew :]e ,e ! all day effici5cy ( ! trans=m]1 w ! full load 9 watts on ! prim>y1 c ! core loss 9 watts1 r ! resi/ance loss 9 watts4 ,illu/ration3 ,,fig4 #b1hed4--,p]=mance curves ( ,we/+h\se air bla/ #eej kw1 #aj1ejj volt trans=m]1 #c1jjj alt]nations4 ,ques4 ,:at are ! usual all day effici5cies8 ,ans4 ,! av]age is ab\t #he p] c5t4 = ^? ( #a kil[att capacity1 #ib p] c5t4 = ^? ( #e kil[atts capacity1 #id p] c5t4 = ^? ( #aj kil[atts capacity1 & ab\t #id4e p] c5t4 = ^? ( #ae kil[atts capacity4 ,ques4 ,:at becomes ( ! en]gy lo/ by a trans=m]8 ,ans4 ,x reappe>s z heat 9 ! w9d+s & core4 ,?is heat n only increases ! resi/ances ( ! w9d+s & core1 produc+ !reby a fur!r increase ( _! respective losses1 b 9 addition causes 9 "t a peculi> effect on ! iron core :i* is int5sifi$ by ! rev]sals ( magnetism con/antly go+ on )9 x4 ,aft] ab\t two ye>s' s]vice1 ! iron app>5tly becomes fatigu$ or tir$1 & ?is ph5om5on is call$ ag+ ( ! iron4 ,s9ce ! life ( ! trans=m] dep5ds to a great ext5t ^u ?is factor1 ! conditions responsible = its exi/5ce %\ld z f> z possible be remov$4 ,means mu/ !re=e be provid$ 9 ! con/ruction to radiate ! heat z quickly z x is g5]at$4 ,ques4 ,:at k9d ( oil is us$ 9 oil cool$ trans=m]s8 ,ans4 ,m9]al oil4 ,illu/ration3 ,,fig4 #b1hee4--;,g5]al arrangem5t ( air bla/ trans=m]s & bl[]s4 ,ques4 ,h[ is x obta9$8 ,ans4 ,by fractional di/illations ( petroleum unmix$ ) any o!r sub/ances & )\t subsequ5t *emical treatm5t4 ,ques4 ,:at is ! important requirem5t = trans=m] oil8 ,ans4 ,x %\ld be free f moi/ure1 acid1 alkali or sulphur comp\nds4 ,ques4 ,h[ may ! pres5ce ( moi/ure be det]m9$8 ,ans4 ,by ?ru/+ a r$ hot iron rod 9 ! oil2 if x crackle1 moi/ure is pres5t4 ,ques4 ,describe ! ,we/+h\se me?od ( dry+ oil4 ,ans4 ,x is circulat$ ?r\gh a tank conta9+ lime1 & aft]w>ds1 ?r\gh a dry s& filt]4 ,ques4 ,:at is ! objection to heat+ ! oil 7rais+ its temp]ature slightly above boil+ po9t ( wat]7 to remove ! moi/ure8 ,ans4 ,! "t consum$ 7sev]al days7 is excessive4 ,illu/ration3 ,,fig4 #b1hef4--,small ,curtis turb9e g5]ator set z made by ! ,g5]al ,electric ,co41 9 sizes f #e kw41 to #cjj kw4 ,x c be arrang$ to op]ate ei!r cond5s+ or non-cond5s+1 & at any /eam pressure above #hj lbs4 = ! small] sizes & #ajj lbs4 = ! l>g]4 ,!re are only two ma9 be>+s4 ,a ?ru/ be>+1 consi/+ ( roll] be>+s & runn+ betwe5 h>d5$ /eel face wa%]s locat$ at ei!r end ( ! ma9 be>+s is provid$ solely = c5t]+ ! rotor s z to equalize ! cle>ance4 ,a c5trifugal gov]nor is provid$ 79 ! small] sizes7 completely h\s$1 & m\nt$ directly on ! ma9 %aft end4 ,x controls a balanc$ poppet valve ?r\gh a bell crank4 ,9 ! l>g] sizes 7#ge kw4 & above7 ! gov]nor is m\nt$ on a v]tical second>y %aft ge>$ to ! ma9 %aft & controls a cam %aft :i* op5s or closes a s]ies ( valves 9 rotation1 admitt+ ! /eam to diff]5t sections ( ! fir/ /age nozzles4 ,9 ?is way ?rottl+ ( ! /eam is avoid$4 ,!re is also an em]g5cy gov]nor :i* closes ! ?rottle valve 9 ! ev5t ( ! spe$ rea*+ a pr$et]m9$ limit4 ,! spe$s ( op]ation range f #e1jjj ,r4,p4,m4 = ! smalle/ size to #a1ejj ,r4,p4,m4 = ! l>ge/4 ,! lubrication sy/em is enclos$ & is automatic4 ,air leakage :]e ! %aft passes ?r\gh ! :eel cas+ is prev5t$ by /eam seal4 ,ques4 ,:at effect has moi/ure8 ,ans4 ,x r$uces ! insulation value ( ! oil4 4#jf p] c5t4 ( moi/ure has be5 f\nd to r$uce ! dielectric /r5g? ( oil ab\t #ej p] c5t4 dry oil w )/& a pressure ( #be1jjj volts betwe5 two #i in* knobs sep>at$ 4#ae in*4 ,ques4 ,:at is und]/ood by trans=m] regulation8 ,ans4 ,x is ! diff]5ce betwe5 ! second>y voltage at no load & at full load1 & is g5]ally express$ z a p]c5tage ( ! second>y voltage at no load4 ,ques4 ,:at gov]ns its value8 ,ans4 ,! resi/ance & reactance ( ! w9d+s4 ,illu/ration3 ,,fig4 #b1heg4--;,cut (f c\pl+ = p[] transmission by l9e %aft+4 ,x is us$ to cut (f a driv+ %aft f a driv5 %aft4 ,its use obviates ! use ( a quill1 su* z is %[n 9 fig4 #b1heh4 ,ques4 ,h[ may ! regulation be improv$8 ,ans4 ,by decreas+ ! resi/ances ( ! w9d+s by employ+ conductors ( great] cross section1 or decreas+ _! reactance by divid+ ! coils into sections & closely int]sp]s+ ^? ( ! prim>y betwe5 ^? ( ! second>y4 ,,note4--,! t]m regulation z "h us$ is synonym\s ) drop4 ,! voltage drop 9 a trans=m] d5otes ! drop ( voltage occurr+ across ! second>y t]m9als ( a trans=m] ) load4 ,?is drop is due to two causes3 #a1 ! resi/ance ( ! w9d+s2 & #b1 ! reactance or magnetic leakage ( ! w9d+s4 ,on non-inductive load1 ! reactive drop1 be+ 9 quadrature1 produces b a slight effect1 b on inductive loads x causes ! voltage to drop1 & on lead+ curr5t loads x causes ! voltage to rise4 ,z ! voltage drop ( a good trans=m] is v small ev5 on inductive load1 direct accurate measurem5t is difficult4 ,x is be/ to measure ! copp] loss ) %ort circuit$ second>y by means ( a wattmet]1 & at ! same "t ! voltage requir$ to drive full load curr5t ?r\gh4 ,f ! watts1 ! resi/ance drop c be f\nd1 & f ?is & ! imp$ance voltage1 ! reactive drop may be calculat$4 ,f ^! data a simple vector diagram w give1 ne> en\gh = all practical purposes1 ! drop = any p[] factor1 or ! foll[+ =mula may be us$ :i* has be5 d$uc$ f ! vector diagram4 ,d 7,w ,x7#b 7,r ,p7#b - #ajj :]e ,r resi/ance drop2 ,x reactive drop2 ,p p[] factor ( load2 ,w wattless factor ( load 7#a - ,p#b72 ,d resultant second>y drop4 ,= non-inductive loads :]e ,p #ajj & ,w #j1 ,d ,x#b 7#ajj ,r7#b - #ajj4 ,9 ! case ( lead+ curr5ts x %\ld be consid]$ negative4 ,9 trans=m]s :]e !re is a great diff]5ce 9 voltage betwe5 ! prim>y & second>y w9d+s1 h[ev]1 ?is rem$y has its limitations on acc\nt ( ! great am\nt ( insulation :i* mu/ necess>ily be us$ betwe5 ! w9d+s1 & :i* !re=e causes ! di/ances betwe5 !m to become su* z to cause consid]able leakage ( ! l9es ( =ce4 ,ques4 ,h[ does ! regulation v>y = diff]5t trans=m]s1 & :at %\ld be ! limit8 ,ans4 ,^? ( l>ge capacity usually h a bett] regulation ?an ^? ( small capacity1 b 9 no case %\ld its value exce$ #b p] c5t4 ,illu/ration3 ,,fig4 #b1heh4--,quill drive4 ,?is is ! prop] transmission arrangem5t sub/itute = heavy s]vice1 requir+ l>ge pulleys1 %eaves1 ge>s1 rotors1 etc4 ,x is a holl[ %aft support$ by indep5d5t be>+s4 ,! ma9 driv+ %aft runn+ ?r\gh ! quill is ?us reliev$ ( all transv]se /resses4 ,! p[] is transmitt$ to ! quill by means ( a friction or jaw clut*4 ,:5 ! clut* is ?r[n out ! pulley or %eave /&s idle & ! driv+ %aft revolves freely )9 ! quill4 ,z !re is no contact betwe5 mov+ p>ts !re is no we>4 ,jaw clut*es %\ld be us$ = drives dem&+ positive angul> displacem5t4 ,!y c only be ?r[n 9 & out ( engagem5t :5 at re/4 ,all v l>ge clut* pulleys1 %eaves1 or ge>s design$ to run loose on ! l9e %aft are pref]ably m\nt$ on quills4 ,! lett]s ,a1 ,b1 ,c1 etc41 indicate ! dim5sions to be specifi$ 9 ord]+ a quill4 ,ques4 ,:at advantages h %ell type trans=m]s ov] ^? ( ! core type8 ,ans4 ,!y h a l>g] proportion ( core surface expos$ = radiation ( heat1 & a %ort] magnetic circuit :i* r$uces ! t5d5cy = a leakage ( ! l9es ( =ce into ! air4 ,bo? types h advantages & disadvantages z comp>$ ) ! o!r4 ,9 ! %ell type1 !re is less magnetic leakage1 b also less surface expos$ = radiation1 & great] difficulty 9 provid+ effici5t insulation betwe5 ! two circuits2 9 ! core type !re is m surface expos$ = radiation & less difficulty 9 insulat+ ! w9d+s1 b !re is also a great leakage ( ! l9es ( magnetic =ce into ! out] air4 ,ques4 ,h[ are ! w9d+s usually arrang$8 ,ans4 ,z a rule1 !re is only "o prim>y w9d+ b ! second>y w9d+ is g5]ally divid$ into two equal sections1 ! f\r t]m9als ( :i* are p]man5tly wir$ to f\r connection blocks :i* may be connect$ s z to ?r[ ! second>y sections ei!r 9 p>allel or 9 s]ies ) ea* o!r at w4 ,ques4 ,:at is necess>y = satisfactory op]ation ( trans=m]s 9 p>allel8 ,ans4 ,!y mu/ be design$ = ! same pressures & capacities1 _! p]c5tages ( regulation %\ld be ! same & !y mu/ h ! same pol>ity at a giv5 in/ant4 ,"o may satisfy himself z to ! fir/ ( ^! conditions by exam9+ ! "n plates fa/5$ to ! trans=m]s1 :]eon are /amp$ ! values ( ! respective pressures & capacities ( ea*4 ,al?\gh equal values ( regulation is giv5 z "o ( ! conditions to be satisfi$1 trans=m]s may be op]at$ 9 p>allel :5 _! p]c5tages ( regulation are n ! same4 ,ideal op]ation1 h[ev]1 c be atta9$ only "u ! =m] /ate ( affairs4 ,suppose1 = in/ance1 a trans=m] hav+ a regulation ( two p] c5t4 be op]at$ 9 p>allel ) ano!r ( simil> size & design b hav+ a regulation ( "o p] c5t4 ,! second>y pressures ( ^! trans=m]s at no load w ( c\rse be ! same1 b at full load if ! second>y pressure ( ! "o be #ih volts1 t ( ! o!r w be #ii volts4 ,!re w1 !re=e1 be a diff]5ce ( pressure ( "o volt betwe5 !m :i* w t5d to =ce a curr5t backw>d ?r\gh ! second>y w9d+ ( ! trans=m] deliv]+ #ih volts4 ,?is rev]s$ curr5t1 al?\gh comp>atively small 9 value1 l[]s ! effici5cy ( ! in/allation by caus+ a displacem5t ( phase & a decrease 9 ! comb9$ p[] factor ( ! trans=m]s4 ,ques4 ,describe ! pol>ity te/4 ,ans4 ,! te/ = pol>ity consi/s 9 jo9+ toge!r by means ( a fuse wire1 a t]m9al ( ! second>y w9d+ ( ea* trans=m]1 & !n ) ! prim>y w9d+s suppli$ ) normal voltage1 connect+ tempor>ily ! rema9+ t]m9als ( ! second>y w9d+s4 ,! melt+ ( ! fuse wire ?us connect$ indicates t ! second>y t]m9als jo9$ toge!r are ( opposite pol>ities1 & t ! connections mu/ !re=e be rev]s$1 :]eas if ! fuse wire d n melt1 x %[s t ! prop] t]m9als h be5 jo9$ & t ! connections may be made p]man5t4 ,illu/ration3 ,,fig4 #b1hei4--,s+le ov]hung tang5tial wat] :eel equipp$ ) ,doble ellipsoidal buckets4 ,! c5tral position ( ! front ent]+ w$ge or lip ( ! bucket is cut away 9 ! =m ( a semi-circul> not*1 :i* all[s a solid circul> wat] jet to dis*>ge ^u ! c5tral divid+ w$ge ( ! bucket )\t be+ split 9 a horizontal plane4 ,! object ( ?is te/ is1 obvi\sly1 n to det]m9e ! exact pol>ity ( ea* second>y t]m9al1 b m]ely to indicate :i* ( !m are ( ! same pol>ity4 ,illu/ration3 ,,fig4 #b1hfj4--,motor g5]ator excit] set driv5 by a ,pelton-,doble tang5tial wat] :eel4 ,! wat] :eel runn] is m\nt$ on ! %aft ov]hung & ! jet is regulat$ by ei!r a h& actuat$ or gov]nor controll$ ne$le nozzle4 ,! spe$ ( ! wat] :eel is equival5t to ! syn*ron\s spe$ ( ! induction motor1 h5ce1 ! latt] floats on ! l9e1 & "u c]ta9 conditions may p]=m ! functions ( an alt]nator by fe$+ into ! circuit1 %\ld ! wat] :eel t5d to op]ate above syn*ron\s spe$4 ,%\ld any int]ruption to ! op]ation ( ! :eel occur1 caus+ a dim9ution ( spe$1 ! induction motor w\ld drop back to full load spe$ & take up ! excit] load1 result+ 9 no appreciable drop ( excit] voltage4 ,! only v>iation ( spe$ possible is dep5d5t ^u ! slip ( ! motor4 ,:]e two or m excit] sets are employ$ 9 ! /ation1 an advantage\s arrangem5t embraces ! in/allation ( a wat] :eel driv5 motor g5]ator set & an excit] set1 consi/+ ( m]ely ! direct curr5t g5]ator & wat] :eel4 ,! induction motor be+ electrically ti$ into ! circuit1 ! possibility ( a runaway ( ! wat] :eel is elim9at$1 s9ce its spe$ c only slightly exce$ ! syn*ron\s spe$ ( ! sy/em4 ,motor ,g5]ators4--,9 motor g5]ator sets1 ei!r ! %unt or s]ies w\nd type ( motor may be employ$ at ! p[] produc+ end ( ! set1 b ! field ( ! g5]ator is ei!r %unt or comp\nd w\nd1 dep5d+ ^u :e!r or n x is desir$ to ma9ta9 or to raise ! second>y voltage ne> full load4 ,9 ei!r case a rheo/at introduc$ 9 ! %unt field w9d+ ( ! g5]ator w be f\nd v ess5tial4 ,bo? g5]ator & motor are s m\nt$ on ! base t _! respective commutators are at ! out] ends ( ! set4 ,by ?is means ample space surr\nds all ( ! work+ p>ts1 & repairs c readily be made4 ,motor g5]ators are frequ5tly us$ z boo/]s to raise or boo/ ! voltage ne> ! extremities ( long di/ance1 direct curr5t transmission l9es4 ,( ^!1 electric railway sy/ems 9 :i* x is desir$ to ext5d c]ta9 ( ! long] l9es1 =m a typical example4 ,illu/ration3 ,,fig4 #b1hfa4--;,automatically gov]n$ ,pelton-,doble tang5tial wat] :eel driv+ excit] dynamo4 ,! wat] :eel is m\nt$ on "o end ( ! %aft1 :ile ! opposite end is ext5d$ to c>ry a fly :eel ( suitable design to comp5sate = ! l[ fly :eel effect ( ! direct curr5t armature4 ,two be>+s support ! %aft :i* c>ries ! rotat+ elem5ts ( ! unit4 ,a ne$le nozzle actuat$ by a direct motion ,pelton-,doble gov]nor 7design$ = op]ation by ei!r oil or wat] pressure7 ma9ta9s con/ant spe$4 ,ow+ to ! great co/ ( *ang+ su* a sy/em ov] to "o employ+ alt]nat+ curr5t1 or /orage batt]ies1 or ( con/ruct+ an additional p[] /ation1 ^! solutions ( ! problem are usually at v>iance ) good judgm5t & ! am\nt ( money at h&4 ,! *oice !n rema9s betwe5 ! pur*ase ( additional wire = fe$]s1 ! connection ( a boo/] 9 ! old fe$]s1 or ! in/allation ( bo? l>g] fe$]s & a boo/]4 ,( ^!1 x is g5]ally f\nd t ei!r ! second or ! ?ird m5tion$ alt]native meets ! conditions mo/ satisfactorily4 ,a boo/] in/all$ 9 a railway sy/em = ! purpose j m5tion$1 w\ld h a s]ies w\nd motor1 & ! conditions to :i* x mu/ con=m w\ld be z foll[s3 ,! motor hav+ a s]ies w9d+ mu/ provide = ! full fe$] curr5t pass+ ?r\gh bo? armature & field w9d+s4 ,ow+ to ! v>y+ loads on a railway sy/em1 due to ! frequ5t />t+ & /opp+ ( c>s1 ! fe$] curr5t v>ies betwe5 z]o & "s su* value z #aej amp]es4 ,?is fluctuation ( curr5t ?r\gh ! field w9d+ w1 9 ord9>y cases1 v>y ! magnetization ( ! pole pieces f z]o almo/ to ! po9t ( saturation2 t is1 ! maximum fe$] curr5t w s ne>ly fill ! magnet cores ) l9es ( =ce t x w\ld be q difficult to cause m l9es ( magnetic =ce to pass ?r\gh !m4 ,s long z ! po9t ( saturation is n rea*$1 h[ev]1 ! proportion ( curr5t to field /r5g? rema9s con/ant1 & !re=e ! ratio ( amp]es to volts w n v>y4 ,! sev]e fluctuations ( ! fe$] curr5t w\ld1 if ! motor 7 %unt or comp\nd w\nd1 cause mo/ s]i\s sp>k+ & v>i\s o!r tr\bles1 b 9 a s]ies motor :]e ! back amp]e turns on ! armature t react on ! field v>y 9 precisely ! same proportion z ! amp]e turns 9 ! field1 !re exi/s at all times a t5d5cy to balance ! active =ces & produce satisfactory op]ation4 ,if1 h[ev]1 ! field magnet cores be v l>ge1 !y _c s quickly respond1 magnetically1 to *anges 9 ! /r5g? ( ! curr5t1 & !re is !n great] liability ( ! armature reaction mom5t>ily weak5+ ! field & !reby produc+ tempor>y sp>k+4 ,ques4 ,are motor g5]ators always compos$ ( direct curr5t sets8 ,ans4 ,no4 ,ques4 ,describe conditions requir+ a diff]5t comb9ation4 ,ans4 ,= purposes :]e = in/ance direct curr5ts ( widely diff]5t voltages are to be obta9$ f an alt]nat+ curr5t circuit1 & x is desir$ to in/all b "o set1 a motor g5]ator consi/+ ( an alt]nat+ curr5t motor su* z an induction motor1 & a dynamo mu/ necess>ily be employ$4 ,9 su* sets1 x is common to f9d bo? motor & dynamo armatures m\nt$ on a common %aft1 & ! respective field frames re/+ on a s+le base1 al?\gh = connection on a v high pressure alt]nat+ curr5t circuit1 sep>ate armature %afts insulat$ f ea* o!r b directly connect$ toge!r1 & sep>ate bases re/+ on a s+le f\ndation1 are usually employ$ to af=d ! highe/ degree ( insulation betwe5 ! respective circuits ( ! two ma*9es4 ,ques4 ,:at is ! objection to a set compos$ ( alt]nat+ curr5t motor & alt]nator8 ,ans4 ,! comm]cial field t w\ld be naturally cov]$ by su* a set is bett] suppli$ by a trans=m]4 ,ques4 ,:y8 ,ans4 ,because a trans=m] conta9s no mov+ p>ts1 & is !re=e simpl] 9 con/ruction1 *eap] 9 price1 & less liable to get out ( ord]4 ,dynamotors4--,a dynamotor diff]s f a motor g5]ator 9 t ! motor armature & ! g5]ator armature are comb9$ into "o1 !reby requir+ b "o field frame4 ,s9ce ! motor & g5]ator armature w9d+s are m\nt$ on a s+le core1 ! armature reaction due to ! "o w9d+ is neutraliz$ by ! reaction caus$ by ! o!r w9d+4 ,!re is1 consequ5tly1 little or no t5d5cy = sp>k+ to occur at ! bru%es1 & !y !re=e ne$ n be %ift$ on ?is acc\nt = diff]5t loads4 ,ques4 ,h[ is a dynamotor usually con/ruct$8 ,ans4 ,x is usually built ) two pole pieces :i* are %unt w\nd4 ,ques4 ,:y does ! voltage develop$ fall (f slightly "u an increase ( load8 ,ans4 ,because a comp\nd w9d+ _c be provid$4 ,illu/ration3 ,,figs4 #b1hfb & #b1hfc4--,me?od ( putt+ on belts :5 ! driv] is 9 motion1 & device us$4 ,! latt] is call$ a belt slipp]1 & consi/s1 z %[n 9 fig4 #b1hfb1 ( a cone & %ield1 :i* revolve ^u ! /em1 ,b1 ?us yield+ easily to ! pull ( ! belt4 ,a /aff or h&le ,c ( any conv5i5t l5g? c be fa/5$ to ! socket4 ,! mode ( op]ation is illu/rat$ 9 fig4 #b1hfc1 :i* is self explanatory4 ,ques4 ,describe ! armature con/ruction & op]ation4 ,ans4 ,x consi/s ( two sep>ate w9d+s2 "o ( :i* is jo9$ to a commutator m\nt$ on "o side ( ! armature = motor purposes1 & ! o!r to ! commutator on ! o!r side ( ! armature = g5]ator purposes4 ,by means ( two /uds ( bru%es press+ on ! motor commutator1 curr5t f ! s]vice wires is f$ into ! w9d+ connect$ to ?is commutator1 & s9ce ! %unt field w9d+ is also excit$ by ! curr5t f ! s]vice wires1 !re is develop$ 9 ! g5]ator w9d+ on ! rotat+ armature a direct voltage :i* is proportional to ! spe$ ( rotation ( ! armature 9 revolutions p] second1 ! numb] ( conductors 9 s]ies :i* con/itute ! g5]ator w9d+1 & ! total /r5g? ( ! field 9 :i* ! armature revolves4 ,?is pressure causes curr5t to pass ?r\gh ! g5]ator w9d+ & ! di/ribut+ circuit :5 ! di/ribut+ circuit to :i* ?is w9d+ is connect$ by means ( its respective commutator1 bru%es1 etc41 is clos$4 ,illu/ration3 ,,figs4 #b1hfd to #b1hff4--;,conv]t] connections2 fig4 #b1hfd d\ble delta connection2 fig4 #b1hfe diametrical connection2 fig4 #b1hff two circuit s+le phase connection4 ,= six phase syn*ron\s conv]t]1 two diff]5t arrangem5ts ( ! connections are g5]ally us$4 ,"o is call$ ! d\ble delta1 & ! o!r ! diametrical connection4 ,let ! armature w9d+ ( ! conv]t] be repres5t$ by a circle z 9 figs4 #b1hfd & #b1hfe1 & let ! six equidi/ant po9ts on ! circumf]5ce repres5t collector r+s1 !n ! second>y ( ! supply trans=m]s c be connect$ to ! collector r+s 9 a d\ble delta z 9 fig4 #b1hfd1 or across diametrical pairs ( po9t] z 9 fig4 #b1hfe4 ,9 ! fir/ in/ance1 ! voltage ratio is ! same z = ! ?ree phase syn*ron\s conv]t] & simply consi/s ( two delta sy/ems4 ,! trans=m]s c also be connect$ 9 d\ble />1 & 9 su* a case ! ratio betwe5 ! ?ree phase voltage betwe5 ! t]m9als ( ea* />1 & ! direct voltage w be ! same z = d\ble delta1 :ile ! voltage ( ea* trans=m] coil1 or voltage to neutral1 is #a #c times z mu*4 ,) ! diametrical connection1 ! ratio is ! same z = ! two r+ s+le phase conv]t]1 x be+ analog\s to ?ree su* sy/ems4 ,h5ce six phase d\ble delta ,e#a #c;,e #bb 4#fab;,e4 ,six phase diametrical1 ,e#a ,e #b 4#gjg;,e4 ,! ratio ( ! virtualvoltage ,e#j betwe5 any collector r+ & ! neutral po9t is always ,e#j 7,e #b7 #b 4#ced;,e4 ,= s+le phase syn*ron\s conv]t]s1 consi/+ ( a clos$ circuit armature w9d+ tapp$ at two equidi/ant po9ts to ! two collector r+s ! virtual voltage is #a #b ! direct curr5t voltage4 ,:ile su* an arrangem5t ( ! s+le phase conv]t] is ! simple/1 requir+ only two collector r+s1 x is undesirable1 especially = l>g] ma*9es1 on acc\nt ( excessive heat+ ( ! armature conductors4 ,9 fig4 #b1hff1 :i* repres5ts ! armature w9d+ ( a s+le phase conv]t]1 ! supply circuits f two second>ies ( ! /ep d[n trans=m]s are connect$ to f\r collector r+s1 s t ! two circuits are 9 phase ) ea* o!r1 b ea* spreads ov] an arc ( #abj electrical degrees in/ead ( ov] #ahj degrees z 9 ! s+le phase circuit conv]t]4 ,to di/+ui% ! two types1 x is g5]ally call$ a two circuit s+le phase syn*ron\s conv]t]4 ,! virtual voltage ,e#b be>s to ! direct voltage ! same relation z 9 ! ?ree phase conv]t]1 t is s+le phase two circuit1 ,e#a #c #bb 4#fab;,e4 ,ques4 ,h[ is a dynamotor />t$8 ,ans4 ,x is connect$ at its motor end & />t$ 9 ! same mann] z any %unt w\nd motor on a con/ant pressure circuit4 ,ques4 ,:at precautions %\ld be tak5 9 />t+ a dynamotor8 ,ans4 ,! necess>y precautions are1 to h ! poles /rongly magnetiz$ be=e pass+ curr5t ?r\gh ! motor w9d+ on ! armature2 to increase gradually ! curr5t ?r\gh ?is w9d+1 & n to close ! g5]at+ circuit until normal conditions reg>d+ spe$1 etc41 are e/abli%$ 9 ! motor circuit4 ,ques4 ,h[ is ! curr5t develop$ 9 ! ma*9e regulat$8 ,ans4 ,x c be regulat$ by ! introduction ( resi/ance 9 "o or ! o!r ( ! armature circuits1 or by a %ift+ ( ! bru%es ar\nd ! commutator4 ,ques4 ,are dynamotors less effici5t ?an motor g5]ators ( a simil> type8 ,ans4 ,no1 !y are m effici5t4 ,ques4 ,:y8 ,ans4 ,because !y h only "o field circuit & at lea/ "o be>+ less ?an a motor g5]ator4 ,a motor g5]ator has at lea/ ?ree be>+s1 & occasionally1 f\r1 :]e ! set consi/s ( two indep5d5t ma*9es directly connect$ toge!r4 ,rot>y ,conv]t]s4--,an important modification ( ! dynamotor is ! rot>y conv]t]4 ,?is ma*9e =ms1 z x 71 a l9k betwe5 alt]nat+ & direct curr5t sy/ems1 be+ 9 g5]al a comb9ation ( an alt]nat+ curr5t motor & a dynamo4 ,illu/ration3 ,,fig4 #b1hfg4--,skeleton diagram %[+ wir+ ( alt]nator1 excit]1 trans=m] & conv]t]4 ,! cut also %[s swit*bo>d & connections4 ,x has practically become a fixture 9 all l>ge electric railway sy/ems & 9 o!r in/allations :]e heavy direct curr5ts ( con/ant pressure are requir$ at a consid]able di/ance f ! g5]at+ plant4 ,9 su* cases a rot>y conv]t] is in/all$ 9 ! sub-/ation1 & be+ simpl] 9 con/ruction1 high] 9 effici5cy1 m economical ( floor space1 & l[] 9 price ?an a motor g5]ator set consi/+ ( an alt]nat+ curr5t motor & a dynamo :i* might be us$ 9 its place1 x has almo/ entirely sup]s$$ ! latt] ma*9e = ! class ( "w m5tion$4 ,ques4 ,:at is ! objection to ! s+le phase rot>y conv]t]8 ,ans4 ,x is n self-/>t+4 ,ques4 ,:at feature ( op]ation is inh]5t 9 a rot>y conv]t]8 ,ans4 ,a rot>y conv]t] is a rev]sible ma*9e4 ,t is to say1 if x be suppli$ ) direct curr5t ( ! prop] voltage at its commutator end1 x w run z a direct curr5t motor & deliv] alt]nat+ curr5t to ! collector r+s4 ,:ile ?is feature is sometimes tak5 advantage ( 9 />t+ ! conv]t] f re/1 ! ma*9e is n (t5 us$ p]man5tly 9 ?is way1 its comm]cial application be+ usually ! conv]sion ( alt]nat+ curr5ts into direct curr5ts4 ,ques4 ,h[ does a rot>y conv]t] op]ate :5 driv5 by direct curr5t8 ,ans4 ,! same z a direct curr5t motor1 its spe$ ( rotation dep5d+ ^u ! relation exi/+ betwe5 ! /r5g? ( ! field & ! direct curr5t voltage appli$4 ,if ! field be weak ) respect to ! armature magnetism result+ f ! appli$ voltage1 ! armature w rotate at a high spe$1 increas+ until ! conductors on ! armature cut ! l9es ( =ce 9 ! field s z to develop a voltage :i* w be equal to t appli$4 ,aga91 if ! field be /rong ) respect to ! armature magnetism1 result+ f ! appli$ voltage1 ! armature w rotate at a l[ spe$4 ,if1 !re=e1 x be desir$ to op]ate ! conv]t] 9 ?is mann] & ma9ta9 an alt]nat+ curr5t ( con/ant frequ5cy1 ! spe$ ( rotation mu/ be kept con/ant by supply+ a con/ant voltage n only to ! bru%es press+ on ! commutator1 b also to ! t]m9als ( ! field w9d+4 ,illu/ration3 ,,fig4 #b1hfh4--;,g5]al ,electric syn*ron\s conv]t] ) s]ies boo/]4 ,?is type ( conv]t] g5]ally consi/s ( an alt]nator ) revolv+ field m\nt$ on ! same %aft z ! conv]t] armature4 ,! armature ( ! alt]nator1 or boo/]1 z x is usually call$1 is /ation>y & connect$ electrically 9 s]ies betwe5 ! supply circuit & ! collector r+s ( ! syn*ron\s conv]t]4 ,! boo/] field has ! same numb] ( pole z ! conv]t] & is g5]ally %unt w\nd4 ,a *ange 9 ! boo/] voltage w correspond+ly *ange ! alt]nat+ voltage impress$ on ! conv]t] & ?is regulation c1 ( c\rse1 be made s z to ei!r increase or decrease ! impress$ voltage by means ( /r5g!n+ or weak5+ ! boo/] field4 ,! voltage v>iation c be made ei!r non-automatic or automatic1 & 9 ! latt] case1 x becomes necess>y to provide a motor op]at$ rheo/at controll$ by suitable relays1 or ! boo/] c be provid$ ) a s]ies field4 ,by means ( a boo/]1 x is possible to v>y ! direct voltage ( ! conv]t] ) a con/ant alt]nat+ supply voltage1 & ?is voltage regulation is obta9$ )\t di/urbance ( ! p[] factor or wave %ape ( ! sy/em4 ,syn*ron\s conv]t]s are frequ5tly in/all$ 9 connection ) ,edison sy/ems1 :]e ?ree wire direct curr5t is requir$4 ,! ?ree wire feature is obta9$ ei!r by provid+ extra collector r+s & comp5sator1 z ) ord9>y direct curr5t g5]ators1 or also by connect+ ! neutral wire directly to ! neutral po9t ( ! second>y w9d+ ( /ep d[n trans=m]s1 if su* be furni%$4 ,ques4 ,h[ does x op]ate ) alt]nat+ curr5t drive8 ,ans4 ,! same z a syn*ron\s motor4 ,ques4 ,:at is ! mo/ tr\blesome "p & :y8 ,ans4 ,! commutator1 because ( ! _m pieces ( :i* x is compos$ & ! necess>y l9es along :i* x is con/ruct$1 its p]iph]al spe$ mu/ be kept )9 reasonable limits4 ,ques4 ,:at %\ld be ! limit ( ! commutator spe$8 ,ans4 ,! commutator spe$1 or tang5tial spe$ at ! bru%es %\ld n exce$ #c1jjj feet p] m9ute4 ,illu/ration3 ,,fig4 #b1hfi4--,wir+ diagram = ,g5]al ,electric syn*ron\s conv]t] ) s]ies boo/] z illu/rat$ 9 fig4 #b1hfh4 ,ques4 ,"n ano!r limitation necess>y = satisfactory op]ation4 ,ans4 ,! pressure betwe5 adjac5t commutator b>s %\ld n exce$ eight or t5 volts4 ,if ! commutator b>s be made n>r[ 9 ord] to obta9 ! necess>y numb] = ! desir$ voltage ) ! m9imum circumf]5ce & !re=e l[ commutator spe$1 ! bru%es employ$ to collect ! curr5t are liable to require excessive wid? 9 ord] to provide ! prop] cross section & yet n cov] m ?an two b>s at once4 ,ques4 ,h[ c ! commutator spe$ be kept )9 reasonable limits1 o!r ?an by r$uc+ ! wid? ( ! commutator b>s8 ,ans4 ,by us+ alt]nat+ curr5t ( comp>atively l[ frequ5cy4 ,= a rot>y conv]t] deliv]+ #ejj volt direct curr5t1 ! prop] frequ5cy = ! alt]nat+ curr5t circuit has be5 f\nd to be #be cycles p] second4 ,ques4 ,:5 a rot>y conv]t] is op]at$ 9 ?is usual mann] on an alt]nat+ curr5t circuit1 h[ c ! direct curr5t be v>i$8 ,ans4 ,x may be v>i$ 7f z]o to a maximum7 by *ang+ ! value ( ! alt]nat+ pressure suppli$ to ! ma*9e1 or x may be alt]$ )9 a limit$ range by mov+ ! bru%es ar\nd ! commutator1 or 9 a comp\nd w\nd conv]t] by *ang+ ! am\nt ( comp\nd+4 ,"u ord9>y conditions1 v>y+ ! voltage develop$ by *ang+ ! voltage at ! motor end is n practical1 h5ce ! voltage develop$ c be v>i$ only ov] a limit$ range4 ,9 addition to ?is1 ! voltage develop$ at ! direct curr5t end be>s always a c]ta9 con/ant proportion to ! alt]nat+ curr5t voltage appli$ at ! motor end2 ?is is due to ! same w9d+ be+ us$ bo? = motor & g5]ator purposes4 ,9 all cases ! proportion is su* t ! alt]nat+ curr5t voltage is ! l[]1 be+ 9 ! s+le phase & 9 ! two phase conv]t]s ab\t 4#gjg ( ! direct curr5t voltage1 & 9 ! ?ree phase conv]t] ab\t 4#fab ( ! direct curr5t voltage4 ,x is ?us se5 t :atev] value ( direct curr5t voltage be desir$1 ! value ( ! appli$ alt]nat+ curr5t voltage mu/ be l[]1 requir+ 9 consequ5ce ! in/allation ( /ep d[n trans=m]s at ! sub-/ation = r$uc+ ! l9e wire voltage to con=m to ! direct curr5t pressure requir$4 ,ques4 ,:at is ! effici5cy ( a rot>y conv]t]8 ,ans4 ,x may be said to h approximately ! same effici5cy z t 9 ! av]age ( ! same output1 al?\gh 9 reality ! conv]t] is a trifle m effici5t on acc\nt ( af=d+ a some:at %ort] av]age pa? = ! curr5t 9 ! armature1 r$uc+ 9 consequ5ce ! resi/ance loss & ! armature reaction4 ,ques4 ,may a conv]t] be ov]load$ m ?an a dynamo ( ! same output1 & :y8 ,ans4 ,yes1 because !re is usually less resi/ance loss 9 ! armature ( ! conv]t] ?an 9 ! armature ( ! dynamo4 ,illu/ration3 ,,fig4 #b1hgj4--,wir+ diagram = ?ree wire syn*ron\s conv]t] ) delta-,y connect$ /ep d[n trans=m] ) ! neutral br\ght out4 ,x is evid5t t 9 ?is case ea* trans=m] second>y receives ( ! neutral curr5t1 & if ?is curr5t be n s small1 z comp>$ ) ! excit+ curr5t ( ! trans=m]1 x w cause an increase 9 ! magnetic d5sity4 ,?us1 a two phase conv]t] may be ov]load$ approximately #fj p] c5t41 & a ?ree phase conv]t] may be ov]load$ ab\t #cj p] c5t4 above _! respective outputs if op]at$ z dynamos4 ,ques4 ,describe h[ a conv]t] is />t$4 ,ans4 ,!re are sev]al me?ods any "o ( :i* may be employ$1 ! *oice 9 any giv5 case dep5d+ ^u :i* ( !m may be/ be foll[$ "u ! exi/+ conditions4 ,if x be f\nd advisable to />t ! conv]t] ) direct curr5t1 ! same connections w\ld be made betwe5 ! s\rce ( ! direct curr5t & ! armature t]m9als on ! commutator side ( ! conv]t] z w\ld be ! case 7 a direct curr5t %unt motor ( consid]able size to be />t$2 ?is naturally means t a />t+ rheo/at & a circuit break] w be introduc$ 9 ! armature circuit4 ,! %unt field w9d+ alone is us$1 & ?is "p ( ! wir+ may be made p]man5t if1 z is usually ! case1 ! same s\rce ( direct curr5t is us$ normally = sep>ate field excitation4 ,illu/ration3 ,,fig4 #b1hga4--,wir+ diagram ( ?ree wire syn*ron\s conv]t] ) di/ribut$ ,y second>y4 ,?is sy/em elim9ates ! flux di/ortion due to ! unbalanc$ direct curr5t 9 ! neutral4 ,two sep>ate int]connect$ w9d+s are us$ = ea* leg ( ! ,y4 ,! unbalanc$ neutral curr5t fl[+ 9 ?is sy/em may be comp>$ 9 action to ! effect ( a magnetiz+ curr5t 9 a trans=m]4 ,! effect ( ! ma9 trans=m] curr5ts 9 ! prim>y & second>y is balanc$ ) reg>d to ! flux 9 ! trans=m] core1 :i* dep5ds ^u ! magnetic curr5t4 ,:5 a direct curr5t is pass$ ?r\gh ! trans=m]1 unless ! fluxes produc$ by ! same neutralize "o ano!r1 its effect on ! trans=m] iron v>ies z ! magnetiz+ curr5t4 ,= example1 assume a trans=m] hav+ a normal amp]e capacity ( #ajj &1 approximately1 #f amp]es magnetiz+ curr5t1 & assume t ?ree su* trans=m]s are us$ ) ,y connect$ second>ies = op]at+ a syn*ron\s conv]t] connect$ to a ?ree wire ,edison sy/em4 ,all[+ #be p] c5t4 unbalanc+1 ! curr5t w divide equally among ! ?ree legs giv+ #h4cc amp]es p] leg1 :i* is m ?an ! normal magnetiz+ curr5t4 ,! loss due to ?is curr5t is1 h[ev]1 inappreciable1 b ! increas$ core losses may be consid]able4 ,if a di/ribut$ w9d+ be us$1 ! direct curr5t fl[s 9 ! opposite direction1 ar\nd ! halves ( ea* core ?us entirely neutraliz+ ! flux di/ortion4 ,:e!r ! /raight ,y connection is to be us$ is m]ely a "q ( balanc+ ! increas$ core loss ( ! /raight ,y connection aga9/ ! increas$ copp] loss & ! great] co/ ( ! int]connect$ ,y sy/em4 ,! /raight ,y connection is mu* simpl]1 & x w\ld be q p]missible to use x = trans=m]s ( small capacities :]e ! direct curr5t circulat+ 9 ! neutral is less ?an #cj p] c5t4 ( ! rat$ trans=m] curr5t4 ,! direct curr5t may be d]iv$ f a /orage batt]y1 f a sep>ate conv]t]1 or f a motor g5]ator set in/all$ 9 ! sub-/ation = ! purpose4 ,an adju/able rheo/at w1 ( c\rse1 be connect$ 9 ! field circuit = regulation4 ,be=e />t+ ! conv]t]1 h[ev]1 x is necess>y to d c]ta9 wir+ betwe5 ! t]m9als on ! collector side ( ! ma*9e & ! alt]nat+ curr5t supply wires1 9 ord] t ! *ange ov] f direct curr5t motive p[] to alt]nat+ curr5t motive p[] may be made :5 ! prop] phase relations are e/abli%$ betwe5 ! alt]nat+ curr5t 9 ! supply wires & ! alt]nat+ curr5t 9 ! armature w9d+ ( ! conv]t]4 ,9 ord] t prop] phase relations exi/1 ! armature ( ! conv]t] mu/ rotate at su* a spe$ t ea* coil !reon passes its prop] rev]sal po9t at ! same "t z ! alt]nat+ curr5t rev]ses 9 ! supply wires4 ,?is spe$ may be calculat$ by d\bl+ ! frequ5cy ( ! supply curr5t & !n divid+ by ! numb] ( pole pieces on ! conv]t]1 b a f> m accurate me?od ( judg+ :5 ! conv]t] is 9 /ep or 9 syn*ronism ) ! supply curr5t consi/s 9 employ+ inc&esc5t lamps z %[n 9 fig4 #b1hgb4 ,ques4 ,h[ is a polyphase conv]t] />t$ ) alt]nat+ curr5t8 ,ans4 ,?is may be done by apply+ ! alt]nat+ pressure directly to ! collector r+s :ile ! armature is at re/4 ,!re ne$ be no field excitation2 9 fact ! field w9d+s on ! sep>ate pole pieces %\ld be disconnect$ f ea* o!r be=e ! alt]nat+ voltage is appli$ to ! armature1 else a high voltage w be induc$ 9 ! field w9d+s :i* may prove injuri\s to _! insulation4 ,! passage ( ! alt]nat+ curr5t ?r\gh ! armature w9d+ produces a magnetic field t rotates ab\t ! armature core1 & induces 9 ! pole pieces eddy curr5ts1 :i*1 react+ on ! armature1 ex]t a suffici5t torque to />t ! conv]t] f re/ & cause x to spe$ up to syn*ronism4 ,ques4 ,h[ mu* alt]nat+ curr5t is requir$ to />t a polyphase conv]t]8 ,ans4 ,ab\t #ajj p] c5t4 m ?an t requir$ = full load4 ,ques4 ,h[ may ?is />t+ curr5t be r$uc$8 ,ans4 ,trans=m]s may be swit*$ into circuit tempor>ily to r$uce ! l9e wire voltage until ! spe$ become normal4 ,illu/ration3 ,,fig4 #b1hgb4--,wir+ diagram %[+ arrangem5t ( inc&esc5t lamps = det]m9+ ! prop] phase relations 9 />t+ a rot>y conv]t]4 ,! alt]nat+ curr5t side ( a ?ree phase conv]t] is %[n at ,c4 ,! ?ree bru%es1 ,d1 ,t & ,g press+ on its collector r+s are jo9$ 9 ord] to ! ?ree s+le pole swit*es ,h1 ,l & ,b :i* c be made to connect ) ! respective wires ,m1 ,r1 & ,v1 ( ! alt]nat+ curr5t supply circuit4 ,across "o ( ! outside swit*es1 ,h1 = example1 a numb] ( inc&esc5t lamps are jo9$ 9 s]ies z indicat$ at ,e1 :ile ! ?ree pole swit* 7n %[n7 9 ! ma9 circuit1 betwe5 ! alt]nator & ! s+le pole swit*es is op54 ,if !n ! ma9 swit* j m5tion$ & ! middle swit* ,l be bo? clos$1 & ! armature ( ! alt]nator be br\ght up to normal spe$ by runn+ x z a direct curr5t motor1 ! lamps at ,e w light up & d>k5 9 rapid succession2 ! light+ & d>k5+ ( ! lamps w cont9ue until1 by a prop] adju/m5t ( ! spe$1 ! correct phase relations be e/abli%$ betwe5 ! alt]nat+ curr5t 9 ! supply circuit & ! alt]nat+ curr5t develop$ 9 ! armature ( ! conv]t]4 ,z ?is condition is approa*$1 ! int]vals betwe5 ! successive light+ up & d>k5+ ( ! lamps w increase until !y rema9 p]fectly d>k4 ,!re is !n no diff]5ce ( pressure betwe5 ! supply circuit ,m ,r ,v & ! rot>y conv]t] armature circuit1 s ! s\rce ( ! direct curr5t may at t in/ant be disconnect$ f ! ma*9e1 & ! swit*es ,h & ,b1 clos$4 ,if ! *ange ov] has be5 accompli%$ be=e ! phase relations ( ! two circuits diff]$1 ! conv]t] w at once con=m itself to ! supply circuit & run !reon z a syn*ron\s motor )\t fur!r tr\ble4 ,! op5+ ( ! direct curr5t circuit & ! clos+ ( ! alt]nat+ curr5t supply circuit may be done by h&1 b pref]ably by employ+ a device t w automatically trip ! circuit break] 9 ! direct curr5t circuit at ! in/ant ! swit*es 9 ! alt]nat+ curr5t circuit are clos$4 ,9 conjunction ) ?is me?od1 ! me?od ( syn*roniz+ %[n 9 fig4 #b1hgb may be us$1 ?us1 9 />t+1 !re is an alt]nat+ curr5t betwe5 ! bru%es :i* pulsates v rapidly1 b :5 syn*ronism is approa*$1 ! pulsations become less rapid until f9ally ) ! conv]t] 9 /ep ) ! alt]nator ! pulsations entirely disappe>4 ,! light giv5 by ! lamps ?us connect$ indicates accurately ! condition ( affairs at any "o "t1 v>y+ f a rapidly fluctuat+ light at ! beg9n+ to "o ( con/ant brilliancy at syn*ronism4 ,illu/ration3 ,,fig4 #b1hgc4--;,diagram ( motor conv]t]4 ,?is ma*9e :i* is only to be us$ = conv]t+ f alt]nat+ to direct curr5t1 consi/s ( an ord9>y induction motor ) phase w\nd armature1 & a dynamo4 ,! revolv+ p>ts ( bo? ma*9es are m\nt$ on ! same %aft & f ! figure x is se5 t ! armature ( ! motor & ! armature ( ! dynamo are also electrically connect$4 ,! motor conv]t] is a syn*ron\s ma*9e1 b ! dynamo receives ! curr5t f ! armature ( ! motor at a frequ5cy mu* r$uc$ f t impress$ ^u ! field w9d+ ( ! motor4 ,assum+ t ! motor & ! conv]t] h ! same numb] ( pole1 ! motor w rotate at a spe$ correspond+ to "o-half ! frequ5cy ( ! supply circuit4 ,! motor w op]ate half z a motor & half z a trans=m]1 & ! conv]t]1 half z a dynamo & half z a syn*ron\s conv]t]1 9 t "o-half ( ! electrical en]gy suppli$ to ! motor w be conv]t$ into me*anical p[] = driv+ ! conv]t]1 :ile ! o!r "o-half is transf]r$ to ! second>y motor w9d+s & !reby to ! conv]t] armature 9 ! =m ( electrical p[]4 ,! capacity ( ! motor is !oretically only half :at x w\ld be if x 7 to conv]t ! :ole ( ! electrical en]gy into me*anical p[] because ! rat+ dep5ds ^u ! spe$ ( ! rotat+ field & n on t ( ! rotor4 ,if ! two ma*9es h a diff]5t numb] ( pole1 or are connect$ to run at diff]5t spe$s1 ! division ( p[] is at a diff]5t b con/ant ratio4 ,! ma*9e />ts up z an ord9>y polyphase induction motor & ! field ( ! conv]t] is built up z ?\gh x 7 an ord9>y dynamo4 ,motor conv]t]s are occasionally us$ on high frequ5cy sy/ems1 z _! commutat+ compon5t is ( half frequ5cy1 & ?us p]mits bett] commutator design ?an a high frequ5cy conv]t]4 ,! advantage ( ?is type ( ma*9e is t = phase control x requires no extra reactive coils1 ! motor itself hav+ suffici5t reactance4 ,x is1 h[ev]1 l>g] ?an /&>d conv]t]s1 b small] ?an motor g5]ators1 z half ! p[] is conv]t$ 9 ea* ma*9e4 ,its effici5cy is less ?an = syn*ron\s conv]t]s1 & ! dang] ( rea*+ d\ble spe$ 9 case ( a %ort circuit on ! direct curr5t side is v great4 ,x has be5 us$ abroad to "s ext5t = #fj cycle "w1 9 pref]5ce to syn*ron\s conv]t]s1 b ) ! pres5t reliable design ( #fj cycle conv]t]s1 & ! g5]al use ( #be cycles1 :]e sev]e s]vice conditions are met1 z 9 railroad+1 motor conv]t]s %\ld n be recomm5d$4 ,ques4 ,if ! armature ( ! />t+ motor h a />t+ resi/ance1 h[ mu/ ?is be connect$8 ,ans4 ,x %\ld be connect$ 9 s]ies ) ! armature inductors be=e ! alt]nat+ voltage is appli$4 ,z ! motor increases 9 spe$1 ! />t+ resi/ance is gradually %ort circuit$ until x is entirely cut out ( circuit4 ,illu/ration3 ,,fig4 #b1hgd4--,sectional view ( ,g5]al ,electric v]tical syn*ron\s conv]t]4 ,9 ?is con/ruction1 ! field frame c>ry+ ! poles is m\nt$ on ca/ iron p$e/als & is split v]tically4 ,?is all[s ! two halves ( ! frame to be sep>at$ = inspection or repairs ( ! armature4 ,! armature1 includ+ commutator & collector r+s1 is m\nt$ on a v]tical /ation>y %aft1 :i* is rigidly support$ f ! f\ndation4 ,! ?ru/ ( ! armature is c>ri$ on a roll] be>+ atta*$ to ! top ( ! %aft & upp] side ( ! armature spid]4 ,! "u side ( ! l[] plate ( ! roll] be>+ is made sph]ical & fits into a correspond+ sph]ical cup on ! end ( ! %aft1 mak+ ! be>+ self align+4 ,! armature spid] has a babbitt$ sleeve along ! fit ( ! v]tical %aft1 :i* acts z a guide be>+ & has to take only ! ?ru/ due to ! unbalanc+ effect ( ! rotat+ p>ts4 ,a circulat+ pump furni%es oil to ! roll] be>+1 ! oil dra9+ (f ?r\gh ! guide be>+4 ,a m>k$ advantage ( ?is type ( con/ruction is ! accessibility ( ! commutator = adju/m5t ( ! bru%es1 etc41 z !re is no pit or p$e/al be>+ to int]f]e4 ,,note4--,"s conv]t]s are provid$ ) a small induction motor = />t+ m\nt$ on an iron bracket ca/ 9 ! conv]t] frame1 & ^: %aft is key$ to t ( ! conv]t]4 ,all[+ = a c]ta9 am\nt ( slip 9 ! induction motor1 ! field ( ?is ma*9e mu/ possess a less numb] ( magnet poles ?an ! conv]t] 9 ord] to enable ! latt] ma*9e to be br\ght to full syn*ronism4 ,to />t ! induction motor1 x is simply necess>y to apply to its field t]m9als ! prop] alt]nat+ voltage4 ,! bracket1 & !re=e ! motor1 is usually m\nt$ outside ! armature be>+ on ! collector side ( ! conv]t]4 ,illu/ration3 ,,fig4 #b1hge4--,resi/ance measurem5t by drop me?od4 ,! circuit ^: resi/ance is to be measur$1 is connect$ 9 s]ies ) an ammet] & an adju/able resi/ance to v>y ! fl[ ( curr5t4 ,a voltmet] is connect$ directly across ! t]m9als ( ! resi/ance to be measur$1 z %[n 9 ! figure4 ,accord+ to ,ohm's law ,i ,e ,r1 f :i*1 ,r ,e ,i4 ,if !n ! curr5t fl[+ 9 ! circuit ?r\gh ! unkn[n resi/ance be measur$1 & also ! drop or diff]5ce ( pressure1 ! resi/ance c be calculat$ by above =mula4 ,9 ord] to secure accurate det]m9ation ( ! resi/ance su* value ( curr5t mu/ be us$ z w give l>ge deflections ( ! ne$le on ! in/rum5ts employ$4 ,a numb] ( indep5d5t read+s %\ld be tak5 ) "s v>iation ( ! curr5t & necess>ily a correspond+ v>iation 9 voltage4 ,! resi/ance %\ld !n be figur$ f ea* set ( read+s & ! av]age ( all read+s tak5 = ! correct resi/ance4 ,great c>e mu/ be tak51 h[ev]1 9 ! read+s1 & ! in/rum5ts mu/ be fairly accurate4 ,= example1 suppose t ! comb9$ in/rum5t error & ! error ( ! read+ 9 ! voltmet] %\ld be #a p] c5t41 ! read+ be+ high1 :ile ! correspond+ error ( ! ammet] is #a p] c5t4 l[4 ,?is w\ld cause an error ( approximately #b p] c5t4 9 ! read+ ( ! resi/ance4 ,9 mak+ c>eful measurem5ts ( ! resi/ance1 x is also necess>y to det]m9e ! temp]ature ( ! resi/ance be+ measur$1 z ! resi/ance ( copp] increases approximately 4#d ( #a p] c5t4 = ea* degree rise 9 temp]ature4 ,use is made ( ?is fact = det]m9+ ! increase 9 temp]ature ( a piece ( app>atus :5 op]at+ "u load4 ,! resi/ance ( ! app>atus at "s kn[n temp]ature is measur$1 ?is be+ call$ ! cold resi/ance ( ! app>atus4 ,at ! end ( ! temp]ature te/ ! hot resi/ance is tak54 ,assume ! resi/ance has increas$ by #ae p] c5t4 ,?is w\ld indicate a rise 9 temp]ature ( #cg degrees above ! orig9al or cold temp]ature ( ! app>atus4 ,suppose !n t 9 measur+ ! cold resi/ance1 results are obta9$ :i* are #b p] c5t4 l[1 & t 9 measur+ ! hot resi/ance1 !re be #b p] c5t4 error 9 ! opposite direction4 ,?is w\ld mean t a total error ( #d p] c5t4 _h be5 made 9 ! diff]5ce betwe5 ! hot & cold resi/ances1 or an error ( #aj degrees4 ,! correct rise 9 temp]ature is1 !re=e1 ab\t #bg in/ead ( #cg degrees4 ,9 o!r words1 an error ( #b p] c5t4 9 measur+ ea* resi/ance has caus$ an error ( approximately #cf p] c5t4 9 ! measurem5t ( ! rise 9 temp]ature4 ,! con/ant 4#d :i* has be5 us$ above is only approximate & %\ld n be us$ = exact "w4 ,= detail in/ructions ( mak+ calculations ( resi/ance & temp]ature1 see ,/&>dization ,rules ( ! ,a4,i4,e4,e4 ,ques4 ,describe ! usual wir+ = ! in/allation ( a rot>y conv]t] 9 a sub-/ation4 ,ans4 ,comm5c+ at ! entrance ( ! high pressure cables1 fir/ !re is ! wir+ = ! lightn+ arre/]s1 !n = ! connection 9 circuit ( ! high t5sion swit*+ devices1 f :i* ! conductors are l$ to bus b>s1 & !nce to ! /ep d[n trans=m]s4 ,illu/ration3 ,figs4 #b1hgf to #b1hgi4--;,h[ to connect in/rum5ts = p[] measurem5t4 ,!re are sev]al ways ( connect+ an ammet]1 voltmet] & wattmet] 9 ! circuit = ! measurem5t ( p[]4 ,a few ( ! me?ods are discuss$ bel[4 ,) "s ( ! connections x is necess>y to correct ! read+s ( ! wattmet] = ! losses 9 ! coil1 or coils1 ( ! wattmet]1 or = losses 9 ammet] or voltmet]4 ,?is is necess>y s9ce ! in/rum5ts may be s connect$ t ! wattmet] n only measures ! load b includes 9 its indications "s ( ! in/rum5t losses4 ,if ! load measur$ be small1 or consid]able accuracy is requir$1 ^! in/rum5t losses may be calculat$ z foll[s3 ,loss 9 pressure coils is ,e#b ,r1 9 :i* ,e is ! voltage at ! t]m9als ( ! pressure coil & ,r is ! resi/ance4 ,loss 9 curr5t coil is ,i#b ,r 9 :i* ,i is ! curr5t fl[+ & ,r ! resi/ance ( ! curr5t coil4 ,9 g5]al let ,ev voltage across t]m9als ( ! voltmet]2 ,ew voltage across ! t]m9als ( ! pressure coil ( ! wattmet]2 ,iw curr5t ?r\gh curr5t coil ( wattmet]2 ,ia curr5t ?r\gh curr5t coil ( ammet]2 ,rv resi/ance ( pressure coil ( voltmet]2 ,rw resi/ance ( pressure coil ( wattmet]2 ,r#aw resi/ance ( curr5t coil ( wattmet]2 ,ra resi/ance ( curr5t coil ( ammet]4 ,!n ! losses 9 ! v>i\s coils w be z foll[s3 ,e#bv ,rv loss 9 pressure coil ( voltmet]4 ,e#bw ,rw loss 9 pressure coil ( wattmet]4 ,i#bw ,rv loss 9 curr5t coil ( wattmet]4 ,i#b;a,ra loss 9 curr5t coil ( ammet]4 ,if connection be made z 9 fig4 #b1hgf1 ! correct p[] ( ! circuit w be ! wattmet] read+ ,w-7,e#bv ,rv ,e#bw ,rw7 9 :i* ,ev ,ew4 ,9 fig4 #b1hgg1 ! p[] is ,w-,e#bw ,rw4 ,9 fig4 #b1hgh1 ! p[] is ,w-,i#bw,r#aw1 or ! correct p[] is ! wattmet] read+ m9us ! loss 9 ! curr5t coil ( ! wattmet]4 ,9 fig4 #b1hgi1 ! p[] is ,w-7,e#bw ,rw ,i#b;a,ra7 ,! usual me?od ( connection is ei!r z 9 fig4 #b1hgf or fig4 #b1hgg4 ,9 ei!r case ! curr5t read+ is t ( ! load plus ! curr5ts 9 ! pressure coils ( ! voltmet] & wattmet]4 ,unless ! curr5t be+ measur$1 h[ev]1 is v small1 or extreme accuracy is desir$1 x is unnecess>y to correct ammet] read+s4 ,9 fig4 #b1hgg a small error is introduc$ due to ! fact t ! actual voltage appli$ to ! load is t giv5 by ! voltmet] m9us ! small drop 9 voltage ?r\gh ! curr5t coil ( ! wattmet]4 ,if an accurate measure ( ! curr5t 9 connection ) ! p[] consum$ by ! load be requir$1 ! connections %[n 9 fig4 #b1hgi are us$1 & if extreme accuracy is requir$1 ! wattmet] read+ is r$uc$ by ! losses 9 ! ammet] & 9 ! pressure coil ( ! wattmet]4 ,! loss 9 ! pressure coil ( a wattmet] or voltmet] may be z high z #ab or #ae watts at #bbj volts4 ,! loss 9 ! curr5t coil ( a wattmet] ) #aj amp]es fl[+ may be #f or #h watts4 ,x c be easily se5 t if ! core or copp] losses ( small trans=m]s are be+ measur$1 x is q necess>y to correct ! wattmet] read+s1 = ! in/rum5t losses4 ,9 measur+ ! losses ( a #be or #ej ,h4,p4 induction motor1 ! in/rum5t losses may be neglect$4 ,a c>eful /udy ( ! above w %[ :5 x becomes necess>y to correct = in/rum5t losses & ! me?od ( mak+ ^! corrections4 ,connections are seldom us$ :i* make x necess>y to correct = ! losses 9 ! curr5t coils ( ei!r ammet] or wattmet]1 z ! losses v>y ) ! *ange 9 ! curr5t4 ,on ! o!r h&1 ! voltages g5]ally us$ are fairly con/ant at #aaj or #bbj1 & :5 ! losses ( ! pressure coils at ^! voltages h once be5 calculat$1 ! necess>y in/rum5t correction c be readily made4 ,on a ?ree phase sy/em ! trans=m]s %\ld be jo9$ 9 delta connection1 z a consid]able advantage is !reby ga9$ ov] ! /> connection1 9 t %\ld "o ( ! trans=m]s become defective1 ! rema9+ two w c>ry ! load )\t *ange except m or less additional heat+4 ,betwe5 ! trans=m]s & rot>y conv]t] ! circuits %\ld be z %ort & simple z possible1 swit*es1 fuses1 & o!r in/rum5ts be+ entirely exclud$4 ,! direct curr5t f ! conv]t] is l$ to ! direct curr5t swit*bo>d1 & f !re di/ribut$ to ! fe$] circuits4 ,,wattmet] ,,error ,,= ,a ,,load ,,( #a1jjj ,,volt-,,amp]es 7,= a lag ( #a degree 9 ! pressure coil7 ---------------------------------------- -------- ,error ( indication ,p[] factor,true watts ,error 9 p] c5t ( true value ---------------------------------------- -------- #a4 #a1jjj 4#c #j4jc 4#i #ijj #g4f #j4he 4#h #hjj #aj4e #a4ca 4#g #gjj #ab4e #a4gh 4#f #fjj #ac4i #b4cb 4#e #ejj #ae4a #c4jb 4#d #djj #ae4i #c4ih 4#c #cjj #af4f #e4ed 4#b #bjj #ag4a #h4ee 4#a #ajj #ag4c #ag4cj ---------------------------------------- -------- ,,note4--,9 ! iron vane type in/rum5t :5 us$ z a wattmet]1 ! curr5t ( ! s]ies coil always rema9s 9 p]fect phase ) ! curr5t ( ! circuit1 provid$ s]ies trans=m]s are n introduc$4 ,! error1 !n1 is entirely due to ! lag ( ! curr5t 9 ! pressure coil1 & ?is error 9 high p[] factor is exce$+ly small1 increas+ z ! p[] factor decreases4 ,9 ! above table x %\ld be not$ t ! value ( ! error z di/+ui%$ f ! p] c5t4 ( error1 in/ead ( indef9itely increas+ z ! p[] factor dim9i%es1 rapidly atta9s a maximum value :i* is less ?an #b p] c5t4 ( ! p[] deliv]$ "u ! same curr5t & )\t inductance4 ,x %\ld also be not$ t ! above tabulation is on ! assumption ( a lag ( #a degree 9 ! pressure coil4 ,! actual lag 9 ,wagn] in/rum5ts = in/ance1 is approximately 4#jhe ( a degree1 & ! error due to ! lag ( ! pressure coil 9 ,wagn] in/rum5ts is1 !re=e1 proportionally r$uc$ f ! figures %[n 9 ! above tabulation4 ,ques4 ,9 l>ge sub-/ations conta9+ sev]al rot>y conv]t]s h[ are !y op]at$8 ,ans4 ,frequ5tly !y are in/all$ to receive _! respective curr5ts f ! same set ( bus b>s2 t is1 !y may be op]at$ z alt]nat+ curr5t motors 9 p>allel4 ,!y are also frequ5tly op]at$ indep5d5tly f s+le bus b>s1 b v seldom 9 s]ies ) ea* o!r4 ,illu/ration3 ,,fig4 #b1hhj4--,s+le phase motor te/4 ,9 ?is me?od ( measur+ ! input ( a s+le phase motor ( any type1 ! ammet]1 voltmet] & wattmet] are connect$ z %[n 9 ! illu/ration4 ,! ammet] measures ! curr5t fl[+ ?r\gh ! motor1 ! voltmet]1 ! pressure across ! t]m9als ( ! motor1 & ! wattmet] ! total p[] :i* fl[s ?r\gh ! motor circuit4 ,) ! connections z %[n1 ! wattmet] w\ld also measure ! slight losses 9 ! voltmet] & ! pressure coil ( ! wattmet]1 b = motors ( ,h4,p4 & l>g]1 ?is loss is s small t x may be neglect$4 ,! p[] factor may be calculat$ by divid+ ! true watts z indicat$ by ! wattmet]1 by ! product ( ! volts & amp]es4 ,ques4 ,h[ may ! direct curr5t circuit be connect$8 ,ans4 ,9 p>allel4 ,,note4--,9 motor te/+1 by ! me?ods illu/rat$ 9 ! accompany+ cuts1 x is assum$ t ! motor is load$ 9 ! ord9>y way by belt+ or direct connect+ ! motor to "s =m ( load1 & t ! object is to det]m9e :e!r ! motor is ov] or "u load$1 & approximately :at p] c5t4 ( full load x is c>ry+4 ,all comm]cial motors h "n plates1 giv+ ! rat+ ( ! motor & ! full load curr5t 9 amp]es4 ,h5ce ! p] c5t4 ( load c>ri$ c be det]m9$ approximately by measur+ ! curr5t input & ! voltage4 ,if an effici5cy te/ ( ! app>atus be requir$1 x becomes necess>y to use "s =m ( absorption by dynamomet]1 su* z a ,prony or o!r =m ( brake4 ,! output ( ! motor c !n be det]m9$ f ! brake read+s4 ,! scope ( ! pres5t treatm5t is1 h[ev]1 too limit$ to g into ! subject ( diff]5t me?ods ( measur+ ! output ( ! app>atus1 & is conf9$ r to me?ods ( measur+ curr5t input1 voltage1 & watts4 ,! accuracy ( all te/s is obvi\sly dep5d5t ^u ! accuracy ( ! in/rum5ts employ$4 ,be=e accept+ ! result obta9$ by any te/1 especially "u light or no load1 correction %\ld be made = wattmet] error4 ,see table ( wattmet] error on page #b1jge4 ,illu/ration3 ,,fig4 #b1hha4--,?ree phase motor te/2 voltmet] & ammet] me?od4 ,if x be desir$ to det]m9e ! approximate load on a ?ree phase motor1 ?is may be done by means ( ! connections z %[n 9 ! figure1 & ! curr5t ?r\gh "o ( ! ?ree l9es & ! voltage across ! phase measur$4 ,if ! voltage be approximately ! rat$ voltage ( ! motor & ! amp]es ! rat$ curr5t ( ! motor 7z not$ on ! "n plate7 x may be assum$ t ! motor is c>ry+ approximately full load4 ,if1 on ! o!r h&1 ! amp]es %[ mu* 9 excess ( full load rat+1 ! motor is c>ry+ an ov]load4 ,! heat g5]at$ 9 ! copp] v>ies z ! squ>e ( ! curr5t4 ,t g5]at$ 9 ! iron v>ies any:]e f ! #a4f p[]1 to ! squ>e4 ,?is me?od is v conv5i5t if a wattmet] be n available1 al?\gh1 x is1 ( c\rse1 ( no value = ! det]m9ation ( ! effici5cy or p[] factor ( ! app>atus4 ,?is me?od gives fairly accurate results1 provid+ ! load on ! ?ree phases ( ! motor be fairly well balanc$4 ,if !re be mu* diff]5ce1 h[ev]1 9 ! voltage ( ! ?ree phases1 ! ammet] %\ld be swit*$ f "o circuit to ano!r1 & ! curr5t measur$ 9 ea* phase4 ,if ! motor be v lightly load$ & ! voltage ( ! diff]5t phases v>y by #b or #c p] c5t41 ! curr5t 9 ! ?ree legs ( ! circuit w v>y #bj to #cj p] c5t4 ,ques4 ,:at provision %\ld be made aga9/ int]ruption ( s]vice 9 sub-/ations8 ,ans4 ,!re %\ld be "o res]ve rot>y conv]t] to e ?ree or f\r conv]t]s actually requir$4 ,ques4 ,:y does a rot>y conv]t] op]ate ) great] effici5cy1 & require less att5tion ?an does a dynamo ( ! same output8 ,ans4 ,!re is less friction1 & less armature resi/ance1 ! latt] because ! alt]nat+ curr5t at c]ta9 portions ( ea* revolution passes directly to ! commutator b>s )\t trav]s+ ! entire armature w9d+ z x does 9 a dynamo2 !re is no di/ortion ( ! field & consequ5tly no sp>k+1 or %ift+ ( ! bru%es1 s9ce ! armature reaction result+ f ! curr5t f$ into ! ma*9e & t due to ! curr5t g5]at$ 9 ! armature completely neutralizes ea* o!r4 ,illu/ration3 ,,fig4 #b1hhb4--,?ree phase motor te/ by ! two wattmet] me?od4 ,if an accurate te/ ( a ?ree phase motor be requir$1 x is necess>y to use ! me?od "h indicat$4 ,assume ! motor to be load$ ) a brake s t its output c be det]m9$4 ,?is me?od gives correct results ev5 ) consid]able unbalanc+ 9 ! voltages ( ! ?ree phases4 ,) ! connections z %[n1 ! sum ( ! two wattmet] read+s gives ! total p[] 9 ! circuit4 ,nei!r met] by itself measures ! p[] 9 any "o ( ! ?ree phases4 ,9 fact1 ) light load "o ( ! met]s w probably give a negative read+1 & x w !n be necess>y to ei!r rev]se its curr5t or pressure leads 9 ord] t ! deflection may be not$4 ,9 su* cases ! algebraic sums ( ! two read+s mu/ be tak54 ,91 o!r words1 if "o read plus #ejj watts & ! o!r1 m9us #cjj watts1 ! total p[] 9 ! circuit w be #ejj m9us #cjj1 or #bjj watts4 ,z ! load comes on1 ! read+s ( ! in/rum5t :i* gave ! negative deflection w decrease until ! read+ drops to z]o1 & x w !n be necess>y to aga9 rev]se ! pressure leads on ?is wattmet]4 ,!reaft] ! read+s ( bo? in/rum5ts w be positive1 & ! num]ical sum ( ! two %\ld be tak5 z ! measurem5t ( ! load4 ,if "o set ( ! in/rum5ts be remov$ f ! circuit1 ! read+ ( ! rema9+ wattmet] w h no mean+4 ,z /at$ above1 x w n indicate ! p[] "u ^! conditions 9 any "o phase ( ! circuit4 ,! p[] factor is obta9$ by divid+ ! actual watts input by ! product ( ! av]age ( ! voltmet] read+s ! av]age ( ! amp]e read+s #a4gc4 ,:at electrical difficulty is exp]i5c$ ) a rot>y conv]t]8 ,ans4 ,regulation ( ! direct curr5t voltage4 ,ques4 ,h[ is ?is done8 ,ans4 ,x c be ma9ta9$ con/ant only by pres]v+ uni=m conditions ( inductance 9 ! alt]nat+ curr5t circuit1 & uni=m conditions 9 ! alt]nator4 ,:ile *anges 9 ei!r ( ^! may be comp5sat$ to a c]ta9 ext5t by adju/m5t ( ! field /r5g? ( ! conv]t]1 !y _c be entirely neutraliz$ 9 ?is mann]2 x is !re=e necess>y t bo? ! l9e circuit & ! alt]nator be giv5 att5tion if ! be/ results are to be obta9$ f ! conv]t]4 ,ques4 ,:at me*anical difficulty is exp]i5c$ ) rot>y conv]t]s8 ,ans4 ,hunt+4 ,ques4 ,:at is ! cause ( ?is8 ,ans4 ,x is due to a v>iation 9 frequ5cy4 ,! in]tia ( ! conv]t] armature t5ds to ma9ta9 a con/ant spe$2 v>iations 9 ! frequ5cy ( ! supply circuit w cause a displacem5t ( phase betwe5 ! curr5t 9 ! armature & t 9 ! l9e wires1 :i* displacem5t1 h[ev]1 ! syn*roniz+ curr5t /rives to decrease4 ,! syn*roniz+ curr5t1 al?\gh b5eficial 9 rem$y+ ! tr\ble aft] x occurs1 ex]ts b little ef=t 9 prev5t+ x1 & _m attempts h be5 made to devise a plan to elim9ate ?is tr\ble4 ,,note4--,?ree phase motor te/2 polyphase wattmet] me?od4 ,?is is id5tical ) ! te/ ( fig4 #b1hhb1 except t ! wattmet] itself comb9es ! movem5t ( ! two wattmet]s4 ,o!rwise ! me?od ( mak+ ! measurem5ts is id5tical4 ,if ! p[] factor be kn[n to be less ?an #ej p] c5t41 connect "o movem5t s z to give a positive deflection2 !n disconnect movem5t "o & connect movem5t two s z to give a positive deflection4 ,!n rev]se ei!r ! pressure or curr5t leads ( ! movem5t1 giv+ ! small] deflection1 leav+ ! rema9+ movem5t ) ! orig9al connections4 ,! read+s n[ obta9$ w be ! correct total watts deliv]$ to ! motor4 ,if ! p[] factor be kn[n to be ov] #ej p] c5t41 ! same me?ods %\ld be employ$1 except t bo? movem5ts %\ld be indep5d5tly connect$ to give positive read+s4 ,an unload$ induction motor has a p[] factor ( less ?an #ej p] c5t41 & may1 !re=e1 be us$ z above = det]m9+ ! correct connections4 ,= a bett] und]/&+ ( ! reasons = ! above me?od ( proc$ure1 ! explanation ( ! two wattmet] me?od1 fig4 #b1hhb1 %\ld be read4 ,! p[] factor may be calculat$ z expla9$ "u fig4 #b1hhb4 ,connect z %[n 9 fig #b1hhb4 ,! foll[+ *eck on connection may be made4 ,let ! polyphase induction motor run idle1 t is1 ) no load4 ,! motor w !n op]ate ) a p[] factor less ?an #ej p] c5t4 ,! polyphase met] %\ld give a positive indication1 b if ea* movem5t be tri$ sep>ately "o w be f\nd to give a negative read+1 ! o!r movem5t w give a positive read+4 ,?is c be done by disconnect+ "o ( ! pressure leads f ! b9d+ po/ ( "o movem5t4 ,:5 ! p[] factor is above #ej p] c5t4 !n bo? movem5ts w give positive deflection4 ,ques4 ,:at are ! me?ods employ$ to prev5t hunt+8 ,ans4 #a1 ! employm5t ( a /rongly magnetiz$ field relative to t develop$ by ! armature2 #b1 a heavy fly:eel effect 9 ! conv]t]2 #c1 ! increas+ ( ! inductance ( ! armature by s9k+ ! w9d+s !reon 9 deep slots 9 ! core1 ! slots be+ provid$ ) ext5d$ heads2 & #d1 ! employm5t ( damp+ devices or amortisseur w9d+ on ! pole pieces ( ! conv]t]4 ,illu/ration3 ,,fig4 #b1hhc4--,?ree phase motor te/2 "o wattmet] me?od4 ,?is me?od is equival5t to ! two wattmet] me?od ) ! foll[+ diff]5ce4 ,a s+le voltmet] 7z %[n above7 ) a swit*1 ,a1 c be us$ to connect ! voltmet] across ei!r "o ( ! two phases4 ,?ree swit*es1 ,b1 ,c & ,d1 are employ$ = *ang+ ! connection ( ! ammet] & wattmet] 9 ei!r "o ( ! two l9es4 ,) ! swit*es ,b & ,d 9 ! position %[n1 ! ammet] & wattmet] s]ies coils are connect$ 9 ! left h& l9e4 ,! swit* ,c mu/ be clos$ "u ^! conditions 9 ord] to h ! middle l9e clos$4 ,ano!r read+ %\ld !n be tak5 be=e any *ange ( load has occurr$1 ) swit* ,a ?r[n to ! "r1 swit* ,b clos$1 swit* ,d ?r[n to ! "r & swit* ,c op5$4 ,! ammet] & ! curr5t coil ( ! wattmet] w !n be connect$ to ! middle l9e ( ! motor4 ,9 ord] to prev5t any int]ruption ( ! circuit1 ! swit*es ,b1 ,d & ,c %\ld be op]at$ 9 ! ord] giv5 above4 ,) v light load on ! motor ! wattmet] w probably give a negative deflection 9 "o phase or ! o!r1 & x w be necess>y to rev]se its connections be=e tak+ ! read+s4 ,= ?is purpose a d\ble pole1 d\ble ?r[ swit* is sometimes ins]t$ 9 ! circuit ( ! pressure coil ( ! wattmet] s t ! indications c be rev]s$ )\t di/urb+ any ( ! connections4 ,x is sugge/$1 be=e und]tak+ ?is te/1 t ! in/ructions = te/ by ! two wattmet] & by ! polyphase wattmet] me?ods be read4 ,ques4 ,:at me?od is ! be/8 ,ans4 ,! damp+ me?od4 ,! devices employ$ = ! purpose are usually copp] %ields plac$ betwe5 or ar\nd ! pole pieces1 al?\gh 9 "s conv]t]s ! copp] is emb$d$ 9 ! poles1 & 9 o!rs x is made simply to surr\nd a portion ( ! pole tips4 ,9 any case its action is z foll[s3 ,! armature rotat+ at a v>iable spe$ has a field develop$ !re9 :i* is assum$ to be also rotat+ at a v>iable spe$2 ! magnetism ( ?is rot>y field induces curr5ts 9 ! copp] :i*1 h[ev]1 react on ! armature & oppose any t5d5cy t[>d a fur!r %ift+ ( ! magnetism 9 ! armature & !re=e prev5t ! developm5t ( additional curr5ts 9 ! copp]4 ,s9ce copp] is ( l[ resi/ance1 ! induc$ curr5ts are suffici5t 9 /r5g? to ?us damp5 any t5d5cy t[>d phase displacem5t1 & s ex]t a /eady+ influ5ce ^u ! in/allation z a :ole4 ,illu/ration3 ,,fig4 #b1hhd4--,?ree phase motor1 "o wattmet] & ,y box me?od4 ,?is me?od is ( s]vice1 only1 provid$ ! voltages ( ! ?ree phases are ! same4 ,a slight v>iation ( ! voltage ( ! diff]5t phases may cause a v l>ge error 9 ! read+s ( ! wattmet]1 & inasmu* z ! voltage ( all comm]cial ?ree phase circuits is m or less unbalanc$1 ?is me?od is n to be recomm5d$ = motor te/+4 ,) balanc$ voltage 9 all ?ree phases1 ! p[] is t indicat$ by ! wattmet]1 multipli$ by ?ree4 ,p[] factor may be calculat$ z be=e4 ,electrical ,measur+ ,in/rum5ts4--,9 ! manufacture ( mo/ measur+ in/rum5ts1 ! graduations ( ! scale are made at ! factory1 by comp>+ ! deflections ( ! po9t] ) voltages z measur$ on /&>d app>atus4 ,! voltmet]s 9 mo/ common use h capacities ( #e1 #ae1 #ge1 #aej1 #cjj1 #ejj & #gej volts ea*1 al?\gh 9 ! measurem5t ( v l[ resi/ances su* z ^? ( armatures1 heavy cables1 or bus b>s1 voltmet]s hav+ capacities z l[ z 4#jb volt are employ$4 ,illu/ration3 ,,fig4 #b1hhe4--,te/ ( ?ree phase motor ) neutral br\ght out2 s+le wattmet] me?od4 ,"s /> connect$ motors h ! connection br\ght out f ! neutral ( ! w9d+4 ,9 ?is case ! circuit may be connect$1 z "h %[n4 ,! voltmet] n[ measures voltage betwe5 ! neutral & "o ( ! l9es1 & ! wattmet] ! p[] 9 "o ( ! ?ree phases ( ! motor4 ,!re=e1 ! total p[] tak5 by ! motor w be ?ree times ! wattmet] read+s4 ,by ?is me?od1 j z accurate results c be obta9$ z ) ! two wattmet] me?od4 ,! p[] factor w be ! indicat$ watts divid$ by ! product ( ! indicat$ amp]es & volts4 ,! diff]5ce betwe5 ! design ( direct curr5t voltmet]s ( diff]5t capacities lies simply 9 ! high resi/ance jo9$ 9 s]ies ) ! f9e wire coil4 ,?is resi/ance is usually ab\t #ajj ohms p] volt capacity ( ! met]1 & is compos$ ( f9e silk cov]$ copp] wire w\nd non-inductively on a wood5 spool4 ,9 ! op]ation ( an in/rum5t1 if ! po9t] :5 deflect$ d n readily come to a position ( re/ ow+ to friction 9 ! mov+ p>ts1 x may be aid$ 9 ?is respect by g5tly tapp+ ! case ( ! in/rum5t ) ! h&2 ?is w (t5 enable ! ob/ruction1 if n ( a s]i\s nature1 to be ov]come & an accurate read+ to be obta9$4 ,illu/ration3 ,,fig4 #b1hhf4--,temp]ature te/ ( a l>ge ?ree phase induction motor4 ,temp]ature te/s are usually made on small induction motors by belt+ ! motor to a g5]ator & load+ ! g5]ator ) a lamp bank or resi/ance until ! motor input is equal to ! full load4 ,if1 h[ev]1 ! motor be ( consid]able size1 su* t ! co/ ( p[] becomes a consid]able item 9 ! co/ ( te/+1 ! me?od "h %[n may be employ$4 ,= ?is purpose1 h[ev]1 two motors1 pref]ably ( ! same size & type1 are requir$4 ,"o is driv5 z a motor & runs slightly bel[ syn*ronism1 due to its slip :5 op]at+ ) load4 ,?is motor is belt$ to a second ma*9e4 ,if ! pulley ( ! second ma*9e be small] ?an ! pulley ( ! fir/ ma*9e1 ! second ma*9e w !n op]ate z an induction g5]ator1 & w return to ! l9e z mu* p[] z ! fir/ motor draws f ! l9e1 less ! losses ( ! second ma*9e4 ,by prop]ly select+ ! ratio ( pulleys1 ! fir/ ma*9e c be caus$ to draw full load curr5t & full load en]gy f ! l9e4 ,9 ?is way1 ! total en]gy consum$ is equival5t to ! total ( ! losses ( bo? ma*9es1 :i* is approximately twice ! losses ( a s+le ma*9e4 ,! figure %[s ! connection ( ! wattmet]s1 )\t necess>y swit*es1 = read+ ! total en]gy by two wattmet] me?od4 ,detail$ connection ( ! wattmet] is %[n 9 fig4 #b1hhc4 ,x is usual1 9 mak+ temp]ature te/s1 to ins]t "o or m !rmomet]s 9 :at is suppos$ to be ! hotte/ "p ( ! w9d+1 "o on ! surface ( ! lam9ae & "o 9 ! air duct betwe5 ! iron lam9ae4 ,! te/ %\ld be cont9u$ until ! diff]5ce 9 temp]ature betwe5 any "p ( ! motor & ! air rea*es a /eady value4 ,! motor %\ld !n be /opp$ & ! temp]ature ( ! armature also measur$4 ,= ! me?od ( te/+ w\nd armature type induction motors ( v l>ge size1 see fig4 #b1hij4 ,= ! approv$ way ( tak+ temp]ature read+s & int]pret+ results1 see ! ,/&>dization ,rules ( ! ,a4,i4,e4,e4 ,ques4 ,describe a two scale voltmet]4 ,ans4 ,9 ?is type ( in/rum5t1 "o scale is = l[ voltage read+s & ! o!r = high voltage read+s2 on ^! scales ! values ( ! graduations = l[ voltages are usually m>k$ ) r$ figures1 :ile ^? = high voltages are m>k$ ) black figures4 ,a voltmet] c>ry+ two scales mu/ also conta9 two resi/ances 9 place ( "o2 a t]m9al f ea* ( ^! coils mu/ be connect$ ) a sep>ate b9d+ po/1 b ! rema9+ t]m9al ( ea* resi/ance is jo9$ to a wire :i* connects ?r\gh ! f9e wire coil ) ! ?ird b9d+ po/ ( ! met]4 ,! two fir/ m5tion$ b9d+ po/s are usually m\nt$ at ! left h& side ( ! met] & ! la/ m5tion$ b9d+ po/ & key at ! "r h& side4 ,illu/ration3 ,,fig4 #b1hhg4--;,alt]nator excitation or magnetization curve te/4 ,! object ( ?is te/ is to det]m9e ! *ange ( ! armature voltage due to ! v>iation ( ! field curr5t :5 ! ext]nal circuit is kept op54 ,z "h %[n1 ! field circuit is connect$ ) an ammet] & an adju/able resi/ance 9 s]ies ) a direct curr5t s\rce ( supply4 ,! adju/able resi/ance is v>i$1 & read+s ( ! voltmet] across ! armature1 & ( ! ammet]1 are record$4 ,! spe$ ( ! g5]ator mu/ be kept con/ant1 pref]ably at ! spe$ :i* is giv5 on ! "n plate4 ,! excitation or magnetization curve ( ! ma*9e is obta9$ by plott+ ! curr5t & ! voltage4 ,! resi/ance correspond+ to ! high read+ scale is compos$ ( copp] wire hav+ ! same diamet] z t con/itut+ ! resi/ance = ! l[ read+ scale1 b z ! capacity ( ! =m] scale is g5]ally a :ole numb] ( times great] ?an t ( ! latt] scale1 ! resi/ances = ! two mu/ be> ! same proportion4 ,illu/ration3 ,,fig4 #b1hhh4--,?ree phase alt]nator syn*ron\s imp$ance te/4 ,9 det]m9+ ! regulation ( an alt]nator1 x is necess>y to obta9 :at is call$ ! syn*ron\s imp$ance ( ! ma*9e4 ,to obta9 ?is1 ! field is connect$1 z %[n above4 ,voltmet]s are remov$ & ! armature %ort circuit$ ) ! ammet]s 9 circuit4 ,! field curr5t is !n v>i$1 ! armature driv5 at syn*ron\s spe$1 & ! armature curr5t measur$ by ! ammet]s 9 circuit4 ,! relation betwe5 field & armature amp]es are !n plott$4 ,! comb9ation ( ! results ( ?is te/1 ) ^? obta9$ f ! te/ %[n 9 fig4 #b1hhg1 are us$ 9 ! det]m9ation ( ! regulation ( an alt]nator4 ,eng9e]s diff] widely 9 ! application ( ! above to ! det]m9ation ( regulation1 & employ _m empirical =mulae & con/ants = diff]5t l9es ( design4 ,ques4 ,h[ is a two scale voltmet] connect$8 ,ans4 ,9 ! connection ( a two scale voltmet] 9 circuit1 ! s+le b9d+ po/ is always employ$ reg>dless ( :i* scale is desir$4 ,if1 !n1 ! voltage be su* t x may be measur$ on ! l[ read+ scale1 ! o!r b9d+ po/ employ$ is t connect$ to ! l[] ( ! two resi/ances conta9$ )92 if1 h[ev]1 ! pressure be high] ?an ^? record$ on ! l[ read+ scale1 ! b9d+ po/ connect$ to ! high] ( ! two resi/ances conta9$ )9 is us$4 ,,note4--,?ree phase alt]nator load te/4 ,by means ( ! connection %[n 9 fig4 #b1hhh1 read+s ( armature curr5t & field amp]es c be obta9$ ) any desir$ load4 ,! field curr5t c be v>i$ also s z to ma9ta9 con/ant armature voltage irrespective ( load2 or ! field curr5t may be kept con/ant & ! armature voltage all[$ to v>y z ! load increases4 ,! connections may also be us$ to make a temp]ature te/ on ! alt]nator by load+ x ) an artificial load4 ,9 "s cases aft] ! alt]nator is in/all$ ! connection may be us$ to make a temp]ature te/1 us+ ! actual comm]cial load ! alt]nator is furni%+4 ,inasmu* z ! capacities ( ! scales are usually m>k$ on or ne> ! correspond+ b9d+ po/s1 !re w g5]ally be no difficulty 9 select+ ! prop] "o ( ! two left h& b9d+ po/s4 ,illu/ration3 ,,fig4 #b1hhi4--,?ree phase alt]nator or syn*ron\s motor temp]ature te/4 ,9 ?is te/ two alt]nators or syn*ron\s motors ( same size & type are us$1 & are belt$ toge!r1 "o to be driv5 z a syn*ron\s motor & ! o!r z an alt]nator4 ,! me?od employ$ is to syn*ronize ! syn*ron\s motor ) ! alt]nator or alt]nators on ! ?ree phase circuit1 & !n connect to ! l9e by means ( a ?ree pole s+le ?r[ swit*4 ,! alt]nator is !n simil>ly syn*roniz$ ) ! alt]nator ( ! ?ree phase circuit & ?r[n onto ! l9e4 ,by v>y+ ! field ( ! alt]nator x c be made to c>ry approximately full load1 & ! motor w !n be also approximately fully load$4 ,! usual me?od is to h ! motor c>ry slightly 9 excess ( full load1 & ! alt]nator slightly less ?an full load4 ,"u ^! conditions ! motor w run a little w>m] ?an x %\ld ) normal load1 :ile ! alt]nator w run slightly cool]4 ,temp]ature measurem5ts are made 9 ! same way z discuss$ "u ?ree phase motors4 ,! necess>y ammet]s1 voltmet]s & wattmet]s = adju/+ ! loads on ! motors & g5]ator are %[n 9 above figure4 ,if pulleys be ( suffici5t size to transmit ! full load1 )1 say "o p] c5t4 slip1 ! pulley on ! motor %\ld be "o p] c5t4 l>g] 9 diamet] ?an ! pulley on ! alt]nator1 s z to enable ! alt]nator to rema9 9 syn*ronism & at ! same "t deliv] p[] to ! circuit4 ,) v l>ge ma*9es "u te/1 x is inadvisable to use ! above me?od z x is sometimes difficult to s adju/ ! pulleys & belt t5sion t ! belt slip w be j "r to make up = ! diff]5ce 9 diamet] ( ! pulleys1 & v viol5t flapp+ ( ! belt results4 ,to meet su* cases1 v>i\s o!r me?ods h be5 devis$4 ,"o :i* gives consi/5t results is %[n 9 fig4 #b1hij4 ,ques4 ,h[ is a two scale voltmet] connect$ :5 ! b9d+ po/s are n m>k$8 ,ans4 ,if only an approximate idea is possess$ ( ! voltage to be measur$1 x is always advisable to connect to ! b9d+ po/ correspond+ to ! high read+ scale ( ! met] 9 ord] to det]m9e if ! measurem5t may n be made safely & m accurately on ! l[ read+ scale4 ,9 any case1 "s k mu/ be _h ( ! voltage at h&1 else ! high read+ portion ( ! in/rum5t may be endang]$4 ,illu/ration3 ,,fig4 #b1hij4--,?ree phase alt]nator or syn*ron\s motor temp]ature te/4 ,supply ! field ) normal field curr5t4 ,! armature is connect$ 9 op5 delta z illu/rat$1 & full load curr5t s5t ?r\gh x f an ext]nal s\rce ( direct curr5t1 c>e be+ tak5 to gr\nd "o t]m9al ( ! dynamo s z to avoid dang] ( %ock due to ! voltage on ! armature w9d+4 ,! field is !n driv5 at syn*ron\s spe$4 ,if ! armature be design$ to be connect$ /> = #b1cjj volts1 ! voltage g5]at$ 9 ea* leg ( ! delta w be #a1ccj volts1 & unless "o leg ( ! dynamo 7 gr\nd$1 ! te/] might receive a sev]e %ock by com+ 9 contact ) ! direct curr5t circuit4 ,! insulation ( ! dynamo w\ld also be subject$ to abnormal /ra9 unless "o t]m9al 7 gr\nd$4 ,by ! above me?od ! field is subject$ to its full copp] loss & ! armature to full copp] loss & core loss4 ,temp]ature read+s are tak5 z p] /&>dization rules ( ! ,a4,i4,e4,e4 ,?is me?od may also be us$ ) satisfactory results on l>ge ?ree phase motors ( ! w\nd rotor type4 ,if ! alt]nator pressure be above #fjj volts1 a pressure trans=m] %\ld be us$ 9 connection ) ! voltmet]4 ,too mu* c>e _c be tak5 to obs]ve ^! precautions :5ev] ! voltmet] is us$1 = ! burn+ out or *>r+ ( ! insulation ei!r 9 ! f9e wire coil or 9 ! high resi/ance ( ! met] by an excessive curr5t1 is "o ( ! mo/ s]i\s accid5ts t c befall ! in/rum5t4 ,if a voltmet] has be5 subject$ to a voltage high] ?an t = :i* x 0 design$1 yet n suffici5tly high to injure ! insulation1 b high en\gh to cause ! po9t] to pass rapidly ov] ! entire scale1 damage has be5 done 9 ano!r way4 ,! po9t] be+ =c$ aga9/ ! side ( ! case 9 ?is mann]1 b5ds x m or less & s introduces an error 9 ! read+s t are aft]w>d tak54 ,! same damage w be done if ! met] be connect$ 9 circuit s ! curr5t does n pass ?r\gh x 9 ! prop] direction1 al?\gh 9 ?is case ! po9t] is n liable to be b5t s mu* z :5 x is =c$ to ! opposite side ( ! met] by an abnormal curr5t1 s9ce !n x has ga9$ consid]able mom5tum :i* causes a sev]] impact4 ,! ext5t ( ! damage may be asc]ta9$ by not+ h[ f> away f ! z]o m>k ! po9t] lies :5 no curr5t is pass+ ?r\gh ! in/rum5t4 ,if ?is di/ance be m ?an two-t5?s ( a division1 ! metal case enclos+ ! work+ "p %\ld be remov$ & ! po9t] /raight5$ by ! c>eful use ( a pair ( p9*]s4 ,illu/ration3 ,,fig4 #b1hia4--;,direct motor or dynamo magnetization te/4 ,! object ( ?is te/ is to det]m9e ! v>iation ( armature voltage )\t load1 ) ! curr5t fl[+ ?r\gh ! field circuit4 ,! armature %\ld be driv5 at normal spe$4 ,! adju/m5t resi/ance 9 ! field circuit is v>i$ & ! voltage across ! armature measur$4 ,! curve obta9$ by plott+ ^! two figures is usually call$ magnetization curve ( ! dynamo4 ,x is usual to />t ) ! high] resi/ance 9 ! field circuit s t v small curr5t fl[s1 gradually increas+ ?is curr5t by cutt+ out ! field resi/ance4 ,:5 ! highe/ no load voltage requir$ is rea*$1 ! field curr5t is !n dim9i%$1 & :at is call$ ! desc5d+ 7z oppos$ to ! asc5d+7 magnetization curves are obta9$4 ,! diff]5ce 9 ! two curves is due to ! lag ( ! magnetization beh9d ! magnetiz+ curr5t1 & is caus$ by ! hy/]esis ( ! iron ( ! armature core4 ,ques4 ,:at %\ld be not$ ) respect to location ( in/rum5ts8 ,ans4 ,if !y be plac$ ne> conductors c>ry+ l>ge curr5ts1 ! magnetic field develop$ !reby w produce a *ange 9 ! magnetism ( ! in/rum5ts & s introduce an error 9 ! read+s4 ,illu/ration3 ,,fig4 #b1hib4--,%unt dynamo ext]nal *>act]i/ic te/4 ,! ext]nal *>act]i/ic ( a %unt dynamo is a curve %[+ ! relation betwe5 ! curr5t & voltage ( ! ext]nal circuit4 ,?is is obta9$ by ! connection z "h %[n4 ,! %unt field is s adju/$ t ! ma*9e gives normal voltage :5 ! ext]nal circuit is op54 ,! field curr5t is !n ma9ta9$ con/ant & ! ext]nal curr5t v>i$ by v>y+ ! resi/ance 9 ! circuit4 ,by plott+ voltage along ! v]tical1 aga9/ ! correspond+ amp]es repres5t$ along ! horizontal1 ! ext]nal *>act]i/ic is obta9$4 ,ques4 ,h[ %\ld portable in/rum5ts be wir$8 ,ans4 ,! wires mu/ be firmly secur$ to ! supports on :i* !y re/1 s z to r$uce ! possibility ( _! be+ pull$ by accid5t1 & s caus+ ! in/rum5ts to fall4 ,a fall or a r\gh h&l+ ( ! met] at once %[s its effect on ! read+s1 = z mu* h>m is done z w\ld result f a simil> treatm5t ( a wat*4 ,! h>d5$ /eel pivots us$ 9 all high grade voltmet]s are gr\nd & poli%$ ) extreme c>e s z to secure & ma9ta9 a high degree ( s5sitiv5ess4 ,! jewels on :i* ! mov+ p>ts revolve are ( sapphire1 & !y too mu/ necess>ily be made ) skill & c>efulness2 if1 !re=e1 ! jewels become crack$ & ! pivots dull$ by c>eless h&l+1 ! met] at once becomes useless z a measur+ in/rum5t4 ,ques4 ,h[ %\ld read+s be tak58 ,ans4 ,! deflection ( ! po9t] %\ld be read to t5?s ( a division2 ?is c be done ) consid]able accuracy1 especially aft] a little practice4 ,illu/ration3 ,,fig4 #b1hic4--,load & spe$ te/ ( direct curr5t %unt motor4 ,! object ( ?is te/ is to ma9ta9 ! voltage appli$ to ! motor con/ant1 & to v>y ! load by means ( a brake & f9d ! correspond+ v>iation 9 spe$ ( ! ma*9e & ! curr5t drawn f ! circuit4 ,if ! motor be a con/ant spe$ motor1 ! field resi/ance is ma9ta9$ con/ant4 ,! above indicates ! me?od ( connect+ in/rum5ts = ! te/ alone2 = />t+ ! ma*9e ! ord9>y />t+ box1 %\ld1 ( c\rse1 be ins]t$4 ,= v accurate results1 a temp]ature correction %\ld be appli$ to comp5sate ! effect :i* ! temp]ature ( ! atmosph]e has ^u ! resi/ance ( ! met] :5 measurem5ts are be+ tak54 ,9 ord9>y /ation practice ! temp]ature correction is negligible1 be+ = resi/ance correspond+ to ! high scale 9 fir/ class met]s1 less ?an "o-qu>t] ( #a p] c5t4 = a range ( #ce degrees above or #ce degrees bel[ #gj degrees ,fahr5heit4 ,ques4 ,:at atta*m5t is sometimes provid$ on /ation voltmet]s us$ = con/ant pressure s]vice8 ,ans4 ,a normal index4 ,illu/ration3 ,,fig4 #b1hid4--,temp]ature te/ ( direct curr5t motor or dynamo2 load+ back me?od4 ,9 mak+ temp]ature te/s on a small dynamo x is usual to drive ! dynamo ) a motor & load ! dynamo by means ( a lamp bank or resi/ance1 ! voltage across ! dynamo be+ ma9ta9$ con/ant1 & ! curr5t ?r\gh ! ext]nal circuit adju/$ to full load value4 ,! temp]atures are !n record$1 & :5 !y rea* a con/ant value above ! temp]ature ( ! atmosph]e1 ! te/ is discont9u$4 ,simil>ly1 9 mak+ a te/ on a small motor1 ! motor is load$ ) a dynamo & ! load increas$ until ! input curr5t rea*es ! normal full load value ( ! motor1 ! te/ be+ conduct$ z = a small dynamo4 ,:51 h[ev]1 ! app>atus1 ei!r motor or dynamo1 rea*es a c]ta9 size1 x becomes necess>y1 9 ord] to economize en]gy1 to use :at is call$ ! load+ back me?od1 z "h illu/rat$4 ,! motor is />t$ 9 ! usual way1 ) ! dynamo belt$ to x1 ! circuit ( ! dynamo be+ op54 ,! field ( ! dynamo is !n adju/$ s t ! dynamo voltage is equal to t ( ! l9e4 ,! dynamo is !n connect$ to ! circuit & its field resi/ance v>i$ until x c>ries normal full load curr5t4 ,"u ^! conditions1 if ! motor & dynamo be ( ! same size & type1 ! motor w c>ry slightly 9 excess ( full load1 ! diff]5ce be+ approximately twice ! losses ( ! ma*9es4 ,"u ^! conditions ! total p[] drawn f ! l9e is equal to twice ! loss ( ei!r ma*9e4 ,temp]ature read+s are tak5 z 9 o!r temp]ature te/s4 ,ques4 ,:at precaution mu/ be tak5 9 connect+ /ation voltmet]s8 ,ans4 ,c>e mu/ be tak5 to gu>d aga9/ any %ort circuit+ ( ! voltmet]1 :i*1 w\ld mean a %ort circuit+ ( ! g5]ator1 & z a result ! probable burn+ out ( its armature4 ,! high resi/ance ( ! voltmet] prev5ts any su* occurr5ce :5 x is connect$ 9 ! prop] way1 b %\ld "o side ( ! circuit be gr\nd$ to ! metal case or frame ( ! met]1 a c>eless h&l+ ( ! lead connect$ ) ! o!r side ( ! circuit w\ld produce ! result j m5tion$4 ,illu/ration3 ,,fig4 #b1hie4--;,comp\nd dynamo ext]nal *>act]i/ics te/2 adju/able load4 ,! object ( ?is te/ is to det]m9e ! relation betwe5 armature voltage & armature curr5t4 ,%unt field is adju/$ to give normal second>y voltage :5 ! ext]nal circuit is op54 ,! load is !n appli$ by means ( an adju/able resi/ance or lamp bank1 & read+s ( ext]nal voltage & curr5t record$4 ,if ! ma*9e be normally comp\nd$1 ! ext]nal voltage w rema9 practically con/ant ?r\gh\t ! load range4 ,if ! ma*9e be "u-comp\nd$1 ! ext]nal voltage w drop ) load1 :ile if ov]-comp\nd$1 !re w be a rise 9 voltage ) increase 9 load4 ,ques4 ,:y d /ation voltmet]s indicate a voltage slightly l[] ?an actually exi/s across ! leads8 ,ans4 ,s9ce !y are usually connect$ p]man5tly 9 circuit2 a c]ta9 am\nt ( heat is develop$ 9 ! wir+ ( ! in/rum5t4 ,illu/ration3 ,,figs4 #b1hif & #b1hig4--,trans=m] core loss & leakage1 or excit+ curr5t te/4 ,) ! prim>y circuit op51 ! ammet] indicates ! excit+ or no load curr5t4 ,x %\ld be not$ t all in/rum5ts are ins]t$ on ! l[ voltage side1 = bo? safety ( ! op]ator & because ! measurem5ts are m accurate4 ,! no load prim>y curr5t1 if ! ratio ( trans=mation be #aj3 #a1 w be "o-t5? ( ! measur$ second>y curr5t4 ,! wattmet] connect$1 z %[n1 measures ! sum ( ! losses1 9 ! trans=m]1 9 ! pressure coil ( ! wattmet]1 & 9 ! voltmet]4 ,on all /&>d makes ( portable in/rum5ts1 ! resi/ance ( ! wattmet] pressure coil & ( ! voltmet] is giv51 & ! loss 9 ei!r in/rum5t is ! squ>e ( ! voltage at its t]m9als1 divid$ by its resi/ance4 ,subtract+ ^! losses f ! total indicat$ ^u ! wattmet]1 gives ! true core or iron loss4 ,x %\ld be not$ t 9 ?is diagram is %[n an auxili>y trans=m] ) a numb] ( taps = obta9+ ! exact rat$ voltage ( ! trans=m] "u te/4 ,9 fig4 #b1hig is %[n1 9 g5]al1 ! same connections z 9 fig4 #b1hif1 except t ! auto-trans=m] has be5 replac$ by a resi/ance4 ,if ! l9e voltage available be n mu* 9 excess ( ! rat$ voltage ( ! trans=m] "u te/1 v little error is introduc$ by ! use ( ! resi/ance me?od4 ,h[ev]1 if ! diff]5ce be #aj p] c5t4 or m ! auxili>y trans=m] %[n 9 fig4 #b1hif %\ld be us$4 ,measurem5ts made "u ! resi/ance me?od always give l[] results ?an ^? obta9$ ) ! auxili>y trans=m]4 ,! effect ( ?is heat increases ! voltmet] resi/ance & consequ5tly r$uces ! curr5t bel[ t :i* o!rwise w\ld pass ?r\gh ! met]2 s9ce ! deflections ( ! po9t] are gov]n$ by ! /r5g? ( ! curr5t1 /ation voltmet]s inv>iably indicate a voltage slightly l[] ?an t :i* actually exi/s across _! leads4 ,illu/ration3 ,,fig4 #b1hih4--;,diagram ( connections = calibrat+ a wattmet]4 ,! calibration ( a portable wattmet] is accompli%$ ) direct curr5t ( con/ant value :i* is pass$ ?r\gh ! s]ies w9d+ by connect+ ! s\rce !re( ) ! curr5t t]m9als4 ,a direct curr5t voltage :i* may be v>i$ ?r\gh\t ! range ( ! wattmet] is also appli$ to ! in/rum5t betwe5 ! middle & "r h& pressure t]m9als ,a & ,e ! wir+ 9 ! met] betwe5 ^! t]m9als be+ su* t its diff]5tial w9d+ is !n cut out ( circuit4 ,! me?od ( proc$ure consi/s 9 comp>+ ! deflections on ! wattmet] at five ( six approximately equidi/ant po9ts ov] its scale ) ! correspond+ products ( volts & amp]es us$ to obta9 !m4 ,! *anges 9 ! wattmet] deflections are effect$ by m]ely v>y+ ! voltage1 ! value ( ! curr5t be+ ma9ta9$ con/ant at a value :i* repres5ts ! full curr5t capacity ( ! met]4 ,,note4--,*eck+ up ( a record+ wattmet]4 ,?is may conv5i5tly be done by not+ ! deflections at %ort int]vals on an ammet] connect$ 9 circuit1 & also ! read+s on ! dial ( ! record+ wattmet] dur+ ?is p]iod4 ,if ?is te/ be cont9u$ = an appreciable "t1 ! product ( ! pressure 9 volts1 ! curr5t 9 amp]es1 & ! "t 9 h\rs1 %\ld equal ! numb] ( wat?\rs record$ on ! c\nt]s ( ! dial4 ,,note4--,trans=m] te/+4 ,9 ! e>ly days ( trans=m] build+1 be=e ! comm]cial wattmet] _h be5 p]fect$1 leakage or excit+ curr5t 0 ! crit]ion ( good design4 ,aft] ! introduction ( ! wattmet]1 core loss became ! all important factor1 & = a long "t ! "q ( leakage curr5t 0 lo/ sight (4 ,) ! introduction ( silicon /eel1 leakage or excit+ curr5t aga9 assum$ prom95ce4 ,keep+ 9 m9d ! fact t all *>act]i/ics ( a trans=m] are ( m or less importance1 x is ess5tial t ! us] ( su* app>atus h at h& ! necess>y facilities = mak+ te/s ( all su* v>iable quantities4 ,! te/s :i* all us]s ( trans=m]s %\ld make1 are giv5 9 ?is *apt]4 ,ques4 ,c direct curr5t be measur$ by an alt]nat+ curr5t voltmet]8 ,ans4 ,yes4 ,illu/ration3 ,,fig4 #b1hii4--,trans=m] copp] loss by wattmet] measurem5t & imp$ance4 ,at fir/ glance1 ?is me?od w\ld seem bett] ?an ! calculation ( loss aft] measurem5t ( ! resi/ance4 ,h[ev]1 x %\ld be not$ t ! wattmet] is1 9 itself1 subject to consid]able error "u ! l[ p[] factor t w exi/ 9 ?is te/4 ,! second>y ( ! trans=m] is %ort circuit$1 & a voltage appli$ to ! prim>y :i* is j suffici5t to cause full load prim>y curr5t4 ,if full curr5t pass ?r\gh ! prim>y ( ! trans=m] ) ! second>y %ort circuit$1 ! second>y w also c>ry full load curr5t4 ,) connections z %[n1 & ) ! full load curr5t1 ! voltmet] indicates ! imp$ance volts ( ! trans=m]4 ,?is divid$ by ! rat$ voltage gives :at is call$ ! p] c5t4 imp$ance ( ! trans=m]4 ,9 a comm]cial trans=m] ( #e kw41 ?is %\ld be approximately #c p] c5t4 ,! iron loss ( ! trans=m] "u approximately #c p] c5t4 ( ! normal voltage w be negligible1 & ! losses measur$ w be ! sum ( ! prim>y & second>y copp] losses4 ,z 9 ! discussion ( ! core loss measurem5ts1 ! wattmet] read+s mu/ be correct$ = ! loss 9 its pressure coil1 ! me?od ( correction be+ ! same z t discuss$ "u ! core loss measurem5t4 ,if ! imp$ance volts1 z measur$1 be divid$ by ! prim>y curr5t1 ! imp$ance ( ! trans=m] is obta9$4 ,! reciprocal ( ?is quantity is kn[n by ! t]m admittance4 ,:5 two or m trans=m]s are connect$ 9 p>allel !y divide ! load 9 proportion to _! admittance4 ,x is1 !re=e1 important t ! us]s ( trans=m]s "k ! imp$ance ( ! app>atus us$1 9 ord] to det]m9e :e!r two or m trans=m]s w op]ate satisfactorily 9 p>allel4 ,= discussion ( wattmet] error on l[ p[] factor1 see note on page #b1jge4 ,= accurate measurem5t ( imp$ance1 ! voltmet] %\ld be connect$ directly across ! t]m9als ( ! trans=m] r ?an z %[n 9 ! diagram4 ,,note4--,trans=m] copp] loss te/4 ,! usual & be/ me?od ( obta9+ copp] losses is to sep>ately measure ! prim>y & second>y resi/ance & calculate f ^! ! prim>y & second>y copp] losses4 ,= g5]al diagram ( connections & discussion ( ! drop me?od1 see fig4 #b1hge4 ,! curr5t %\ld be kept well )9 ! load curr5t ( ! trans=m] to avoid temp]ature rise dur+ ! te/4 ,9 o!r words1 ! resi/ance ( ! coil is ! voltage across its t]m9als divid$ by ! curr5t4 ,! resi/ance ( ! prim>y coil c be measur$ simil>ly4 ,! copp] loss 9 watts 9 ea* coil w !n be ! product ( ! resi/ance & ! squ>e ( ! rat$ curr5t = t coil4 ,! total copp] loss w be ! sum4 ,ques4 ,:at w\ld be ! effect ( plac+ a direct voltmet] across an alt]nat+ curr5t circuit1 & :y8 ,ans4 ,!re w\ld be no deflection ( ! po9t] ow+ to ! rapid rev]sals ( ! alt]nat+ curr5t4 ,ques4 ,:at are ! usual capacities ( alt]nat+ curr5t voltmet]s8 ,ans4 ,!y are #c1 #g4e1 #aj1 #ab1 #ae1 #bj1 #fj1 #ge1 #abj1 #aej1 #cjj & #fjj volts1 b ^! capacities may ea* be increas$ by ! use ( a multipli]4 ,illu/ration3 ,,fig4 #b1ijj4--,temp]ature te/ ( trans=m] ) non-inductive load4 ,! figure %[s ! simple/ way ( mak+ ! te/4 ,connect ! prim>y ( ! trans=m] to ! l9e z %[n1 & c>ry normal second>y load by means ( a bank ( lamps or o!r suitable resi/ance1 until full load second>y curr5t is %[n by ! ammet] 9 ! second>y circuit4 ,! trans=m] %\ld !n be all[$ to run at its rat$ load = ! desir$ int]val ( "t1 temp]ature read+s be+ made ( ! oil 9 its hotte/ "p1 & also ( ! surr\nd+ air4 ,:]e temp]atures ( ! coil r ?an temp]atures ( ! oil are desir$1 x is necess>y to use ! resi/ance me?od4 ,?is is obta9$ by fir/ c>efully measur+ ! resi/ance ( bo? prim>y & second>y coils at ! temp]ature ( ! room1 & !n1 aft] ! trans=m] has be5 "u heat te/ = ! desir$ "t1 disconnect x f ! circuit & aga9 measure ! resi/ance ( prim>y & second>y4 ,= prop] me?od ( calculat+ ! temp]ature rise f resi/ance measurem5ts1 ! read] is ref]r$ to ! /&>dization rules ( ! ,a4,i4,e4,e4 ,9 mak+ resi/ance measurem5ts ( l>ge trans=m]s by ! drop me?od c>e %\ld be tak5 to all[ bo? ammet] & voltmet] indications to settle d[n to /eady values be=e read+s are tak54 ,?is may require sev]al m9utes4 ,ea* "t ! curr5t is *ang$ x is necess>y 9 ord] to obta9 *eck values on resi/ance measurem5ts1 to wait until ! curr5t is aga9 settl$ to its p]man5t value be=e tak+ read+s4 ,all resi/ance measurem5ts mu/ be tak5 ) great c>e1 z small errors 9 ! measurem5t ( ! resi/ance may make v l>ge errors 9 ! det]m9ation ( ! temp]ature rise4 ,! me?od above describ$ is satisfactory = small trans=m]s4 ,:]e l>ge units are to be te/$1 ! co/ ( curr5t = te/+ becomes an important item4 ,! buck+ te/ z 9 fig4 #b1ija1 is m economical4 ,ques4 ,h[ are /ation voltmet]s usually atta*$ to ! swit*bo>d8 ,ans4 ,!y are usually bolt$ to ! swit*bo>d by means ( f\r iron supports m\nt$ on ! back ( ! in/rum5t2 two ( ^! are fa/5$ ne> ea* side ( ! case4 ,"u c]ta9 conditions1 h[ev]1 z 9 p>allel+ ( alt]nators1 x is conv5i5t to h ! alt]nat+ curr5t voltmet] m\nt$ on a sw++ bracket at ! side ( ! swit*bo>d4 ,! voltmet] may !n be swung ar\nd 9 any desir$ direction s z to enable ! att5dant to keep in=m$ ( ! voltage :ile swit*+ 9 ea* additional alt]nator4 ,illu/ration3 ,,fig4 #b1ija4--,trans=m] temp]ature buck+ te/4 ,= ?is purpose two trans=m]s ( ! same size & ratio are requir$4 ,! connections are z %[n4 ,full second>y voltage is appli$1 & rheo/ats or auxili>y auto-trans=m]s are ins]t$ 9 ! circuit to prop]ly regulate ! voltage4 ,! prim>ies are connect$ ) "o buck+ ! o!r1 & a voltage equal to twice ! imp$ance voltage ( ei!r trans=m] ins]t$ 9 ! prim>y circuit4 ,x %\ld be not$ t :5 ! second>ies are subject$ to ! full second>y voltage1 a full prim>y voltage exi/s across ei!r prim>y1 b ) ! prim>ies connect$ s t ! voltage ( "o is buck$ aga9/ ! voltage ( ! o!r1 ! resultant voltage 9 ! circuit w be z]o4 ,by apply+ to ! prim>y circuit twice ! imp$ance voltage ( ei!r trans=m]1 full prim>y & second>y curr5t w circulate ?r\gh bo? trans=m]s4 ,on ! o!r h&1 by subject+ ! second>ies to ! full second>y voltage1 ! iron ( ! trans=m] w be magnetiz$ z "u its regul> op]at+ conditions1 & ! full iron loss ( ! trans=m] introduc$4 ,?is me?od p]mits ! op]ation ( two trans=m]s "u temp]ature te/ ) _! full losses1 )\t tak+ en]gy f ! l9e equal to ! rat$ capacity4 ,measurem5ts ( temp]ature are tak5 9 exactly ! same way z above4 ,?is me?od is successfully employ$ = mak+ temp]ature te/s on trans=m]s ( all sizes4 ,ques4 ,h[ %\ld an ammet] be op]at$ to get accurate read+s1 & :y8 ,ans4 ,x %\ld be cut out ( circuit except :ile tak+ a read+1 because ( ! error introduc$ by ! heat+ effect ( ! curr5t4 ,illu/ration3 ,,fig4 #b1ijb4--,trans=m] insulation te/4 ,9 apply+ a #aj1jjj volt insulation te/ betwe5 ! prim>y & second>y ( a trans=m]1 ! te/+ leads %\ld be disconnect$ f ! trans=m] "u te/1 & a sp>k gap introduc$ z %[n1 ) ! te/ ne$le set at a prop] sp>k+ di/ance = #aj1jjj volts4 ,a high resi/ance %\ld be connect$ 9 ! second>y be=e clos+ its circuit1 & ! voltage gradually increas$ by cutt+ out ?is second>y resi/ance until a sp>k jumps across ! sp>k gap4 ,:5 ! sp>k jumps across ! sp>k gap1 ! voltmet] read+ %\ld be record$ & ! te/+ trans=m] disconnect$4 ,! sp>k gap %\ld !n be increas$ ab\t #aj p] c5t4 & ! high t5sion leads connect$ to ! trans=m] "u te/ z indicat$ 9 ! diagram4 ,9 ord] to equalize ! insulation /ra9s1 all prim>y leads %\ld be connect$ toge!r1 all second>y leads n only connect$ toge!r1 b to ! core z well4 ,all resi/ance 9 ! rheo/at 9 ! l[ t5sion circuit %\ld !n be ins]t$ & ! swit* clos$4 ,gradually cut out second>y resi/ance until ! voltmet] %[s ! same voltage z 0 record$ previ\sly :5 ! sp>k jump$ across ! gap1 & apply ?is voltage to ! trans=m] = "o m9ute4 ,insulation te/s = a p]iod ( ov] "o m9ute are v unadvisable1 z trans=m]s ) excell5t insulation may be s]i\sly damag$ by prolong$ insulation te/s4 ,! long] ! /ra9 to :i* any insulation is subject$1 ! %ort] ! subsequ5t life ( ! insulation4 ,also ! great] ! appli$ voltage above ! actual op]at+ voltage ( ! app>atus1 ! %ort] ! subsequ5t life ( ! insulation4 ,9 te/+ small trans=m]s1 ! sp>k gap may be omitt$ & ! voltage ( ! l[ pressure coil ( ! te/+ trans=m] measur$4 ,?is multipli$ by ! ratio ( trans=mation gives ! te/+ voltage4 ,9 an ammet] hav+ a capacity ( #ej amp]es1 ! error ?us introduc$ w be less ?an #a p] c5t4 if connect$ cont9u\sly 9 circuit ) a curr5t n exce$+ ?ree-qu>t]s ?is capacity4 ,an ammet] ( #ajj amp]es capacity may be us$ indef9itely 9 circuit ) less ?an #a p] c5t4 error up to "o-half its capacity1 & = five m9utes at ?ree-qu>t]s capacity )\t exce$+ ! #a p] c5t4 limit4 ,illu/ration3 ,,fig4 #b1ijc4--,trans=m] insulation te/ z made :5 a special high t5sion trans=m] be n available4 ,9 ?is me?od a numb] ( /&>d trans=m]s1 connect$ z %[n may be employ$1 b great c>e %\ld be tak5 to h su* trans=m] cases ?or\ghly insulat$ f ! gr\nd & f "o ano!r1 9 ord] to m9imize ! insulation /ra9s 9 ! te/+ trans=m]s4 ,c>e %\ld be tak5 to ins]t 9 ! circuit ( ea* te/+ trans=m] a fuse1 n 9 excess ( ! trans=m] capacity1 :i* w bl[1 9 case ( a break d[n 9 ! app>atus "u te/4 ,9 te/+ insulation betwe5 second>y & core1 disconnect ! prim>y entirely1 apply "o t]m9al ( ! te/+ trans=m] to ! second>y t]m9als ( ! trans=m] "u te/1 & ! o!r t]m9al ( ! te/+ trans=m] to ! core ( ! trans=m] "u te/4 ,?is te/ %\ld also n be 9 excess ( "o m9ute4 ,! #aej scale ammet] may be left 9 circuit = an indef9ite l5g? ( "t at "o-?ird its full capacity1 & = ?ree m9utes at "o-half its full capacity1 ) a negligible error4 ,ammet]s ( #bjj & ( #cjj amp]e capacities mu/ n cont9u\sly c>ry m ?an "o-qu>t] ( ^! loads respectively if ! read+s are to h an accuracy )9 #a p] c5t4 nor m ?an "o-half ^! respective numb] ( amp]es = ?ree m9utes if ! same degree ( accuracy be desir$4 ,9 ord] to cut or %unt ! ammet] out ( circuit :5 n 9 use1 x is cu/om>y :5 wir+ ! in/rum5t 9 place1 to introduce a swit* z a %unt across x2 ?is swit* is kept clos$ except :5 a measurem5t is be+ tak54 ,:5 curr5ts l>g] ?an #cjj amp]es h to be measur$1 ammet] %unts are g5]ally employ$1 al?\gh ammet]s up to #ejj amp]es capacity are manufactur$4 ,illu/ration3 ,,fig4 #b1ijd4--,trans=m] int]nal insulation te/1 sometimes call$ d\ble normal voltage te/1 f ! fact t mo/ trans=m]s are te/$ ) d\ble normal voltage across _! t]m9als4 ,if ei!r ! prim>y or second>y ( ! trans=m] be connect$ to "s s\rce ( curr5t ) voltage d\ble t ( ! voltage ( ! trans=m] "u te/1 ! insulation betwe5 adjac5t turns1 & also ! insulation betwe5 adjac5t lay]s w be subject$ to twice ! normal op]at+ voltage4 ,x is good practice to employ high frequ5cy = ?is te/ 9 ord] to prev5t an abnormal curr5t f pass+ ?r\gh ! trans=m]4 ,sixty cycle trans=m]s are usually te/$ on #acc cycles1 & #be cycle trans=m]s on #fj cycle circuits = ?is d\ble normal voltage te/4 ,x is necess>y to ins]t ! resi/ance 9 ! circuit ( ! trans=m] & br+ ! voltage up gradually1 ! same z apply+ o!r high insulation te/s 9 ord] to prev5t abnormal rises 9 pressure at ! in/ant ( clos+ ! circuit4 ,ques4 ,:at is us$ 9 place ( in/rum5t %unts = high pressure alt]nat+ curr5t measurem5ts8 ,ans4 ,in/rum5t trans=m]s4 ,ques4 ,:at important att5tion %\ld be p]iodically giv5 to measur+ in/rum5ts8 ,ans4 ,!y %\ld be frequ5tly te/$ by comp>ison ) /&>ds t are kn[n to be correct4 ,electrical measur+ in/rum5ts1 ow+ to ! nature ( _! con/ruction & ! conditions "u :i* !y mu/ necess>ily be us$1 are subject to v>iations 9 accuracy4 ,?is feature is an annoy+ "o on acc\nt ( ! difficulty ( detect+ x2 a met] may1 z f> z appe>ances g1 be 9 excell5t work+ ord] & yet give read+s :i* are n to be reli$ ^u4 ,ridicul\s z x may appe>1 ! av]age /ation att5dant may frequ5tly be se5 /ra9+ 8 eyes to read to t5?s ( a division on ! scale ( a met] :i*1 if subject$ to te/1 w\ld %[ an inaccuracy ( ov] #b p] c5t4 ,9 te/+ a met]1 by comp>+ x ) a /&>d1 9 ord] to obta9 ! be/ results !re %\ld be "o man at ea* met] s t simultane\s read+s may be tak5 on bo? in/rum5ts1 & ! man at ! /&>d met] %\ld ma9ta9 ! voltage con/ant :ile a read+ is be+ tak51 by means ( a rheo/at 9 ! field circuit ( ! g5]ator supply+ ! curr5t4 ,illu/ration3 ,,fig4 #b1ije4--,trans=m] insulation resi/ance te/4 ,! insulation1 besides be+ able to resi/ puncture1 due to increas$ voltage1 mu/ also h suffici5t resi/ance to prev5t any appreciable am\nt ( curr5t fl[+ betwe5 prim>y & second>y coils4 ,x is1 !re=e1 sometimes important t ! insulation resi/ance betwe5 prim>y & second>y be measur$4 ,?is c be done1 z "h %[n4 ,great c>e %\ld be tak5 to h all wires ?or\ghly insulat$ f ! gr\nd1 & to h an ammet] plac$ z ne> z possible to ! t]m9als ( ! trans=m] "u te/1 9 ord] t curr5t leak+ f "o side ( ! l9e to ! o!r1 ext]nal to ! trans=m]1 may n be measur$4 ,great c>e is requir$ 9 mak+ ?is measurem5t1 9 ord] to obta9 consi/5t results4 ,ea* met] %\ld be *eck$ or calibrat$ at five or six approximately equidi/ant po9ts ov] its scale2 ! adju/able resi/ance be+ v>i$ ea* "t to give a deflection on ! /&>d met] ( an ev5 numb] ( divisions & ! deflection on ! o!r met] record$ at :atev] x may be4 ,hav+ obta9$ ! necess>y read+s1 ! calculation ( ! con/ant or multiply+ factor ( ! met] und]go+ te/ is next 9 ord]4 ,?is may be/ be %[n by tak+ an actual case 9 :i* a #aej scale voltmet] is be+ te/$ to det]m9e its accuracy4 ,! data & calculations are z foll[s3 ,read+s on ,read+s on ,con/ant /&>d met] met] te/$ #aej #adi4b #aej #adi4b #a4jje #abe #abe4j #abe #abe4j #a4jjj #ajj #ih4i #ajj #ih4i #a4jaa #ge #gc4f #ge #gc4f #a4jai #ej #ej4j #ej #ej4j #a4jjj #be #bd4h #be #bd4h #a4jjh ------ #f4jdc ,av]age con/ant = six read+s1 #f4jdc #f #a4jjg4 ,illu/ration3 ,,fig4 #b1ijf4--,trans=m] w9d+ or ratio te/4 ,! object ( ?is te/ is to *eck ! ratio betwe5 ! prim>y & ! second>y w9d+s4 ,= ?is purpose a trans=m] ( kn[n ratio is us$ z a /&>d4 ,connect ! trans=m] "u te/ ) a /&>d trans=m] z %[n4 ,leave swit* ,s#b op54 ,) ! s+le pole d\ble ?r[ swit* 9 position ,s#a;,b1 ! voltmet] is ?r[n across ! t]m9als ( ! /&>d trans=m]4 ,) ! swit* 9 position ,s#a;,a1 ! voltmet] is ?r[n across ! t]m9als ( ! trans=m] "u te/4 ,! voltmet] %\ld be read ) ! swit* 9 ea* position4 ,if ! w9d+ ratio be ! same z t ( ! /&>d trans=m]1 ! two voltmet] read+s w be id5tical4 ,x may be /at$ 9 g5]al t be=e tak+ ! read+s = ?is te/1 ! z]o position ( ! po9t] on ! met] te/$ %\ld be not$1 & if x be m ?an two-t5?s ( a division (f ! z]o m>k1 ! case ( ! met] %\ld be remov$ & ! po9t] /raight5$4 ,fur!rmore1 x w be notic$ f ! read+s "h record$ t ! te/ is />t$ at ! high read+ end ( ! scale2 ?is is done 9 ord] t ! po9t] may gradually be br\ght up to ?is spot1 by sl[ly cutt+ out ( circuit ! adju/able resi/ance1 & ?us %[ :e!r or n ! po9t] has a t5d5cy to /ick at any "p ( ! scale4 ,if ! met] seem to be defective 9 ?is respect1 x %\ld be rem$i$ ei!r by b5d+ ! po9t] or scale1 or by r5ew+ "o or bo? ( ! jewels1 be=e ! comp>ison ) ! /&>d is comm5c$4 ,x is obvi\s f ! read+s record$ = ! #aej scale voltmet]1 t z comp>$ ) ! correspond+ deflections ( ! /&>d1 ! =m] are a trifle l[4 ,9 ord] to det]m9e = ea* obs]vation h[ mu* too l[ !y are1 x is necess>y to divide ea* read+ on ! /&>d by ! correspond+ read+ on ! met] te/$4 ,! result is ! am\nt by :i* a deflection ( ?is size on ! met] te/$ mu/ be multipli$ 9 ord] to obta9 ! exact read+4 ,?is multipli] is call$ a con/ant1 & z %[n1 a con/ant is det]m9$ = ea* ( ! six obs]vations4 ,! av]age con/ant = ! six read+s is !n f\nd1 & ?is is tak5 z ! con/ant = ! met] z a :ole2 t is1 :5ev] ?is #aej-scale voltmet] is us$1 ea* read+ tak5 !reon mu/ be multipli$ by #a4jjg 9 ord] to correct = its inaccuracy4 ,! mo/ conv5i5t & sy/ematic way ( regi/]+ ! con/ant ( a met] is to write x1 toge!r ) ! numb] ( ! met] & ! date ( its calibration1 9 ink on a c>dbo>d tag & loop ! same by means ( a /r+ to ! h&le or "s o!r conv5i5t "p ( ! met]4 ,,note4--,trans=m] pol>ity te/4 ,a te/ ( importance 9 ! manufacture ( trans=m]s1 & sometimes necess>y = ! us]1 is ! s call$ bank+ or pol>ity te/4 ,! trans=m]s f any p>ticul> manufactur] h ! leads br\ght out 9 su* a mann] t a trans=m] ( any size c be connect$ to prim>y & second>y l9es 9 a giv5 ord] )\t dang] ( bl[+ ! fuses due to incorrect connections4 ,all manufactur]s ( trans=m]s1 h[ev]1 d n bank trans=m]s 9 ! same way1 s t x is necess>y 9 plac+ trans=m]s ( diff]5t makes to te/ = pol>ity4 ,?is is done z %[n 9 fig4 #b1ijf4 ,"o trans=m] is select$ z a /&>d & ! leads ( ! second trans=m] connect$ z indicat$ 9 ! diagram4 ,if ! trans=m]s be #a1ajj-b1bjj volts to #aaj-bbj1 two #aaj volt lamps are connect$ 9 ! second>ies ( ! trans=m]s z indicat$1 :ile ! prim>y ( ! trans=m] is connect$ across ! l9e4 ,9 trans=m]s built = two prim>y & two second>y voltages1 x is necess>y to te/ ea* prim>y & ea* second>y4 ,! diagram %[s ! me?od ( connect+ "o #b1bjj volt coil & "o #aaj volt coil to ! trans=m] to be te/$4 ,:5 ! prim>y circuit ( ! trans=m] "u te/ is clos$1 & if ! second>y leads ( ! #aaj volt coil "u te/ be br\ght out ( ! case prop]ly1 ! two #aaj volt lamps %\ld be brightly illum9at$4 ,if1 on ! o!r h&1 ! two #aaj volt t]m9als h be5 rev]s$1 no curr5t w fl[ ?r\gh ! lamps4 ,if ^! two t]m9als be f\nd to be br\ght out correctly1 transf] ! second>y leads ( ! trans=m] "u te/ to ! second #aaj volt coil4 ,^u clos+ ! prim>y circuit1 ! lamp %\ld aga9 be brightly illum9at$4 ,repeat ?is process ) ea* ( ! second>y coils & ! o!r prim>y coil1 & if ! lamps %[ up brightly 9 e case on clos+ ! prim>y circuit1 all leads h be5 prop]ly br\ght out4 ,if on any te/s ! lamps d n light up brightly1 ! leads on ! trans=m] mu/ be s *ang$ z to produce ! prop] bank+4 ,ques4 ,:at are ! usual rem$ies appli$ to a voltmet] to correct a #c or #d p] c5t4 error8 ,ans4 ,!y consi/ ( /raight5+ ! po9t]1 v>y+ ! t5sion ( ! spiral spr+s1 r5ew+ ! jewels 9 ! be>+s1 alt]+ ! value ( ! high resi/ance1 &1 9 ! case ( a direct curr5t in/rum5t1 /r5g!n+ ! p]man5t magnet4 ,ques4 ,h[ is ! p]man5t magnet /r5g!n$8 ,ans4 ,aft] deta*+ x f ! in/rum5t1 wrap ar\nd sev]al turns ( insulat$ wire1 & pass ?r\gh ?is wire = a %ort "t #c or #d amp]es ( direct curr5t 9 su* a direction z to re9=ce ! magnet magnetism4 ,ques4 ,h[ may ! value ( ! high resi/ance ( a voltmet] be alt]$8 ,ans4 ,det]m9e ! resi/ance ( ! voltmet] & add or subtract1 accord+ z ! read+ is high or l[1 a c]ta9 l5g? ( wire ^: resi/ance is 9 p] c5t4 ( ! voltmet] resi/ance ! same z ! p] c5t4 ( error4 ,,note4--,! complete calibration ( a two scale voltmet] does n1 z might be suppos$1 necessitate t ! read+s on bo? scales be *eck$ ) /&>ds1 = s9ce ! resi/ance correspond+ to ! "o scale is always "s multiple ( ! resi/ance ( ! o!r1 ! con/ants ( ! two scales are proportional4 ,= in/ance1 if ,s ! read+ at ! end ( ! high scale ( ! voltmet]2 ,s#a ! read+ at ! end ( ! l[ scale ( ! voltmet]2 ,r ! resi/ance 9 ! met] correspond+ to ! high scale2 ,r#a ! resi/ance 9 ! met] correspond+ to ! l[ scale2 ,k ! con/ant = ! high scale1 & ,k#a ! con/ant = ! l[ scale4 ,!n ,,sk ,r ,s#a,k#a ,r#a f :i* ,k#a ,,skr ,s#a,r ,t is to say1 if ! respective resi/ances correspond+ to ! two scales be kn[n1 & ! con/ant ( ! high scale be det]m9$ by comp>ison ) a /&>d1 !n by aid ( ^! kn[n values & ! maximum read+s on ! two scales1 ! con/ant ( ! l[ scale may be calculat$4 ,x is also possible to calculate ! con/ant ( ! high scale if ! con/ant ( ! l[ scale be kn[n1 toge!r ) ! values ( ! resi/ances correspond+ to ! two scales2 = f ! equation previ\sly giv54 ,k ,,rs#a,k#a ,r#a,s ,ques4 ,:at is a frequ5t cause ( error 9 an alt]nat+ curr5t met]1 & :y8 ,ans4 ,! det]ioration ( its insulation1 :i* p]mits ! work+ p>ts ( ! in/rum5t com+ 9 contact ) ! surr\nd+ metal case4 ,a conv5i5t me?od ( te/+ = det]ioration ( insulation is %[n 9 fig4 #b1ije4 ,illu/ration3 ,,fig4 #b1ijg4--;,diagrams %[+ v>i\s syn*ron\s conv]t] trans=m] connections4 ,! diametrical connection is us$ mo/ frequ5tly z x requires only "o second>y coil on ea* trans=m]1 ?is be+ connect$ to diametrically opposite po9ts on ! armature w9d+4 ,! middle po9ts c be connect$ toge!r & a neutral obta9$ ! unbalanc$ ?ree wire direct curr5t hav+ no di/ort+ effect4 ,) diametrical second>ies1 ! prim>ies %\ld pref]ably be connect$ delta1 except ) regulat+ pole conv]t]s :]e !y mu/ be connect$ ,y4 ,diametrical second>ies ) delta prim>ies %\ld n be us$ ) regulat+ pole conv]t]s4 ,d\ble /> connection ( second>ies may1 h[ev]1 be us$ ) delta prim>ies1 & is free f ! tr\ble ( ! triple h>monic ( ! trans=m] appe>+ 9 ! prim>y4 ,9 ?is case1 h[ev]1 ! two second>y neutrals mu/ n be connect$ ) ea* o!r4 ,h[ to ,te/ ,g5]ators4--,9 ! op]ation ( electrical /ations1 _m problems deal+ ) ! g5]ators in/all$ !re9 c be readily solv$ by ! aid ( *>act]i/ic curves1 :i* be> a relation to ! g5]ators simil>ly z d indicator diagrams to /eam eng9es4 ,illu/ration3 ,,fig4 #b1ijh4--;,g5]al =m ( *>act]i/ic curves = a s]ies dynamo4 ,! g5]al curve t may be expect$ is ,,oa4 ,x is obta9$ practically 9 ! same mann] z = ! %unt *>act]i/ic curve1 except t no field rheo/at is employ$4 ,comm5c+ ) no load or amp]es1 !re w probably be a small deflection noticeable on ! voltmet]1 due to ! residual magnetism4 ,! o!r read+s are tak5 ) successive r$uctions ( ma9 curr5t resi/ance4 ,! curve ,,oa ?us obta9$ = a c]ta9 s]ies g5]ator is practically a /raight l9e at ! beg9n+1 repres5t+ !reby a proportional increase ( voltage ) increase ( curr5t1 b aft] a c]ta9 curr5t is rea*$ 7ab\t #bj amp]es 9 ?is case7 ! curve flatt5s & takes a d[nw>d direction4 ,! turn+ po9t occurs 9 ! *>act]i/ic curves ( all s]ies g5]ators1 & x d5otes ! /age at :i* ! iron magnet cores become s saturat$ ) l9es ( magnetic =ce t !y w n readily all[ m to pass ?r\gh !m2 ?is turn+ po9t is te*nically kn[n z ! po9t ( saturation1 & ! curr5t correspond+ 7#bj amp]es 9 ?is case7 is call$ ! critical curr5t ( ! dynamo4 ,! po9t ( saturation 9 any giv5 s]ies ma*9e is gov]n$ by ! am\nt ( iron 9 ! magnetic circuit2 its position 9 ! curve !re=e v>ies accord+ to ! design ( ! g5]ator z does also ! critical curr5t4 ,! value ( ! latt] is important inasmu* z ! valuable features ( a s]ies g5]ator ass]t !mselves only :5 ! ma*9e is supply+ a great] numb] ( amp]es ?an t ( ! critical curr5t1 = if ! s]ies g5]ator be work$ along t "p ,m ,a ( ! curve to ! "r ( ! po9t ( saturation x becomes ne>ly self-regulat+ z reg>ds curr5t1 because z ! curr5t increases ! voltage drops4 ,9 ! diagram 9 addition to ! *>act]i/ic curve ,o ,a1 :i* may m def9itely be call$ an ext]nal *>act]i/ic curve on acc\nt ( repres5t+ ! conditions ext]nal to ! g5]ator1 !re is %[n a total *>act]i/ic curve1 ,o ,c ,b4 ,! latt] curve repres5ts ! relation betwe5 ! curr5t & ! total voltage develop$ 9 ! armature1 & may be plott$ f ! ext]nal *>act]i/ic curve if ! resi/ance ( ! armature betwe5 bru%es & ! resi/ance ( ! s]ies field w9d+ be kn[n4 ,= example1 assume ^! comb9$ resi/ances am\nt to 4#f ohm4 ,at #cj amp]es !re w\ld be requir$ #cj 4#f #ah volts to =ce ?is curr5t ?r\gh ! armature & field w9d+s4 ,at #cj amp]es ! ext]nal pressure is #fe volts1 z %[n by ! curve ,o ,a2 ! total voltage develop$ = #cj amp]es is1 !re=e1 ! ext]nal voltage plus ! int]nal voltage or #fe #ah #hc volts4 ,plott+ #hc volts = #cj amp]es w give "o po9t = ! ext]nal *>act]i/ic curve ( ?is ma*9e1 & by det]m9+ 9 l mann] ! total voltages develop$ = six or eight diff]5t curr5ts ov] ! scale1 suffici5t data w be at h& = plott+ & draw+ 9 ! curve ,o ,c ,b4 ,9 /eam eng9e]+1 a man :o did n fully und]/& ! me?od ( tak+ an indicator diagram w\ld be consid]$ n 9 t\* ) 8 pr(ession1 & 9 electrical eng9e]+ ! same w\ld be true ( "o ignorant ( ! me?od ( obta9+ *>act]i/ic curves4 ,! necess>y arrangem5t or connection ( ! g5]ator f :i* x is desir$ to obta9 a *>act]i/ic curve1 consi/s 9 provid+ a con/ant motive p[] s t ! ma*9e may be run at a uni=m spe$1 & :5 ! field magnets ( ! g5]ator are sep>ately excit$ ! field curr5t f ! outside s\rce mu/ also be ma9ta9$ con/ant1 pref]ably by a rheo/at connect$ 9 ! field ( ! auxili>y excit+ ma*9e4 ,x is also necess>y 9 e case t means be provid$ = v>y+ ! ma9 curr5t ( ! g5]ator /ep by /ep f z]o to maximum4 ,?is may be/ be done by employ+ a wat] rheo/at1 z %[n 9 fig4 #b1iji4 ,ques4 ,:at in/rum5ts are ne$$ 9 mak+ a te/ ( dynamo *>act]i/ics8 ,ans4 ,a voltmet]1 ammet]1 spe$ indicator1 ! usual swit*es & rheo/ats4 ,ques4 ,h[ is ! app>atus connect$8 ,ans4 ,x is connect$ z %[n 9 fig4 #b1iaj4 ,ques4 ,describe ! te/4 ,ans4 ,hav+ complet$ ! prelim9>ies z 9 fig4 #b1iaj1 ! te/ %\ld be />t$ ) ! ma9 circuit ( ! g5]ator op54 ,!n1 9 ! case ( ! %unt ma*9e1 ! spe$ %\ld be made normal & ! field rheo/at adju/$ until ! voltmet] read+ indicates ! rat$ voltage ( ! ma*9e at no load & read+s tak54 ,! electrodes ( ! wat] rheo/at %\ld be adju/$ = maximum resi/ance & ma9 circuit clos$1 & a second set ( read+s tak54 ,sev]al sets ( read+s are tak51 ) successive r$uctions ( wat] rheo/at resi/ance4 ,! results are !n plott$ on coord9ate pap] giv+ ! *>act]i/ic curve %[n 9 fig4 #b1ijh4 ,illu/ration3 ,,fig4 #b1iji4--,wat] rheo/at4 ,x consi/s ess5tially ( a tank ( suitable size conta9+ salt wat] into :i* are plac$ two electrodes hav+ means ( adju/m5t ( ! di/ance sep>at+ !m4 ,! solution dep5ds on ! voltage4 ,pure wat] is seldom us$ = pressures "u #a1jjj volts4 ,! size ( ! tank is det]m9$ by ! size ( ! electrodes1 & r\ghly ! size ( ! latt] equal ! numb] ( amp]es4 ,) a curr5t d5sity ( "o amp]e p] squ>e in*1 a wat] solution gives a drop ( #b1ejj to #c1jjj volts p] in* di/ance betwe5 ! plates4 ,:]e high voltage is us$1 ! wat] mu/ be circulat$ ?r\gh & f ! tank by rubb] hose all[+ = #b1ejj volts1 a l5g? ( #ae to #bj feet ( #a in* hose to prev5t gr\nd+4 ,9 place ( ! arrangem5t %[n above1 a b>rel may be us$ = ! tank1 & = ! electrodes1 coils ( galvaniz$ iron wire4 ,?is is ! simple/ =m & is satisfactory4 ,ques4 ,:at does ! *>act]i/ic curve 7fig4 #b1iaa7 %[8 ,ans4 ,an exam9ation ( ! curve %[s t ! highe/ po9t ( ! curve occurs at no load or #j amp]es2 t z ! curr5t is increas$1 ! voltage drops1 fir/ slightly to ! po9t ,b & !n rapidly until ! po9t ,e is rea*$1 :5 any fur!r l[]+ ( resi/ance 9 ! ma9 circuit to increase ! curr5t causes n only a rapid decl9e 9 ! voltage b also ( ! curr5t until bo? voltage & curr5t become approximately z]o4 ,illu/ration3 ,,fig4 #b1iaj4--;,connections = te/ ( dynamo4 ,dur+ ! te/1 "o man %\ld be assign$ to ! ta*omet]1 ano!r man to ! wat] rheo/at1 & !re %\ld pref]ably be "o man at ea* ( ! electrical measur+ in/rum5ts4 ,9 ord] to enable ! man at ! ta*omet] to keep ! spe$ con/ant1 he %\ld be 9 communication ei!r directly or indirectly ) ! s\rce ( ! driv+ p[]1 & ! man at ! wat] rheo/at %\ld be 9 pla9 view ( ! man read+ ! ammet] s t ! latt] p>ty may signal him = ! prop] adju/m5t ( ! rheo/at 9 ord] t ! desir$ increase ( curr5t be obta9$ = ea* set ( read+s4 ,9 "s g5]ators1 a v slight curr5t results ev5 :5 ! t]m9als ( ! ma*9e are actually %ort circuit$2 t is1 due to residual magnetism 9 ! pole pieces1 ! l[] portion ( ! curve (t5 t]m9ates1 n exactly at z]o1 b at a po9t "s di/ance along ! curr5t l9e4 ,! work+ portion ( ! curve is f ,a to ,c1 at :i* "t ! ma*9e is supply+ a fairly con/ant voltage4 ,f ,c to ,e %[s a critical condition ( affairs1 :ile ! /raight portion ,d ,o repres5ts ! un/able "p ( ! curve caus$ by ! field curr5t be+ bel[ its prop] value4 ,! position ( ! po9t ,c det]m9es ! maximum p[] ! ma*9e is capable ( develop+1 be+ 9 ?is case 7#dg4e #be7 #gdf #a4ei horse p[]4 ,ques4 ,h[ may ! comm]cial effici5cy ( a g5]ator be det]m9$8 ,ans4 ,to obta9 ! comm]cial effici5cy1 ! input & output mu/ be f\nd = diff]5t loads4 ,! input may be f\nd by runn+ ! g5]ator z a motor at its rat$ spe$1 load+ x by means ( a ,prony brake4 ,! g5]ator mu/ be /ripp$ ( all belt+ or o!r me*anical connections1 suppli$ ) its normal voltage & full load curr5t1 & ! pressure ( ! ,prony brake ^u its armature %aft or pulley adju/$ until ! rat$ spe$ ( ! armature is obta9$4 ,! data ?us obta9$ is sub/itut$ 9 ! =mula4 #b ,l ,w ,r input 9 brake horse p[] ---------- 7#a7 #cc1jjj 9 :i* ,l l5g? ( ,prony brake lev]2 ,w p\nds pull at end ( lev]2 ,r revolutions p] m9ute4 ,! output or electrical horse p[] = ! same load is easily calculat$ f ! =mula amp]es volts output 9 electrical horse p[] --------------- 7#b7 #gdf ,aft] obta9+ value = 7#a7 & 7#b7 ! comm]cial effici5cy = ! load tak5 is obta9$ f ! =mula output comm]cial effici5cy ------ 7#c7 input ,hav+ obta9$ ! comm]cial effici5cy1 ! diff]5ce betwe5 ! ideal #ajj p] c5t4 & ! effici5cy f\nd w be due to c]ta9 losses 9 ! g5]ator4 ,^! losses may be classifi$ z #a4 ,me*anical4 #b4 ,electrical4 ,! me*anical losses are ! friction ( ! be>+s & bru%es1 & air friction4 ,! electrical losses consi/ ( ! eddy curr5t loss1 hy/]esis loss1 armature resi/ance loss1 & field resi/ance loss4 ,9 te/+ = ^! losses1 ! g5]ator to be te/$ %\ld be belt$ to a calibrat$ motor :i* latt] ma*9e %\ld pref]ably be ( ! con/ant pressure1 %unt w\nd type4 ,! friction ( ! be>+s & belt ( ! g5]ator are det]m9$ toge!r by rais+ ! bru%es (f its commutator & runn+ x at ! rat$ spe$ by means ( ! calibrat$ motor4 ,illu/ration3 ,,fig4 #b1iaa4--;,*>act]i/ic curve ( %unt dynamo4 ,suppose 9 mak+ ! te/1 ! deflections on ! met]s = ! fir/ read+s be #fc volts & #j amp]es1 ! plott+ ( ^! values w give ! fir/ po9t on ! curve4 ,simil>ly1 ! second read+s ) ma9 circuit clos$ & maximum resi/ance 9 ! wat] rheo/at may be assum$ to be #fb4e volts & #g4e amp]es1 :i* plott$ gives ! second po9t ,b4 ,a /ill fur!r l[]+ ( ! plate w p]mit a /rong] curr5t 9 ! ma9 circuit1 & ! value ( ?is toge!r ) its correspond+ voltage w give a ?ird po9t = ! curve4 ,nei!r = ?is read+1 h[ev]1 nor = ! foll[+ read+s ( ! te/ %\ld ! field rheo/at be alt]$4 ,:5 six or eight po9ts rang+ f z]o to a maximum curr5t h be5 obta9$ & plott$1 a curv$ l9e %\ld be drawn ?r\gh !m su* z %[n ?r\gh ,,abcdefg#j1 ! *>act]i/ic curve ( ! dynamo4 ,:ile ! curve may be sket*$ 9 free h&1 x %\ld pref]ably be drawn by ! aid ( ,fr5* curves4 ,9 case ! ,fr5* curve _c be exactly made to co9cide ) all ! po9ts z = in/ance ,c & ,d1 x %\ld be run 9 betwe5 giv+ an av]age result1 & smoo?+ out irregul>ities1 or small errors due to ! p]sonal equation4 ,! met] ( c\rse mu/ be correct or calibrat$ & ! read+s correct$ by ! calibration coeffici5t4 ,! am\nt ( p[] z asc]ta9$ f ! calibration curve ( ! motor = ! voltage & curr5t us$ !re9 :5 driv+ ! g5]ator z j expla9$1 is a measure ( ^! two losses4 ,! p[] ?us us$ is practically con/ant at all loads & is ab\t #b p] c5t4 ( t necess>y to drive ! g5]ator at full load4 ,illu/ration3 ,,fig4 #b1iab4--;,*>act]i/ic curves = a comp\nd dynamo4 ,if ! ma*9e be ov] comp\nd$1 ! *>act]i/ic curve has ! =m ( ! curve ,a ,b1 :i* curve 0 obta9$ f a ma*9e ov]-comp\nd$ f #aah to #abc volts1 & design$ to give #bjc amp]es at full load4 ,! prelim9>y arrangem5ts = te/+ a comp\nd dynamo are simil> to ^? = a %unt g5]ator1 & if ! %unt across ! s]ies field w9d+ be already made up & 9 position1 ! read+s are tak5 precisely 9 ! same mann]4 ,x is g5]ally consid]$ suffici5t if obs]vations be record$ at z]o1 1 1 & full load4 ,if x be desir$ to asc]ta9 ! effect :i* residual magnetism has ^u ! field magnets ! curr5t is decreas$ aft] ! full load po9t is rea*$ )\t op5+ ! circuit1 & read+s are tak5 9 succession at 1 1 & z]o load giv+ 9 ?is case ! curve ,b ,c ,d ,e ,s4 ,x is ?us se5 t residual magnetism ex]ts no small effect ^u ! voltage obta9$ at ! diff]5t loads1 = _h !re be5 no residual magnetism 9 ! field magnets ! curve ,b ,c ,d ,e ,s w\ld h co9cid$ ) ! curve ,a ,b4 ,! curve ,a ,b1 & ! /raight l9e ,a ,x drawn ?r\gh ! po9ts ,a & ,b1 are almo/ id5tical1 & z ,a ,x repres5ts ! !oretical *>act]i/ic curve = ! ma*9e1 x is se5 t comp\nd+ is practically p]fect4 ,9 ord] to insure su* accurate results be+ obta9$1 provid+ ! ma*9]y be correctly design$1 requires consid]able c>e 9 tak+ ! read+s2 = example1 ea* /ep or load on ! asc5d+ curve %\ld n be exce$$ be=e ! correspond+ deflection is tak51 else ! residual magnetism w cause ! pressure read+ to be high] ?an x actually %\ld be1 & ! foll[+ pressure read+s w also be affect$ 9 ! same mann]4 ,9 case ! %unt to be employ$ across ! s]ies field has n be5 made up1 x is advisable to p]=m a trial te/ be=e tak+ ! read+s = ! curve z previ\sly describ$4 ,! trial te/ consi/s 9 tak+ two read+s1--"o at no load & ! o!r at full load1 ! %unt be+ s adju/$ z to l5g? & section t ! desir$ am\nt ( comp\nd+ w be obta9$ 9 ! latt] read+ ) normal voltage at no load4 ,if ! fir/ trial fail to produce ! desir$ result by giv+ too l[ a voltage at full load1 ! l5g? ( ! %unt across ! s]ies field %\ld be increas$1 or its section %\ld be r$uc$ by employ+ a less numb] ( /rips 9 its makeup2 aga91 if ! voltage at full load be high] ?an t desir$1 !re mu/ be made a decrease 9 l5g? or an increase ( section 9 ! %unt employ$4 ,! friction ( ! bru%es c v conv5i5tly be det]m9$ next by l[]+ !m on ! commutator & giv+ !m ! prop] t5sion4 ,! increase 9 p[] result+ f ! great] curr5t t w n[ be tak5 by ! motor to run ! dynamo at its rat$ spe$1 w be a measure ( ?is loss4 ,9 g5]al1 its value w be ab\t 4#e p] c5t4 ( ! total p[] requir$ to drive ! dynamo at full load1 & ?is also w rema9 con/ant at all loads4 ,! friction ( ! air ^u ! mov+ armature ( ! dynamo _c be det]m9$ exp]im5tally1 b !oretically ?is loss is small & may be e/imat$ z 4#e p] c5t42 x is also con/ant at all loads4 ,! core loss may be det]m9$ exp]im5tally by excit+ ! field magnets ( ! dynamo ) ! normal full load field curr5t ?r\gh ! magnet coils1 & not+ ! increase ( p[] requir$ by ! motor to ma9ta9 ! rat$ spe$ ( ! dynamo ?us excit$ "u no load1 ov] t necess>y "u ! same conditions ) no field excitation4 ,?is increase ( p[] w be ! value ( ! core loss4 ,! core loss is approximately #c p] c5t4 ( ! p[] requir$ to op]ate ! dynamo at full load1 & x is con/ant at v>y+ loads4 ,if x be desir$ to divide ! core loss into its compon5t p>ts1 x is necess>y also to run ! dynamo "u ! same conditions z be=e ) field excitation b at half its rat$ spe$4 ,if1 !n1 ,h ! p[] lo/ 9 hy/]esis at rat$ spe$1 ,e ! p[] lo/ 9 eddy curr5ts at rat$ spe$1 ,t ! p[] lo/ 9 hy/]esis & eddy curr5ts at rat$ spe$1 ,s ! p[] lo/ 9 hy/]esis & eddy curr5ts at half spe$4 !re may be =m$ ! two foll[+ equations3 ,h ,e ,t ,h ,e1 & ,s --- ---1 #b #b f :i* ! elim9ation ( ,h w give ,e #b,t - #d,s4 ,! value ( ! eddy curr5t loss ?us f\nd w be ab\t #a p] c5t41 & con/ant at all loads4 ,hav+ previ\sly asc]ta9$ ! p[] lo/ 9 bo? eddy curr5ts & hy/]esis1 & kn[+ n[ ! p[] lo/ 9 eddy curr5ts alone1 x is easy to f9d t lo/ 9 hy/]esis by simply subtract+ ! latt] kn[n value f ! =m]4 ,! value ( ! hy/]esis loss is !re=e approximately #a p] c5t41 & x is con/ant at diff]5t loads4 ,!re yet rema9s to be det]m9$ ! armature resi/ance loss & ! field resi/ance loss4 ,z = ! calibrat$ motor1 ?is may be disconnect$ f ! dynamo1 z x ne$ n be us$ fur!r 9 ! te/4 ,! armature resi/ance is ! resi/ance ( ! armature w9d+ ( ! dynamo1 betwe5 ! commutator b>s ^u :i* press ! positive & negative bru%es4 ,assume t ! value ( ! armature resi/ance be kn[n1 call ?is value ,r ohms1 toge!r ) t ( ! full load armature curr5t1 :i* is also kn[n & :i* call ,i amp]es1 ?is is suffici5t data = calculat+ ! armature resi/ance loss at full load4 ,x is evid5t t to =ce ! full load curr5t ,i ?r\gh ! armature resi/ance ,r w require a pressure ( ,r volts1 & t ! watts lo/ 9 do+ s w be ! voltage multipli$ by ! curr5t4 ,! armature resi/ance is consequ5tly ,,ir ,i ,i#b,r watts or1 express$ 9 horse p[] x is ,i#b,r #gdf ,at full load x is usually ab\t #b p] c5t4 ( ! total p[] requir$ to drive ! g5]ator fully load$4 ,! armature resi/ance loss v>ies 9 proportion to ! load1 9 fact1 z ! la/ expression %[s1 x increases z ! squ>e ( ! armature curr5t4 ,! field resi/ance loss is calculat$ 9 ! same mann] z j expla9$ = ! armature resi/ance loss1 x be+ equal 9 horse p[] to ! squ>e ( ! full load field curr5t multipli$ by ! resi/ance ( ! field w9d+ & divid$ by #gdf4 ,9 a %unt dynamo x is practically con/ant at #b p] c5t4 ( ! total p[] at full load1 b 9 a s]ies or 9 a comp\nd g5]ator x w v>y 9 proportion to ! load4 ,,hawk9s ,,practical ,,libr>y ,,( ,,electricity ,,9 ,,h&y ,,pocket ,,=m ,,price #a ,,ea* ,!y are n only ! be/1 b ! *eape/ "w publi%$ on ,electricity4 ,ea* numb] be+ complete 9 itself4 ,sep>ate numb]s s5t po/paid to any address on receipt ( price4 ,!y are gu>ante$ 9 e way or y\r money w be return$4 ,complete catalog ( s]ies w be mail$ free on reque/4 ,,electrical ,,guide1 ,,no4 #a ,conta9+ ! pr9ciples ( ,elem5t>y ,electricity1 ,magnetism1 ,induction1 ,exp]im5ts1 ,dynamos1 ,electric ,ma*9]y4 ,,electrical ,,guide1 ,,no4 #b ,! con/ruction ( ,dynamos1 ,motors1 ,armatures1 ,armature ,w9d+s1 ,in/all+ ( ,dynamos4 ,,electrical ,,guide1 ,,no4 #c ,electrical ,in/rum5ts1 ,te/+1 ,practical ,managem5t ( ,dynamos & ,motors4 ,,electrical ,,guide1 ,,no4 #d ,di/ribution ,sy/ems1 ,wir+1 ,wir+ ,diagrams1 ,sign ,fla%]s1 ,/orage ,batt]ies4 ,,electrical ,,guide1 ,,no4 #e ,pr9ciples ( ,alt]nat+ ,curr5ts & ,alt]nators4 ,,electrical ,,guide1 ,,no4 #f ,alt]nat+ ,curr5t ,motors1 ,trans=m]s1 ,conv]t]s1 ,rectifi]s4 ,,electrical ,,guide1 ,,no4 #g ,alt]nat+ ,curr5t ,sy/ems1 ,circuit ,break]s1 ,measur+ ,in/rum5ts4 ,,electrical ,,guide1 ,,no4 #h ,alt]nat+ ,curr5t ,swit* ,bo>ds1 ,wir+1 ,p[] ,/ations1 ,in/allation & ,op]ation4 ,,electrical ,,guide1 ,,no4 #i ,telephone1 ,telegraph1 ,wireless1 ,bells1 ,light+1 ,railways4 ,,electrical ,,guide1 ,,no4 #aj ,mod]n ,practical ,applications ( ,electricity & ,ready ,ref]5ce ,index ( ! #aj ,numb]s4 ,!o4 ,audel ,co41 ,publi%]s4 #gb ,,fif? 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