,,! ,,?\ght ,,is ,,9 ,,! ,,"q ,,! ,,in=mation ,,is ,,9 ,,! ,,answ] ,illu/ration3 ,,hawk9s ,,electrical ,,guide ,,numb] ,,sev5 ,,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 ,illu/ration3 ,,!o4 ,,audel ,,co4 #gb ,,fif? ,,ave4 ,,new ,,york4 ,,copyright$1 #aiae1 ,,by ,,!o4 ,,audel ,,co41 ,,new ,,york4 ,pr9t$ 9 ! ,unit$ ,/ates4 ,,table ,,( ,,cont5ts ,,guide ,,no4 #g4 ,,alt]nat+ ,,curr5t ,,sy/ems #a1eca to #a1ehf ,advantages ( ! alt]nat+ curr5t--classification ( sy/ems--vector summation2 examples--=ms ( circuit3 s]ies1 p>allel1 p>allel s]ies1 s]ies p>allel--trans=m] sy/ems3 individual trans=m]s2 trans=mation at di/ribution c5t]s--s+le phase sy/em2 two wire transmission & ?ree wire di/ribution2 objections to s+le phase sy/ems2 advantages--monocyclic sy/em--two phase sy/ems3 adaptation2 ord9>y voltages us$2 two phase ?ree wire sy/em2 two phase five wire sy/em--?ree phase sy/ems3 six wire2 f\r wire2 ?ree wire2 connections3 />1 delta1 /> delta1 delta />2 evolution ( ?ree wire sy/em2 pressure & curr5t relations2 connection ( trans=m]s2 op5 delta connection--*ange ( frequ5cy--,s*aghticoke-,s*5ectady transmission l9e--trans=mation ( phases3 ?ree to "o1 ?ree to two1 two to six1 & ?ree to six phase--,scott connection = trans=m+ f ?ree to two phase--?ree to two phase ) ?ree /> connect$ trans=m]s--economy ( a4c4 sy/ems--relative weights ( copp] requir$ = polyphase sy/ems--a]motor t[]s ( ,s\!rn ,p[] ,co4--*oice ( voltage--usual transmission voltages--diagram ( ?ree phase di/ribution--mix$ curr5t sy/ems2 usual d4c4 pressure on traction l9es2 use ( mix$ sy/ems4 ,,auxili>y ,,app>atus #a1ehg to #a1ehh ,classification ( auxili>y devices3 swit*+ devices1 types--curr5t or pressure limit+ devices1 types--lightn+ protection devices1 types--regulat+ devices1 types--syn*ron\s cond5s]s1 types--indicat+ devices4 ,,swit*+ ,,devices #a1ehi to #a1fab ,def9ition ( a swit*--behavi\r ( ! curr5t :5 ! circuit is brok5--po9ts on design--in/allation ( s+le ?r[ & d\ble ?r[ swit*es--plug swit*es--=ms ( break3 op51 enclos$1 fuse1 horn1 oil--disconnect+ swit*es--pole top swit*es--horn break swit*es--motor />t+ swit*--oil swit*es2 nature ( an oil break--remote control oil swit*es--motor op]at$ swit*es--ruptur+ capacity ( oil swit*es--float swit*es4 ,,curr5t ,,& ,,pressure ,,limit+ ,,devices #a1fac to #a1fgf ,necessity = ^! devices2 /eam analogy--fuses3 advantages & disadvantages2 types3 plug1 cut out1 expulsion1 no arc1 magnetic bl[ out1 quick break fuse1 etc4--metal us$--curr5t limit+ inductances3 con/ruction1 location--circuit break]s3 progressive break+ ( ! circuit2 c>bon contacts--automatic features3 ov]load trip1 und]load trip1 l[ voltage trip1 auxili>y circuit trip--relays3 adaptation2 classification3 protective1 regulative1 communicative1 a4c4 & d4c41 circuit op5+1 circuit clos+1 prim>y1 second>y1 ov]load1 und]load1 ov] voltage1 l[ voltage1 rev]se en]gy1 rev]se phase1 in/antane\s1 "t limit1 inv]se "t limit1 diff]5tial--h[ to select relays4 ,,lightn+ ,,protection ,,devices #a1fgg to #a1gad ,ess5tial p>ts3 air gaps1 resi/ances1 inductances1 arc suppress+ devices--requirem5ts--air gap arre/]s--multi-gap arre/]s2 diff]5ce betwe5 sp>k & arc2 di/ribution ( /ress2 sp>k+ at ! gaps2 h[ ! arc is ext+ui%$2 effect ( frequ5cy2 grad$ %unt resi/ances2 ! cumulative or break+ back effect--arre/]s = gr\nd$ ,y & non-gr\nd$ neutral sy/ems--multiplex connection--horn gap arre/]s3 op]ation2 objection to ! horn gap--electrolytic arre/]s3 critical voltage1 tempor>y & p]man5t2 det]m9ation ( numb] ( cell2 putt+ cell 9 commission2 nature ( ! film2 horn gaps on electrolytic arre/]s2 *>g+ ( electrolytic arre/]s2 *>g+ arre/]s = non-gr\nd$ circuits--gr\nd$ & non-gr\nd$ neutral circuits--gr\nd connections--*oke coils3 pr9cipal objects2 pr9cipal electrical conditions to be avoid$2 :y *oke coils are made 9 ! =m ( an h\r glass2 cool+--/atic int]rupt]s2 h[ to connect cond5s] & *oke coil2 effect ( cond5s]4 ,,regulat+ ,,devices #a1gae to #a1gfb ,regulation ( alt]nators--a4c4 fe$] regulation--application ( induction type regulators2 types3 induction1 & v>iable ratio trans=m] regulators2 op]ation ( induction regulators2 neutral position2 regulator capacity--polyphase induction regulators3 con/ruction1 op]ation2 automatic control2 :y two relays are us$2 difficulties enc\nt]$ 9 op]ation ( relays2 vibration or *att]+ ( ! contacts2 poor contact ( prim>y relay--v>iable ratio trans=m] voltage regulators3 types3 drum1 & dial2 dial type = high voltage--small fe$] voltage regulators3 con/ruction & op]ation2 adju/m5t--automatic voltage regulators = alt]nators3 me?od ( regulation--l9e drop comp5sators3 ess5tial p>ts2 connections2 con/ruction & op]ation2 diagram ( automatic voltage regulator us+ a l9e drop comp5sator--/>t+ comp5sators3 necessity =2 con/ruction & op]ation--/> delta swit*es4 ,,syn*ron\s ,,cond5s]s #a1gfc to #a1ggf ,*>act]i/ics--effect ( fully load$ & lightly load$ induction motors on ! p[] factor--syn*ron\s motor us$ z cond5s]--effects ( l[ lagg+ p[] factors2 example--co/ ( syn*ron\s cond5s] vs4 co/ ( copp]--location ( cond5s]--syn*ron\s cond5s] calculations & diagram = same4 ,,indicat+ ,,devices #a1ggg to #a1hch ,virtual value ( an alt]nat+ curr5t or pressure--! ^w effective errone\sly us$ = virtual3 /eam eng9e analogy illu/rat+ ?is error--classification ( in/rum5ts3 electromagnetic or mov+ wire1 hot wire1 induction1 dynamomet]--electromagnetic or mov+ iron in/rum5ts3 types3 plung]1 incl9$ coil1 magnetic vane2 "* ( scale2 objections & precautions--incl9$ coil in/rum5ts--magnetic vane in/rum5ts--hot wire in/rum5ts--induction in/rum5ts3 types3 %ield$ pole1 rot>y field2 op]ation ( bo? types--dynamomet]s3 con/ruction & op]ation2 h[ arrang$ to measure watts--wat?\r met]s3 types3 commutator1 induction1 ,f>aday disc2 ess5tial p>ts2 object ( ! motor2 object ( g5]ator2 objection to commutator met]--pr9ciples ( induction wat?\r met]s3 ess5tial p>ts2 /r5g? ( rotat+ field2 mov+ elem5t2 ret>d+ elem5t2 regi/]+ elem5t2 frame & be>+s2 friction comp5sator2 p[] factor adju/m5t2 frequ5cy adju/m5t--,f>aday disc1 or m]cury motor amp]e h\r met]3 con/ruction & op]ation--frequ5cy indicators3 types3 syn*ron\s motor1 resonance1 induction2 syn*ron\s motor z frequ5cy indicator--resonance frequ5cy indicators3 adaptation--induction frequ5cy met]3 con/ruction & op]ation--syn*ronism indicators3 types3 lamp or voltmet]1 resonance or vibrat+ re$1 rotat+ field--p[] factor indicators3 wattmet] type2 disc1 or rotat+ field type--gr\nd detectors4 ,,*apt] ,,lv ,,alt]nat+ ,,curr5t ,,sy/ems ,! facility ) :i* alt]nat+ curr5t c be trans=m$ f "o voltage to ano!r1 ?us p]mitt+ high pressure transmission ( electric en]gy to long di/ances ?r\gh small wires1 & l[ pressure di/ribution = ! op]ation ( light+ sy/ems & motors1 gives a f> great] v>iety ( sy/ems ( transmission & di/ribution ?an is possible ) direct curr5t4 ,fur!rmore1 :5 ! fact t two phase curr5t c be readily trans=m$ into ?ree phase curr5t1 & ^! conv]t$ into direct curr5t1 & vice v]sa1 by means ( rot>y conv]t]s & rectifi]s1 is add$ to ! advantages d]iv$ by ! use ( high t5sion sy/ems1 x is app>5t t ! opportunity = elaboration becomes almo/ unlimit$4 ,^! conditions h naturally t5d$ t[>d ! developm5t ( a great v>iety ( sy/ems1 employ+ m or less complicat$ circuits & app>atus1 & al?\gh alt]nat+ curr5t practice is /ill mu* less def9ite ?an direct curr5t "w1 c]ta9 polyphase sy/ems are n[ be+ g5]ally accept$ z repres5t+ ! highe/ /&>ds ( p[] g5]ation1 transmission & di/ribution4 ,a classification ( ! v>i\s alt]nat+ curr5t sy/ems1 to be compreh5sive1 %\ld be made accord+ to sev]al po9ts ( view1 z foll[s3 #a4 ,) respect to ! arrangem5t ( ! circuit1 z a4 ,s]ies2 b4 ,p>allel2 c4 ,s]ies p>allel2 d4 ,p>allel s]ies4 #b4 ,) respect to trans=mation1 z ,trans=m]2 #c4 ,) respect to ! mode ( transmitt+ ! en]gy1 z a4 ,con/ant pressure2 b4 ,con/ant curr5t4 #d4 ,) respect to ! k9d ( curr5t1 z a4 ,s+le phase two wire2 ?ree wire2 b4 ,monocyclic f\r wire2 c4 ,two phase ?ree wire2 five wire2 six wire2 ?ree wire2 f\r wire2 d4 ,?ree phase /> connection2 delta connection2 /> delta connection2 delta /> connection2 e4 ,multi-phase ( m ?an ?ree phases2 #e4 ,) respect to transmission & di/ribution1 z a4 ,frequ5cy *ang+2 b4 ,phase *ang+2 c4 ,conv]t]2 d4 ,rectifi]4 ,9 ord] to compreh5d ! relative advantages ( ! v>i\s alt]nat+ curr5t sy/ems1 x is fir/ necess>y to und]/& ! pr9ciple ( vector summation4 ,vector ,summation4--,?is is a simple geometrical process = asc]ta9+ ! pressure at ! free t]m9als ( alt]nat+ curr5t circuits4 ,! foll[+ laws %\ld be c>efully not$3 #a4 ,if two alt]nat+ pressures :i* agree 9 phase are connect$ toge!r 9 s]ies1 ! voltage at ! free t]m9als ( ! circuit w be equal to _! ari?metical sum1 z 9 ! case ( direct curr5ts4 ,illu/ration3 ,,fig4 #b1abc4--,vectors4 ,a vector is def9$ z3 a l9e1 conceiv$ to h bo? a fix$ l5g? & a fix$ direction 9 space1 b no fix$ position4 ,?us ,a & ,b are l9es1 ea* hav+ a fix$ l5g?1 b no fix$ direction4 ,by add+ an arr[ head ! direction is fix$ & ! l9e becomes a vector1 z = example vector ,c4 ,! fix$ l5g? is usually tak5 to repres5t a def9ite =ce1 ?us ! fix$ l5g? ( vector ,c is #d4g :i* may be us$ to repres5t #d4g lbs41 #d4g tons1 etc41 z may be arbitr>ily assum$4 ,:5 !re is phase diff]5ce betwe5 ! two alt]nat+ pressures1 connect$ 9 s]ies1 ! foll[+ relation holds3 #b4 ,! value ( ! t]m9al voltage w diff] f _! ari?metical sum1 dep5d+ on ! am\nt ( _! phase diff]5ce4 ,:5 !re is phase diff]5ce1 ! value ( ! resultant is conv5i5tly obta9$ z expla9$ bel[4 ,ques4 ,h[ are vector diagrams con/ruct$ = obta9+ resultant electric pressure8 ,ans4 ,on ! pr9ciple ( ! p>allelogram ( =ces4 ,ques4 ,:at is und]/ood by ! p>allelogram ( =ces8 ,ans4 ,x is a graphical me?od ( f9d+ ! resultant ( two =ces1 accord+ to ! foll[+ law3 ,if two =ces act+ on a po9t be repres5t$ 9 direction & int5sity by adjac5t sides ( a p>allelogram1 _! resultant w be repres5t$ by ! diagonal ( ! p>allelogram :i* passes ?r\gh ! po9t4 ,illu/ration3 ,,fig4 #b1abd4--,p>allelogram ( =ces4 ,,oc is ! resultant ( ! two =ces ,,oa & ,,ob4 ,! l5g? & direction ( ! l9es repres5t ! int5sity & direction ( ! respective =ces1 ! con/ruction be+ expla9$ 9 ! accompany+ text4 ,?us 9 fig4 #b1abd1 let ,,oa & ,,ob repres5t ! int5sity & direction ( two =ces act+ at ! po9t ,o1 ,draw ,,ac & ,,bc1 respectively p>allel to ,,ob & ,,oa1 complet+ ! p>allelogram1 !n w ,,oc1 ! diagonal f ! po9t at :i* ! =ces act1 repres5t ! int5sity & direction ( ! resultant1 t is1 ( a =ce equival5t to ! comb9$ action ( ! =ces ,,oa & ,,ob1 ^! =ces be+ call$ ! compon5ts ( ! =ce ,,oc4 ,ques4 ,^u :at does ! magnitude ( ! resultant ( two =ces dep5d8 ,ans4 ,^u ! diff]5ce 9 directions 9 :i* !y act1 z %[n 9 figs #b1abe to #b1abh4 ,ques4 ,is ! p>allelogram ( =ces appli$ :5 ! diff]5ce 9 direction or phase diff]5ce ( two =ces is #ij degrees8 ,ans4 ,x is sometimes m conv5i5tly done by calculation accord+ to ! law ( ! "r angle triangle4 ,illu/ration3 ,,figs4 #b1abe to #b1abh4--,p>allelograms ( =ces %[+ increase 9 magnitude ( ! resultant ( two =ces1 z _! diff]5ce ( direction1 or electrically speak+1 _! phase diff]5ce is dim9i%$4 ,! diagrams %[ ! gr[? ( ! resultant ( ! two equal =ces ,,oa & ,,ob z ! phase diff]5ce is r$uc$ f #afe successively to #abj1 #fj1 & #ae degrees4 ,accord+ to ?is pr9ciple1 if two alt]nat+ pressures h a phase diff]5ce ( #ij degrees !y may be repres5t$ 9 magnitude & direction by ! two sides ( a "r angle triangle z ,,oa & ,,ob 9 fig4 #b1abi2 !n w ! hypot5use ,,ab repres5t ! magnitude & direction ( ! resultant pressure4 ,t is to say1 ! resultant pressure ,,ab 77,,oa7 7,,ob77 7#a7 ,,example4--,a two phase alt]nator is w\nd = #cjj volts on "o phase & #bjj volts on ! o!r phase1 ! phase diff]5ce be+ #ij4 ,if "o end ( ea* w9d+ 7 jo9$ s z to =m a s+le w9d+ ar\nd ! armature1 :at w\ld be ! resultant pressure8 ,by calculation1 sub/itut+ ! giv5 values 9 equation 7#a71 ,resultant pressure 7#cjj #bjj7 7#acj1jjj7 #cfj4f volts4 ,?is is easily done graphically z 9 fig4 #b1abi by tak+ a scale1 say1 #a #ajj volts & lay+ (f ,,oa #c #cjj volts1 & at "r angles ,,ob #b #bjj volts1 !n by measurem5t ,,ab #c4fjf #cfj4f volts4 ,illu/ration3 ,,fig4 #b1abi4--,me?od ( obta9+ ! resultant ( two compon5t pressures act+ at "r angles by solution ( "r angle triangle4 ,! equation ( ! "r angle triangle is expla9$ at l5g? 9 ,guide ,no4 #e1 page #a1jgj4 ,ques4 ,:5 ! two pressures are equal & ! phase diff]5ce is #ij1 is x necess>y to use equation 7#a7 to obta9 ! resultant8 ,ans4 ,no4 ,! resultant is obta9$ by simply multiply+ "o ( ! pressures by #a4da4 ,?is is evid5t f fig4 #b1acj4 ,"h ! two pressures ,,oa & ,,ob are equal z indicat$ by ! dott$ arc4 ,s9ce !y act at "r angles1 ,,ob is drawn at #ij to ,,oa4 ,accord+ to ! equation ( ! "r angle triangle1 ! resultant ,,ab 7#a #a7 #b #a4dadb :i* ord9>ily is tak5 z #a4da4 ,?is value w always repres5t ! ratio betwe5 ! magnitude ( ! resultant & ! two compon5t =ces1 :5 ! latt] are equal1 & h a phase diff]5ce ( #ij degrees4 ,=ms ( ,circuit4--,alt]nat+ curr5t sy/ems ( di/ribution may be class$1 ) respect to ! k9d ( circuit us$1 9 a mann] simil> to direct curr5t sy/ems1 t is1 !y may be call$ s]ies1 p>allel1 s]ies p>allel1 or p>allel s]ies sy/ems1 z %[n 9 figs4 #b1aca to #b1acd4 ,illu/ration3 ,,fig4 #b1acj4--;,diagram = obta9+ ! resultant ( two equal compon5t pressures act+ at "r angles4 ,s]ies ,circuits4--,^! are us$ 9 arc light+1 & s]ies inc&esc5t light+1 a con/ant curr5t be+ ma9ta9$2 also = con/ant curr5t motors & g5]ators supply+ second>y circuits4 ,illu/ration3 ,,figs4 #b1aca to #b1acd4--,v>i\s =ms ( circuit4 ,^! well kn[n =ms ( circuit are us$ 9 bo? alt]nat+ & direct curr5t sy/ems4 ,! simple s]ies circuit1 fig4 #b1aca1 is suitable = con/ant curr5t arc light+4 ,fig4 #b1acb1 %[s ! p>allel con/ant pressure circuit2 ?is =m ( circuit is l>gely us$ b is seldom connect$ direct to ! alt]nator t]m9als1 b to a /ep d[n trans=m]1 on acc\nt ( ! l[ pressure g5]ally requir$4 ,fig4 #b1acc illu/rates a p>allel s]ies circuit1 & #b1acd1 a s]ies p>allel circuit4 ,sev]al =ms ( con/ant curr5t alt]nator1 analog\s to ! ,?ompson-,h\/on & ,bru% s]ies arc dynamos1 h be5 introduc$4 ,9 ! design ( su* alt]nators self-induction & armature reaction are purposely exagg]at$2 s t ! curr5t does n increase v mu*1 ev5 :5 ! ma*9e is %ort circuit$4 ,) ?is provision1 no regulat+ device is requir$4 ,illu/ration3 ,,fig4 #b1ace4--,typical ,am]ican ov]head #f1fjj volt s+le phase int]urban trolley l9e1 ,baltimore & ,annapolis %ort l9e1 ,annapolis1 ,md4 ,an objectionable feature is t ! voltage ( a con/ant curr5t alt]nator w rise v high if ! circuit be op5$1 because x is !n reliev$ ( inductance drop & armature reaction4 ,to gu>d aga9/ a dang]\s rise ( voltage1 a film cut out or equival5t device is connect$ to ! t]m9al ( ea* ma*9e s t x w %ort circuit ! latt] if ! voltage rise too high4 ,ques4 ,:at advantage h con/ant curr5t alt]nators ov] con/ant curr5t dynamos8 ,ans4 ,! high pressure curr5t is deliv]$ to ! ext]nal circuit )\t a commutator1 h5ce !re is no sp>k+ difficulty4 ,! above relates to ! revolv+ field type ( alt]nator4 ,!re are1 h[ev]1 alt]nators 9 :i* ! armature revolves1 ! curr5t be+ deliv]$ to ! ext]nal circuit ?r\gh collector r+s & bru%es4 ,?is type ( alt]nator1 x %\ld be not$1 is = mod]ate pressures1 & moreov] !re is no int]ruption to ! fl[ ( ! curr5t su* z w\ld be occasion$ by a tang5tial bru% on a dynamo 9 pass+ f "o commutator segm5t to ! next4 ,9 ! revolv+ field ma*9e1 ?\gh ! armature curr5t be ( v high pressure1 ! field curr5t :i* passes ?r\gh ! bru%es & slip r+s is ( l[ pressure & accord+ly pres5ts no transmission difficulties4 ,illu/ration3 ,,fig4 #b1acf4--;,diagram ( p>allel circuit4 ,x is a con/ant pressure circuit & is v widely us$ = light+ & p[]4 ,if ea* lamp takes say amp]e1 ! curr5t fl[+ 9 ! circuit w v>y ) ! numb] ( lamps 9 op]ation2 9 ! above circuit ) all lamps on1 ! curr5t is #e #b amp]es4 ,ques4 ,/ate a disadvantage4 ,ans4 ,"s s\rce ( direct curr5t = field excitation is requir$4 ,ques4 ,9 a con/ant curr5t s]ies sy/em1 ^u :at does ! voltage at ! alt]nator dep5d8 ,ans4 ,! numb] ( devices connect$ 9 ! circuit1 ! volts requir$ = ea*1 & ! l9e drop4 ,p>allel ,circuits4--,^! are us$ = con/ant pressure op]ation4 ,su* arrangem5t provides a sep>ate circuit = ea* unit mak+ !m indep5d5t s t !y may v>y 9 size & ea* "o c be />t$ or /opp$ )\t int]f]+ ) ! o!rs4 ,p>allel circuits are l>gely us$ = inc&esc5t light+1 & s9ce l[ pressure curr5t is commonly us$ on su* circuits !y are usually connect$ to /ep d[n trans=m]s1 in/ead ( direct to ! alt]nators4 ,illu/ration3 ,,fig4 #b1acg4--;,diagram ( p>allel s]ies circuit1 %[+ fall ( pressure betwe5 units4 ,?is sy/em is v r>ely us$2 x has ! disadvantage t if a lamp filam5t breaks1 ! resi/ance ( ! circuit is alt]$ & ! /r5g? ( ! curr5t *ang$4 ,! voltmet] %[s ! fall ( pressure along ! l9e4 ,x %\ld be not$ t1 al?\gh ! met] across ,,ab is %[n z regi/]+ z]o pressure1 !re is1 /rictly speak+1 a slight pressure across ,,ab1 9 am\nt1 be+ t requir$ to ov]come ! resi/ance ( ! conductor betwe5 ,a & ,b4 ,p>allel ,s]ies ,circuits4--,fig4 #b1acg %[s ! arrangem5t ( a p>allel s]ies circuit & ! pressure conditions 9 same4 ,su* a circuit consi/s ( gr\ps ( two or m lamps or o!r devices connect$ 9 p>allel & ^! gr\ps connect$ 9 s]ies4 ,su* a circuit1 :5 us$ = light+1 obvi\sly has ! disadvantage t if a lamp filam5t breaks1 ! resi/ance ( ! gr\p is increas$1 ?us r$uc+ ! curr5t & decreas+ ! brilliancy ( ! lamps4 ,?is arrangem5t accord+ly does n admit ( turn+ (f any ( ! lights4 ,s]ies ,p>allel ,circuits4--,! arrangem5t ( circuits ( ?is k9d is %[n 9 fig4 #b1acd2 !y are us$ to economize 9 copp] s9ce by jo9+ gr\ps ( l[ pressure lamps 9 s]ies !y may be suppli$ by curr5t at correspond+ly high] pressure4 ,?us1 if 9 fig4 #b1acd1 #aaj volt1 amp]e lamps be us$1 ! pressure on ! ma9s1 t is1 betwe5 any two po9ts z ,a & ,b w\ld be #aaj #c #ccj volts4 ,ea* gr\p w\ld require amp]e & ! five gr\ps #e #b amp]es4 ,illu/ration3 ,,fig4 #b1ach4--dd1jjj volt l9es ent]+ ! ,ga/onia sub-/ation ( ! ,s\!rn ,p[] ,co4 ,! poles us$ are ( ! tw9 circuit two arm type1 built ( /ructural /eel1 _! height v>y+ f #de to #hj feet1 ! latt] weigh+ #i1jjj p\nds ea*4 ,^! poles h _! bases weight$ ) concrete4 ,trans=m] ,sy/ems4--,ne>ly all alt]nat+ curr5t sy/ems are trans=m] sy/ems1 s9ce ! *ief feature ( alt]nat+ curr5t is ! ease ) :i* x may be trans=m$ f "o pressure to ano!r4 ,accord+ly1 consid]able economy 9 copp] may be effect$ by transmitt+ ! curr5t at high pressure1 especially if ! di/ance be great1 &1 by means ( /ep d[n trans=m]s1 r$uc+ ! voltage at po9ts :]e ! curr5t is us$ or di/ribut$4 ,ord9>ily & = l9es ( mod]ate l5g?1 curr5t is s5t out direct f ! alt]nator to ! l9e & trans=m$ by /ep d[n trans=m]s at ! po9ts ( application4 ,) respect to ! /ep d[n trans=m]s1 !re are two arrangem5ts3 #a4 ,individual trans=m]s2 #b4 ,"o trans=m] = sev]al cu/om]s4 ,illu/ration3 ,,fig4 #b1aci4--;,diagram ( trans=m] sy/em ) individual trans=m]s4 ,! effici5cy is l[1 b su* me?od ( di/ribution is necess>y 9 sp>sely settl$ or rural di/ricts4 ,individual trans=m]s1 t is1 a sep>ate trans=m] = ea* cu/om] is necess>y 9 rural di/ricts :]e ! int]v5+ di/ances are great z %[n 9 fig4 #b1aci4 ,ques4 ,:at are ! objections to ?is me?od ( di/ribution8 ,ans4 ,x requires ! use ( small trans=m]s :i* are necess>ily less effici5t & m exp5sive p] kil[att ?an l>ge trans=m]s4 ,! trans=m] mu/ be built to c>ry1 )9 its ov]load capacity1 all ! lamps in/all$ by ! cu/om] s9ce all may be us$ occasionally4 ,usually1 h[ev]1 only a small "p ( ! lamps are 9 use1 & ^? only = a small "p ( ! day1 s t ! av]age load on ! trans=m] is a v small "p ( its capacity4 ,s9ce ! core loss cont9ues :e!r ! trans=m] be load$ or n1 b is n paid = by ! cu/om]1 ! economy ( ! arrangem5t is v l[4 ,9 ! second case1 :]e "o l>ge trans=m] may be plac$ at a di/ribution c5t]1 to supply sev]al cu/om]s1 z 9 fig4 #b1adj1 ! effici5cy ( ! sy/em is improv$4 ,ques4 ,:y is ?is arrangem5t m effici5t ?an :5 individual trans=m]s are us$8 ,illu/ration3 ,,fig4 #b1adj4--;,diagram ( trans=m] sy/em ) "o trans=m] locat$ at a di/ribution c5t] & supply+ sev]al cu/om]s z ,a1 ,b1 & ,c4 ,su* arrangem5t is consid]ably m effici5t ?an t %[n 9 fig4 #b1aci1 z expla9$ 9 ! accompany+ text4 ,ans4 ,less trans=m] capacity is requir$ ?an ) individual trans=m]s4 ,ques4 ,:y is ?is8 ,ans4 ,) sev]al cu/om]s suppli$ f "o trans=m] x is extremely improbable t all ! cu/om]s w burn all _! lamps at ! same "t4 ,x is !re=e unnecess>y to in/all a trans=m] capable ( op]at+ ! full load1 z is necess>y ) individual trans=m]s4 ,ques4 ,does ! diff]5ce 9 trans=m] capacity repres5t all ! sav+8 ,ans4 ,no2 "o l>ge trans=m] is m effici5t ?an a numb] ( small trans=m]s4 ,ques4 ,:y8 ,ans4 ,! core loss is less4 ,= in/ance1 if f\r cu/om]s hav+ #bj lamps ea* 7 suppli$ f a s+le trans=m]1 ! av]age load w\ld be ab\t #h lamps1 & at mo/ n ov] #aj or #ae lamps1 & a trans=m] c>ry+ #cj to #ce lamps at ov] load w\ld probably be suffici5t4 ,a #a1ejj watt trans=m] w\ld !re=e be l>g] ?an necess>y4 ,at #c p] c5t4 core loss1 ?is gives a con/ant loss ( #de watts1 :ile ! av]age load ( #h lamps = #c h\rs p] day gives a useful output ( #fj watts1 or an all ye> effici5cy ( ne>ly #fj p] c5t41 :ile a #a1jjj watt trans=m] w\ld give an all ye> effici5cy ( #fg p] c5t4 ,= long di/ance transmission l9es1 ! voltage at ! alt]nator is increas$ by pass+ ! curr5t ?r\gh a /ep up trans=m]1 ?us transmitt+ x at v high pressure1 & r$uc+ ! voltage at ! po9ts ( di/ribution by /ep d[n trans=m]s z 9 fig4 #b1ada4 ,illu/ration3 ,,fig4 #b1ada4--;,diagram illu/rat+ ! use ( /ep up & /ep d[n trans=m]s on long di/ance transmission l9es4 ,! sav+ 9 copp] is consid]able by employ+ extra high voltages on l9es ( mod]ate or great l5g? z indicat$ by ! relative sizes ( wire4 ,ques4 ,9 practice1 w\ld su* a sy/em z %[n 9 fig4 #b1ada be us$8 ,ans4 ,if ! greate/ economy 9 copp] 7 aim$ at1 a ?ree phase sy/em w\ld be us$4 ,! purpose ( fig4 #b1ada is to %[ ! importance ( ! trans=m] 9 giv+ a flexibility ( voltage1 by :i* ! co/ ( ! l9e is r$uc$ to a m9imum4 ,ques4 ,does ! sav+ indicat$ 9 fig4 #b1ada repres5t a net ga98 ,ans4 ,no4 ,! r$uction 9 co/ ( ! transmission is p>tly (fset by ! co/ ( ! trans=m]s z well z by trans=m] losses & ! high] insulation requirem5ts4 ,illu/ration3 ,,fig4 #b1adb4--,s+le & tw9 circuit poles 7,s\!rn ,p[] ,co474 ,! tw9 circuit pole at ! "r is us$ = #aa1jjj volt circuits1 :ile ! s+le circuit poles at ! left c>ry #dd1jjj volt conductors1 be+ us$ on ano!r division = #ajj1jjj volt l9e4 ,e case ( electric transmission pres5ts its own problem1 & ne$s ?or\gh eng9e]+ /udy to intellig5tly *oose ! sy/em be/ adapt$ = ! p>ticul> case4 ,s+le ,phase ,sy/ems4--,!re are v>i\s arrangem5ts = transmission & di/ribution class$ z s+le phase sy/ems4 ,?us1 s+le phase curr5t may be convey$ to ! v>i\s receiv+ units by ! well kn[n circuit arrangem5ts kn[n z s]ies1 p>allel1 s]ies p>allel1 p>allel s]ies1 connections previ\sly describ$ & illu/rat$ 9 figs4 #b1aca to #b1acd4 ,aga9 s+le phase curr5t may be transmitt$ by two wires & di/ribut$ by ?ree wires4 ,?is is done 9 sev]al ways1 ! simple/ be+ %[n 9 fig4 #b1adc4 ,illu/ration3 ,,fig4 #b1adc4--;,diagram illu/rat+ s+le phase two wire transmission & ?ree wire di/ribution4 ,! simplifi$ ?ree wire arrangem5t at ,a1 is n p]missible except 9 cases ( v little unbalanc+4 ,:]e ! diff]5ce betwe5 loads on ea* side ( ! neutral may be great "s =m ( balanc+ z an auto-trans=m] or equival5t %\ld be us$1 z at ,b4 ,ques4 ,"u :at conditions is ! arrangem5t %[n 9 fig4 #b1adc desirable8 ,ans4 ,?is me?od ( treat+ ! neutral wire is only p]missible :]e !re is v little unbalanc+1 t is1 :]e ! load is kept practically ! same on bo? sides ( ! neutral4 ,ques4 ,:at advantage is obta9$ by ?ree wire di/ribution8 ,ans4 ,! pressure at ! alt]nator c be d\bl$1 :i* means1 = a giv5 numb] ( lamps1 t ! curr5t is r$uc$ to half1 ! p]missible drop may be d\bl$1 ! resi/ance ( ! wires quadrupl$1 & _! co/ r$uc$ ne>ly #ge p] c5t4 ,illu/ration3 ,,fig4 #b1add4--ajj1jjj volt ,millik5 t[]s ) "o circuit /rung 7,s\!rn ,p[] ,co474 ,^! t[]s are m\nt$ on metal /ubs sunk #f feet 9 ! gr\nd4 ,:]e ! angle ( ! l9e is ov] #ae degrees1 h[ev]1 ^! /ubs are weight$ ) rock & concrete1 & :]e an angle ( ov] #cj degrees occurs1 two & sometimes ?ree t[]s are us$ = mak+ ! turn4 ,! weight ( ! /&>d ,millik5 t[] is #c1jhj lbs41 & its height f ! gr\nd to peak is #ea feet4 ,! t[]s are spac$ to av]age eight to a mile & a /ra9 t[] weigh+ #d1bej lbs4 is us$ e mile4 ,= p>ticul>ly long spans a special heavy t[] weigh+ #f1jjj lbs4 is us$4 ,! circuits are transpos$ e #cj miles4 ,multiple disc insulators are us$1 f\r discs be+ us$ to susp5d ea* conductor f /&>d t[]s & t5 discs to ea* conductor on /ra9 t[]s4 ,! /&>d span is #fjj feet1 sag #aa ft at #ej ,fahr4 ,ques4 ,:at modification ( circuit ,a 7fig4 #b1adc71 %\ld be made to all[ = unbalanc+ 9 ! ?ree wire circuit8 ,ans4 ,an auto-trans=m] or balance coil z x is sometimes call$ %\ld be us$ z at ,b4 ,?is is a v desirable me?od ( balanc+ :5 ! ratio ( trans=mation is n too l>ge4 ,ques4 ,= :at s]vice w\ld ! sy/em %[n 9 fig4 #b1adc be suitable8 ,ans4 ,= %ort di/ance transmission1 z = in/ance1 9 ! case ( an isolat$ plant because ( ! l[ pressure at :i* ! curr5t is g5]at$4 ,! /&>d voltages ( l[ pressure alt]nators are #djj1 #dhj1 & #fjj volts4 ,illu/ration3 ,,fig4 #b1ade4--,view ( a typical isolat$ plant4 ,! illu/ration repres5ts an electric light+ plant on a f>m %[+ ! light+ ( ! dwell+1 b>n1 tool h\se & pump h\se4 ,! in/allation consi/s ( a l[ voltage dynamo ) gas eng9e drive & /orage batt]y toge!r ) ! necess>y auxili>y app>atus4 ,ques4 ,9 practice are s+le phase alt]nators us$ z indicat$ 9 fig4 #b1adc8 ,ans4 ,alt]nators are w\nd = "o1 two or ?ree phases4 ,?ree phase ma*9es are m commonly suppli$ & 9 _m cases x w pay to in/all !m 9 pref]5ce to s+le phase1 ev5 if !y be op]at$ s+le phase tempor>ily4 ,= a giv5 output1 ?ree phase ma*9es are small] ?an s+le phase & ! s+le phase load c usually be approximately balanc$ betwe5 ! ?ree phases4 ,moreov]1 if a ?ree phase ma*9e be in/all$1 polyphase curr5t w be available 9 case x may be necess>y to op]ate polyphase motors at "s future "t4 ,/&>d ?ree phase alt]nators w c>ry ab\t #gj p] c5t4 ( _! rat$ kil[att output :5 op]at$ s+le phase1 ) ! same temp]ature rise4 ,ques4 ,h[ are ?ree phase alt]nators us$ = s+le phase circuits8 ,ans4 ,! s+le phase circuit is connect$ to any two ( ! ?ree phase t]m9al leads4 ,illu/ration3 ,,fig4 #b1adf4--;,diagram %[+ arrangem5t ( s+le phase sy/em = two wire transmission & ?ree wire di/ribution1 :]e ! transmission di/ance is consid]able4 ,9 ord] to r$uce ! co/ ( ! transmission l9e1 ! curr5t mu/ be transmitt$ at high pressure2 ?is necessitates ! use ( a /ep d[n trans=m] at ! di/ribut+ c5t] z %[n 9 ! illu/ration4 ,ques4 ,:at =m ( s+le phase sy/em %\ld be us$ :]e ! transmission di/ance is consid]able8 ,ans4 ,! curr5t %\ld be transmitt$ at high pressure1 a /ep d[n trans=m] be+ plac$ at ea* di/ribution c5t] to r$uce ! pressure to ! prop] voltage to suit ! s]vice requirem5ts z %[n 9 fig4 #b1adf4 ,?us1 if #aaj volt lamps be us$ on ! ?ree wire circuit1 ! pressure betwe5 ! two out] wires w\ld be #bbj volts4 ,a trans=mation ratio ( say #aj3a w\ld give #b1bbj volts = ! prim>y circuit4 ,! curr5t requir$ = ! prim>y ) ?is ratio be+ only 4#a t us$ 9 ! second>y1 a consid]able sav+ is effect$ 9 ! co/ ( ! transmission l9e z mu/ be evid5t4 ,) ! high pressure alt]nator only "o trans=mation ( ! curr5t is ne$$1 z %[n at ! di/ribution end4 ,9 place ( ! high pressure alt]nator1 a l[ pressure alt]nator c\ld be us$ 9 connection ) a /ep up trans=m] z %[n 9 fig4 #b1adg1 b !re w\ld be an extra loss due to ! additional trans=m]1 r5d]+ ! sy/em less effici5t ?an ! "o %[n 9 fig4 #b1adf4 ,su* an arrangem5t z %[n 9 ! fig4 #b1adg might be ju/ifi$ 9 ! case ( a /ation hav+ a l[ pressure alt]nator already 9 use & x %\ld be desir$ to transmit a portion ( ! en]gy a consid]able di/ance4 ,ques4 ,h[ c\ld ! sy/em %[n 9 fig4 #b1adg be made m effici5t ?an t ( fig4 #b1adf8 ,ans4 ,by us+ a high pressure alt]nator 9 ord] to consid]ably increase ! transmission voltage4 ,?us1 a #b1bjj volt alt]nator & #a3aj /ep up trans=m] w\ld give a l9e pressure ( #bb1jjj volts1 :i* at ! di/ribution end c\ld be r$uc$1 to #bbj volts = ! ?ree wire circuit1 us+ a #ajj3a /ep d[n trans=mation4 ,illu/ration3 ,,fig4 #b1adg4--;,diagram illu/rat+ h[ electricity c be economically transmitt$ a consid]able di/ance ) l[ pressure alt]nator already 9 use4 ,ques4 ,w\ld ?is be ! be/ arrangem5t8 ,ans4 ,no4 ,ques4 ,:at sy/em w\ld be us$ 9 practice = maximum economy8 ,ans4 ,?ree phase f\r wire4 ,ques4 ,:at are ! objections to s+le phase g5]ation & transmission8 ,ans4 ,x does n p]mit ( ! use ( syn*ron\s conv]t]s1 self-/>t+ syn*ron\s motors1 or induction motor />t+ "u load4 ,x is poorly adapt$ to g5]al p[] di/ribution1 h5ce x is op5 to grave objections ( a comm]cial nature :]e !re exi/s any possibility ( sell+ p[] or 9 any way utiliz+ x = g5]al conv]t] & motor "w4 ,illu/ration3 ,,fig4 #b1adh4--;,angle t[] %[+ ,g5]al ,electric /ra9 insulators4 ,! t[] be+ subject to great torsional /ra9s is erect$ on a massive concrete f\ndation4 ,! con/ruction is simil> to ! /&>d t[] b ( heavi] mat]ial1 & hav+ ! same v]tical dim5sions b ) bases #bj ft4 squ>e4 ,ques4 ,= :at s]vice is x desirable8 ,ans4 ,= alt]nat+ curr5t railway op]ation4 ,!re are advantages ( simplicity 9 ! entire g5]at+1 prim>y1 & second>y di/ribution sy/ems = s+le phase roads4 ,^! advantages are s great t !y ju/ify consid]able exp5se1 look$ at f ! railway po9t ( view only1 ! s+le phase sy/em ?r\gh\t may be consid]$ z (f]+ ! mo/ advantage4 ,ques4 ,:at are ! objectionable features ( s+le phase alt]nators8 ,ans4 ,?is type ( alt]nator has an unbalanc$ armature reaction :i* is ! cause ( consid]able flux v>iation 9 ! field pole tips & 9 fact ?r\gh\t ! field /ructure4 ,9 ord] to m9imize eddy curr5ts1 su* alt]nators mu/ accord+ly be built ) ?9n] lam9ations & frequ5tly poor] me*anical con/ruction1 result+ 9 increas$ co/ ( ! ma*9e4 ,! l>ge armature reaction results 9 a mu* poor] regulation ?an t obta9$ ) ?ree phase alt]nators1 & an increas$ am\nt ( field copp] is requir$1 also l>g] excit+ units4 ,^! items augm5t ! co/ s t ! s+le phase ma*9e is consid]ably m exp5sive ?an ! ?ree phase1 ( ! same output & heat+4 ,illu/ration3 ,,fig4 #b1adi4--;,elem5t>y alt]nator develop+ "o volt at frequ5cies ( #fj & #be1 %[+ ! effect ( r$uc+ ! frequ5cy4 ,s9ce = ! same numb] ( pole1 ! ,r4,p4,m4 h to be decreas$ to decrease ! frequ5cy1 increas$ flux is requir$ to develop ! same voltage4 ,h5ce 9 con/ruction1 l[ frequ5cy ma*9es require l>g] magnets1 increas$ numb] ( turns 9 s]ies on ! armature coils1 l>g] excit+ units z comp>$ ) ma*9es built = high] frequ5cy4 ,ques4 ,:at factor increases ! difficulties ( s+le phase alt]nator con/ruction8 ,ans4 ,! difficulties appe> to increase ) a decrease 9 frequ5cy4 ,! adoption ( any l[] frequ5cy ?an #be cycles may result 9 s]i\s difficulties 9 con/ruction = a complete l9e ( ma*9e1 especially ^? ( ! two or f\r pole turb9e driv5 type :]e ! field flux is v l>ge p] pole4 ,monocyclic ,sy/em4--,9 ?is sy/em1 :i* is due to ,/e9metz1 ! alt]nator is ( a special type4 ,9 con/ruction1 !re is a ma9 s+le phase w9d+ an auxili>y or teas] w9d+ connect$ to ! c5tral po9t ( ! ma9 w9d+ 9 quadrature !re)4 ,! teas] coil g5]ates a voltage equal to ab\t #be p] c5t4 ( t ( ! ma9 coil s t ! pressure betwe5 ! t]m9als ( ! ma9 coil & ! free end ( ! teas] is ! resultant ( ! pressure ( ! two coils4 ,illu/ration3 ,,fig4 #b1aej4--;,diagram ( monocyclic sy/em1 %[+ light+ & p[] circuits4 ,by v>i\s trans=m] connections x is possible to obta9 a practically correct ?ree phase relation%ip s t polyphase motors may be employ$4 ,9 ?is sy/em1 two wires lead+ f ! ends ( ! s+le phase w9d+ 9 ! alt]nator supply s+le phase curr5t to ! light+ load1 a ?ird wire connect$ to ! end ( ! teas] be+ run to po9ts :]e ! polyphase motors are in/all$ z %[n 9 fig4 #b1aej4 ,! monocyclic sy/em is describ$ at l5g? 9 ! *apt] on alt]nators1 ,guide ,no4 #e1 pages1 #a1aef to #a1aei4 ,two ,phase ,sy/ems4--,a two phase circuit is equival5t to two s+le phase circuits4 ,ei!r f\r or ?ree wire may be employ$ 9 transmitt+ two phase curr5t1 & ev5 9 ! latt] in/ance ! conditions are practically ! same z = s+le phase transmission1 except+ ! unequal curr5t di/ribution 9 ! ?ree wires4 ,fig4 #b1aea %[s a two phase f\r wire sy/em4 ,illu/ration3 ,,fig4 #b1aea4--;,diagram ( two phase f\r wire sy/em4 ,x is desirable = supply+ curr5t = light+ & p[]4 ,! arrangem5t "h %[n %\ld be us$ only = l9es ( %ort or mod]ate l5g?1 because ( ! l[ voltage4 ,motors %\ld be connect$ to a circuit sep>ate f ! light+ circuit to avoid drop on ! latt] :ile />t+ a motor4 ,ques4 ,= :at s]vice is ! sy/em %[n 9 fig4 #b1aea desirable8 ,ans4 ,x is adapt$ to supply+ curr5t = light+ & p[] at mod]ate or %ort di/ances4 ,ei!r #aaj or #bbj volts are ord9>ily us$ :i* is suitable = inc&esc5t light+ & = con/ant pressure arc lamps1 ! lamps be+ connect$ s+ly or two 9 pairs4 ,ques4 ,:]e curr5t = bo? p[] & light are obta9$ f ! same s\rce h[ %\ld ! circuits be arrang$8 ,ans4 ,a sep>ate circuit %\ld be employ$ = ea*1 9 ord] to avoid ! objectionable drop & consequ5t dimm+ ( ! lights due to ! sudd5 ru% ( curr5t dur+ ! />t+ ( a motor4 ,illu/ration3 ,,fig4 #b1aeb4--;,diagram ( two phase ?ree wire sy/em4 ,a wire is connect$ to "o end ( ea* phase w9d+ z at ,a & ,b1 & a ?ird wire ,c1 to ! o!r end ( bo? phases z %[n4 ,disagreeable fluctuation ( ! lights are always met ) :5 motors are connect$ to a light+ circuit & ! effect is m m>k$ ) alt]nat+ curr5t ?an ) direct curr5t1 because mo/ types ( alt]nat+ curr5t motor require a heavy curr5t usually lagg+ consid]ably :5 />t+4 ,?is n only causes a l>ge drop on ! l9e1 b also reacts injuri\sly ^u ! regulation ( trans=m]s & alt]nators1 _! voltage fall+ mu* m ?an ) an equal non-inductive load4 ,ques4 ,:at voltages are ord9>ily us$ on two phase l9es ( m ?an mod]ate l5g?8 ,ans4 ,= transmission di/ances ( m ?an two or ?ree miles1 pressures ( f #a1jjj to #b1jjj volts or m are employ$ to economize 9 copp]4 ,= long di/ance transmission ( ov] fifty miles1 f #cj1jjj to #ajj1jjj volts & ov] are us$4 ,ques4 ,= long di/ance transmission at #cj1jjj to #dj1jjj volts1 :at additional app>atus is necess>y8 ,ans4 ,/ep up & /ep d[n trans=m]s4 ,illu/ration3 ,,fig4 #b1aec4--;,diagram illu/rat+ two phase ?ree wire transmission4 ,! ?ird wire ,c is atta*$ to ! connector betwe5 "o end ( phase ,a1 & phase ,b w9d+s4 ,ques4 ,expla9 ! me?od ( transmitt+ two phase curr5t ) ?ree wires4 ,ans4 ,! connections at ! alt]nator are v simple z %[n 9 fig4 #b1aeb4 ,"o end ( ea* phase w9d+ is connect$ by ! bru%es a & b'1 to "o ( ! circuit wires1 t is to ,a & ,b respectively4 ,! o!r end ( ea* phase w9d+ is connect$ by a lead across bru%es a' & b1 to :i* ! ?ird wire ,c is jo9$4 ,! curr5t & pressure conditions ( ?is sy/em are repres5t$ diagrammatically 9 fig4 #b1aec4 ,! lett]s correspond to ^? 9 fig4 #b1aeb1 ) :i* x %\ld be comp>$4 ,z %[n 9 ! figure ea* coil is c>ry+ #ajj amp]es at #a1jjj volts pressure4 ,s9ce ! phase diff]5ce betwe5 ! two coils is #ij1 ! voltage betwe5 ,a & ,b is #b #a4dad times t betwe5 ei!r ,a or ,b & ! common return wire ,c4 ,! curr5t 9 ,c is #b #a4dad times t 9 ei!r outside wire ,a or ,b1 z indicat$4 ,ques4 ,h[ %\ld ! load on ! two phase ?ree wire sy/em be di/ribut$8 ,ans4 ,! load on ! two phases mu/ be c>efully balanc$4 ,illu/ration3 ,,fig4 #b1aed4--;,diagram ( two phase ?ree wire sy/em & connections = motors & light+ circuits4 ,ques4 ,:y %\ld ! p[] factor be kept high8 ,ans4 ,a high p[] factor %\ld be ma9ta9$ 9 ord] to keep ! voltage on ! phases ne>ly ! same at ! receiv+ ends4 ,ques4 ,h[ %\ld s+le phase motors be connect$ & :at precaution %\ld be tak58 ,ans4 ,s+le phase motors may be connect$ to ei!r or bo? phases1 b 9 su* cases1 no load %\ld be connect$ betwe5 ! out] wires o!rwise ! voltages on ! diff]5t phases w be badly unbalanc$4 ,fig4 #b1aed %[s a two phase ?ree wire sy/em1 ) two wire & ?ree wire di/ribution circuits1 illu/rat+ ! connection = light+ & = "o & two phase motors4 ,illu/ration3 ,,fig4 #b1aee4--;,diagram ( two phase sy/em ) f\r wire transmission & ?ree wire di/ribution4 ,9 ! ?ree wire circuits ! relative pressures betwe5 conductors are z indicat$2 t is1 ! pressure betwe5 ! two out] wires ,a & ,b is #ada volts1 :5 ! pressure betwe5 ea* out] wire & ! c5tral is #ajj volts4 ,ques4 ,describe ano!r me?od ( transmission & di/ribution ) two phase curr5t4 ,ans4 ,! curr5t may be transmitt$ on a f\r wire circuit & di/ribut$ on ?ree wire circuit z 9 fig4 #b1aee4 ,! f\r wire transmission circuit is evid5tly equival5t to two indep5d5t s+le phase circuits4 ,9 *ang+ f f\r to ?ree wires1 x is j z well to connect ! two outside wires ,a & ,b toge!r 7fig4 #b1aeb71 z x is to connect a & b4 ,x makes no diff]5ce :i* two second>y wires are jo9$ toge!r1 s long z ! o!r wires ( ea* trans=m] are connect$ to ! outside wires ( ! second>y sy/em4 ,ques4 ,= :at s]vice is ! two phase ?ree wire sy/em adapt$8 ,ans4 ,x is desirable = supply+ curr5t ( m9imum pressure to app>atus 9 ! vic9ity ( trans=m]s4 ,x is m frequ5tly us$ 9 connection ) motors op]at+ f ! second>ies ( ! trans=m]s4 ,ques4 ,h[ %\ld ! ?ird or common return wire be proportion$8 ,ans4 ,s9ce ! curr5t 9 ! common return wire is #da4d p] c5t4 high] ?an t 9 ei!r ( ! o!r wires x mu/ be ( correspond+ly l>g] cross section1 to keep ! loss equal4 ,illu/ration3 ,,figs4 #b1aef & #b1aeg4--;,conv5tional diagrams illu/rat+ /> & delta connect$ ?ree phase alt]nator armatures4 ,ques4 ,:at is ! effect ( an inductive load on ! two phase ?ree wire sy/em & :y8 ,ans4 ,x causes an unbalanc+ ( bo? sides ( ! sy/em ev5 ?\gh ! en]gy load be equally divid$4 ,! self-induction pressure 9 "o side ( ! sy/em is 9 phase ) ! virtual pressure 9 ! o!r side1 ?us di/ort+ ! curr5t di/ribution 9 bo? circuits4 ,ques4 ,describe ! two phase five wire sy/em4 ,ans4 ,a two phase circuit may be *ang$ f f\r to five wires by arrang+ ! trans=m] connections z 9 fig4 #b1aeh4 ,z %[n1 ! second>ies ( ! trans=m]s are jo9$ 9 s]ies & leads br\ght out f ! middle po9t ( ea* second>y w9d+ & at ! connection ( ! two w9d+s1 giv+ five wires4 ,) #a1jjj volts 9 ! prim>y w9d+s & a /ep d[n ratio ( #aj3a1 ! pressure betwe5 ,a & ,c & ,c & ,e w be #ajj volts & betwe5 ! po9ts & ! connections ,b or ,d at ! middle ( ! second>y coils1 #ej volts4 ,! pressure across ! two out] wires ,a & ,e is1 z 9 ! ?ree wire sy/em1 #b or #a4da times t f ei!r out] wire to ! middle wire ,c1 t is #ada volts4 ,! pressure across ! two wires connect$ to ! middle ( ! coils1 t is1 across ,b & ,d1 is #ej #b #gj4e volts4 ,illu/ration3 ,fig4 #b1aeh4--,two phase f\r wire transmission & five wire di/ribution sy/em4 ,! relative pressures betwe5 ! v>i\s conductors are indicat$ 9 ! diagram4 ,?ree ,phase ,sy/ems4--,!re are v>i\s ways ( arrang+ ! circuit = ?ree phase curr5t giv+ num]\s ?ree phase sy/ems4 #a4 ,) respect to ! numb] ( wires us$ !y may be classifi$ z a4 ,six wire2 b4 ,f\r wire2 c4 ,?ree wire4 ,illu/ration3 ,,fig4 #b1aei4--,l9e connections ( ?ree phase ?ree wire long di/ance transmission1 & di/ribution sy/em4 ,! ?ree phase alt]nator ,a1 is driv5 by ! wat] :eel ,b1 & furni%es curr5t at say #b1bjj volts plus suffici5t pressure to comp5sate = l9e drop4 ,) #a3aj /ep up trans=m]s ,c1 ?is w\ld give a transmission pressure ( #bb1jjj volts plus l9e drop4 ,x is ?is trans=mation t secures ! copp] economy ( ! sy/em4 ,at ! di/ribution end are ! /ep d[n trans=m]s2 "o set r$uc+ ! voltage d[n to #b1bjj volts1 & supply+ curr5t direct to ! syn*ron\s motor1 & ?r\gh ano!r set ( o!r /ep d[n trans=m]s1 z ,l & ,k1 to light+ & p[] circuits at #bbj volts4 ,ano!r set ( /ep d[n trans=m]s ,m r$uce ! pressure directly to #abj volts = p[] & light+1 ! pressure be+ regulat$ by ! regulators ,g4 ,arc lamps ) individual trans=m]s fur!r r$uc+ ! pressure to #ej volts are connect$ to ?is circuit z %[n4 #b4 ,) respect to ! connections1 z a4 ,/>2 b4 ,delta2 c4 ,/> delta2 d4 ,delta />4 ,! six wire sy/em is %[n 9 fig4 #b1afj4 ,x is equival5t to ?ree indep5d5t s+le phase circuits4 ,su* arrangem5t w\ld only be us$ 9 v r>e in/ances4 ,illu/ration3 ,,fig4 #b1afj4--,?ree phase six wire sy/em4 ,x is equival5t to ?ree indep5d5t s+le phase circuits & w\ld be us$ only 9 v r>e cases4 ,ques4 ,h[ c ?ree phase curr5t be transmitt$ by ?ree conductors8 ,ans4 ,! arrangem5t %[n 9 fig4 #b1afj may be resolv$ into ?ree s+le circuits ) a common or gr\nd$ return4 ,:5 ! circuits are balanc$ ! sum ( ! curr5t be+ z]o no curr5t w fl[ 9 ! return conductor1 & x may be disp5s$ )1 ?us giv+ ! ord9>y /> or ,y connect$ ?ree wire circuit1 z %[n 9 fig4 #b1afc4 ,! trans=mation f six to ?ree wires be+ %[n 9 figs4 #b1afa to #b1afc4 ,illu/ration3 ,,figs4 #b1afa to #b1afc4--;,evolution ( ! ?ree phase ?ree wire sy/em4 ,fig4 #b1afa is a conv5tional diagram ( ! ?ree phase six wire sy/em %[n 9 fig4 #b1afj4 ,a wire is connect$ to bo? ends ( ea* phase w9d+1 giv+ six conductors1 or ?ree indep5d5t two wire circuits4 ,9 place ( ! wires runn+ f ,a1 ,b1 & ,c1 !y may be remov$ & ea* circuit provid$ ) a gr\nd return z %[n 9 fig4 #b1afb4 ,! sum ( ! ?ree curr5ts be+ z]o1 or ne>ly z]o1 accord+ to ! degree ( unbalanc+1 ! gr\nd return may be elim9at$ & ! ends ,a1 ,b1 & ,c ( ! ?ree phase w9d+ connect$1 z 9 fig4 #b1afc1 giv+ ! s call$ /> po9t4 ,fig4 #b1aff is a view ( an elem5t>y ?ree phase ?ree wire /> connect$ alt]nator4 ,ques4 ,:at are ! pressure & curr5t relations ( ! /> connect$ ?ree wire sy/em8 ,illu/ration3 ,,figs4 #b1afd & #b1afe4--,?ree phase f\r wire /> connect$ alt]nator & conv5tional diagram %[+ pressure & curr5t relations4 ,illu/ration3 ,,figs4 #b1aff & #b1afg4--,?ree phase /> connect$ alt]nator1 & conv5tional diagram %[+ pressure relations4 ,ans4 ,^! are %[n 9 ! diagram1 fig4 #b1aff & #b1afg4 ,assum+ #ajj amp]es & #a1jjj volts 9 ea* phase w9d+1 ! pressure betwe5 any two conductors is equal to ! pressure 9 "o w9d+ multipli$ by #c1 t is #a1jjj #a4gcb #a1gcb volts4 ,! curr5t 9 ea* conductor is equal to ! curr5t 9 ! w9d+1 or #ajj amp]es4 ,ques4 ,describe ! delta connection4 ,ans4 ,9 ! delta connection1 ! ?ree phase coils are connect$ toge!r =m+ an endless w9d+1 leads be+ br\ght out f ^! po9ts4 ,fig4 #b1afh %[s a delta connect$ ?ree phase alt]nator1 ! pressure & curr5t relation be+ giv5 9 fig4 #b1afi4 ,illu/ration3 ,,figs4 #b1afh & #b1afi4--,?ree phase delta connect$ alt]nator & conv5tional diagram %[+ pressure & curr5t relations4 ,ques4 ,:at are ! pressure & curr5t relations ( ! delta connect$ ?ree wire sy/em8 ,ans4 ,!y are z %[n 9 fig4 #b1afi4 ,assum+ #ajj amp]es & #a1jjj volts 9 ea* phase w9d+1 ! pressure betwe5 any two conductors is ! same z ! pressure 9 ! w9d+1 & ! curr5t 9 any conductor is equal to ! curr5t 9 ! w9d+ multipli$ by #c1 t is #ajj #a4gcb #agc4b amp]es1 t is1 disreg>d+ ! fraction1 #agc amp]es4 ,ques4 ,:at are ! relative m]its ( ! /> & delta connections8 ,ans4 ,! p[] output ( ea* is ! same1 b ! /> connection gives a high] l9e voltage1 h5ce small] conductors may be us$4 ,illu/ration3 ,,fig4 #b1agj4--,t connection ( trans=m]s 9 :i* ?ree phase curr5t is trans=m$ ) two trans=m]s4 ,! connections are cle>ly %[n 9 ! illu/ration4 ,! voltage across "o trans=m] is only #hf4f ( t across ! o!r1 s t if ea* trans=m] be design$ especially = its "w "o w h a rat+ ( 4#hff ,,ei & ! o!r ,,ei4 ,! comb9$ rates w !n be #a4hff z comp>$ ) #a4gcb ,,ei = ?ree s+le phase trans=m]s connect$ ei!r /> or delta4 ,:5 x is rememb]$ t ! co/ ( copp] conductors is inv]sely z ! squ>e ( ! voltage1 ! advantage ( ! ,y connect$ sy/em c be se5 at once4 ,assum+ t ?ree trans=m]s are us$ = a ?ree phase sy/em ( giv5 voltage1 ea* trans=m]1 /> connect$1 w\ld be w\nd = #a #c #eh ( ! giv5 voltage1 & = full curr5t4 ,= delta connection1 ! w9d+ ( ea* trans=m] is = #eh ( ! curr5t4 ,accord+ly ! turns requir$ = /> connection are only #eh ( ^? requir$ = delta connection4 ,ques4 ,:at is ! objection to ! /> connection = ?ree phase "w8 ,ans4 ,x requires ! use ( ?ree trans=m]s1 & if any?+ happ5 to "o1 ! entire set is disabl$4 ,ques4 ,does ?is defect exi/ ) ! delta connection8 ,ans4 ,no4 ,"o trans=m] may be cut out & ! o!r two op]at$ at full capacity1 t is at ! capacity ( ! ?ree4 ,ques4 ,describe ! ,t connection4 ,ans4 ,9 ?is me?od two trans=m]s are us$ = trans=m+ ?ree phase curr5t4 ,x consi/s 9 connect+ "o end ( bo? w9d+s ( "o trans=m] to ! middle po9t ( l w9d+s ( ! o!r trans=m] z 9 fig4 #b1agj4 ,illu/ration3 ,,fig4 #b1aga4--,op5 delta connection or me?od ( connect+ two trans=m]s 9 delta = ?ree phase trans=mation4 ,x is us$ :5 "o ( ! ?ree s+le phase delta connect$ trans=m]s becomes disabl$4 ,ques4 ,:at is ! op5 delta connection8 ,ans4 ,x is a me?od ( arrang+ ! connections ( a bank ( ?ree delta connect$ trans=m]s :5 "o becomes disabl$ z 9 fig4 #b1aga4 ,*ange ( ,frequ5cy4--,!re are num]\s in/ances :]e x is desirable to *ange f "o frequ5cy to ano!r1 z = in/ance to jo9 two sy/ems ( diff]5t frequ5cy :i* may supply ! same or adjac5t t]ritory1 or1 9 ! case ( a l[ frequ5cy in/allation1 9 ord] to op]ate inc&esc5t lights satisfactorily x w\ld be desirable to increase ! frequ5cy = su* circuits4 ,?is is done by motor g5]ator sets1 ! motor tak+ its curr5t f ! l[ frequ5cy circuit4 ,syn*ron\s motors are g5]ally us$ = su* s]vice z ! frequ5cy is n di/urb$ by load *anges2 x also makes x possible to use ! set 9 ! rev]se ord]1 t is1 tak+ p[] f ! high frequ5cy ma9s & deliv]+ en]gy at l[ frequ5cy4 ,illu/ration3 ,,fig4 #b1agb4--;,c\rse ( ! ,s*aghticoke-,s*5ectady transmission l9e ( ! ,s*5ectady ,p[] ,co4 ,?is transmission l9e c>ries practically ! entire output ( ! ,s*aghticoke p[] h\se to ,s*5ectady1 ,n4 ,y41 a di/ance ( approximately #ba miles4 ,! l9e consi/s ( two sep>ate ?ree phase1 #dj cycle1 #cb1jjj volt circuits1 ea* ( #f1jjj kw4 normal capacity4 ,^! circuits />t f opposite ends ( ! p[] h\se1 &1 aft] cross+ ! ,hoosic ,riv]1 are transf]r$ by means ( two t]m9al t[]s1 fig4 #b1agc1 to a s+le l9e ( transmission t[]s4 ,! two circuits are c>ri$ on ^! on opposite ends ( ! cross arms1 ! ?ree phases be+ sup]impos$4 ,! p[] h\se ends ( ! l9e are held by six %ort quadrangul> /eel lattice "w an*or poles ) _! bases firmly emb$d$ 9 concrete1 ! cables be+ dead end$ by ,g5]al ,electric disc /ra9 insulators4 ,?is equipm5t1 toge!r ) ! lightn+ arre/] horn gaps & ! heavy l9e outlet insulators m\nt$ on ! ro( ( ! p[] h\se1 is %[n 9 fig4 #b1agd4 ,:ile ea* circuit c>ries only #f1jjj kw4 "u normal conditions1 ei!r is capable ( c>ry+ ! entire output ( ! /ation2 9 ?is case1 h[ev]1 ! l9e losses are necess>ily augm5t$4 ,?is feature prev5ts any int]ruption ( ! s]vice f ! failure ( "o ( ! circuits4 ,!re are altoge!r #aig transmission t[]s1 compris+ sev]al di/9ct types4 ,ques4 ,9 ! p>allel op]ations ( frequ5cy *ang+ sets :at is necess>y to secure equal division ( ! load8 ,ans4 ,! relative angul> position ( ! rotat+ elem5ts ( motor & g5]ator mu/ be ! same respectively 9 ea* set4 ,illu/ration3 ,,fig4 #b1agc4--;,beg9n+ ( ,s*aghticoke-,s*5ectady transmission l9e2 view %[+ transf] t[]s ) p[] h\se 9 backgr\nd4 ,ques4 ,h[ is ?is obta9$8 ,ans4 ,because ( ! me*anical difficulty ( accurately locat+ ! p>ts1 ! equival5t result is secur$ by arrang+ ! /ation>y elem5t 9 "o ( ! two ma*9es s t x c be giv5 a small angul> %ift4 ,trans=mation ( ,phases4--,9 alt]nat+ curr5t circuits x is frequ5tly desirable to *ange f "o numb] ( phases to ano!r4 ,= in/ance1 9 ! case ( a conv]t]1 x is less exp5sive & m effici5t to use "o built = six phases ?an = ei!r two or ?ree phases4 ,illu/ration3 ,,fig4 #b1agd4--,view f ro( ( p[] h\se ( ! ,s*aghticoke-,s*5ectady transmission l9e1 %[+ an*or poles1 /ra9 insulators1 lightn+ arre/] horn gap & l9e entrance bu%+s4 ,! num]\s conditions met ) necessitate v>i\s phase trans=mations1 z #a4 ,?ree phase to "o phase2 #b4 ,?ree phase to two phase2 #c4 ,two phase to six phase2 #d4 ,?ree phase to six phase4 ,^! trans=mations are accompli%$ by ! num]\s arrangem5ts & comb9ations ( ! trans=m]s4 ,illu/ration3 ,,fig4 #b1age4--,?ree phase to "o phase trans=mation ) two trans=m]s4 ,! diagram %[s ! necess>y connections & ! relative pressures obta9$4 ,?ree ,phase to ,"o ,phase4--,?is trans=mation may be accompli%$ by ! use ( two trans=m]s connect$ z 9 fig4 #b1age 9 :i* "o end ( "o prim>y w9d+ is connect$ to ! middle ( ! o!r prim>y w9d+ & ! second end ( ! fir/ prim>y w9d+ at a po9t giv+ #hf4f p] c5t4 ( t w9d+ z %[n4 ,! two second>y w9d+s are jo9$ 9 s]ies4 ,?ree ,phase to ,two ,phase4--,! ?ree phase sy/em is univ]sally us$ = long di/ance transmission1 because x requires less copp] ?an ei!r ! s+le or two phase sy/ems4 ,= di/ribution1 h[ev]1 ! two phase sy/em pres5ts c]ta9 advantages1 ?us1 x becomes desirable at ! di/ribution c5t]s to *ange f ?ree phase to two phase4 ,?is may be done 9 sev]al ways4 ,ques4 ,describe ! ,scott connection4 ,illu/ration3 ,,fig4 #b1agf4--,! ,scott connection = trans=m+ f ?ree phase to two phase4 ,9 ?is me?od "o ( ! prim>y wires ,b ( ! 4#hff ratio trans=m] is connect$ to ! middle ( ! o!r prim>y z at ,c1 ! ends ( :i* are connect$ to two ( ! ?ree phase wires4 ,! o!r phase wire is connect$ at ,d1 ! po9t giv+ ! 4#hff ratio4 ,! second>y wires are connect$ z %[n4 ,ans4 ,two trans=m]s are us$1 "o hav+ a #aj3a ratio1 & ! o!r1 a #c3a1 t is1 an #h4ff3a ratio4 ,! connections are arrang$ z 9 fig4 #b1agf4 ,x is cu/om>y to employ /&>d trans=m]s hav+ ! ratios #aj3a1 & #i3a4 ,ques4 ,:at names are giv5 to ! two trans=m]s8 ,ans4 ,! "o hav+ ! #aj3a ratio is call$ ! ma9 trans=m]1 & ! o!r ) ! #h4ff3a ratio1 ! teas] trans=m]4 ,9 con/ruction1 ! trans=m]s may be made exactly alike s t ei!r may be us$ z ma9 or teas]4 ,9 ord] t ! connections may be prop]ly & conv5i5tly made1 ! prim>y w9d+s %\ld be provid$ ) #ej & #hf4f taps4 ,illu/ration3 ,,fig4 #b1agg4--,?ree phase to two phase trans=mation ) ?ree /> connect$ trans=m]s4 ,two ( ! second>y w9d+s are tapp$ at po9ts correspond+ to #eg4g ( full voltage2 ^! two w9d+s are connect$ 9 s]ies to =m "o second>y phase ( voltage equal to t obta9$ by ! o!r full second>y w9d+4 ,ques4 ,describe ano!r way ( trans=m+ f ?ree to two phases4 ,ans4 ,! trans=mation may be made by ?ree /> connect$ trans=m]s1 proportion+ ! w9d+s z 9 fig4 #b1agg1 f :i* x w be se5 t two ( ! second>y w9d+s are tapp$ at po9ts correspond+ to #eg4g p] c5t4 ( full voltage4 ,?ree ,phase to ,six ,phase4--,?is trans=mation is usually made = use ) rot>y conv]t]s & may be accompli%$ 9 sev]al ways4 ,z ^! me?ods h be5 illu/rat$ 9 ! *apt] on ,conv]t]s 7page #a1dfb71 x is unnecess>y to aga9 discuss !m "h4 ,fig4 #b1agh1 bel[ %[s ! diametrical connection = trans=m+ ?ree phase to six phase4 ,illu/ration3 ,,fig4 #b1agh4--;,diagram ( diametrical connection1 ?ree phase to six phase4 ,x is obta9$ by br++ bo? ends ( ea* second>y w9d+ to opposite po9ts on ! rot>y conv]t] w9d+1 utiliz+ ! conv]t] w9d+ to give ! six phases4 ,?is trans=mation ( phases may also be obta9$ ) trans=m]s hav+ two second>y w9d+s4 ,alt]nat+ ,curr5t ,sy/ems4--,! sav+ 9 ! co/ ( transmission obta9$ by us+ alt]nat+ in/ead ( direct curr5t is n due to any diff]5ce 9 ! *>act]i/ics ( ! curr5ts !mselves1 b to ! fact t 9 ! case ( alt]nat+ curr5t v high pressures may be employ$1 ?us p]mitt+ a giv5 am\nt ( en]gy to be transmitt$ ) a relatively small curr5t4 ,9 ! case ( direct curr5t sy/ems1 commutator tr\bles limit ! transmission pressure to ab\t #a1jjj volts1 :]eas ) alt]nat+ curr5t x may be comm]cially g5]at$ at pressures up to ab\t #ac1jjj & by means ( /ep up trans=m]s1 transmitt$ at #aaj1jjj volts or m4 ,illu/ration3 ,,fig4 #b1agi4--;,end ( ,s*aghticoke-,s*5ectady transmission l9e at ,s*5ectady2 view %[+ entrance bu%+s & lightn+ arre/] horn gaps4 ,relative ,weights ( ,copp] ,requir$ by ,polyphase ,sy/ems4--,a comp>ison betwe5 ! weights ( copp] requir$ by ! diff]5t alt]nat+ curr5t sy/ems is r5d]$ q difficult by ! fact t ! voltage ord9>ily measur$ is n ! maximum voltage1 & z ! insulation has to )/& ! /ra9 ( ! maximum voltage1 ! relative value ( copp] obta9$ by calculation dep5ds ^u ! basis ( comp>ison adopt$4 ,z a g5]al rule1 ! highe/ voltage practicable is us$ = long di/ance transmission1 & a l[] voltage = local di/ribution4 ,fur!rmore1 "s polyphase sy/ems give a multiplicity ( voltages1 & ! "q arises z to :i* ( ^! voltages %all be consid]$ ! transmission voltage4 ,if ! transmission voltage be tak5 to repres5t t ( ! di/ribution circuit1 & ! polyphase sy/em has z _m indep5d5t circuits z !re are phases1 ! sy/em w\ld repres5t a gr\p ( sev]al s+le phase sy/ems1 & !re w\ld be no sav+ ( copp]4 ,"u ^! conditions1 if ! voltage at ! di/ant end be tak5 z ! transmission voltage1 & ! copp] requir$ by a s+le phase two wire sy/em z %[n 9 fig4 #b1ahj1 be tak5 z ! basis ( comp>ison1 ! relative weights ( copp] requir$ by ! v>i\s polyphase sy/ems is giv5 9 figs4 #b1aha to #b1ahh4 ,illu/ration3 ,,fig4 #b1ahj4--,s+le phase l9e1 us$ z basis ( comp>ison 9 obta9+ ! relative weights ( copp] requir$ by polyphase sy/ems1 z indicat$ 9 figs4 #b1aha to #b1ahh4 ,9 ! case repres5t$ 9 fig4 #b1ahj1 if ! total drop on ! l9e be #ajj volts1 ! g5]at$ voltage mu/ be #a1ajj volts1 & ! resi/ance ( ea* l9e mu/ be #ej #a1jjj 4#je ohms4 ,calculat$ on ?is basis1 a two phase f\r wire sy/em is equival5t to two s+le phase sy/ems & gives no economy ( copp] 9 p[] transmission ov] ! ord9>y s+le phase two wire sy/em4 ,?is is ! case also ) any ( ! o!r two phase sy/ems1 except ! two phase ?ree wire sy/em4 ,illu/ration3 ,,figs4 #b1aha to #b1ahh4--;,circuit diagrams %[+ relative copp] economy ( v>i\s alt]nat+ curr5t sy/ems4 ,9 ?is sy/em two ( ! f\r wires ( ! f\r wire two phase sy/em are replac$ by "o ( full cross section4 ,! am\nt ( copp] requir$1 :5 comp>$ ) ! s+le phase sy/em1 w diff] consid]ably accord+ z ! comp>ison is bas$ on ! highe/ voltage p]missible = any giv5 di/ribution1 or on ! m9imum voltage = l[ pressure s]vice4 ,if ,e be ! greate/ voltage t c be us$ on acc\nt ( ! insulation /ra91 or = any o!r reason1 ! pressure betwe5 ! o!r conductors ( ! two phase ?ree wire sy/em mu/ be r$uc$ to ,e #b4 ,! weight ( copp] requir$ "u ?is condition is #ade4g t ( ! s+le phase copp]4 ,on ! basis ( m9imum voltage1 ! relative am\nt ( copp] requir$ is #gb4i t ( ! s+le phase sy/em4 ,illu/ration3 ,,fig4 #b1ahi4--,tw9 circuit a]motor t[]s c>ry+ #dd1jjj volt conductors 7,s\!rn ,p[] ,co474 ,^! t[]s v>y 9 height f #ce to #ej feet1 & ! circuits are transpos$ e #aj miles4 ,! t[]s are assembl$ on ! gr\nd & erect$ by means ( g9 poles4 ,!y are normally spac$ #ejj feet ap>t ) a sag ( #e feet #h in*es4 ,! m9imum di/ance betwe5 t[]s is #cjj feet & ! maximum #gjj feet4 ,figs4 #b1ahg & #b1ahh are two examples ( ?ree phase f\r wire sy/ems4 ,! relative am\nt ( copp] requir$ z comp>$ ) ! s+le phase sy/em dep5ds on ! cross section ( ! f\r? wire4 ,! arrangem5t %[n 9 fig4 #b1ahh1 :]e ! f\r? wire is only half size1 is us$ only = second>y di/ribution sy/ems4 ,illu/ration3 ,,fig4 #b1aij4--;,g5]al ,electric /&>d t[] = high t5sion ?ree phase transmission l9e4 ,illu/ration3 ,,fig4 #b1aia4--;,g5]al ,electric transposition t[] = high t5sion ?ree phase transmission l9e4 ,*oice ( ,voltage4--,9 ord] to prop]ly det]m9e ! voltage = a transmission sy/em !re are a numb] ( conditions :i* mu/ be consid]$ 9 ord] t ! economy ( ! entire in/allation %all be a maximum4 ,! nature ( ! div]sely v>i\s factors :i* affect ! problem makes a ma!matical expression difficult & unsatisfactory4 ,ques4 ,:at is ! relation betwe5 ! cross sectional area ( ! conductors & ! voltage8 ,ans4 ,= a giv5 circuit1 ! cross sectional area ( ! conductors1 or weight v>ies inv]sely z ! voltage4 ,illu/ration3 ,,fig4 #b1aib4--;,g5]al ,electric /&>d t[] "u con/ruction4 ,ques4 ,w\ld ! highe/ possible voltage !n be us$ = a transmission l9e8 ,ans4 ,! mo/ economical voltage dep5ds on ! l5g? ( ! l9e & ! co/ ( app>atus4 ,= in/ance1 alt]nators1 trans=m]s1 insulation & circuit control & lightn+ protection devices become exp5sive :5 manufactur$ = v high pressures4 ,h5ce if a v high pressure 7 us$1 x w\ld involve t ! transmission di/ance be great en\gh s t ! extra co/ ( ! high pressure app>atus w\ld be (fset by ! sav+ 9 copp] effect$ by us+ ! high pressure4 ,9 ! case ( ! longe/ l9es1 f ab\t #ajj miles up1 ! sav+ 9 copp] ) ! highe/ practicable voltage is s great t ! increase 9 o!r exp5ses is r5d]$ comp>atively small4 ,9 ! %ort] l9es z ^? rang+ 9 l5g? f ab\t "o mile to #ej or #ge miles1 ! mo/ suitable voltage mu/ be det]m9$ 9 ea* individual case by a c>eful consid]ation ( all ! conditions involv$4 ,no fix$ rule c be e/abli%$ = prop] voltage bas$ on ! l5g?1 b ! foll[+ table w s]ve z a guide3 ,illu/ration3 ,,fig4 #b1aic4--,l9e ( ! ,s*5ectady ,p[] ,company cross+ ! tracks ( ! ,bo/on & ,ma9e ,railroad ne> ,s*aghticoke4 ,usual ,transmission ,voltages ---------------------------------------- ,l5g? ( l9e ,voltage 9 miles --------------------------------------- #a #ejj to #a1jjj #a to #b #a1jjj to #b1cjj #b to #c #b1cjj to #f1fjj #c to #aj #f1fjj to #ac1bjj #aj to #ae #ac1bjj to #bb1jjj #ae to #bj #bb1jjj to #dd1jjj #bj to #dj #dd1jjj to #ff1jjj #dj to #fj #ff1jjj to #hh1jjj #fj to #ajj #hh1jjj to #aaj1jjj --------------------------------------- ,ques4 ,:at are ! /&>d voltages = alt]nat+ curr5t transmission circuits8 ,ans4 #f1fjj1 #aa1jjj1 #bb1jjj1 #cc1jjj1 #dd1jjj1 #ff1jjj1 #hh1jjj4 ,! am\nt ( p[] to be transmitt$ det]m9es1 9 a measure1 ! limit ( l9e voltage4 ,if ! mo/ economical voltage consid]$ f ! po9t ( view ( ! l9e alone1 be some:]e 9 excess ( #ac1bjj1 /ep up trans=m]s mu/ be employ$1 s9ce ! highe/ voltage = :i* /&>d alt]nators are manufactur$ is #ac1bjj4 ,9 a giv5 case1 ! sav+ 9 conductor by us+ ! high] voltage may be m ?an (fset by ! increas$ co/ ( trans=m]s1 & ! "q mu/ be det]m9$ = ea* case4 ,illu/ration3 ,,fig4 #b1aid4--,view ( a ?ree phase1 #b1cjj volt1 #fj cycle l9e at ,*azy1 ,n4 ,y4 ,! curr5t is transmitt$ at ! alt]nator voltage #b miles ov] ! s+le circuit pole l9e4 ,! poles are ( c$> ) fir cross arms1 & are fitt$ ) p9 insulators4 ,!y are f #ce to #dj feet high & are spac$ at an av]age ( ab\t #abj feet4 ,! conductors are b>e copp] wire ,no4 #jj ,b4 ,s4 ,! alt]nators consi/ ( "o #ej kw41 & "o #ajj kw4 ,g5]al ,electric ma*9es4 ,ques4 ,:at are ! /&>d trans=m] ratios8 ,ans4 ,multiples ( #e or #aj4 ,illu/ration3 ,,figs4 #b1aie to #b1aig4--;,diagram %[+ electric railway sy/em4 ,?ree phase curr5t is g5]at$ at ! ma9 /ation :]e x passes to /ep up trans=m]s to increase ! pressure a suitable am\nt = economical transmission4 ,at v>i\s po9ts along ! railway l9e are sub-/ations1 :]e ! ?ree phase curr5t is r$uc$ 9 pressure to #ejj or #fjj volts by /ep d[n trans=m]s1 & conv]t$ into direct curr5t by rot>y conv]t]s4 ,! relatively l[ pressure direct curr5t is !n convey$ by fe$]s to ! rails1 ?is result+ 9 a consid]able sav+ 9 copp]4 ,mix$ ,curr5t ,sy/ems4--,x is (t5 desirable to transmit electrical en]gy 9 ! =m ( alt]nat+ curr5t1 & di/ribute x z direct curr5t or vice v]sa4 ,su* sy/ems may be class$ z mix$ curr5t sy/ems4 ,! usual conv]sion is f alt]nat+ curr5t to direct curr5t because ( ! sav+ 9 copp] secur$ by ! use ( alt]nat+ curr5t 9 transmission1 especially 9 ! case ( long di/ance l9es4 ,su* conv]sion involves ! use ( a rot>y conv]t]1 motor g5]ator set1 or rectifi]1 accord+ to ! conditions ( s]vice4 ,illu/ration3 ,,fig4 #b1aih4--;,example ( conv]t] sub-/ation1 %[+ ! ,brooklyn ,edison ,co4 ,madison sub-/ation4 ,! trans=m]s are se5 on ! left1 ! conv]t] %[n at ! "r is a ,we/+h\se syn*ron\s boo/] rot>y conv]t]1 consi/+ ( a /&>d rot>y conv]t] 9 comb9ation ) a revolv+ armature alt]nator m\nt$ on ! same %aft ) ! conv]t] & hav+ ! same numb] ( poles4 ,! function ( ! ma*9e is to conv]t & regulate ! pressure4 ,by v>y+ ! field excitation ( ! alt]nator1 ! ,a4 ,c4 voltage impress$ on ! rot>y conv]t] prop] c be increas$ or decreas$ z desir$4 ,?us1 ! ,d4 ,c4 voltage deliv]$ by ! conv]t] is v>i$ accord+ly4 ,?is type ( conv]t] is well adapt$ = any application = :i* a relatively wide v>iation1 ei!r automatic or non-automatic1 9 direct curr5t voltage is necess>y4 ,also especially = s]v+ inc&esc5t light+ sy/ems :]e consid]able voltage v>iation is requir$ = ! comp5sation ( drop 9 long fe$]s1 = op]ation 9 p>allel ) /orage batt]ies & = electrolytic "w :]e extreme v>iations 9 voltage are requir$ by *anges 9 ! resi/ance ( ! electrolytic cells4 ,! suburban trolley =ms a good example ( a mix$ sy/em1 9 :i* alt]nat+ curr5t is g5]at$ at ! c5tral /ation & transmitt$ to sub-/ations1 :]e x is trans=m$ to l[ pressure1 & conv]t$ into direct curr5t = use on ! l9e4 ,fig4 #b1aie %[s ! int]ior ( a sub-/ation ( ?is k9d4 ,ques4 ,:at direct curr5t pressure is usually employ$ on traction l9es8 ,ans4 #ejj volts4 ,ques4 ,m5tion ano!r important s]vice p]=m$ by a mix$ sy/em4 ,ans4 ,if ! g5]ator furni% alt]nat+ curr5t x mu/ be conv]t$ into direct curr5t 9 ord] to *>ge /orage batt]ies4 ,,*apt] ,,lvi ,,auxili>y ,,app>atus ,= ! prop] control ( ! alt]nat+ curr5t 9 any ( ! num]\s sy/ems describ$ 9 ! previ\s *apt]1 v>i\s devices1 :i* might be class$ z auxili>y app>atus1 are requir$4 ,^! may be gr\p$ into sev]al divisions1 accord+ to ! nature ( ! duty :i* !y p]=m1 z #a4 ,swit*+ devices2 a4 ,ord9>y swit*es2 b4 ,oil break swit*es2 c4 ,remote control swit*es4 #b4 ,curr5t or pressure limit+ devices2 a4 ,fuses2 b4 ,reactances2 c4 ,circuit break]s2 d4 ,relays4 #c4 ,lightn+ protection devices2 a4 ,air gap arre/]s2 b4 ,multi-gap arre/]s2 c4 ,horn gap arre/]s2 d4 ,electrolytic arre/]s2 e4 ,vacuum tube arre/]s2 f4 ,*oke coils2 g4 ,/atic int]rupt]s4 #d4 ,regulat+ devices2 a4 ,induction voltage regulators2 b4 ,v>iable ratio trans=m] regulators drum type2 dial type2 c4 ,comp5sation %unts2 d4 ,pole type regulators2 e4 ,small fe$] voltage regulators2 f4 ,automatic voltage regulators2 g4 ,l9e drop comp5sators2 h4 ,/>t+ comp5sators2 i4 ,/> delta swit*es4 #e4 ,p[] factor regulat+ devices2 a4 ,cond5s]s2 b4 ,syn*ron\s cond5s]s4 #f4 ,indicat+ devices2 plung] type2 a4 ,mov+ iron in/rum5ts incl9$ coil type2 magnetic vane type2 b4 ,hot wire in/rum5ts2 c4 ,induction in/rum5ts %ield$ pole type2 repulsion type2 d4 ,dynamomet]s2 e4 ,in/rum5t trans=m]s2 commutator type2 f4 ,wat?\r met]s induction type2 ,f>aday disc type2 syn*ron\s motor type2 g4 ,frequ5cy indicators resonance type2 induction type2 lamp type2 h4 ,syn*ronism indicators voltmet] type2 resonance type2 rotat+ field type2 i4 ,p[] factor indicators wattmet] type2 rotat+ field type2 j4 ,gr\nd detectors2 k4 ,e>? leakage cut outs2 l4 ,oscillographs4 ,,*apt] ,,lvii ,,swit*+ ,,devices ,a swit* is a piece ( app>atus = mak+1 break+1 or *ang+ ! connections 9 an electric circuit4 ,! p>ticul> =m & con/ruction ( any swit* is gov]n$ by ! electrical conditions "u :i* x mu/ op]ate4 ,s9ce ! electric curr5t _c be /opp$ in/antly :5 ! circuit 9 :i* x is fl[+1 is brok51 an arc is =m$ z ! swit* contacts sep>ate2 ?is t5ds to burn ! contacts1 & to %ort circuit1 ! sev]ity ( su* action dep5d+ on ! voltage & ! proximity ( ! swit* t]m9als4 ,accord+ly 9 swit* design1 provision mu/ be made to c\nt]act ^! t5d5cies4 ,?us1 #a4 ,! contacts %\ld sep>ate along _! entire l5g?1 r ?an at a po9t2 #b4 ,! t]m9als %\ld be f> en\gh ap>t & prop]ly protect$ to prev5t %ort circuit+ ( ! arcs2 #c4 ,! break %\ld be quick2 #d4 ,! gap %\ld be surr\nd$ by ! prop] m$ium 7air or oil7 to meet ! requirem5ts ( ! electrical conditions4 ,a great v>iety ( swit*es h be5 introduc$ to suit ! diff]5t requirem5ts4 ,knife swit*es are us$ = l[ pressure s]vice1 ! multiple break =m be+ us$ :]e x is desir$ to r$uce ! arc+ di/ance4 ,ques4 ,h[ %\ld s+le ?r[ swit*es be in/all$8 ,ans4 ,!y %\ld op5 d[nw>d s gravity w keep !m op54 ,illu/ration3 ,,figs4 #b1aii & #b1bjj4--;,g5]al ,electric triple pole sol5oid op]at$1 s+le ?r[ remote control swit*1 & pu% button swit* = op]at+ same4 ,swit* is a self-conta9$ unit ) two sets ( contacts1 ma9 lam9at$ copp] bru%es1 & c>bon auxili>y contacts to take ! arc on break+ ! circuit4 ,! ma9 bru%es are s made t ea* lam9ation makes an end on contact ) ! swit* blade )\t any t5d5cy to =ce ! lam9ations ap>t4 ,a wip+ effect1 giv5 to ! contacts e "t ! swit* is clos$1 keeps ! contact surfaces clean & insures good contact at all times4 ,! c>bon auxili>y contacts are made ( blocks ( c>bon fa/5$ )\t screws4 ,9 op]ation1 ! swit* is actuat$ by a d\ble coil sol5oid1 "o coil = clos+ & "o = op5+1 controll$ by ! s+le pole d\ble ?r[ pu% button swit* %[n 9 fig4 #b1bjj1 :i* is normally 9 ! op5 position & rema9s clos$ only :5 held by ! op]ator4 ,"o ( ^! swit*es is furni%$ ) ea* control swit* & mu/ always be us$1 z ! sol5oid coils are n int5d$ = cont9u\s s]vice4 ,! p[] requir$ to op]ate ! remote control swit* is small1 be+ approximately #a4f amp]es at #aaj volts1 #j4ha amp]es at #bbj volts direct curr5t1 & #aj amp]es at #aaj volts1 & #f amp]es at #bbj volts alt]nat+ curr5t #fj cycles4 ,! ma9 swit* c be clos$ & op5$ by h&1 & ! pu% button locat$ at any po9t4 ,ques4 ,h[ %\ld d\ble ?r[ swit*es be in/all$8 ,ans4 ,horizontally4 ,illu/ration3 ,,figs4 #b1bja & #b1bjb4--,palm] s]vice swit* & fuse box1 = ei!r plug1 c>tridge or op5 l9k fuses4 ,fig4 #b1bja illu/rates ! box 9 op5 position = ! inspection ( fuses1 etc4 ,! cov] is held op5 by a simple lock s t ! swit* _c fall clos$ by gravity1 ! box may be m\nt$ s t ! s]vice wires lead directly into a seal$ t]m9al *amb] f any direction1 & all curr5t c>ry+ p>ts made accessible by ! op5+ ( ! swit* are dead4 ,fig4 #b1bjb illu/rates ! device ) side ( box & cov] cut away to %[ int]ior & ! normally seal$ cov] ( t]m9al *amb] remov$4 ,! swit* contacts d n ent] _! contact clips until ! flang$ cov] ( ! box has clos$ ! swit* op5+1 no curr5t connections be+ made to l9e or load until ! box is completely clos$1 & 9 consequ5ce !re is no opportunity to make improp] connections to any live p>ts ( swit*1 :5 conduit connections are us$ to ! s]vice & met] wires4 ,ques4 ,:at is a plug swit*8 ,ans4 ,a swit* 9 :i* ! curr5t is ruptur$ 9 a tube enclos$ at "o end1 !reby conf9+ ! arc & limit+ ! supply ( air4 ,!y are us$ on high pressure circuits ( f #aj1jjj to #bj1jjj volts1 = transf]r+ live circuits & = voltmet] & syn*roniz+ circuits :]e !re is v little en]gy4 ,! usual curr5t capacity is f #d to #g amp]es4 ,illu/ration3 ,,fig4 #b1bjc & #b1bjd4--;,bus transf] plug swit*4 ,! me?od ( support+ ! contact f>!/ f ! panel consi/s ( a porcela9 pill> ( ! same height z ! receptacle1 clamp$ to a brass connect+ or bus b> :i* 9 turn is fa/5$ to ! receptacle4 ,illu/ration3 ,,fig4 #b1bje4--;,ammet] jack4 ,?is plug swit* is insulat$ = high pressure & consi/s ( two p>ts3 ! ammet] jack1 & ! ammet] jack plug1 cable1 & bu%+4 ,! receptacle1 :i* is simple 9 con/ruction1 consi/s ( a brass bu%+ well insulat$ f ! panel & protect$ on ! front ( ! panel by a porcela9 bu%+4 ,on ! end ( ?is tube & insulat$ f x1 is a phosphor bronze spr+ :i*1 :5 ! plug is out1 re/s on ! brass tube & keeps ! circuit clos$4 ,! plug consi/s ( a brass rod well insulat$ & set 9 a brass tube1 bo? be+ fa/5$ 9 a h&le :i* is /a9$ black & poli%$4 ,inside ! h&le is run a tw9 conductor cable1 "o side be+ sold]$ 9 ! brass tube & ! o!r to ! brass rod4 ,! o!r end ( ! cable is run ?r\gh a bu%+ set 9 ! panel & !nce to ! ammet] or curr5t trans=m]4 ,:]e x is desir$ to remove ! plug & cable f ! bo>d1 or to plug bo? ends ( ! cable 9 diff]5t receptacles1 a plug in/ead ( a bu%+ %\ld be us$4 ,9 ?is case a cable %\ld be provid$ ) a plug on ea* end4 ,=ms ( ,break4--,on high pressure circuits !re are sev]al types ( swit*3 !y are classifi$ ) respect to ! break1 t is to say1 accord+ z ! break takes place1 #a4 ,9 op5 air2 #b4 ,9 an enclos$ air space2 #c4 ,aid$ by a metal fuse2 #d4 ,aid$ by a horn2 #e4 ,9 oil4 ,illu/ration3 ,,fig4 #b1bjf4--,we/+h\se fus$ />t+ swit* = squirrel cage motors4 ,x is arrang$ = ,national ,electric ,code fuses on "o end only & has spr+s on ! o!r end to op5 ! swit* automatically if left clos$ at ?is end4 ,! correspond+ t]m9als at bo? ends ( ! swit* are connect$ 9 grooves 9 ! back ( ! slate base s t ! wir+ ne$ be connect$ to "o set ( ^! t]m9als only1 ?us decreas+ ! numb] ( connections necess>y1 z %[n 9 fig4 #b1bjg4 ,9 />t+ an induction motor1 ! swit* is ?r[n to ! end t is n fus$ & held !re until ! motor is up to runn+ spe$2 !n x is quickly ?r[n to ! fus$ position1 ?us protect+ ! circuit "u runn+ conditions4 ,illu/ration3 ,,fig4 #b1bjg4--;,diagram ( connections ( ,we/+h\se fus$ />t+ swit* = squirrel cage motors4 ,! />t+ curr5t ( induction motors is sev]al times ! normal runn+ curr5t &1 :5 ! controll+ swit* is fus$ to c>ry ! runn+ load only1 ! fuses are apt to bl[ :5 ! motor is />t$4 ,! fuses mu/ be ( a capacity to prev5t ov]loads "u runn+ conditions4 ,^! swit*es are design$ to meet ?is difficulty & are us$ )\t auto-/>t]s to control motors up to #e horse p[] rat+4 ,ques4 ,:at is ! objection to op5 air break8 ,ans4 ,! relatively long gap requir$ to ext+ui% ! arc1 limit+ ?is =m ( swit* to l[ or mod]ate pressure circuits4 ,! op5 air arc may cause v high voltage oscillations :5 ! circuit conta9s inductance & capacity unless ! break occur at z]o value4 ,illu/ration3 ,,fig4 #b1bjh4--,we/+h\se s+le pole disconnect+ swit*4 ,disconnect+ swit*es are us$ prim>ily = isolat+ app>atus f ! circuit = purposes ( inspection & repair2 also = sectionaliz+ fe$]s4 ,!y are n design$ = op5+ "u load1 & !re=e no attempt %\ld be made to op5 !m ) curr5t 9 ! circuit4 ,9 connection ) lightn+ arre/] in/allations1 disconnect+ swit*es are p>ticul>ly useful1 provid+ a simple & effective means = isolat+ ! arre/]s :ile clean+ & inspect+4 ,! swit* is op5$ & clos$ ) a hook on ! end ( a wood5 pole1 :i* hook engages 9 a hole provid$ 9 ! swit* blade4 ,?is type ( disconnect+ swit* is int5d$ = wall m\nt+4 ,! live p>ts are m\nt$ on porcela9 insulators c>ri$ on a ca/ iron yoke or base1 =m+ a simple & sub/antial con/ruction4 ,ques4 ,:at are disconnect+ swit*es8 ,ans4 ,knife swit*es 9 s]ies ) o!r swit*es s t ! app>atus controll$ by ! latt] may be repair$ 9 safety by entirely disconnect+ x f ! bus b>s or live circuit4 ,su* swit*es are n int5d$ to rupture ! load curr5t4 ,illu/ration3 ,,figs4 #b1bji & #b1baj4--,we/+h\se disconnect+ swit*es = pressures ov] #c1cjj volts4 ,illu/ration3 ,,figs4 #b1baa & #b1bab4--,we/+h\se selector type disconnect+ swit*4 ,fig4 #b1baa1 view %[+ bo? sides clos$2 fig4 #b1bab1 view ) "o side op54 ,! selector type ( disconnect+ swit* is a transf] swit* :i* does n require ! circuit to be int]rupt$ :ile mak+ ! *ange4 ,x c also be us$ to connect two indep5d5t circuits 9 p>allel4 ,9 con/ruction1 x is 9 effect two s+le ?r[1 s+le pole disconnect+ swit*es ) ! h+e jaws connect$ toge!r & m\nt$ on ! same insulator4 ,! h+e jaw is also provid$ ) dummy jaws to hold ei!r blade ( ! swit* 9 ! op5 position4 ,except = ^! diff]5ces 9 ! h+e jaws1 ! con/ruction is simil> to ! swit* %[n 9 fig4 #b1bji4 ,x %\ld n be us$ to op5 ! circuit :5 load$4 ,illu/ration3 ,,fig4 #b1bac4--;,hook /ick = op]at+ a disconnect+ swit*4 ,ques4 ,:at are ! features ( ! enclos$ air break8 ,ans4 ,! swit* is m compact ?an ! op5 air break type1 b pressure oscillations are caus$ on op5+ ! circuit ! same z ) ! op5 air break1 & x is n desirable = heavy curr5t4 ,illu/ration3 ,,fig4 #b1bad4--;,baum #ce1jjj volt1 #bjj amp]e1 d\ble break pole type swit*4 ,:ile design$ = disconnect+ purposes only1 x c break consid]able amp]age4 ,! lev]s & c\pl+s are fa/5$ ) tape p9s4 ,! control %aft c\pl+ is adju/able to any angle1 & ! swit* c be lock$ 9 ! op5 or clos$ position4 ,a removable wood5 h&le is suppli$ & ! swit* c be h&l$ 9 any wea!r4 ,! arms c be ext5d$ to hold fuse fitt+s1 or dead end insulators 9 ! ev5t ( a heavy /ra91 b x is pref]able to h fuses on ano!r /ructure z a precaution aga9/ com+ 9 contact ) ! en]giz$ portion ( ! swit*1 & x is also pref]able to take ! /ra9 ( ! l9e on a pole a few feet f ! swit*1 r ?an on ! swit* /ructure1 p>ticul>ly 9 ! l>g] sizes4 ,an insulat+ wood section 9 ! control %aft sep>ates ! control h&le f ! rema9d] ( ! swit*4 ,dis*>g+ horns c be fitt$ to ?is type ( swit* & :5 s equipp$ !y h be5 f\nd capable ( break+ consid]able loads4 ,ques4 ,h[ is ! fuse arrang$ 9 ! metal fuse break type ( swit*8 ,ans4 ,x is plac$ 9 a tube fitt$ ) p[d]$ c>bonate ( lime or "s o!r insulat+ p[d]4 ,illu/ration3 ,,fig4 #b1bae4--,pacific swivel type blade = ,baum pole top swit*es4 ,! twi/ type ( blade1 "h %[n1 is especially adapt$ to swit*es op]at+ 9 freez+ or sleety wea!r4 ,x w be se5 t ! fir/ few degrees ?r\gh :i* ! rotat+ insulator is mov$ h ! effect ( twi/+ ! blade betwe5 ! %oes ( ! contact1 :i* breaks any seal ?r\gh freez+1 or corrosion4 ,illu/ration3 ,,fig4 #b1baf4--,pacific #bb1jjj volt1 #ajj amp]e1 pole top swit* equipp$ ) fuse tubes2 design$ to meet ! ne$ = a small gr\p controll$ disconnect+ swit*1 hav+ sev]al features mak+ x suitable = use ) s]vice trans=m] in/allations & l9e bran*es4 ,! swit* is made ) clamp$ pipe arms p]mitt+ adju/m5t4 ,x is equipp$ ) fuse tubes & fitt+s1 b %\ld ! fuses be n desir$1 ! arm may be %ort5$4 ,provision is made = fitt+ insulator p9s to ! top ( ! arms1 :5 ! swit* is m\nt$ v]tically1 :i* w hold insulators at "r angles to ! swit*1 mak+ x possible to end a l9e on ! top ( ^! arms & !n drop d[n ?r\gh ! swit* to ! bank ( trans=m]s4 ,! swit* is s con/ruct$ t gravity t5ds to hold x 9 ei!r ! op5 or ! clos$ position4 ,provision c be made = lock+4 ,illu/ration3 ,,fig4 #b1bag4--;,horn break swit*4 ,9 op]ation1 ! arc =m$ at break1 w travel t[>d ! extremities ( ! horns because ( ! fact t a circuit w t5d to move s z to embrace ! l>ge/ possible numb] ( l9es ( =ce set up by x4 ,h5ce1 ! arc t />ts betwe5 ! horns :]e !y are ne> toge!r rises betwe5 !m until x becomes s att5uat$ t x is ext+ui%$4 ,illu/ration3 ,,fig4 #b1bah4--,we/+h\se re> connect$ motor />t+ swit*1 = pressures up to #fjj volts4 ,x is us$ = />t+ rot>y conv]t]s & direct curr5t motors ( l>ge capacity hav+ />t+ torque small en\gh to p]mit cutt+ out ! />t+ resi/ance 9 few /eps4 ,! clips c be connect$ to any type ( resi/or1 ! /eps ( :i* are successively %ort circuit$ z ! swit* closes2 ! am\nt ( resi/ance 9 ! armature circuit is ?us gradually r$uc$4 ,a pause %\ld be made aft] ea* /ep ( resi/ance is ?r[n 9 to all[ ! motor spe$ to accel]ate4 ,if ! />t+ swit* d n h to c>ry ! full load curr5t & c be %ort circuit$ by ano!r swit*1 a />t+ swit* ( small] capacity equival5t to #ej p] c5t ( runn+ curr5t ( ! ma*9e c be us$4 ,! swit* is ( ! s+le pole1 s+le ?r[1 re> connect$1 f\r po9t1 knife blade type4 ,ques4 ,describe its op]ation4 ,ans4 ,! mov+ arm ( ! swit* draws ! fuse ?r\gh ! tube1 ?us op5+ ! circuit )\t mu* di/urbance4 ,illu/ration3 ,,fig4 #b1bai4--;,baum disconnect+ swit* ) horns & auxili>y contacts 7,pacific ,mfg4 ,co474 ,?is swit* is = use on sy/ems op]at+ at #ajj1jjj volts or ov]4 ,x has a spac+ ( five feet betwe5 out] insulators1 is equipp$ ) auxili>y %oes t break ! circuit betwe5 ! horns1 div]t+ x f ! curr5t c>ry+ contacts s t !y are n attack$ by ! arc4 ,ques4 ,:at is ! objection to ! metal fuse swit*8 ,ans4 ,! p[d] is set fly+ by ! explosion ( ! arc1 :i*1 z x settles1 gets into ! be>+s ( any ma*9e t may be 9 ! vic9ity4 ,ques4 ,:at is a horn break swit*8 ,ans4 ,"o provid$ ) horn %ap$ ext5sions to ! contacts1 z %[n 9 fig4 #b1bai4 ,! arc =m$ on break+ ! circuit1 z x travels t[>d ! extremities ( ! horns1 becomes att5uat$ & is f9ally ruptur$4 ,illu/ration3 ,,fig4 #b1bbj4--,kelman swit*+ me*anism4 ,! pantograph arrangem5t ( ! contact blades gives a d\ble horizontal break deep d[n 9 ! oil4 ,?is gives ov] ! break a heavy head ( oil :i* imm$iately closes 9 ar\nd ! ?9 blades z !y leave ! contacts 9 op5+1 ?us effectually ext+ui%+ ! arc4 ,! op5+ spr+ acts )9 ! pantograph itself )\t any int]v5+ me*anism1 & ! light weight ( ! few mov+ p>ts enables ! spr+ to accel]ate ! blades rapidly1 ?us obta9+ a quick break4 ,! contacts are ( ! return b5d type1 :i* makes a flexible contact1 to obta9 alignm5t ) ! blades at all times4 ,! pantograph & contacts are support$ on corrugat$ porcela9 insulators on a h>dwood base or insulator bo>d4 ,! insulators are fitt$ ) iron ends = secur+ ! diff]5t p>ts4 ,at ea* end ( ! insulator bo>d is an upright or lift+ bo>d :i* s]ves to lift ! swit*+ me*anism out ( ! tank4 ,! leads are heavily insulat$4 ,ques4 ,:at are ! objections to ?is type ( swit*8 ,ans4 ,! consid]able space requir$ = ! horns & arcs1 & ! l9e surges caus$ by ! arc4 ,horn swit*es 7 us$ ext5sively = high pressure alt]nat+ curr5t circuits be=e ! introduction ( oil swit*es4 ,illu/ration3 ,,fig4 #b1bba4--,sectional view ( ,pacific wea!rpro( oil swit* = use 9 places expos$ to ! wea!r4 ,all mov+ & contact p>ts are support$ f ! ca/ iron top & are readily removable = inspection or repair4 ,oil ,swit*es4--,! ext5sive use ( high pressure curr5ts & alt]nat+ curr5t motors & o!r devices introduc+ inductance make x necess>y to use swit*es radically diff]5t f ! ord9>y air break types4 ,illu/ration3 ,,fig4 #b1bbb4--;,g5]al ,electric c5tral /ation triple pole s+le ?r[ oil swit*2 view ( swit* 9 tank4 ,?is type is = pressures up to #aaj1jjj volts1 be+ adapt$ = /ations employ+ op5 wir+1 s9ce ! connections are made at ! top ( ! swit* & its con/ruction obviates ! ne$ = isolat+ x 9 a cell4 ,"o tank ) two breaks 9 s]ies are us$ = ea* phase4 ,! op5+ ( circuits ( consid]able curr5t value ) inductive loads is n possible ) old /yle swit*es :i* 7 q adequate = ! s]vice = :i* !y 7 design$4 ,^! circuits are controll$ ) ease & c]ta9ty by ! oil swit*4 ,illu/ration3 ,,figs4 #b1bbc to #b1bbf4--,we/+h\se indoor1 two pole d\ble ?r[ oil swit* = pressures n ov] #f1fjj volts4 ,fig4 #b1bbc1 op5 position2 fig4 #b1bbe1 clos$ position4 ,?is type ( swit* is suit$ = a wide range ( application1 be+ made 9 bo? swit*bo>d & wall m\nt+ /yles2 also = remote me*anical control by ! use ( bell cranks & connect+ rods4 ,! wall m\nt+ /yle is adaptable to motor in/allations on acc\nt ( ! facility ) :i* x may be m\nt$ on any support1 conv5i5t to ! motor op]ator4 ,! lev] & h&le ext5d outw>d ov] ! oil tank1 s t ! swit* may readily be m\nt$ aga9/ a wall1 po/ or any v]tical support4 ,! *>act]i/ic features ( ?is type ( swit* are3 knife blade contacts subm]g$ 9 oil2 live p>ts c>ri$ on a porcela9 base af=d+ a p]man5t insulation betwe5 adjac5t poles1 & betwe5 ! frame & live p>ts2 compactness & accessibility2 enclosure ( all live metal p>ts2 & l[ fir/ co/4 ,ea* contact jaw has atta*$ to x an arc+ piece :i* takes ! f9al break1 ?us prev5t+ any burn+ ( ! jaws4 ,^! arc+ pieces are inexp5sive & readily replac$ :5 worn or burnt away4 ,! contact mak+ p>ts are enclos$ 9 a %eet metal oil tank :i* has an insulat+ l9+4 ,! leads are br\ght out at ! top4 ,connections to ! outside circuit are made inside ! swit* & a porcela9 insulator is slipp$ ov] ! jo9t1 ?us provid+ a /raight cont9u\s connection f ! l9e ) maximum insulation4 ,on ! #f1fjj volt swit*1 insulation is obta9$ by ! use ( porcela9 bases = support+ ! live p>ts4 ,9 ! #c1cjj volt swit* specially treat$ wood5 bases are us$1 suitable b>ri]s be+ provid$ betwe5 ! poles :]e necess>y to prev5t arcs communicat+4 ,ques4 ,:at is an oil swit*8 ,ans4 ,"o 9 :i* ! contact is brok5 "u oil4 ,?is type ( swit* is ! "o almo/ univ]sally us$ on high pressure alt]nat+ curr5t circuits1 because ( ! fact t ! oil t5ds to cause ! curr5t to break :5 at its z]o value1 ?us prev5t+ ! heavy arc+ :i* w\ld occur ) an air break swit*1 & ! consequ5t surges 9 ! l9e :i* are s (t5 ! cause ( breakd[n ( ! insulation ( ! sy/em4 ,illu/ration3 ,,fig4 #b1bbg4--,kelman electric control unit = oil swit*4 ,x consi/s ( an iron frame :i* conta9s ! op5+ & clos+ coils & ! be>+s = ! op]at+ bell crank4 ,a small swit* on ! frame automatically op5s ! coil circuit at ! end ( ! /roke 9 ei!r direction & op]ates signal lamps to indicate ! op5 or clos$ position4 ,! automatic ov]load release op5s ! swit* by clos+ ! op5+ coil circuit4 ,?is electrical op]at+ unit gives satisfactory s]vice ?r\gh a wide v>iation ( voltage4 ,x requires a mom5t>y exp5diture ( en]gy ( f #a1ejj to #d1jjj watts1 dep5d+ on ! size4 ,ques4 ,:at is ! nature ( an oil break8 ,ans4 ,x is n a quick break4 ,oscillograph records %[ t ! effect ( ! oil is to all[ ! arc to cont9ue dur+ sev]al cycles & !n to break ! curr5t1 usually at ! z]o po9t ( ! wave4 ,remote ,control ,oil ,swit*es4--,x is desirable 9 ! case ( swit*es on high pressure circuits to locate ! p>ts :i* c>ry ! high pressure curr5t at "s di/ance f ! swit*bo>d 9 ord] t !y may be op]at$ ) safety4 ,) respect to ! mann] 9 :i* ! swit*es are op]at$ !y may be class$1 z #a4 ,h& op]at$2 #b4 ,p[] op]at$4 ,illu/ration3 ,,figs4 #b1bbh & #b1bbi4--,views %[+ me*anism ( h& op]at$ remote control swit*es4 ,fig4 #b1bbh1 /raight me*anism2 fig4 #b1bbi1 angul> me*anism4 ,ques4 ,:at k9d ( p[] is us$8 ,ans4 ,electricity is us$ 9 mo/ cases2 9 "s in/allations1 swit*es are op]at$ by compress$ air4 ,ques4 ,= :at pressures %\ld remote control swit*es be us$8 ,ans4 ,= pressures above #a1ajj volts4 ,ques4 ,describe ! op]at+ me*anism ( a remote control1 h&1 & electrically op]at$ swit*4 ,ans4 ,= h& op]ation1 ! me*anism betwe5 ! op]at+ lev] & swit* prop]1 consi/s simply ( a sy/em ( l9ks & bell cranks4 ,v>i\s %apes ( bell crank are us$1 to p]mit *ange 9 direction or position ( ! =ce appli$ to op]ate ! swit*4 ,illu/ration3 ,,fig4 #b1bcj4--,pacific oil swit* ) sol5oid control1 design$ = #fj1jjj & #gj1jjj volt in/allations2 x is capable ( h&l+ a #be1jjj kw4 g5]at+ /ation4 ,! break is horizontal1 made by ! rotation ( a flat memb] edgewise ?r\gh ! oil4 ,! sol5oid1 at its extreme out] position1 has a free />t be=e comm5c+ to move ! control p>ts ( ! swit*4 ,z x approa*es ! extreme inn] position1 :]e ! op5+ spr+ & ! contacts beg9 to (f] ! greate/ resi/ance1 ! magnetic action is1 ( c\rse1 mo/ p[]ful1 & ! lev]age by :i* x is appli$ moves to an increas+ radius1 by means ( roll]s work+ 9 ! curv$ slots ( ! control %aft lev]s4 ,^! curv$ slots & roll]s h ! additional advantage ( mak+ ! op5+ action v free & smoo?4 ,! tripp+ coil does n act on ! lat* directly1 b gives a hamm] bl[ t is positive4 ,! lat* prop] is a roll] hav+ a p[]ful hold & easy release4 ,curr5t c n be left on ei!r ! clos+ or op5+ coils1 z !y are automatically cut out by ! movem5t ( ! swit*4 ,ques4 ,"n two classes ( electrically op]at$ remote control swit*4 ,ans4 ,^? op]at$ by sol5oids1 & ^? op]at$ by motors4 ,! sol5oid type are clos$ by ! action ( a plung] sol5oid1 & op5$ ei!r by ano!r sol5oid call$ a tripp+ coil or by gravity4 ,"s examples ( remote control are %[n 9 ! accompany+ illu/rations4 ,ques4 ,:at indicat+ devices are us$ ) electrically op]at$ swit*es8 ,ans4 ,r$ & gre5 lamps2 r$ = clos$ & gre5 = op5 z %[n 9 fig4 #b1bca4 ,illu/ration3 ,,fig4 #b1bca4--;,diagram ( connections ( motor op]at$ remote control swit*4 ,! motor :i* op]ates ! swit* is controll$ by a small lev] g5]ally m\nt$ on ! panel ) ! in/rum5ts :i* are 9 ! circuit controll$ by ! swit*4 ,! /&>d pressure = op]at+ ! motors is #abe volts4 ,ques4 ,= :at s]vice are motor op]at$ swit*es us$8 ,ans4 ,= exceptionally heavy "w :]e ! kil[att ruptur+ capacity is great] ?an t = :i* ! o!r types are suitable4 ,illu/ration3 ,,fig4 #b1bcb4--;,g5]al ,electric motor op]at$ ?ree phase oil swit*4 ,! op]ation ( ! oil swit* is accompli%$ by a small h& controll+ swit*1 g5]ally m\nt$ on ! panel1 ) ! in/rum5ts :i* are 9 ! circuit controll$ by ! oil swit*4 ,! /&>d pressure = ! op]at+ motor is #abe volts4 ,! swit* has six breaks1 ea* break be+ a sep>ate tank4 ,9 addition to ?is isolation ( ! breaks1 ea* phase is enclos$ 9 a firepro( brick comp>tm5t1 mak+ x impossible = tr\ble 9 "o phase to be communicat$ to ano!r4 ,! cells are con/ruct$ ( brick ) top & bottom slabs ( slate4 ,! capacities ( su* swit*es1 range f #b1ejj to #fj1jjj volts1 & f #ajj to #a1jjj amp]es4 ,ruptur+ ,capacity ( ,oil ,swit*es4--,:ile an oil swit* may be design$ = a giv5 pressure & to c>ry a def9ite am\nt ( curr5t1 x %\ld n be und]/ood t ! swit* w necess>ily rupture ! am\nt ( normal en]gy equival5t to its volt amp]e rat+4 ,illu/ration3 ,,figs4 #b1bcc to #b1bce4--;,diagrams %[+ connections = ,g5]al ,electric s+le1 d\ble1 & triple pole1 sol5oid op]at$ remote control swit*es4 ,! op]at+ coils are %[n connect$ to ma9 swit* circuit1 b may be connect$ to an entirely sep>ate control circuit4 ,connections are ! same = ei!r alt]nat+ or direct curr5t4 ,oil swit*es are (t5 us$ on sy/ems ) g5]ator capacity ( _m ?\s& kil[atts4 ,x is !re=e ess5tial t ! swit*es %all be able to break n only _! normal curr5t1 b also greatly increas$ curr5t t w\ld fl[ if a %ort circuit or p>tial %ort circuit occur4 ,illu/ration3 ,,fig4 #b1bcf4--,we/+h\se ?ree pole h& op]at$ remote control oil swit*1 adapt$ = ! control ( alt]nat+ curr5t circuits ( small & mod]ate capacities1 ! pressures ( :i* d n exce$ #be1jjj volts4 ,ea* unit is in/all$ 9 a sep>ate masonry comp>tm5t4 ,! op5 position ( contacts is ma9ta9$ by gravity4 ,up to & includ+ ! #fjj amp]e capacity1 ! contacts are cone %ap$ ) an arc+ tip1 z %[n = capacities 9 excess ( #fjj amp]es1 bru% contacts are furni%$ ) auxili>y arc+ contacts ( ! butt type4 ,ea* pole has two sets ( contacts1 ?us provid+ a d\ble break 9 ea* l9e4 ,) bo? types ( contact1 ! f9al break ( ! arc is tak5 & ! ma9 contacts protect$ by auxili>y arc+ contacts :i* are inexp5sive & readily r5ewable4 ,! upp] or /ation>y contacts are m\nt$ on porcela9 insulators secur$ 9 ! soap/one base4 ,! l[] or movable contacts are c>ri$ by a wood5 rod connect$ to & mov$ v]tically by ! op]at+ me*anism4 ,! op]at+ me*anism ( ! h& op]at$ break] consi/s ( a simple sy/em ( lev]s1 bell cranks1 & rods4 ,! necess>y en]gy = mak+ a positive contact is small ow+ to ! use ( a toggle me*anism4 ,! leads are br\ght out ( ! top ( ! break] ?r\gh heavy porcela9 insulators4 ,on break]s above #c1ejj volts1 ! connections to ! l9e wires are made by means ( a union :i* c be tight5$ ) a socket wr5* fitt+ inside ! insulator4 ,z ! leads com+ into ! swit* are necess>ily insulat$ wire or cable1 ?is arrangem5t elim9ates all expos$ live p>ts & is well adapt$ to mak+ connections readily to bus b>s locat$ above or 9 ! re> ( ! circuit break]s4 ,illu/ration3 ,,fig4 #b1bcg4--;,cutl]-,hamm] enclos$ float swit*1 design$ = ! automatic control ( alt]nat+ curr5t motors op]at+ pumps us$ to fill or empty tanks1 sumps or o!r res]voirs4 ,! swit* is op]at$ by ! rise & fall ( a copp] float :i* is connect$ to ! swit* lev] by a brass rod or copp] *a94 ,z ! wat] level rises & falls1 ! float moves up & d[n4 ,?is movem5t is transmitt$ to ! swit* lev] & ! swit* 7if ! movem5t be suffici5t7 is tripp$ to make or break ! motor circuit4 ,to insure ! be/ op]ation x is necess>y t ! float rod be provid$ ) a guide s t ! float w move up or d[n 9 a v]tical l9e1 z %[n4 ,! m9imum diff]5ce 9 wat] level at :i* ! swit* w op]ate is approximately #aj to #ab in*es4 ,:5 ! float is plac$ 9 a clos$ tank1 ! m9imum height inside f ! bottom ( ! tank to ! top %\ld be at lea/ #f in*es great] ?an ! diff]5ce 9 wat] level to provide suffici5t cle>ance = ! float4 ,:5 ?is type swit* is us$ z a tank swit*1 ! contacts are clos$ :5 ! wat] level is l[1 putt+ ! motor1 driv+ ! pump1 9 motion4 ,:5 ! wat] 9 ! tank rea*es a pr$et]m9$ high level ! float arm op5s ! swit* contacts1 & ! motor is disconnect$ f ! l9e4 ,= sump pump purposes1 ! contacts op5 on l[ level & close on high level1 ! lev] be+ rev]s$ = ?is purpose4 ,two pole1 ?ree pole & f\r pole swit*es ( ?is type are made1 all arrang$ to completely disconnect s+le phase1 two phase & ?ree phase motors f _! circuits4 ,:5 us$ ) small motors :i* may be ?r[n across ! l9e to />t1 ! swit* may be us$ )\t a self />t] if desir$4 ,"u %ort circuit conditions alt]nators develop in/antane\sly _m times _! normal load curr5t1 :ile ! su/a9$ %ort circuit curr5t is approximately two & a half to ?ree times normal1 or ev5 high] ) turb9e alt]nators4 ,h5ce1 circuit break]s ( ! s call$ in/antane\s type mu/ be capable ( ruptur+ ! circuit :5 ! curr5t is at a maximum1 :]eas1 non-automatic swit*es1 or circuit break]s ) "t limit relays w be requir$ to int]rupt only ! su/a9$ %ort curr5t circuit4 ,! reason is evid5t1 s9ce ! delay 9 op5+ ! swit* all[s ! curr5t to approa* ! su/a9$ %ort circuit conditions4 ,,*apt] ,,lviii ,,curr5t ,,& ,,pressure ,,limit+ ,,devices ,9 any electric in/allation !re mu/ be provid$ a numb] ( automatic devices to secure prop] control4 ,! great multiplicity ( devices design$ = ?is purpose may be divid$ into two g5]al classes1 z #a4 ,curr5t limit+2 #b4 ,pressure limit+4 ,because ( ! heat+ effect ( ! curr5t :i* increases 9 proportion to ! squ>e ( ! /r5g? ( ! curr5t1 x is necess>y to protect circuits ) devices :i* d n all[ ! curr5t to exce$ a pr$et]m9$ value4 ,accord+ly fuses1 circuit break]s1 reactances1 etc41 are us$1 ea* possess+ c]ta9 *>act]i/ics1 :i* r5d] x suitable = p>ticul> conditions ( s]vice4 ,= in/ance1 j z 9 analogy1 /eam boil]s mu/ be protect$ aga9/ abnormal pressures by safety valves1 electric circuits mu/ be gu>d$ aga9/ excessive voltages by pressure limit+ devices1 o!rwise mu* damage w\ld occur1 su* z ! burn+ out ( inc&esc5t lamps1 gr\nd+ ( cables1 etc4 ,! control ( /eam is simple z comp>$ to ! electric curr5t1 ! latt] be+ ! m difficult to manage because ( its peculi> behavi\r 9 c]ta9 respects1 especially 9 ! case ( alt]nat+ curr5t :i* necessitates num]\s devices ( m or less delicate con/ruction = safety bo? to ! app>atus & ! op]ator4 ,fuses4--,a fuse is an electrical safety valve1 or m specifically1 ! actual wire or /rip ( metal 9 a cut out1 :i* may be fus$ by an excessive curr5t1 t is to say1 by a curr5t :i* exce$s a pr$et]m9$ value4 ,a fuse1 ?us s]ves to protect a circuit f any h>m result+ f an undue ov]load4 ,fuses h be5 treat$ at su* l5g? 9 ,guide ,no4 #b1 ,*apt] ,,xxv1 t v little c be said "h1 )\t repetition4 ,illu/ration3 ,,fig4 #b1bch4--,sectional view ( ,no>k #bej volt1 #djj amp]e enclos$ fuse4 ,! fusible elem5t is divid$ into /rips ,a1 ,b1 ,c1 & ,d4 ,?is p>allel l9k con/ruction results1 ^u ! op]ation ( ! fuse1 9 ! =mation ( a numb] ( small arcs1 ?us facilitat+ ! absorption ( ! metal vapor =m$ :5 ! fuse bl[s4 ,! fusible /rips1 ( :i* !re are two or f\r 9 numb]1 accord+ to ! amp]e capacity ( ! fuse1 are entirely surr\nd$ by a granul> mat]ial :i* is *emically inactive ) respect to ! fusible l9k & ^: function is to absorb ! metallic vapor =m$ ^u ! bl[+ ( ! fuse4 ,! contact blades ,t & ,l are made ( r\nd edge copp]1 ! r\nd edges facilitat+ ! ins]tion ( ! fuses 9 ! circuit t]m9als4 ,r & ,s are ! end f]rules1 atta*$ to cov] ,e1 by ! p9 ,m4 ,ques4 ,:at effect h ! t]m9als on a fuse8 ,ans4 ,! curr5t at :i* a fuse melts may be greatly *ang$ by ! size & %ape ( ! t]m9als4 ,if ne> toge!r & l>ge1 !y may conduct consid]able heat f ! fuse ?us increas+ ! curr5t requir$ to bl[ ! fuse4 ,ques4 ,:at is ! objection to l>ge fuses8 ,ans4 ,! dis*>ge ( molt5 metal :5 ! fuse bl[s is a s\rce ( dang]4 ,ques4 ,:at %\ld be us$ 9 place ( l>ge fuses8 ,ans4 ,circuit break]s4 ,ques4 ,:at are ! objections to fuses 9 g5]al8 ,ans4 ,! unc]ta9ty z to ! curr5t requir$ to bl[ !m2 ! con/ant expansion & contraction is liable to loos5 ! t]m9al screws :5 screws are us$4 ,ques4 ,:at is ! advantage ( fuses8 ,ans4 ,!y =m an inexp5sive means ( protect+ small circuits4 ,illu/ration3 ,,fig4 #b1bci4--;,cross section ?r\gh plug fuse4 ,) ?is type ( fuse x is impossible to place any except ! correct size ( plug 9 ! socket4 ,ques4 ,describe a plug fuse4 ,ans4 ,x is con/ruct$ z %[n 9 fig4 #b1bci1 ! fuse wire be+ visible & /ret*+ betwe5 ! two metal portions ( ! plug4 ,ques4 ,:at is a cut out fuse8 ,ans4 ,"o simil> to a simple fuse1 b provid$ ) clip contacts z us$ = knife swit* contacts4 ,! fuse wire is usually conta9$ 9 a *9a or porcela9 tube1 :i* also s]ves ! purpose ( a h&le = )draw+ ! fuse4 ,ques4 ,:at is an expulsion fuse8 ,ans4 ,"o 9 :i* ! fuse is plac$ 9 an enclos$ *amb] ) a v5t hole4 ,9 op]ation1 :5 ! fuse bl[s1 ! hot air & molt5 metal are expell$ ?r\gh ! v5t4 ,ques4 ,:at is a no arc fuse8 ,ans4 ,a c>tridge type fuse1 9 :i* ! space surr\nd+ ! fuse wire is fill$ ) p[d]$ mat]ial4 ,illu/ration3 ,,fig4 #b1bdj4--;,inside view ( end f]rule ( ,no>k enclos$ fuse4 ,two prongs ,o & ,v1 :i* are a "p ( ! knife blade ,k1 pass ?r\gh ! squ>e holes 9 ! ends ( ! f]rule ,r1 & are rivet$ to ! an*or plate ,t4 ,! object ( ?is plate is to /iff5 ! /ructure & to increase ! curr5t c>ry+ capacity ( ! metal betwe5 ! holes1 also to p]mit ( prop] alignm5t ( ! plates4 ,9 ea* f]rule is plac$ a v5t scre51 compos$ ( reticulate mat]ial1 su* z *eese clo?4 ,! fuzz betwe5 ! ?reads ( ! *eese clo? prev5ts ! escape ( ! granul> mat]ial ?r\gh ! v5t holes ,a1 b :5 ! fuse op]ates1 all[s free egress ( ! air1 !reby p]mitt+ ! vapor =m$ ^u ! op]ation ( ! fusible elem5t to quickly & freely pass ?r\gh ! int]/ices ( ! fill+ mat]ial & become cool$1 elim9at+ any possibility ( flame issu+ f ! ends ( ! tube4 ,! object ( ! p[d]$ mat]ial is to assi/ 9 ext+ui%+ ! arc =m$ :5 ! fuse bl[s4 ,ques4 ,:at is a magnetic bl[ out fuse8 ,ans4 ,an enclos$ fuse :i* is subject to ! action ( a magnetic field produc$ by ! curr5t1 ! magnetic field t5d+ to bl[ out ! arc :5 fus+ occurs4 ,ques4 ,:at is a quick break fuse8 ,ans4 ,"o hav+ a weight susp5d$ f its c5t]1 or spr+s atta*$ to its ends s t ! arc =m$ at fus+ is quickly att5uat$ & ext+ui%$4 ,ques4 ,:at is ! disadvantage ( a fuse z comp>$ to an oil swit* circuit break]8 ,ans4 ,:5 a fuse bl[s1 ! arc causes oscillations 9 ! l9e1 :i* cause excessive rise ( pressure "u c]ta9 capacity conditions1 :]eas ?is di/urbance is r$uc$ to a m9imum ) an oil swit*4 ,illu/ration3 ,,fig4 #b1bda4--,quick break fuse4 ,! fuse wire is connect$ betwe5 ! fix$ t]m9al ,a & ! movable arm ,b1 & is held "u t5sion by ! spr+ :i* ex]ts pressure on ! movable arm 9 a direction t5d+ to sep>ate ,a & ,b4 ,9 op]ation1 :5 ! fuse bl[s1 ! movable arm quickly moves to ! position ,b1 ?us att5uat+ ! arc & accel]at+ its ext+ui%m5t4 ,ques4 ,:at metal is us$ = fuse wires8 ,ans4 ,v>i\s metals4 ,ord9>y fuse wire is made ( lead or an alloy ( lead & t94 ,ques4 ,:at is ! objection to alum9um8 ,ans4 ,x becomes coat$ ) oxide or sulphide1 :i* acts z a tube t5d+ to reta9 ! metal inside & prev5t rupture4 ,ques4 ,:at is ! objection to copp]8 ,ans4 ,its high fus+ po9t4 ,curr5t ,limit+ ,inductances4--,! great increase 9 capacity ( p[] /ations1 = supply+ ! dem&s ( d5sely populat$ c5t]s & l>ge manufactur+ di/ricts1 toge!r ) ! decrease 9 ! reactance ( mod]n alt]nators & trans=m]s due to improvem5t 9 design to obta9 bett] regulation1 has pres5t$ a problem 9 app>atus protection n contemplat$ 9 ! e>li] days ( alt]nat+ curr5t di/ribution4 ,?is problem is entirely sep>ate & di/9ct f t ( elim9at+ ! t5d5cy t[>d %ort circuit1 incid5t to ! high voltages n[ common 9 transmission l9es4 ,x accepts t all %ort circuits mu/ occasionally occur & consid]s only ! protection ( ! connect$ app>atus aga9/ ! me*anical =ces due to ! magnetic /resses ( su* enorm\s curr5ts4 ,illu/ration3 ,,fig4 #b1bdb4--,not*$ end fuse4 ,?is is a simple =m ( fuse consi/+ ( a /rip ( metal 7or wire7 fix$ betwe5 two end pieces to fit ar\nd ! t]m9als4 ,?is type is (t5 proportion$ s t x is only possible to place ! correct size ( fuse 9 ! t]m9als4 ,sometimes1 9 place ( ! end pieces z %[n1 ! fuse metal is fix$ betwe5 two clamp+ screws4 ,ques4 ,:at means are employ$ to limit ! value ( a %ort circuit curr5t8 ,ans4 ,a curr5t limit+ inductance coil 7call$ a reactance7 is plac$ 9 s]ies ) ! alt]nators or trans=m]s4 ,illu/ration3 ,,fig4 #b1bdc4--;,g5]al ,electric curr5t limit+ reactance2 view %[+ details ( con/ruction4 ,! core consi/s ( a holl[ concrete cyl9d]1 alloy an*or plates or sockets be+ emb$d$ 9 ! core ne> ! ends to receive ! radial brass bolts4 ,an ext5sion at ea* end ( ! core provides = clamp+ & brac+ ! reactance 9 in/allation4 ,! supports = ! w9d+ are made ( res9 treat$ maple & are locat$ ^u ! core by radial brass /uds screw$ into ! alloy sockets1 & insulat$ by mica tubes4 ,! nuts by :i* ! /ructure is tight5$1 re/ ^u heavy fibre wa%]s4 ,wood5 b>ri]s fitt$ & %ellack$ into ! supports add to ! creepage surface betwe5 lay]s ( ! w9d+ & betwe5 ! w9d+ & ! core4 ,! supports ( ! lay] next to ! core are sep>at$ f ! core by /rips ( treat$ pressbo>d4 ,! coil consi/s ( b>e /r&$ cable 9 sev]al lay]s1 usually ?ree 9 numb]4 ,x is w\nd into grooves 9 ! treat$ wood supports1 :i* are protect$ f contact ) ! cable by heat %ields ( asbe/os %ellack$ into ! grooves4 ,! w9d+ is usually 9 ! =m ( two back turn sections1 !reby all[+ ! t]m9als ( ! coil to be br\ght out at ! ends ( ! outside lay]4 ,?is assures accessibility & ease ( connection1 & ! removal ( ! leads f proximity to ! core4 ,two turns at ea* end ( ! w9d+ are giv5 extra spac+ = ! purpose ( additional insulation4 ,! f9al turn at ea* end ( ! coil is securely held 9 place by alloy clamps bolt$ to ! supports4 ,! wood is protect$ f contact ) ! clamps by %ields ( asbe/os4 ,! ends ( ! cable betwe5 ! two sections are weld$ by ! oxyacetyl5e process4 ,ques4 ,:at are its ess5tial features ( con/ruction8 ,ans4 ,x consi/s ( b>e /r&$ cable w\nd ar\nd a concrete core & held 9 place by wood5 supports z %[n 9 fig4 #b1bdc4 ,9 ord] to avoid ! prohibitive exp5se ( high voltage insulation1 ! reactance coil is design$ = ! l[ t5sion circuit4 ,?is requirem5t prohibits ! use ( a magnetic core :i*1 if economically design$ = normal op]ation1 w\ld become saturat$ at high] d5sities1 or1 if design$ l>ge en\gh to avoid saturation at %ort circuit conditions1 w\ld become prohibitive 9 co/ & dim5sions4 ,! elim9ation ( all magnetic mat]ial f ! con/ruction ( ! concrete core reactance p]mits ( no saturation1 & assures a /raight l9e voltage *>act]i/ic at all curr5t loads4 ,illu/ration3 ,,fig4 #b1bdd4--,we/+h\se magnetic bl[ out circuit break]1 design$ = ! protection ( /reet railway & electric locomotive equipm5ts2 x s]ves ! comb9$ purpose ( fuse block & canopy swit*4 ,! contact tips are surr\nd$ by a m\ld$ arc *ute :i* conf9es & directs ! arc until ! magnetic bl[ out ext+ui%es x4 ,! curr5t c>ry+ contacts consi/ ( copp] /rips sep>at$ by air spaces4 ,an auxili>y contact or arc+ tip at ! end ( ! swit* lev] takes ! burn+ ( ! arc :5 ! break] op5s1 & ?us conf9es ! burn+ to a v small piece :i* c be easily remov$ & replac$ at small co/4 ,! h& tripp+ lev] & ! resett+ lev] h insulat$ h&les1 s t !y c be safely h&l$1 ev5 9 ! d>k4 ,ques4 ,:]e is ! prop] location = a curr5t limit+ reactance8 ,ans4 ,z ne> ! alt]nator z possible4 ,ques4 ,:y8 ,ans4 ,to less5 ! possibility ( a %ort circuit occurr+ betwe5 ! reactance & ! alt]nator4 ,ques4 ,beside limit+ ! curr5t1 :at o!r s]vice is p]=m$ by ! reactance8 ,ans4 ,x protects ! alt]nator f high frequ5cy surges com+ 9 f ! outside1 & limits ! curr5t f o!r ma*9es on ! same bus4 ,illu/ration3 ,,fig4 #b1bde4--;,g5]al ,electric magnetic bl[ out circuit break]4 ,?is type may be us$ 9 air or wat] tight boxes & is peculi>ly adapt$ = s]vice :]e ! arc mu/ be conf9$4 ,circuit ,break]s4--,! importance ( circuit protective devices1 commonly call$ circuit break]s1 is fully recogniz$4 ,! duty ( a circuit break] is to protect ! app>atus 9 an electrical circuit f undesirable effects aris+ f abnormal conditions1 by automatically break+ ! circuit4 ,accord+ly a circuit break] mu/ comprise a swit* 9 comb9ation ) electrical control devices design$ to act "u abnormal conditions 9 ! circuit4 ,a circuit break] is a device :i* automatically op5s ! circuit 9 ev5t ( abnormal conditions1 9 ! circuit4 ,illu/ration3 ,,fig4 #b1bdf4--,magnetic bl[ out circuit break]4 ,?is is a direct curr5t break] 9 :i* ! f9al break occurs 9 a magnetic field4 ,x is a pr9ciple 9 electromagnetics t a conductor c>ry+ a curr5t 9 a magnetic field w t5d to move 9 a direction at "r angles to ! field4 ,! arc set up on break+ a circuit con/itutes a conductor1 & 9 magnetic bl[ out circuit break]s1 z g5]ally manufactur$1 !re is an electromagnet1 en]giz$ by ! curr5t to be brok51 :i* produces a field 9 ! neighborhood ( ! arc1 ) ! result t ! arc moves outw>d1 & s becomes att5uat$ & is f9ally ext+ui%$4 ,! =m %[n 9 ! figure is us$ on c>s equipp$ ) heavy motors4 ,:5 s us$1 x is 9 _m cases m\nt$ 9 a box ) ! h&le ,h project+ at "o end4 ,a & ,k are ! t]m9als ( ! break] & ,b is ! tripp+ coil1 :i* also s]ves to set up ! magnetic field necess>y = bl[+ out ! arc4 ,x is ! armature ( coil ,b & is pull$ d[n aga9/ ! action ( ! spr+ ,s :5ev] ! curr5t exce$s t = :i* ! break] is set4 ,! tripp+ curr5t is adju/$ by means ( nut ,t4 ,! iron plate ,p & a simil> "o back ( x are magnetiz$ by ! curr5t 9 coil ,b1 & z ! break takes place betwe5 ^! two poles1 ! arc is promptly ext+ui%$ by ! field t exi/s !re4 ,9 op]ation1 ,a & ,k are ! t]m9als1 ,d ,d is a contact t is =c$ up aga9/ ,f1 ,f :5 ! break] is set4 ,! curr5t !n takes ! pa? ,a-,b-,f-,d ,d-,f-,k4 ,:5 ! break] trips1 ! contact piece ,d ,d flies d[n & ! t5d5cy is = an arc to =m betwe5 ,f1 ,f2 ! magnetic field bl[s ! arc upw>ds1 & :atev] burn+ takes place is on ! contacts ,e1 ,e1 :i* are s con/ruct$ t !y may be readily r5ew$4 ,to trip ! break] by h&1 ! knob ,n is press$4 ,9 ! design ( circuit break]s1 !re are sev]al me?ods us$ to effect ! ruptur+ ( ! arc betwe5 contacts :5 op5$ on heavy ov]load1 su* z3 #a4 ,magnetic bl[ out2 #b4 ,!rmal break2 #c4 ,c>bon break4 ,9 ! magnetic bl[ out type1 ! arc is ext+ui%$ betwe5 auxili>y contacts conf9$ by a *ute 9 :i* ! arc is rapidly bl[n out due to a p[]ful magnetic field f "o or m electromagnets4 ,?is type may be us$ 9 air or wat]tight boxes & is peculi>ly adapt$ = s]vice :]e ! arc mu/ be conf9$4 ,illu/ration3 ,,fig4 #b1bdg4--,!rmal ov]load circuit break]4 ,9 con/ruction two contact blocks are fix$ rigidly to1 b insulat$ f1 ! swit* arm4 ,!y are connect$ electrically by two p>allel /rips ( suitable metal1 ea* fitt$ ) a /eel cat* piece4 ,:5 ! swit* is clos$ ! /rips are sprung ap>t ov] a fix$ cat*1 & ! full rat$ curr5t does n release ! cat*4 ,ov]load causes ! /rips to move ap>t1 & ! circuit break] flies (f "u ! action ( a spr+4 ,9 a c>bon break type1 ! arc is f9ally ruptur$ betwe5 c>bon break contacts4 ,! break+ ( ! circuit is accompli%$ progressively1 t is to say1 x is done 9 ?ree /ages1 by sev]al sets ( contact1 kn[n respectively z #a4 ,! ma9 contacts2 #b4 ,! int]m$iate contacts2 #c4 ,! c>bon contacts4 ,9 op]ation1 z ! circuit break] acts to break ! circuit1 fir/ ! ma9 contacts1 sep>ate1 !n ! int]m$iate contacts1 & f9ally ! c>bon contacts betwe5 :i* ! arc is ruptur$4 ,ques4 ,:at is ! object ( ! int]m$iate contacts8 ,ans4 ,to prev5t ! =m+ ( an arc on ! ma9 contacts4 ,illu/ration3 ,,fig4 #b1bdh4--;,c>bon break discs ( ,condit circuit break]4 ,! two pairs ( simil> discs :i* slide pa/ ea* o!r are s arrang$ t ^! surfaces co9cide at ! in/ant ! int]m$iate contacts sep>ate aft] :i*1 z ! contact arm op5s fur!r1 !y gradually dis5gage4 ,ques4 ,:at is ! object ( ! c>bon contacts8 ,ans4 ,fir/ to protect ! int]m$iate contacts by provid+ a pa? = ! curr5t aft] ! int]m$iate contacts sep>ate1 & #b1 to sl[ d[n ! curr5t by means ( ! consid]able resi/ance ( ! c>bon1 ?us r$uc+ to a m9imum ! arc :i* is =m$ :5 ! c>bon contacts sep>ate4 ,ques4 ,h[ is ! automatic op]ation ( a circuit break] usually accompli%$8 ,ans4 ,usually ?r\gh ! m$ium ( a sol5oid1 or electromagnet en]giz$ by curr5t f ! circuit controll$ by ! break]4 ,illu/ration3 ,,fig4 #b1bdi4--,me*anically connect$ insulat$ lat*es us$ on ,condit circuit break]s to produce int]-lock+ tripp+4 ,! ess5tial features ( con/ruction & op]ation ( a circuit break] is %[n 9 ! elem5t>y diagrams1 figs4 #b1bej to #b1bec4 ,9 con/ruction z %[n 9 fig4 #b1bej x consi/s ess5tially ( ?ree sets ( contacts1 a sw++ contact arm :i* is set 9 ! clos$ position by ! h&le op]at+ ?r\gh ! toggle jo9t1 ! movem5t ( :i* is limit$ 9 ! clos+ direction by ! /op4 ,! latt] is made adju/able by an ecc5tric p9 or equival5t4 ,connect$ to ! toggle is ! plung] ( ! sol5oid ^: w9d+ is en]giz$ by curr5t f ! circuit :i* ! circuit break] is to control4 ,illu/ration3 ,,figs4 #b1bej to #b1bec4--;,elem5t>y diagrams illu/rat+ ! op]ation ( a c>bon circuit break] ( ! ov]load type1 %[+ ! progressive op5+ ( su* device4 ,fig4 #b1bej1 clos$ position2 fig4 #b1bea1 ma9 contacts op52 fig4 #b1beb1 int]m$iate contacts op52 fig4 #b1bec1 c>bon contacts op51 circuit brok54 ,9 op]ation1 ! circuit is clos$ by h& by turn+ ! h&le d[nw>d to ! position %[n 9 fig4 #b1bej1 t is z f> z x w g4 ,s9ce ! toggle has pass$ ! c5t] l9e ! arm w be held normally 9 ?is position because ( ! spr+ action ( ! contacts4 ,n[1 if ! curr5t rise above a pr$et]m9$ limit1 ! pull ex]t$ by ! sol5oid w ov]balance ! t5d5cy ( ! toggle to rema9 9 ! clos$ position1 & pull ! two toggle l9ks d[nw>d bel[ ! c5t] l9e1 draw+ ! contact arm back & break+ ! circuit4 ,illu/ration3 ,,fig4 #b1bed4--;,i-,t-,e ov]load circuit break]4 ,9 op]ation3 ! curr5t f "o side ( ! circuit ent]s ! circuit break] at ,a1 pass+ ?r\gh ! lam9at$ bridge ,b to contact block ,c1 !nce ?r\gh coil ,d & t]m9al ,e to ! motor4 ,! coil ,d surr\nds a magnetic core1 hav+ pole pieces ,f & ,g & armature ,h4 ,! effect ( ! curr5t 9 ! coil is to en]gize ! magnet1 ?us t5d+ to lift ! armature aga9/ ! =ce ( gravitation4 ,! volume ( curr5t requir$ to trip ! circuit break] is det]m9$ by ! position ( ! armature1 :i* is subject to ready adju/m5t1 & is indicat$ on ! calibration plate ,p4 ,f ! opposite side ( ! l9e1 ! curr5t ent]s at ,i1 pass+ d[nw>d ?r\gh ! lam9at$ bridge memb] ,j1 into t]m9al ,k1 :5ce x passes out to ! motor4 ,:5 ! curr5t pass+ ?r\gh ! circuit break] atta9s suffici5t volume1 ! =ce g5]at$ by ! magnetic coil ov]comes ! weight ( ! armature ,h2 & ! latt] is drawn upw>d t[>d ! pole pieces ) con/antly increas+ =ce1 until ! insulat$ projections ,l & ,m /rike aga9/ ! respective re/ra9+ lat*es ,n & ,o1 !reby releas+ ! two swit* memb]s1 :i* at once op5 9 response to ! =ce suppli$ by ! spr+ ( ! contact memb]s & auxili>y spr+s provid$ = ! purpose4 ,positiv5ess 9 op5+ is fur!r assur$ by ! bl[ ( ! armature1 :i* is add$ to ! o!r op5+ =ces2 h5ce1 ! heavi] ! ov]load1 ! m viol5t ! bl[ & ! quick] ! circuit break] op5s2 or ! great] ! curr5t ! m promptly x is int]rupt$4 ,?is is ! ,i-,t-,e or ,inv]se ,time ,elem5t pr9ciple4 ,illu/ration3 ,,fig4 #b1bee4--;,condit #fjj volt1 #a1bjj amp]e1 s+le pole1 type ,k1 circuit break] ) pull d[n h&le4 ,illu/ration3 ,,fig4 #b1bef4--;,condit #fjj volt1 #f1jjj amp]e1 s+le pole1 swit* bo>d m\nt+1 circuit break]1 ) pull d[n h&le4 ,illu/ration3 ,,fig4 #b1beg4--;,g5]al ,electric triple pole1 ov]load1 circuit break]1 ) two ov]load coils1 capacity #cjj amp]es1 #dhj volts4 ,! progressive action :i* takes place dur+ ?is op]ation is %[n 9 figs4 #b1bej to #b1bec 9 :i* ! ma9 contacts sep>ate fir/1 !n ! int]m$iate1 & f9ally ! c>bon contacts z m5tion$ be=e4 ,ques4 ,:at "n is giv5 to ?is type ( circuit break]8 ,ans4 ,x is call$ an ov]load circuit break]4 ,illu/ration3 ,,fig4 #b1beh4--,p>ts ( ,g5]al ,electric #b1jjj amp]e #fej volt circuit break]4 ,a1 cov] = second>y contact bracket2 ,b1 spr+ wa%] = ,ea42 ,c1 p9 = l9ks & ,g2 ,d1 spr+ = c>bon support2 ,e1 plate = ,f2 ,f1 c>bon support2 ,g1 second>y contact bracket2 ,h1 contact plate2 ,i1 screw = ,h2 ,j1 nut = ,k & ,w2 ,k1 contact /ud1 upp]2 ,l1 lam9at$ bru%1 complete ) support2 ,m1 lea!r buff] = ,l2 ,n1 ma9 l9k2 ,o1 p9 = ,na & ,la left h& & ,cb & ,na "r & left h&2 ,p1 screw = ,n & magnet frame %aft2 ,q1 wa%] = ,n & magnet frame %aft2 ,r1 screw = ,s & ,v2 ,s1 index plate2 ,t1 plate = ,gb2 ,u1 screw = ,t2 ,v1 magnet frame2 ,w1 contact /ud1 l[]2 ,x1 p9 = ,cb1 ,na & ,v2 ,y1 wa%] = ,x & ,o2 ,z1 calibrat+ screw ) ?umb nut2 ,aa1 armature ) contact plate2 ,ba1 cat* lev] complete ) cat* ,ca1 button h&le = ,ba2 ,da1 spr+ cott] = ,ea2 ,ea1 p9 = ,f & ,fa2 ,fa1 op]at+ l9k = ,g2 ,ga1 p9 = ,d2 ,ha1 c>bon hold] ) copp] & c>bon contacts2 ,ia1 flexible connections = ,g & ,f2 ,ja1 screw = ,g & flexible connection plate2 ,ka1 screw = ,na & ,ha2 ,la1 copp] second>y contact2 ,ma1 screw = ,la2 ,na1 second>y contact lev]2 ,oa1 cross b> = ,na2 ,pa1 screw = ,l & ,m2 ,qa1 second>y toggle l9k 7left h&72 ,ra1 spr+ cott] = ,wa & ,o2 ,sa1 bru% lev]2 ,ta1 buff] = ,cb & ,sa2 ,ua1 second>y toggle l9k 7"r h&72 ,va1 wa%] = ,wa2 ,wa1 p9 = ,cb1 ,qa1 ,ua & ,n2 ,xa1 p9 = ,sa & ,cv2 ,ya1 spr+ cott] = all p9s1 except ,wa1 cat* lev] p9 & buff]2 ,za1 second>y contact l9k2 ,ab1 wa%] = ,fb2 ,bb1 gu>d = ,fb2 ,cb1 h&le lev]2 ,db1 cat* = ,cb2 ,eb1 screw = ,db2 ,fb1 h&le ) /ud2 ,gb1 second>y connection4 ,automatic ,features4--,!re are ?ree me?ods ( connect+ ! w9d+ ( ! sol5oid1 or trip coil z x is call$3 ,illu/ration3 ,,figs4 #b1bei to #b1bfb4--;,elem5t>y diagrams illu/rat+ ! v>i\s me?ods ( electromagnetic control = circuit break]s4 ,fig4 #b1bei1 ov]load trip2 fig4 #b1bfj1 und]load trip1 fig4 #b1bfa1 l[ voltage trip2 fig4 #b1bfb1 control f auxili>y circuit by means ( a relay4 #a4 ,9 s]ies ) ! ma9 circuit2 #b4 ,9 %unt ) ! ma9 circuit2 #c4 ,9 %unt ) an auxili>y circuit4 ,illu/ration3 ,,fig4 #b1bfc4--;,diagram ( ,g5]al ,electric l[ voltage trip ) tripp+ swit* normally op54 ,! automatic controls aris+ f ^! connections give v>i\s k9ds ( protection to ! circuit & are kn[n z #a4 ,ov]load trip2 #b4 ,und]load trip2 #c4 ,l[ voltage trip2 #d4 ,auxili>y circuit trip4 ,illu/ration3 ,,fig4 #b1bfd4--;,diagram ( ,g5]al ,electric l[ voltage trip1 ) tripp+ swit* normally clos$4 ,ques4 ,:at is ! object ( ! ov]load trip8 ,ans4 ,x is int5d$ to op5 ! circuit :5 ! curr5t exce$s a pr$et]m9$ value4 ,ques4 ,:at modifications are made 9 ! me*anism %[n 9 ! elem5t>y diagrams8 ,ans4 ,sometimes a lat* is us$ 9 place ( ! toggle & a magnet 9 place ( ! sol5oid z 9 figs4 #b1bfe & #b1bff4 ,ques4 ,:y is a magnet us$ 9 comb9ation ) a lat*8 ,ans4 ,because ) ?is arrangem5t v little movem5t is requir$ to trip ! break]1 & = su* conditions1 a magnet is m effici5t ?an a sol5oid4 ,illu/ration3 ,,figs4 #b1bfe & #b1bff4--;,circuit break] ) automatic control me*anism consi/+ ( magnet & lat*2 views %[+ break] 9 op5 & clos$ positions1 & ess5tial features4 ,! toggle is us$ to obta9 suffici5t lev]age to easily close swit* aga9/ ! pressure ( ! bru% contacts b n to lock swit*1 ?is be+ done by ! lat* z %[n1 ! latt] clos+ by ! action ( a spr+1 !re be+ a roll] ,r at ! end :i* engages ! arm to r$uce friction4 ,9 op]ation1 :5 ! curr5t exce$s a pr$et]m9$ limit ! magnet attracts ! lat* & releases ! contact arm4 ,! bru% contacts :i* are ex]t+ pressure aga9/ ! contact arm1 rapidly pu% x away1 & assi/$ by gravity1 ! arm flies op5 to ! position %[n 9 fig4 #b1bff4 ,ques4 ,h[ does ! lat* arrangem5t "w8 ,ans4 ,:5 ! prop] curr5t is rea*$1 ! magnet pulls op5 ! lat* & ! contact arm ( ! break] moves by ! =ce ( gravity or o!r means & op5s ! circuit4 ,ques4 ,h[ does ! und]load trip op]ate8 ,ans4 ,! same z ! ov]load type except t !y op]ate on a dim9ution ( curr5t in/ead ( an excess4 ,illu/ration3 ,,figs4 #b1bfg & #b1bfh4--,positions 9 circuit ( curr5t & pressure coils ( circuit break]s4 ,ques4 ,describe ! no voltage trip4 ,ans4 ,! en]gy = ! trip ( ?is break] is d]iv$ f a high resi/ance or f9e wire coil :i* is arrang$ to be plac$ directly across ! l9e1 9 op]ation1 :5 ! curr5t fl[+ ?r\gh ! circuit falls bel[ a pr$et]m9$ value1 ! en]gy ( ! coil is insuffici5t to c\nt]act ! =ce ( a spr+1 :i* !n trips ! break]4 ,illu/ration3 ,,fig4 #b1bfi4--;,diagram ( ,g5]al ,electric %unt trip ) coil connect$ beyond break] & ?r[n out ( circuit aft] tripp+4 ,ques4 ,describe ! auxili>y circuit trip4 ,ans4 ,a pressure coil is us$ :i* is en]giz$ by curr5t f an auxili>y circuit4 ,! coil is only mom5t>ily en]giz$1 by pu% button1 relay or o!r control1 z di/+ui%$ f ! prec$+ types1 9 :i* ! coil is con/antly en]giz$4 ,illu/ration3 ,,fig4 #b1bgj4--;,diagram ( ,g5]al ,electric %unt trip ) auxili>y circuit op5+ swit* to ?r[ coil out ( circuit aft] tripp+4 ,illu/ration3 ,,fig4 #b1bga4--;,g5]al ,electric %unt trip atta*m5t4 ,! %unt trip atta*m5t has be5 design$ to provide = conditions "u :i* ! l[ voltage atta*m5t _c be successfully appli$4 ,x resembles ! l[ voltage atta*m5t 9 con/ruction1 b diff]s 9 t x trips ! circuit break] :5 en]giz$4 ,! %unt trip %\ld be all[$ to rema9 only mom5t>ily 9 circuit2 h5ce x %\ld be s connect$ t ! op5+ ( ! circuit break] imm$iately disconnects x f ! circuit4 ,:5ev] x is impossible to connect ! %unt trip 9 ?is mann]1 ! circuit op5+ auxili>y swit* %\ld be us$ 9 connection ) x4 ,illu/ration3 ,,fig4 #b1bgb4--;,g5]al ,electric l[ voltage atta*m5t = circuit break]s4 ,?is l[ voltage trip is design$ to op]ate ! circuit break] :5 ! l9e voltage drops to approximately #ej p] c5t or less ( ! normal voltage4 ,x %\ld be not$ t ! coil is always 9 circuit1 z is ! case ) ! ov]load & und]load coils1 & t x op]ates ) ! releas+ ( its armature4 ,x is always necess>y to use a fix$ am\nt ( resi/ance 7dep5d+ ^u ! voltage ( ! sy/em7 9 s]ies ) ! l[ voltage release4 ,! l[ voltage release p]=ms ! functions ( a %unt trip coil :5 us$ 9 conjunction ) a pu% button1 auxili>y swit* or spe$ limit+ device1 & is g5]ally pref]r$ to ! %unt trip atta*m5t4 ,illu/ration3 ,,fig4 #b1bgc4--;,g5]al ,electric circuit op5+ auxili>y swit*4 ,?is swit* op5s an auxili>y circuit :5 ! circuit break] op5s1 & is int5d$ to be us$ 9 connection ) a %unt trip atta*m5t to insure ! imm$iate disconnection ( ! %unt coil f ! circuit4 ,x may also be employ$ to s]ve o!r purposes1 su* z tripp+ ano!r circuit break] hav+ a l[ voltage atta*m5t1 & p]mitt+ ano!r circuit break] to rema9 clos$ only :5 ! circuit break] equipp$ ) ! auxili>y swit* is op54 ,ques4 ,:at o!r "n is giv5 to ! auxili>y circuit trip8 ,ans4 ,x is sometimes call$ ! %unt trip1 ?\gh ill advis$ly s4 ,illu/ration3 ,,fig4 #b1bgd4--;,g5]al ,electric circuit clos+ auxili>y swit*4 ,?is swit* closes :5 ! circuit break] op5s1 & may be us$ to ann\nce ! automatic op5+ ( ! circuit break] ?r\gh ! means ( an indicat+ lamp or an al>m bell4 ,x is (t5 necess>y to arrange "o circuit break] s t1 9 op5+1 x w trip o!rs4 ,?is may be accompli%$ by us+ a circuit clos+ auxili>y swit* 9 connection ) a l[ voltage or %unt trip atta*m5t on ! circuit break]s to be tripp$4 ,! con/ruction ( ?is type ( swit* is su* t x may be op5$ by h& aft] ! circuit break] op5s1 b x is automatically reset :5 ! circuit break] is clos$4 ,relays4--,oil break swit*es & c>bon break circuit break]s are commonly us$ to op5 electrical circuits at "s giv5 ov]load & on %ort circuit4 ,to secure additional protection "u a v>iety ( abnormal conditions or to provide = a c]ta9 pr$et]m9$ op]ation or sequ5ce ( op]ations1 relays may be employ$4 ,illu/ration3 ,,fig4 #b1bge4--;,g5]al ,electric type ,c circuit break]4 ,specially adapt$ to motor driv5 ma*9e tool applications4 ,= use 9 mills1 ma*9e %ops1 factories1 f\ndries & (fice build+s4 ,= g5]al motor "w1 automobile *>g+ outfits1 /orage batt]ies1 rectifi] sets1 cranes1 etc4 ,li/ ( p>ts3 ,a1 calibrat+ po/2 ,b1 lam9at$ contact2 ,c1 second>y contact spr+2 ,d1 contact blade2 ,e1 cott] p9 = ,g2 ,f1 toggle l9k2 ,g1 p9 = ,d & ,f2 ,h1 /op = ,aa2 ,i1 h+e frame2 ,j1 op]at+ lev]2 ,k1 p9 = ,i & ,j2 ,l1 toggle l9k2 ,m1 connection2 ,n1 screw = ,m1 ,o & ,p2 ,o1 nut = ,n & ,p2 ,p1 t]m9al2 ,q1 tripp+ coil2 ,r1 calibrat+ screw2 ,s1 lam9at$ contact2 ,t1 calibrat+ scale2 ,u1 calibrat+ spr+2 ,v1 connection po/2 ,w1 knob2 ,x1 wa%] = ,y2 ,y1 h&le2 ,z1 buff]2 ,aa1 armature2 ,ba1 lam9at$ connection2 ,ca1 connection2 ,da1 base4 ,a relay is def9$ z3 ,a device :i* op5s or closes an auxili>y circuit "u pr$et]m9$ electrical conditions 9 ! ma9 circuit4 ,! object ( a relay is g5]ally to act z a sort ( electrical multipli]1 t is to say1 x enables a comp>atively weak curr5t to br+ into op]ation a mu* /rong] curr5t4 ,illu/ration3 ,,fig4 #b1bgf4--;,diagram ( connections ( ,g5]al ,electric %unt trip coil ) & )\t circuit op5+ auxili>y swit*4 ,ques4 ,= :at s]vice are relays l>gely us$8 ,ans4 ,!y are employ$ 9 connection ) high voltage swit*es :]e ! small am\nt ( en]gy d]iv$ f an ord9>y in/rum5t trans=m] is insuffici5t = tripp+4 ,! connections betwe5 relays & circuit op5+ devices are usually electrical4 ,comb9ations ( ?is nature are extremely flexible s9ce !y p]mit ! use ( a numb] ( devices1 ea* hav+ a diff]5t function1 ) a s+le circuit break] or oil swit* z well z ) two or m swit*es1 to secure ! desir$ op]ation & protection4 ,selection4--,9 all electrical in/allations protection ( app>atus is important1 b 9 "s l>ge c5tral /ations ?is is second>y to cont9uity ( s]vice4 ,to comb9e maximum protection )\t int]ruptions ( s]vice is n always possible1 b ^! requirem5ts c be approximat$ v closely by ! use ( reliable & simple controll+ or protect+ devices if prop] c>e be tak5 to select ! relays suit$ to ! special conditions ( ! in/allation4 ,to d ?is intellig5tly1 a k ( ! v>i\s types ( relay is necess>y4 ,illu/ration3 ,,fig4 #c1jgc4--;,diagram ( connections ( ,g5]al ,electric l[ voltage release coil :5 us$ ) spe$ limit+ device on rot>y conv]t]4 ,!re is a multiplicity ( types & a classification to be compreh5sive1 %\ld1 z 9 num]\s o!r cases1 be made f sev]al po9ts ( view4 ,accord+ly relays may be classifi$3 #a4 ,) respect to ! nature ( ! s]vice p]=m$1 z a4 ,protective2 b4 ,regulative2 c4 ,communicative4 #b4 ,) respect to ! op]at+ curr5t1 z a4 ,alt]nat+ curr5t2 b4 ,direct curr5t4 #c4 ,) respect to ! mann] ( p]=m+ _! function1 z a4 ,circuit op5+2 b4 ,circuit clos+4 #d4 ,) respect to ! op]at+ curr5t circuit1 z a4 ,prim>y2 b4 ,second>y4 #e4 ,) respect to ! abnormal conditions :i* caus$ !m to op]ate1 z a4 ,ov]load2 b4 ,und]load2 c4 ,ov] voltage2 d4 ,l[ voltage2 e4 ,rev]se en]gy2 f4 ,rev]se phase4 #f4 ,) respect to ! "t consum$ 9 p]=m+ _! function1 z a4 ,in/antane\s 7s call$72 b4 ,def9ite "t limit2 c4 ,inv]se "t limit4 #g4 ,) respect to ! "* ( its action1 z a4 ,selective2 b4 ,diff]5tial4 #h4 ,) respect to :e!r x acts directly or indirectly on ! circuit break]1 z a4 ,ma92 b4 ,auxili>y4 ,illu/ration3 ,,fig4 #b1bgh4--;,g5]al ,electric ov]load & l[ voltage type ,c circuit break] = #fjj volts or less4 ,x has "o ov]load1 & "o l[ voltage coil z %[n4 ,scre5s are provid$ betwe5 contacts4 ,protective ,relays4--,^! are us$ to protect circuits f abnormal conditions ( voltage1 or curr5t1 :i* w\ld be undesirable or dang]\s to ! circuit & app>atus conta9$ !re94 ,ques4 ,h[ d protective relays op]ate8 ,ans4 ,!y act 9 comb9ation ) automatic circuit break]s1 op]at+ :5 _! pr$et]m9$ sett+ has be5 rea*$1 en]giz+ ! trip coil ( ! circuit break] & op5+ ! circuit4 ,fig4 #b1bgi %[s ! pr9ciples ( relay op]ation4 ,:5 ! curr5t or pressure 9 ! ma9 circuit rea*es ! pr$et]m9$ value at :i* ! protective sy/em %\ld op]ate1 ! relay magnet attracts ! pivot$ contact arm & closes ! auxili>y circuit2 ?is p]mits curr5t to fl[ f ! curr5t s\rce 9 t circuit & en]gize ! trip coil ?us op5+ ! ma9 circuit4 ,illu/ration3 ,,fig4 #b1bgi4--;,diagram illu/rat+ ! op]ation ( a circuit clos+ relay4 ,:5 ! pr$et]m9$ abnormal condition is rea*$ 9 ! ma9 circuit1 ! relay closes ! auxili>y circuit1 ?us en]giz+ ! trip coil & op5+ ! break]4 ,regulative ,relays4--,?is class ( relay is us$ to control ! condition ( a ma9 circuit ?r\gh control devices op]at$ by a second>y circuit4 ,ques4 ,= :at s]vice are relays ( ?is class employ$8 ,ans4 ,!y are us$ z fe$] circuit or g5]ator regulators4 ,ques4 ,h[ d !y diff] f protective relays8 ,ans4 ,!y h diff]5tially arrang$ contacts1 t is to say1 arrang$ = contact on ei!r side ( a c5tral or normal position4 ,illu/ration3 ,,fig4 #b1bhj4--;,diagram %[+ a railway syn*ron\s conv]t] protect$ by a s+le pole ov]load circuit break] ) l[ voltage release atta*m5t & bell al>m swit*4 ,! l[ voltage atta*m5t trips ! break] on failure ( direct curr5t voltage also :5 spe$ limit device closes4 ,int]nal tr\bles are tak5 c>e ( by ! alt]nat+ curr5t automatic devices 7n %[n74 ,communicative ,relays4--,^! are us$ = signall+ 9 a great v>iety ( ways = indicat+ ! position ( swit*+ app>atus or pr$et]m9+ ! condition ( electric circuits4 ,a4 ,c4 & ,d4 ,c4 ,relays4--,z "h us$1 ! classification ref]s to ! k9d ( curr5t us$ on ! auxili>y circuit4 ,9 "s cases direct curr5t is us$ to en]gize ! trip ge> ( ! circuit break] or oil swit*1 & 9 o!rs1 alt]nat+ curr5t4 ,illu/ration3 ,,fig4 #b1bha4--;,diagram %[+ ?ree phase motors protect$ by triple pole ov]load circuit break]s1 ) two ov]load coils1 also "o ov]load coil & l[ voltage release coil4 ,! use ( ! l[ voltage release all[s ! break] to be tripp$ f a di/ance by means ( a %ort circuit+ swit* or pu% button4 ,a4 ,c4 & ,d4 ,c4 relays are respectively kn[n z circuit op5+ & circuit clos+ relays1 be+ lat] fully describ$4 ,circuit ,op5+ ,relays4--,! duty ( a circuit op5+ relay is to op5 ! auxili>y circuit1 usually alt]nat+ curr5t1 nd !reby cause ! oil swit* or circuit break] to be op5$ by ! use ( a trip coil 9 ! second>y ( a curr5t trans=m]1 or by l[ voltage release coil4 ,! trip coil ( ! break] is g5]ally %unt$ by ! relay contacts & :5 ! mov+ contact ( ! relay dis5gages f ! /ation>y contact1 ! curr5t f ! trans=m] :i* supplies ! relay1 fl[s ?r\gh ! trip coil ?us op5+ ! break]4 ,^! features ( op]ation are %[n 9 fig4 #b1bhb4 ,illu/ration3 ,,fig4 #b1bhb4--;,diagram illu/rat+ ! op]ation ( a circuit op5+ relay4 ,:5 ! relay contacts are 9 ! normal clos$ position1 z %[n1 ! coil is %ort circuit$4 ,:5 ! pr$et]m9$ abnormal condition is rea*$ 9 ! ma9 circuit1 ! relay contacts are op5$ ) a quick break1 s5d+ ! curr5t ?r\gh ! trip coil mom5t>ily1 & op5+ ! break]4 ,ques4 ,:]e are circuit op5+ relays *iefly employ$8 ,ans4 ,9 places :]e direct curr5t is n available = en]giz+ ! trip coil4 ,ques4 ,:at is ! objection to alt]nat+ curr5t trip coils8 ,ans4 ,!y h relatively high imp$ance & impose a heavy volt amp]e load on ! trans=m]s4 ,circuit ,clos+ ,relays4--,! duty ( a circuit clos+ relay is to close ! auxili>y circuit at ! "t :5 ! pr$et]m9$ abnormal condition is rea*$ 9 ! prim>y circuit4 ,! clos+ ( ! auxili>y circuit en]gizes ! trip coil & op5s ! break]4 ,illu/ration3 ,,figs4 #b1bhc to #b1bia4--;,g5]al ,electric in/antane\s ov]load circuit op5+ relays1 cov]s remov$4 ,circuit op5+ relays are us$ *iefly 9 ^? cases :]e direct curr5t = ! tripp+ circuit is n available4 ,alt]nat+ curr5t trip coils h relatively high imp$ance & impose a heavy volt amp]e load on ! curr5t trans=m]s4 ,to r$uce ?is load dur+ normal op]ation ! circuit op5+ relay is frequ5tly us$ & is usually necess>y :]e in/rum5ts & met]s are to be op]at$ on ! same curr5t trans=m]s z ! trip coils if ! greate/ accuracy be requir$4 ,! relay contacts 9 ! normal1 clos$ position1 %ort circuits ! trip coil4 ,:5 ! relay op]ates on ov]load or o!r abnormal condition ! contacts are op5$ ) a quick break1 s5d+ ! curr5t ?r\gh ! trip coil circuit mom5t>ily & tripp+ ! swit*4 ,) circuit op5+ relays1 ! trip coils ( ! oil swit* mu/ be set to trip some:at l[] ?an ! sett+ ( ! relay4 ,9 con/ruction ! relay consi/s ( a sol5oid ) iron frame =m+ ! support = ! relay2 a c5tral plung] or armature ( special con/ruction :i* is pick$ up or releas$ by ! magnetic action ( ! sol5oid2 a plung] rod :i* actuates ! relay contacts1 :i* are m\nt$ on an insulat$ base usually above ! sol5oid2 a tube or plate = ! calibration m>k+ & adju/m5t2 cov]s ( glass or metal to keep out du/2 t]m9al bo>ds ) po9ts correspond+ to tagg$ leads f relay coils & ext]nal wir+ diagrams4 ,! relay contacts are ( two k9ds1 circuit op5+1 z %[n above1 & circuit clos+1 z %[n 9 figs4 #b1bib to #b1cjj4 ,ques4 ,:at k9d ( curr5t is g5]ally us$ = ! auxili>y circuit ( a circuit clos+ relay8 ,ans4 ,direct curr5t4 ,ques4 ,at :at pressure8 ,ans4 ,f #abe to #bej volts4 ,ques4 ,:]e is ?is curr5t usually obta9$8 ,ans4 ,f a /orage batt]y1 or f ! excit]4 ,ques4 ,= :at curr5t are ! contacts ord9>ily design$8 ,ans4 ,ab\t #aj amp]es4 ,illu/ration3 ,,figs4 #b1bib to #b1cjj4--;,g5]al ,electric alt]nat+ curr5t1 in/antane\s ov]load circuit clos+ relays1 cov]s remov$4 ,! function ( a circuit clos+ relay is to close an electrical circuit1 usually direct curr5t1 ?r\gh a trip coil on an oil swit* or circuit break]1 or x may %ort circuit a l[ voltage release coil1 & !reby op5 ! oil swit* or circuit break] on occurr5ce ( ! condition ^u :i* ! relay is design$ to op]ate4 ,direct curr5t at #abe or #bej volts tak5 f excit] bus b>s or /orage batt]y sy/em is g5]ally us$ = ! tripp+ circuit4 ,circuit clos+ contacts h a cone %ap$ c5tral elem5t ( c>bon or metal :i* makes contact ) flexible contact f+]s symmetrically arrang$ above ! cone4 ,^! contacts w make & break a circuit ( #aj amp]es at #abe volts )\t ! use ( auxili>y circuit op5+ swit*es4 ,relays are made ) two or ?ree contacts = connect+ "o side ( a direct curr5t circuit ?r\gh "o or two sep>ate circuits1 or trip coils respectively1 to ! side ( opposite pol>ity4 ,usually only two contacts are requir$4 ,:]e two or m trip coils are us$1 :i* may n be connect$ p]man5tly 9 p>allel1 ! ?ree contact relays are select$ & 9 "s cases f\r contacts furni%$4 ,prim>y & ,second>y ,relays4--,prim>y relays are sometimes call$ s]ies relays z !y h ! curr5t coils connect$ directly 9 s]ies ) ! l9e1 bo? on high & l[ t5sion circuits4 ,second>y relays receive _! curr5t supply f ! second>y circuits ( curr5t trans=m]s4 ,alt]nat+ curr5t relays connect$ to second>y ( pressure trans=m]s & relays ) bo? curr5t & pressure w9d+s are includ$ 9 ?is class4 ,ques4 ,:at is ! usual w9d+ ( ! coils8 ,ans4 ,! curr5t coils are usually w\nd = #e amp]es & ! pressure coils = #aaj volts4 ,illu/ration3 ,,fig4 #b1cja4--;,alt]nat+ curr5t l[ voltage circuit clos+ l[ voltage relay1 = #fjj volts or less4 ,! contacts are simil> to ^? ( ! circuit clos+ ov]load type except t !y are inv]t$4 ,z long z ! pressure is normal ! contact cone is held above ! contacts4 ,:5 ! pressure falls bel[ "o half normal1 ! cone & plung] rod drop & close ! contact4 ,?is relay does n pick up its own plung]4 ,! plung] rod is pu%$ up by h& aft] ! pressure circuit is e/abli%$4 ,l[ voltage relays are g5]ally us$ 9 connection ) a l[ voltage release or %unt trip coil on an oil swit* or a circuit break]4 ,!y are us$ 9 connection ) motor boo/] sets to prev5t a disa/r\s spe$ ( ! boo/] :i* might result f ! loss ( alt]nat+ curr5t p[]4 ,!y are also sometimes us$ = indicat+ purposes4 ,ques4 ,:at ref9em5t is made 9 ! design ( relays & :y8 ,ans4 ,c>e is ex]cis$ to r$uce to a m9imum ! volt amp]e load impos$ by ! relay on ! curr5t trans=m] to p]mit ! use ( un-/r&$ met]s & relays ^u ! same trans=m]4 ,! use ( circuit op5+ relays to cut out ! trip coil ( an oil swit* dur+ normal op]ation1 has be5 describ$1 & 9 ! %ort "t t ! trip coil is 9 circuit1 x does n affect ! accuracy ( ! in/rum5t read+s4 ,?is practice1 h[ev]1 does n apply 9 ! case ( curve draw+ met]s1 voltage comp5sators or o!r devices :i* h 9 !mselves suffici5t load = sep>ate curr5t trans=m]s4 ,9 ?is connection x %\ld be not$ t to obta9 accurate in/rum5t & met] read+s2 ! curr5t trans=m]s %\ld n be load$ beyond c]ta9 limits :i* dep5d ^u ! volt amp]e load & p[] factor ( ea* ( ! connect$ devices4 ,illu/ration3 ,,fig4 #b1cjb4--;,condit type ,k circuit break] ) %unt trip & no voltage atta*m5t4 ,! %unt trip is usually appli$ z an auxili>y to o!r types ( trip4 ,x consi/s ( a f9e wire coil :i* is m\nt$ z a self-conta9$ "p ( ! break] & :i* :5 en]giz$1 trips ! circuit break]4 ,x is us$ to op5 ! break] f "s di/ant po9t1 & ! coil is arrang$ to be connect$ across ! l9e4 ,! coils are s arrang$ t ! circuit break]s w op]ate on a voltage #be above or #be bel[ normal4 ,! %unt trip coil is n int5d$ to rema9 across ! l9e & %\ld be only mom5t>ily en]giz$4 ,! no voltage trip1 receives en]gy f a high resi/ance or f9e wire coil :i* is arrang$ to be plac$ directly across ! l9e1 b 9 contradi/9ction to ! %unt trip type1 9 :i* ! coil is mom5t>ily en]giz$ to trip ! break]1 ! no voltage coil is con/antly en]giz$ & a decrease or failure ( pressure trips ! break]4 ,x c be us$ z a remote control device ! same z ! %unt trip4 ,its g5]al use1 h[ev]1 is to cause ! circuit break] to op5 :5 ! voltage ( ! l9e fails f any cause4 ,its use is recomm5d$ on all motor circuits1 z x af=ds an additional protection aga9/ accid5ts1 = if ! voltage %\ld fail1 ! break] imm$iately op5s1 & be=e ! ma*9e c />t aga9 ! att5dant mu/ close ! break]4 ,x w n "w = ! protection ( /orage batt]ies or ( motor g5]ator sets *>g+ /orage batt]ies1 z1 :5 ! voltage ( ! g5]ator fails1 ! voltage ( ! batt]y /ill ma9ta9s its full value4 ,! action ( ! coil is indep5d5t ( ! direction ( fl[ ( curr5t2 x simply all[s ! break] to /ay clos$ z long z ! voltage is on ! l9e & op5s ! break] :5 ! voltage on ! l9e ceases4 ,no voltage circuit break]s are normally s adju/$ t !y w n release until ! voltage approa*es #ej ( normal4 ,s great is ! v>iety ( comb9ation us$ & ! v>iations ( ^! factors 9 _! sev]al comb9ations at diff]5t loads & sett+s1 t special consid]ation ( ea* arrangem5t is advisable4 ,illu/ration3 ,,fig4 #b1cjc4--;,g5]al ,electric alt]nat+ curr5t high pressure s]ies ov]load relays controll+ #de1jjj volt oil swit*es4 ,^! relays are connect$ 9 s]ies ) ! l9e4 ,if curr5t trans=m]s are to be us$ on ! same circuit = o!r purposes1 & h suffici5t capacity to supply en]gy = op]at+ relay coils1 !n second>y relays w\ld be m economical1 o!rwise ! s]ies relays are mu* less exp5sive4 ,by means ( a specially treat$ wood5 rod1 ! relay op]ates a tripp+ swit*1 clos+ a sep>ate tripp+ circuit1 usually #abe or #bej volts direct curr5t4 ,relays & swit*es are = m\nt+ on flat surfaces4 ,s]ies relays are ess5tially ! same z second>y relays except 9 ! coil w9d+ & insulation4 ,! corrugat$ horizontal arms :i* c>ry ! relays1 z %[n1 are insulat$ po/s1 insulat+ ! relays f ! gr\nd4 ,! wood rod f ea* relay is connect$ directly to a tripp+ %aft on ! oil swit* :i* buckles an auxili>y toggle1 !reby op5+ ! ma9 toggle & tripp+ ! oil swit*4 ,ov]load ,relays4--,s]ies relays are connect$ directly 9 s]ies ) ! l9e & are *iefly us$ ) high pressure oil break swit*es = ov]load protection4 ,if curr5t trans=m]s are to be us$ on ! same circuits = o!r purposes1 & h suffici5t capacity to admit ( add+ a relay coil1 second>y relays w\ld be m economical2 o!rwise1 ! s]ies relays are less exp5sive4 ,by means ( a specially treat$ wood5 rod1 ! relay op]ates a tripp+ swit*1 clos+ a sep>ate tripp+ circuit1 usually #abe or #bej volts direct curr5t4 ,s]ies relays are ess5tially ! same z second>y relays except 9 ! coil w9d+ & insulation4 ,und]load ,relays4--,^! are simil> 9 con/ruction to l[ voltage relays b h curr5t in/ead ( pressure w9d+s4 ,ov] ,voltage ,relays4--,^! are usually ( ! circuit clos+ type & are simil> to second>y ov]load relays1 b h pressure in/ead ( curr5t w9d+s4 ,l[ ,voltage ,relays4--,relays ( ?is class are 9 mo/ cases us$ ,illu/ration3 ,,fig4 #b1cjd4--;,condit #fjj volt1 #a1ejj amp]e s+le pole back connect$ type ,k circuit break]1 motor op]at$4 ,! me*anical & electrical features ( ! circuit break]s are no diff]5t ?an :5 h& op]at$1 ! only diff]5ce be+ t ! motor is us$ = ! op]at+ means4 ,?is motor is s arrang$ t ev5 %\ld x ov] travel1 due to an accid5t to ! controll+ circuit1 x _c produce m ?an a pr$et]m9$ /ra9 on ! circuit break]4 ,9 o!r words1 aft] ! motor has clos$ ! circuit break]1 fur!r travel ( ! motor w n result 9 putt+ a /ra9 on ! op]at+ p>ts4 ,suitable motors are suppli$ = ?is s]vice1 ! type ( motor v>y+ 9 accordance ) ! "* ( ! op]at+ curr5t suppli$4 ,! advantage ( ?is type ( electrical op]ation is t x puts v little /ra9 on ! swit* me*anism1 takes v little op]at+ curr5t1 all[s ! use ( /&>d p>ts1 & makes an extremely sub/antial & flexible /ructure4 ,its disadvantage is t x closes sl[ly1 & x mu/ n1 !re=e1 be us$ 9 places :]e quick clos+ is ess5tial4 = ! protection ( motors 9 ! ev5t ( a tempor>y weak5+ or failure ( ! pressure4 ,!y are also us$ 9 connection ) a l[ voltage release or %unt trip coil on an oil swit* or a circuit break]4 ,rev]se ,en]gy ,relays4--,! *ief object ( ?is species ( relay is to protect ! g5]ator4 ,:5 s us$1 ! ov]load adju/m5t is set at ! maximum value to give ov]load protection only at ! maximum c>ry+ capacity ( ! g5]ator & a s5sitive rev]se protection to prev5t a return ( en]gy f ! l9e4 ,illu/ration3 ,,fig4 #b1cje4--;,g5]al ,electric direct curr5t sol5oid control relay4 ,sol5oids = op]at+ l>ge swit*es1 etc41 frequ5tly require comp>atively l>ge op]at+ curr5ts 9 ! clos+ coils4 ,?is necessitates ! use ( relatively heavy leads betwe5 ! control swit* & ! sol5oid & is ! cause ( sev]e arc+ at ! control swit*1 especially ) sol5oids ( high inductance4 ,^! objectionable features c be/ be elim9at$ by ! use ( a suitable control relay locat$ ne> ! sol5oids4 ,! control relay consi/s ( a sol5oid plung] & swit*1 ! latt] insulat$ f ! frame ( ! relay4 ,x op]ates satisfactorily on "o-half ! rat$ voltage & requires only a v small op]at+ curr5t4 ,! t]m9als ( ! swit* & ! relay coils are indep5d5t4 ,! relay c be w\nd = op]ation on #abe1 #bej1 or #fjj volt circuits4 ,rev]se ,phase ,relays4--,?is type ( relay is us$ *iefly to prev5t damage 9 case ( rev]sal ( leads 9 reconnect+ wir+ to two or ?ree phase motors4 ,"t ,elem5t4--,x is (t5 inconv5i5t t a circuit break] %\ld be op5$ imm$iately on ! occurr5ce ( :at may prove to be m]ely a mom5t>y ov]load1 s t "t lag atta*m5ts are frequ5tly provid$1 p>ticul>ly ) relays4 ,^! devices1 :i* may =m "p ( ! relay or may be q di/9ct f x1 ret>d its action until ! ov]load has la/$ = a pr$et]m9$ "t--sev]al seconds or m4 ,illu/ration3 ,,fig4 #b1cjf4--;,alt]nat+ curr5t s]ies rev]se phase s+le pole1 circuit clos+1 two contact relay = #fjj volts or less4 ,?is type ( relay is us$ *iefly to op5 motor circuits = elevators to prev5t damage 9 case ( rev]sal ( leads 9 reconnect+ wir+ to two or ?ree phase motors4 ,! relay is provid$ ) a du/ pro( metal cov]4 ,ques4 ,:at %\ld pref]ably gov]n ! "t lag8 ,ans4 ,x %\ld dep5d on ! ext5t to :i* ! ov]load is r$uc$ z ! "t elapses4 ,in/antane\s ,relays4--,! s call$ in/antane\s relays op]ate almo/ in/antly on ! occurr5ce ( ! abnormal condition t !y are to control4 ,!re is ( c\rse a slight "t elem5t comp>able ) t ( an ov]load circuit break]1 b = practical purposes1 ! op]ation may be consid]$ z in/antane\s4 ,illu/ration3 ,,fig4 #b1cjg4--;,electric circuits ( ,condit type ,a relay4 ,! con/ruction is describ$ 9 fig4 #b1cji4 ,z "h %[n1 ! relay is n 9 op]ation1 b %\ld ! curr5t pass+ ?r\gh ! coil be ( suffici5t value to cause ! l[] movable half ( ! magnetic circuit to approa* ! upp] /ation>y half ( ! circuit1 ! relay w be trans=m$ f an ord9>y electromagnet into a repulsion motor4 ,! contact w %ort circuit ! bru%es ( ! armature & ?us cause x to revolve1 ! spe$ ( rotation be+ dep5d5t on ! am\nt ( curr5t fl[+ to a pr$et]m9$ po9t1 & !reaft] ! spe$ ( rotation ( ! motor rema9s con/ant irrespective ( ! curr5t value4 ,"t adju/m5t3 ,?is is obta9$ by v>y+ ! di/ance ?r\gh :i* ! contact travels1 provision be+ made :]eby adju/m5t c be made z close z 4#a ( a second4 ,curr5t adju/m5t3 ,?is is obta9$ by means ( a calibrat$ spr+4 ,/&>d relays are calibrat$ at #f1 #h1 #aj1 & #ab amp]es1 ! coils be+ design$ to c>ry five amp]es cont9u\sly1 ) a temp]ature rise n exce$+ #hf ,fahr4 ,p[] to op]ate relay3 ,! relay requires tw5ty volt amp]es = its op]ation at full load2 ! influ5ce ( ?is type ( relay on ! ratio & phase angle ( curr5t trans=m]s is small4 ,"t ,limit ,relays4--,"u ?is classification !re are two sub-divisions4 #a4 ,def9ite "t limit2 #b4 ,inv]se "t limit4 ,illu/ration3 ,,fig4 #b1cjh4--;,*>act]i/ic curves ( ,condit type ,a selective relay4 ,curves #a1 #b1 #c1 & #d %[ ! "t v>iation ( ?is relay ) diff]5t sett+s at ! v>i\s curr5t values4 ,! relay may be adju/$ to trip ! swit* at any po9t repres5t$ betwe5 curves #a & #d4 ,?is relay is a comb9ation ( an inv]se "t limit relay & a def9ite "t limit relay4 ,! comb9ation ( ! *>act]i/ics ( ! two types are se5 9 ! curve1 ! fir/ "p ( :i* is inv]se1 & ! latt] "p def9ite f a po9t ( ?ree or f\r times full load curr5t4 ,?is comb9ation ( features be+ desirable z1 = in/ance1 9 transmission "w1 p>ticul>ly :]e x is necess>y to use circuit break]s set selectively1 z1 due to ! inv]se feature ( ! curve1 ! relays c be set s t on a mod]ate ov]load1 !y w require ! prop] l5g? ( "t to op]ate1 & at ! same "t w op]ate quickly en\gh on heavy %ort circuits to prev5t damage to ! di/ribution sy/em or its app>atus4 ,due to ! def9ite feature ( ! latt] "p ( ! curve1 ! relays ( ! v>y+ circuit break]s :5 once set to op]ate at diff]5t "t values w nev] op]ate simultane\sly irrespective ( ! value ( ! %ort circuit curr5t1 ?us t5d+ t[>d cont9uity ( s]vice4 ,ques4 ,describe ! "t me*anism ( a def9ite "t limit relay4 ,ans4 ,x consi/s ( an air da% pot1 & an air diaphragm or equival5t ret>d+ device connect$ to ! contact me*anism4 ,ques4 ,h[ does x op]ate8 ,ans4 ,9 "s designs1 :5 ! contacts are releas$1 !y desc5d by gravity aga9/ ! action ( ! ret>d+ device !reby mak+ contact a def9ite int]val aft] ! occurr5ce ( ! abnormal condition4 ,illu/ration3 ,,fig4 #b1cji4--;,condit type ,a selective relay1 design$ = use ) circuit break]s :]e selective or discrim9at+ action is requir$4 ,! circuits & connections ( ?is relay are illu/rat$ 9 fig4 #b1cjg1 & its *>act]i/ics 9 fig4 #b1cjh4 ,9 con/ruction1 ! relay consi/s ( a special motor ) a %ort circuit$ armature & a split field4 ,"u normal conditions1 ! fields are sep>at$ f ea* o!r & ! motor armature does n revolve4 ,! =ce t5d+ to pull ! two faces ( ! field toge!r is oppos$ by a spr+1 ! compression ( :i* det]m9es ! numb] ( amp]es necess>y to cause ! relay to beg9 op]ation4 ,! motor /ructure p]=ms ! :ole "w & ! motor itself un-me%es & me%es ! ge>s )\t ! aid ( any ext]nal device4 ,ques4 ,h[ does ! inv]se "t limit type op]ate8 ,ans4 ,! actuat+ & contact me*anism is atta*$ directly to an air bell[s & 9 op]ation t5ds to compress ! bell[s aga9/ ! action ( a specially con/ruct$ escape valve 9 ! latt]4 ,illu/ration3 ,,fig4 #b1caj4--;,condit type ,b "t limit atta*m5t1 design$ to give suffici5t "t to all[ an induction motor to />t )\t op5+ ! circuit break]1 & n h ! circuit break] trip on ! mom5t>y ru% ( curr5t4 ,its action is inv]se2 t is1 ! great] ! curr5t ! less "t x takes to op]ate & is s arrang$ t f\r to five times full load curr5t or a %ort circuit w trip ! circuit break] in/antly4 ,! "t limit atta*m5t is appli$ directly to ! armature :i* trips ! circuit break] & is adapt$ = ! s call$ prim>y trip4 ,x consi/s ( an air vacuum da% pot ) a graphite pi/on1 ! da% pot be+ fa/5$ to ! /ation>y calibrat+ r+ ( ! trip coil & ! mov+ outside cyl9d] is fa/5$ to ! armature ( ! circuit break]4 ,:5 ! curr5t rea*es a po9t :]e x ov]comes ! weight ( ! armature & lifts ! same1 ! magnetic =ce t5d+ to raise ! armature is oppos$ by ! vacuum creat$ 9 ! int]ior ( ! cyl9d]4 ,z ! magnetic =ce cont9ues ! vacuum is ov]come due to ! leakage ( air pa/ ! plung] & ! armature gradually moves up until x rea*es ! po9t :]e x trips ! circuit break]4 ,if at any po9t ( ! armature travel1 ! curr5t drop back to normal1 ! armature imm$iately resets itself by means ( a ball valve 9 ! top ( ! brass cyl9d]4 ,ques4 ,:y is ! arrangem5t call$ inv]se "t limit8 ,ans4 ,because ! ret>dation v>ies inv]sely ) ! pressure on ! bell[s1 & !re=e inv]sely ) ! magnitude ( ! abnormal condition4 ,ques4 ,:at o!r device may be us$ to ret>d ! op]ation8 ,ans4 ,a damp+ magnet is sometimes us$ :i* acts on a disc or drum & :i* may be adju/able4 ,illu/ration3 ,,figs4 #b1caa & #b1cab4--;,g5]al ,electric alt]nat+ curr5t l[ pressure s]ies ov]load relays4 ,fig4 #b1caa1 in/antane\s "t limit relay2 fig4 #b1cab1 inv]se "t limit relay4 ,^! relays h c>bon contacts & w make or break a direct curr5t circuit ( #aj amp]es at #abe volts )\t auxili>y circuit op5+ swit*4 ,!y are us$ :]e sev]al circuits are controll$ by "o automatic oil break swit* or "o %unt trip1 ov]load & %unt trip or l[ voltage release c>bon break circuit break]4 ,^! relays may be us$ = signal purposes2 !y are back connect$1 ! connections c be se5 9 ! illu/rations4 ,ques4 ,h[ is ! inv]se "t elem5t introduc$ by ?is arrangem5t8 ,ans4 ,! ret>dation is due to eddy curr5ts induc$ by mov+ ! disc or drum ?r\gh ! magnetic field4 ,! reaction ?us induc$ v>ies inv]sely ) ! magnitude ( ! =ce ) :i* ! disc or drum is urg$ ?r\gh ! field & h5ce inv]sely ) ! abnormal condition4 ,ques4 ,:at are ! ord9>y limits ( adju/m5t = inv]se "t limit relays8 ,ans4 ,f "o-half second to #cj seconds1 dep5d+ ^u ! "t sett+ & magnitude ( ! ov]load curr5t4 ,illu/ration3 ,,figs4 #b1cac to #b1cba4--;,g5]al ,electric "t limit ov]load circuit op5+ relays ) cov]s remov$4 ,! con/ruction ( ?is relay is simil> to t ( ! inv]se "t limit relay1 except t x has a compression spr+ int]pos$ betwe5 ! plung] & diaphragm4 ,! plung] compresses ! spr+ & fur!r motion is prev5t$ by a /op1 mak+ ! relay practically indep5d5t ( ! am\nt ( ! ov]load1 only ! /or$ en]gy ( ! spr+1 if ! ov]load cont9ue1 applies p[]1 dep5d5t on its own me*anical /r5g?1 to ! diaphragm4 ,! "t limit !re=e becomes practically a con/ant = any giv5 sett+ "u ord9>y conditions ( ov]load or %ort circuit4 ,if1 h[ev]1 ! ov]load come on sl[ly s t ! spr+ is n fully compress$ at once1 ! "t limit w v>y slightly4 ,if ! s*eme ( selective op]ation make x necess>y to take c>e ( a creep+ load ( ?is "*1 two relays may be us$ & def9ite "t limit positively secur$4 ,9 ?is case1 an in/antane\s circuit clos+1 ov]load relay w\ld be us$ & a def9ite "t limit relay1 provid$ ) a direct curr5t coil 9 circuit ) ! clos+ contacts ( ! fir/ relay4 ,! "t limit relay w\ld be ( ! circuit clos+ type & control a direct curr5t trip coil on ! oil swit*4 ,a sett+ ( f two to six seconds is ord9>ily us$1 dep5d+ ^u ! requirem5ts4 ,:]e selective op]ation is desir$ a m9imum sett+ ( two seconds is recomm5d$4 ,diff]5tial ,relays4--,9 ?is type ( relay !re are two electromagnets4 ,9 normal work+ ^! oppose & neutralize ea* o!r4 ,%\ld1 h[ev]1 ei!r w9d+ become /rong] or weak] ?an ! o!r1 ! balance is upset1 ! magnet en]giz$1 & ! relay comes into op]ation4 ,illu/ration3 ,,fig4 #b1cbb4--;,diff]5tial relay trans=m] & rev]se curr5t circuit break] discrim9at+ device4 ,a diff]5tial relay is "o ^: electromagnet has two w9d+s4 ,9 normal work+ ^! oppose & neutralize "o ano!r4 ,%\ld h[ev]1 ei!r w9d+ become /rong] or weak] ?an ! o!r1 ! balance is upset1 ! magnet is en]giz$1 & ! relay comes into op]ation4 ,a modification ( su* a relay = alt]nat+ curr5t is "h %[n1 f :i* x w be se5 t :5 ! curr5ts are z indicat$1 ! circuit ,a has ! l>g] pressure induc$ 9 x1 :]eas1 %\ld ! ma9 curr5t rev]se ) ref]5ce to ! %unt curr5t1 ! circuit ,b w\ld h ! l>g] induc$ pressure4 ,a modification ( su* a relay = alt]nat+ curr5t is %[n 9 fig4 #b1cbb1 f :i* x w be se5 t :5 ! curr5ts are z indicat$1 ! circuit ,a has ! l>g] pressure induc$ 9 x1 :]eas1 %\ld ! ma9 curr5t rev]se ) ref]5ce to ! %unt curr5t1 ! circuit ,b w\ld h ! l>g] induc$ pressure4 ,illu/ration3 ,,fig4 #b1cbc4--;,diagram ( mod]n p[] h\se wir+ & busses %[+ location ( relays4 #a;,h[ to ,select ,relays4--,! foll[+ g5]al in=mation on relays1 toge!r ) ref]5ce to ! "o l9e diagram1 fig4 #b1cbc1 w be ( int]e/ & assi/ance 9 mak+ a selection f ! v>i\s relays previ\sly describ$ to meet ! requirem5ts ( mod]n p[] h\se & sub-/ation lay\ts4 #a ,,note4--,z sugge/$ by ! ,g5]al ,electric ,co4 ,s+le pole relays are us$ on s+le phase & on balanc$ ?ree phase circuits4 ,d\ble pole relays are us$ on ungr\nd$ ?ree phase & on qu>t] phase4 ,illu/ration3 ,,fig4 #b1cbd to #b1cbi4--;,g5]al ,electric inv]se "t limit ov]load circuit clos+ relays4 ,9 ?is type ( relay its me*anism is s design$ t a delay or lapse ( "t 9 op5+ ! circuit break] aft] a pr$et]m9$ condition ( ! circuit has be5 rea*$1 dep5ds on ! fl[ ( curr5t1 t is1 if ! curr5t be great1 ! "t w be small1 & if ! curr5t be ( a mod]ate value1 ! "t w be correspond+ly long]4 ,triple pole relays are us$ on ?ree phase gr\nd$ neutral & int]connect$ qu>t]-phase4 ,circuit clos+ relays are recomm5d$ 9 all cases :]e a con/ant s\rce ( direct curr5t is available = op]at+ trip coils4 ,! conditions = :i* relays h be5 design$ = p[] circuits may p]haps be be/ describ$1 by consid]+ a "o l9e diagram f ! g5]ator end to ! sub-/ation auxili>y ma*9es & fe$]s4 ,consid]+ fir/ alt]nat+ curr5t circuits1 ! prevail+ practice is to make ! circuit break]s by :i* ! alt]nators are connect$ to ! l[ t5sion bus non-automatic1 9 ord] to insure m9imum int]ruption ( alt]nator s]vice4 ,! *ance ( tr\ble 9 ?is "p ( ! circuit is remote1 b %\ld x occur1 ! /ation att5dant c\ld g5]ally op5 ! circuit break] be=e ! ma*9es w\ld be injur$4 ,rev]se curr5t relays ( in/antane\s or "t limit types are (t5 connect$ to ! second>ies ( curr5t & ( pressure trans=m]s to indicate by lamp or bell any tr\ble t may occur 9 ! g5]ator circuit4 ,^! relays op]ate ) a l[ curr5t rev]sal at full pressure & conv]sely ) a proportionally great] curr5t at voltages less ?an normal4 ,at z]o pressure1 ! relay w\ld act z an ov]load "o1 set = high ov]load4 ,at z]o curr5t1 a voltage consid]ably 9 excess ( normal w\ld be requir$ to op]ate x4 ,illu/ration3 ,,fig4 #b1ccj4--;,diagram %[+ two phase motor or fe$] circuit protect$ by d\ble pole d\ble coil1 ov]load circuit break] 7or two s+le pole break]s int]lock$7 ) bell al>m swit*4 ,specifications sometimes call = automatic g5]ator circuit break]s3 9 ?is case def9ite "t limit ov]load relays are us$4 ,!y are connect$ 9 ! second>ies ( curr5t trans=m]s & are design$ to give ! same "t delay = all tr\ble conditions2 !y all[ ! defective circuit to be op5$1 if possible1 at a po9t m remote f ! g5]ator ?an ! g5]ator circuit break]4 ,:5 ! total g5]ator capacity exce$s ! rat$ ruptur+ capacity ( ! circuit break]s1 "o or m sectionaliz+ circuit break]s are plac$ 9 ea* bus4 ,if op]at+ conditions admit1 ^! devices are made non-automatic & are left disconnect$ except 9 case ( em]g5cy2 b if x be necess>y = !m to be cont9ually 9 s]vice1 !y may be made automatic by means ( in/antane\s ov]load relays connect$ to curr5t trans=m]s 9 ! l[ voltage bus2 ! relays be+ adju/$ to trip ! circuit break] "u %ort circuit conditions1 conf9+ ! tr\ble to "o section & prev5t+ ! circuit break]s ruptur+ m ?an _! rat$ capacity4 ,in/allations ) b "o bank ( p[] trans=m]s1 & )\t high voltage bus1 are provid$ ) automatic circuit break]s op]at$ by an inv]se "t limit relay4 ,! relay is connect$ to ! second>ies ( curr5t trans=m]s1 :i* 9 turn are connect$ 9 ! l[ voltage side ( ! p[] trans=m]4 ,/ations ) m ?an "o bank ( p[] trans=m]s1 a high voltage bus1 & high & l[ voltage circuit break]s1 may h bo? circuit break]s arrang$ to trip at ! same "t or "o aft] ! o!r4 ,z 9 ! =m] case1 !y are op]at$ f ! inv]se "t limit relay connect$ 9 ! l[ voltage side4 ,illu/ration3 ,,fig4 #b1cca4--;,condit #fjj volt1 #a1ejj amp]e1 s+le pole type ,k circuit break] pneumatically op]at$4 ,x is ! same z ! electrically op]at$ circuit break]1 except t a pneumatic cyl9d] me*anism is suppli$ 9 place ( ei!r ! electromagnet or ! motor4 ,?is cyl9d] me*anism is s arrang$ t ! air pressure is only on ! cyl9d] at ! in/ant ( op]ation4 ,at all o!r times ! air pressure is %ut (f by means ( a control valve4 ,! k9d ( remote control to be us$ dep5ds on local conditions4 ,9 g5]al1 ! h& op]at$ remote control device is pref]able :]e conditions are su* t x c be us$1 & :]e x is necess>y to use electrically op]at$1 ! motor op]at$ type is recomm5d$ if conditions be su* t sl[ clos+ is n objectionable4 ,illu/ration3 ,,figs4 #b1ccb & #b1ccc4--;,diagram %[+ two phase f\r wire no voltage connections = ,i-,t-,e circuit break]4 ,! two no voltage coils = two phase f\r wire circuits are connect$ respectively to b9d+ po/s ,b1 ,c & ,a1 ,d on ! face ( ! base4 ,b & ,d are connect$ to l[] spr+ contacts #b & #a respectively1 ( ! small disconnect+ swit*4 7,9 in/rum5ts suppli$ on individual bases1 ^! connections are made 9 ! factory1 let into *annels 9 back ( base & cov]$ ) wax47 ,ea* ( ! upp] contacts a & b ( ! disconnect+ swit* is connect$ respectively ?r\gh resi/ance ,r#b & ,r#a to "o ma9 9 ea* phase at aa & bb4 ,c & ,a are respectively connect$ to ! o!r ma9 9 ea* phase at #c & #d4 ,?us ea* ( ! no voltage coils op]ates across "o phase indep5d5t ( ! o!r4 ,! t]m9als #c1 aa1 bb & #d1 mu/1 9 all cases1 be s connect$ t !y w be subject to ! full voltage ( ! circuit1 irrespective ( ! position ( ! />t+ swit*4 ,illu/ration3 ,,figs4 #b1ccd & #b1cce4--;,diagram %[+ two phase ?ree wire no voltage connections = ,i-,t-,e circuit break]4 ,! two no voltage coils = two phase1 ?ree wire circuits are connect$ respectively to b9d+ po/s ,b1 ,c & ,a ,d on ! face ( ! base1 & f ,a & ,c connections are made to l[] contacts #b & #a respectively ( ! disconnect+ swit*4 ,b9d+ po/s ,b & ,d are connect$ toge!r on ! back ( ! bo>d4 7,9 in/rum5ts suppli$ on individual bases1 ^! connections are made 9 ! factory1 let into *annels 9 back ( base & cov]$ ) wax47 ,ea* ( ! upp] contacts a & b is connect$ respectively ?r\gh resi/ance ,r#b & ,r#a to "o ( ! ma9s at aa & bb z %[n4 ,d is connect$ ?r\gh resi/ance ,r#c to ! common wire ( bo? phases at #c ,b & ,d be+ connect$ z a=esaid1 ?us =m+ a common connection = bo? no voltage coils4 ,t]m9als aa & bb ( ! resi/ances mu/ be connect$ to ! outside ma9 across ! two phases1 t]m9al #c to ! ma9 common to bo? phases1 ! connections be+ s made t ^! t]m9als w be subject to ! full voltage ( ! circuit irrespective ( ! position ( ! />t+ swit*4 ,illu/ration3 ,,fig4 #b1ccf & #b1ccg4--;,diagram %[+ ?ree phase no voltage connections = ,i-,t-,e circuit break]4 ,! no voltage coils = ?ree phase circuits are connect$ 9 by means ( b9d+ po/s ,a1 ,b1 ,c & ,d on ! face ( ! base1 & f ! ,a & ,b ( ! no voltage coils1 connections are made respectively to spr+ contacts #a & #b ( ! small disconnect+ swit*4 ,ea* ( ! contacts a & b ( ! disconnect+ swit* is connect$ respectively ?r\gh resi/ance ,r#b & ,r#a to "o ( ! ma9s at aa & bb4 ,! t]m9al ,c is connect$ ?r\gh resi/ance ,r#c on ! back ( ! bo>d to ! middle ma9 z %[n at po9t #c4 ,! t]m9al ,d is l9k$ on ! back ( ! bo>d to t]m9al ,b to complete ! ,greek3 ,d connection4 ,! t]m9als aa1 bb & #c ( ! circuit break] mu/1 9 all cases1 be s connect$ t !y w be subject to full voltage ( ! circuit irrespective ( ! position ( ! />t+ swit*4 ,ea* no voltage coil is suppli$ ) two t]m9al wires1 "o cov]$ ) gre5 & "o ) black insulation4 ,9 replac+ ^! coils p>ticul> c>e %\ld be tak5 to see t ! t]m9al wires connect$ to any "o b9d+ po/ are ( unlike color4 ,9 plants 9 :i* two or m banks ( trans=m]s are op]at$ 9 p>allel betwe5 high & l[ voltage busses1 x is desirable to h = ea* trans=m] bank1 an automatic circuit break] equipm5t :i* w act selectively & disconnect only ! bank 9 :i* tr\ble may occur4 ,) a circuit break] on ea* side ( trans=m] bank1 selective action may be secur$ 9 two ways z foll[s3 #a4 ,by means ( an in/antane\s diff]5tial relay connect$ 9 ! second>ies ( curr5t trans=m]s in/all$ on bo? ! high & l[ voltage sides ( ea* trans=m] bank4 ,! relay op]ates on a l[ curr5t1 rev]sal on ei!r side ( ! bank4 #b4 ,by means ( "o inv]se "t limit1 second>y or s]ies relay in/all$ on t side ( ! trans=m] bank :i* is opposite ! s\rce ( p[]1 ! relay be+ arrang$ to trip bo? ! high & l[ voltage circuit break]s4 ,! fir/ me?od has ! disadvantage ( high fir/ co/ due to ! high voltage curr5t trans=m]s requir$1 b is m positive ?an ! second me?od & is indep5d5t ( ! numb] ( trans=m] banks 9 p>allel4 ,! second me?od is ! less exp5sive ( ! two & protects aga9/ ov]loads z well z %ort circuits 9 ! trans=m]s1 b x is less positive & introduces delay 9 ! disconnection ( ! trans=m] :5 tr\ble occurs4 ,fur!rmore1 x is n selective :5 less ?an ?ree banks are op]at+ 9 p>allel4 ,! automatic circuit break]s 9 ! outgo+ l9e may be op]at$ f inv]se "t limit relays connect$ 9 ! second>ies ( curr5t trans=m]s2 or 9 case trans=m]s are n necess>y = use ) in/rum5ts1 s]ies high voltage inv]se "t limit relays connect$ directly 9 ! l9e may be us$4 ,:e!r to select curr5t trans=m]s ) relays insulat$ = l[ voltage1 or to *oose s]ies relays1 is a "q ( fir/ co/ & adaptability to s]vice conditions4 ,bel[ #cc1jjj volts1 ! comm]cial advantages 9 favor ( ! s]ies relay are slight1 & s9ce x is some:at difficult to design ?is device = ! l>ge curr5t capacities met ) at ! l[] voltage1 x is g5]ally ! practice to use ! relay ) curr5t trans=m]1 because ( its op]at+ advantage4 ,?is practice1 h[ev]1 is n entirely foll[$1 s9ce "s s]vice conditions 7describ$ lat]7 make ! use ( s]ies relays v desirable & practical4 ,illu/ration3 ,,figs4 #b1cch & #b1cci4--;,g5]al ,electric in/antane\s direct curr5t rev]se curr5t or discrim9at+ relays4 ,fig4 #b1bch1 = #ejj amp]es2 fig4 #b1cci = #b1jjj amp]es4 ,^! relays are design$ = m\nt+ directly on circuit break] /uds4 ,^! relays consi/ ( a horse%oe magnet ) a %unt w\nd armature pivot$ betwe5 its poles4 ,! magnet is m\nt$ on ! curr5t c>ry+ /ud ( ! circuit break] betwe5 ! back ( ! panel & ! fir/ contact or support+ nut1 & is plac$ 9 a v]tical position4 ,! contacts are insulat$ f ! magnet p]mitt+ ! use ( an auxili>y circuit = ! tripp+ device1 indep5d5t ( ! circuit controll$ by ! circuit break]4 ,! magnet is excit$ by ! curr5t fl[+ ?r\gh ! /ud1 & ! armature is connect$ across ! l9e 9 s]ies ) suitable resi/ance4 ,rotation ( ! armature 9 ! normal direction is prev5t$ by a /op4 ,rev]sal ( ! curr5t fl[+ ?r\gh ! /ud *anges ! direction 9 :i* ! armature t5ds to rotate1 caus+ x to move away f ! /op & close ! circuit ?r\gh an auxili>y trip coil & trip ! circuit break]4 ,^! relays are us$ to protect dynamos1 /orage batt]ies1 or ma9 /ation busses f damage on rev]sal ( curr5t due to %ort circuit1 or f ! gr\nd+ ( ma*9es or connection4 ,relay contacts mu/ n be us$ to op5 ! %unt trip coil circuits4 ,an auxili>y swit* %\ld be provid$ = ?is purpose 9 all cases :]e ! op5+ ( ! circuit break] does n disconnect ! trip coil f ! s\rce ( supply4 ,inv]se "t limit relays are satisfactory = "o1 or m ?an two outgo+ l9es 9 p>allel z !y act selectively to disconnect ! defective l9e only1 b in/allations ) only two outgo+ l9es 9 p>allel h ! same load conditions 9 bo? l9es & selective tripp+ ( ! circuit break]s 9 ! defective l9e is obta9$ by means ( a selective relay act+ in/antane\sly "u %ort circuit conditions only4 ,illu/ration3 ,,fig4 #b1cdj4--;,g5]al ,electric direct curr5t1 rev]se curr5t relay1 us$ to protect dynamos1 /orage batt]ies1 or ma9 /ation busses f damage on rev]sal ( curr5t due to %ort circuits or f ! gr\nd+ ( ma*9e or connections4 ,x is m\nt$ on v]tical bus b>s z 9 ! case ( cables1 on ! side wall1 or o!r flat surface1 & ! cables ?read$ ?r\gh ! frame4 ,:5 us$ to trip a circuit break]1 ! break] is provid$ ) a %unt trip connect$ across ! circuit1 ! tripp+ circuit be+ clos$ ?r\gh ! relay contacts on ! occurr5ce ( suffici5t rev]se curr5t to lift ! relay armature4 ,! relay is ei!r in/antane\s or "t limit z desir$4 ,9 ! "t limit relay1 ! "t int]val is obta9$ by ! lea!r bell[s %[n 9 ! illu/ration4 ,! "t sett+ c be v>i$ )9 c]ta9 limits by means ( a valve on ! bell[s outlet4 ,! op]ation ( ! relay dep5ds on ! relative value & direction ( magnetic flux set up by a pressure coil1 %[n 9 ! illu/ration1 & ! curr5t 9 ! v]tical b>s4 ,"u normal conditions ^! fluxes are 9 ! same direction & circulate ar\nd a clos$ magnetic circuit4 ,:5 ! curr5t 9 ! b>s rev]ses1 ! two fluxes oppose ea* o!r & =ce flux ?r\gh ! normally op5 leg ( ! magnetic circuit4 ,:5 ! rev]sal ( curr5t is ( pr$et]m9$ value1 ! relay armature is lift$ & ! purpose ( ! relay accompli%$4 ,! relay design & action is simil> to ! rev]se curr5t relay previ\sly m5tion$1 & is connect$ to ! second>ies ( curr5t trans=m]s 9 ea* high voltage l9e & pressure trans=m]s 9 ! l[ voltage bus4 ,9 ! sub-/ation1 ! conditions are ! rev]se ( ^? 9 ! ma9 /ation1 ! incom+ l9es becom+ ! s\rce ( p[]4 ,if !re be only "o incom+ l9e & no high voltage bus1 ! l9e circuit break] is g5]ally non-automatic4 ,) "o incom+ l9e & high voltage bus1 ! circuits f ! s]vice side ( ! bus are equipp$ ) automatic circuit break]s & relays4 ,^! relays & ^? us$ = o!r arrangem5ts ( two or m incom+ l9es 9 p>allel1 z well z high & l[ voltage circuit break]s1 are ( ! same design & are appli$ 9 ! same mann] z = ! g5]at+ /ation4 ,reg>d+ ! relay equipm5ts = auxili>y ma*9es1 ! same practice is recomm5d$ ) ! g5]ator end ( alt]nat+ curr5t motor g5]ator sets z ) ! ma9 g5]ators1 ! outgo+ fe$] circuit break]s be+ tripp$ f inv]se "t limit or in/antane\s relays4 ,illu/ration3 ,,fig4 #b1cda4--;,g5]al ,electric direct curr5t diff]5tial relay = balanc] set2 in/antane\s1 #ejj 7or less7 volt type = m\nt+ on panel4 ,9 _m p[] plants direct curr5t1 ?ree wire1 p[] s]vice is furni%$ by high voltage two wire dynamos op]at+ 9 connection ) balanc] sets consi/+ ( two l[ voltage ma*9es on a common %aft4 ,) ?is comb9ation ( ma*9e1 a %ort circuit or heavy ov]load on "o side ( ! sy/em w %ift ! neutral consid]ably1 & ! lamps on ! opposite side may burn out4 ,to protect ! lamps1 a diff]5tial relay op]at+ on #ae volts unbalanc+1 is commonly us$2 x is connect$ to trip ei!r ! dynamo's circuit break]s 7or a circuit break] connect$ 9 ! bus betwe5 ! balanc] set & ! o!r dynamos74 ,) sev]al syn*ron\s ma*9es 9 p>allel1 ! relays are arrang$ to op]ate ) ! lea/ "t delay ) :i* x is possible to get selective action1 9 ord] to prev5t ! ma*9es be+ ?r[n out ( /ep 9 ev5t ( tr\ble conditions caus+ a decrease ( voltage4 ,! v>i\s types ( induction motor & v>i\s conditions "u :i* !y are employ$1 h br\ght ab\t ! developm5t ( sev]al types ( relay to protect ! motors & ! app>atus ) :i* !y are us$4 ,x is desirable to disconnect a l>ge motor 9 case ( voltage failure1 & ) conditions requir+ ei!r a motor op]at$1 or a sol5oid op]at$ circuit break]1 a l[ voltage relay is us$ to close ! tripp+ circuit :5ev] ! voltage decreases to1 approximately1 #ej p] c5t4 bel[ normal4 ,illu/ration3 ,,fig4 #b1cdb4--;,condit "t limit relay1 design$ prim>ily = use 9 connection ) fe$] circuits1 :]e close selection or discrim9ation ( circuit break]s is n requir$4 ,x may be us$ satisfactorily on light+ & p[] circuits & also :]e !re are sudd51 mom5t>y fluctuations ( curr5t4 ,?is relay is us$ 9 connection ) s]ies trans=m]s4 ,! contact arrangem5ts are provid$ s t ! relays may be us$ z circuit clos+ or circuit op5+ relays4 ,! delay$ action is produc$ by an air vacuum da% pot ) a graphite pi/on4 ,! pi/on ( ! da% pot is connect$ to an arm arrang$ to be mov$ by ! armature4 ,:5 ! curr5t rea*es a po9t :]e x ov]comes ! weight ( ! armature & lifts ! same1 ! magnetic =ce t5d+ to lift ! armature is oppos$ by ! pull ( ! vacuum creat$ 9 ! int]ior ( ! %ell into :i* fits ! graphite pi/on4 ,z ! magnetic pull cont9ues ! vacuum is ov]come due to ! leakage ( air pa/ ! pi/on1 & ! armature gradually moves until x rea*es a po9t :]e x causes ! circuit break] to trip1 ei!r by clos+ ! contacts 9 ! circuit clos+ type1 or by op5+ ! contacts 9 ! circuit op5+ type4 ,if1 at any portion ( its travel1 ! curr5t drop to normal1 ! armature imm$iately resets4 ,! "t adju/m5t consi/s ( an arrangem5t :]eby ! di/ance ?r\gh :i* ! armature moves be=e tripp+ ! break]1 may be *ang$1 ?us alt]+ ! "t ( tripp+4 ,! curr5t adju/m5t is made by *ang+ ! effective turns ( ! actuat+ coil1 ! travel ( ! armature & ! =ce ex]t$ by x be+ ! same = all curr5t adju/m5t4 ,! w9d+ is design$ to c>ry #e amp]es cont9u\sly ) a temp]ature rise n exce$+ #fh ,fahr4 /&>d calibration is provid$ s t ! relay w />t to op]ate at #e1 #f1 #h & #ab amp]es4 ,up to #eej volts1 ^! relays may be connect$ across ! l9e1 b = high] voltages !y are connect$ to second>ies ( pressure trans=m]s4 ,small] motors ) :i* h& op]at$ circuit break]s are us$1 are g5]ally provid$ ) l[ voltage release atta*m5ts t p]=m ! same function z ! relay4 ,induction motors are sometimes subject$ to high voltage conditions & to protect !m f injury1 high or excess voltage relays are employ$ to trip ! automatic circuit break]4 ,^! relays are ( simil> design & wir$ 9 ! same mann] z ! l[ voltage relays4 ,illu/ration3 ,,fig4 #b1cdc4--;,*>act]i/ic curves ( ,condit "t limit relay z illu/rat$ 9 fig4 #b1cdb4 ,sett+s3 curve ,a1 #e amp]es2 curve ,b1 #f amp]es2 curve ,c1 #h amp]es2 curve ,d1 #ab amp]es4 ,rev]se phase relays h be5 develop$ = op]at+ conditions "u :i* a rev]sal ( phase w\ld cause tr\ble1 z = example1 9 ! case ( elevator motors4 ,^! are s design$ t any phase rev]sal t w\ld rev]se an induction motor1 w\ld op]ate ! relay & disconnect ! automatic circuit break]4 ,! design is bas$ on ! pr9ciple ( ! induction motor1 & 9 ! case ( l[ voltage motors ( limit$ capacity1 ! relay may be connect$ 9 s]ies 9 ! motor leads4 ,if ! voltage or capacity ( ! motor make ?is arrangem5t inexp$i5t1 ! relay may be plac$ 9 ! second>ies ( curr5t or pressure trans=m]s connect$ 9 ! motor leads4 ,und]load relays are (t5 us$ to trip ! automatic circuit break] t is plac$ 9 ! prim>ies ( arc light+ circuits to prev5t an abnormal rise ( second>y voltage 9 case ( a break 9 ! second>y circuit4 ,illu/ration3 ,,fig4 #b1cdd4--;,diagram %[+ /orage batt]y & *>g+ dynamo protect$ by d\ble pole s+le coil und]load circuit break]4 ,9 op]ation1 ! circuit break] disconnects ! batt]y :5 fully *>g$1 & protects ! dynamo f rev]se curr5t4 ,! und]load relay is simil> 9 design to ! l[ voltage relay except+ t x acts on a decrease ( curr5t4 ,! problem ( protect+ induction motors1 f injury1 t may result f runn+ on s+le phase1 or f an ov]load1 & at ! same "t p]mit ! motor to be />t$ ) ! necess>ily high />t+ curr5t t may be greatly 9 excess ( ! ov]load curr5t1 has caus$ ! developm5t ( ! s]ies relay4 ,illu/ration3 ,,fig4 #b1cde4--;,diagram %[+ direct curr5t motors protect$ by ov]load circuit break]s ) bell al>m swit*es3 a1 d\ble pole s+le coil break] no swit* requir$4 ,l[ voltage device is on ! />t+ rheo/at2 b1 s+le pole break] 9 s]ies ) lev] swit*4 ,l[ voltage atta*m5t on ! break]4 ,illu/ration3 ,,fig4 #b1cdf4--;,diagram %[+ two wire dynamo1 protect$ by a s+le pole ov]load circuit break] ) bell al>m swit*4 ,break]s mu/ be on opposite side f ! s]ies field4 ,illu/ration3 ,,fig4 #b1cdg4--;,diagram %[+ dynamo protect$ by a s+le pole ov]load circuit break] ) rev]se curr5t relay & comb9$ circuit op5+ & bell al>m swit*4 ,?is device may be connect$ 9 s]ies ) ! motor leads = voltages up to #b1ejj2 x is design$ ) an inv]se "t limit device :i* may be adju/$ to give ! desir$ protection4 ,! field = relays is m ext5sive = alt]nat+ curr5t ?an = direct curr5t p[] circuits1 ! latt] be+ g5]ally conf9$ to mu* small] & simpl] sy/ems & areas ( di/ribution1 & g5]ally suffici5t selective action c be obta9$ by ! use ( fuses or circuit break]s arrang$ ) in/antane\s trip4 ,illu/ration3 ,,fig4 #b1cdh4--;,diagram %[+ ?ree wire dynamo protect$ by d\ble pole d\ble coil ov]load circuit break] 7or two s+le pole break]s ) int]lock7 ) bell al>m swit*es4 ,complete protection is secur$ z break] is connect$ betwe5 armature & s]ies field4 ,op]at+ conditions sometimes make x advisable = ! g5]ator circuit break]s to op5 only aft] ! auxili>y & fe$] circuit break]s h fail$ to isolate ! tr\ble4 ,?is is accompli%$ by us+ direct curr5t s]ies inv]se "t limit relays to trip ! g5]ator circuit break]s4 ,in/antane\s rev]se curr5t relays are us$ to trip ! ma*9e circuit break] ( batt]y *>g+ sets1 rot>ies & motor g5]ator sets to prev5t _! runn+ z a motor on ! *>g+ or direct curr5t end4 ,^! relays c act only 9 case ( curr5t rev]sal4 ,to prev5t s]i\s unbalanc+ ( voltages 9 ,edison ?ree-wire sy/ems caus+ tr\ble1 diff]5tial balance relays are us$ to trip ! circuit break]s on a small p]c5tage ( unbalanc+4 ,,*apt] ,,lix ,,lightn+ ,,protection ,,devices ,lightn+ protection devices1 or lightn+ arre/]s1 are devices = provid+ a pa? by :i* lightn+ di/urbances or o!r /atic dis*>ges may pass to ! e>?4 ,lightn+ arre/]s1 design$ = ! protection ( transmission l9es1 mu/ p]=m ?is function ) a m9imum impairm5t ( ! insulation ( ! l9es4 ,9 g5]al ! con/ruction ( lightn+ arre/]s comprise #a4 ,air gaps2 #b4 ,resi/ances2 #c4 ,inductances2 #d4 ,arc suppress+ devices4 ,ques4 ,:at are ! causes ( /atic *>ges8 ,ans4 ,!y may be caus$ by s&/orms 9 dry climates1 or may be due to gr\nds on ! high pressure side ( a sy/em4 ,ques4 ,:at causes high frequ5cy oscillations8 ,ans4 ,!y are usually due to lightn+ dis*>ges 9 ! vic9ity ( ! l9e4 ,ques4 ,:at are ! requirem5ts ( lightn+ protection devices8 ,ans4 ,!y mu/ prev5t excessive pressure diff]5ces betwe5 l9e & gr\nd1 l9e & l9e1 & betwe5 conductor turns 9 ! electrical app>atus4 ,air ,gap ,arre/]s4--me?od ( reliev+ any abnormal pressure condition is to connect a dis*>ge air gap betwe5 "s po9t on an electric conductor & ! gr\nd4 ,! resi/ance ?us int]pos$ betwe5 ! gr\nd & ! conductor is su* t any voltage v mu* 9 excess ( ! maximum normal w cause a dis*>ge to gr\nd1 :]eas at o!r times ! conductor is ungr\nd$ because ( ! air gap4 ,?is =ms ! pr9ciple ( air gap arre/]s4 ,illu/ration3 ,,fig4 #b1cdi4--,non-arc+ multi-gap arre/]4 ,bas$ on ! pr9ciple ( employ+ = ! t]m9als across :i* ! arc is =m$1 su* metals z are lea/ capable ( ma9ta9+ an alt]nat+ arc betwe5 !m4 ,?is s call$ non-arc+ prop]ty ( c]ta9 metals 0 discov]$ by ,alex&] ,wurtz4 ,! action is su* t ! l9e curr5t :i* foll[s ! lightn+ dis*>ge foll[s z an arc1 b is /opp$ at ! end ( "o alt]nation because ( ! prop]ty ( ! non-arc+ metals to c>ry an arc 9 "o direction1 b requir+ an extremely high voltage to />t a rev]se arc4 ,! non-arc+ metals ord9>ily employ$ are alloys ( z9c & copp]4 ,pla9 multi-gap arre/]s z "h %[n op]ate satisfactorily ) ! small] ma*9es & on circuits ( limit$ p[]1 b = l>ge ma*9es ( close regulation1 & !re=e ( v l>ge mom5t>y ov]load capacity1 especially :5 a numb] ( su* are op]at$ 9 p>allel1 su* arre/]s 7 f\nd insuffici5t1 ! l9e curr5t foll[+ ! lightn+ dis*>ge frequ5tly 0 s enorm\s t ! circuit did n op5 at ! end ( ! half wave1 t is ! arre/] held ! arc & 0 de/roy$4 ,! introduction ( syn*ron\s motors made x necess>y t ! arc %\ld be ext+ui%$ imm$iately1 o!rwise ! syn*ron\s motors & conv]t]s w\ld drop out ( /ep1 & ! sy/em w\ld 9 ?is way be %ut d[n4 ,to insure ! break+ ( ! arc1 resi/ance 0 introduc$ 9 ! arre/]1 ! modifi$ device be+ kn[n z ! l[ equival5t arre/] z %[n 9 fig4 #b1cej4 ,! s+le gap :ile adequate = telegraph l9e protection1 0 f\nd insuffici5t = electric light & p[] circuits1 because s9ce ! curr5t 9 su* circuits is consid]able & usually at high pressure x w\ld foll[ ! lightn+ dis*>ge across ! gap4 ,?us ! problem arose to devise means = %ort circuit+ ! l9e curr5t result+ 9 v>i\s modifications ( gap arre/]4 ,multi-gap ,arre/]s4--,! ess5tial elem5ts ( an arre/] ( ?is type are a numb] ( cyl9d]s spac$ ) a small air gap betwe5 !m & plac$ betwe5 ! l9e to be protect$ & ! gr\nd1 or betwe5 l9e & l9e4 ,9 op]ation1 ! multi-gap arre/] dis*>ges at a mu* l[] voltage ?an w\ld a s+le gap hav+ a l5g? equal to ! sum ( ! small gaps4 ,9 expla9+ ! action ( multi-gaps1 !re are ?ree ?+s to consid]3 ,illu/ration3 ,,fig4 #b1cej4--,l[ equival5t arre/]4 ,?is is a modification ( ! multi-gap arre/] %[n 9 fig4 #b1cdi4 ,ab\t half ( ! total numb] ( gaps are %unt$ by a resi/ance1 & ano!r resi/ance ins]t$ betwe5 ! cyl9d]s & ! e>?4 ,) ?is arrangem5t ! middle po9t is at gr\nd pressure1 & !re are betwe5 l9e & gr\nd only "o half ( ! total numb] ( gaps4 ,?is is suffici5t to prev5t a bridg+ ( ! gaps "u normal conditions4 #a4 ,! transmission ( ! /atic /ress along ! l9e ( ! cyl9d]s2 #b4 ,! sp>k+ at ! gaps2 #c4 ,! action & duration ( ! curr5t :i* foll[s ! sp>k1 & ! ext+ui%m5t ( ! arc4 ,ques4 ,:at is a sp>k8 ,ans4 ,! conduction ( electricity by air4 ,ques4 ,:at is an arc4 ,ans4 ,! conduction ( electricity by vapor ( ! electrode4 ,di/ribution ( ,/atic ,/ress4--,! cyl9d]s ( ! multi-gap arre/] act l plates ( cond5s]s 9 s]ies4 ,?is cond5s] function is ! ess5tial feature ( its op]ation4 ,:5 a /atic /ress is appli$ to a s]ies ( cyl9d]s betwe5 l9e & gr\nd1 ! /ress is imm$iately c>ri$ f end to end4 ,if ! top cyl9d] be positive x w attract a negative *>ge on ! face ( ! adjac5t cyl9d] & repel an equal positive *>ge to ! opposite face & s on d[n ! entire r[4 ,! second cyl9d] has a def9ite capacity relative to ! ?ird cyl9d] & also to ! gr\nd2 consequ5tly ! *>ge induc$ on ! ?ird cyl9d] w be less ?an on ! second cyl9d]1 due to ! fact t only "p ( ! positive *>ge on ! second cyl9d] induces negative electricity on ! ?ird1 :ile ! re/ ( ! *>ge induces negative electricity to ! gr\nd4 ,ea* successive cyl9d]1 c\nt+ f ! top ( ! arre/]1 w h a slightly small] *>ge ( electricity ?an ! prec$+ "o4 ,illu/ration3 ,,fig4 #b1cea4--;,g5]al ,electric #b1bjj volt multi-gap arre/] = /ation in/allation4 ,x consi/s ( f\rte5 knurl$ cyl9d]s & two %unt resi/ance rods m\nt$ on a porcela9 base4 ,"o ( ^! rods has a l[ resi/ance1 & %unts n9e gaps2 ! o!r rod has a high resi/ance1 & %unts elev5 gaps4 ,! effect ( ! %unt resi/ance 9 ext+ui%+ ! l9e curr5t arc is ! same1 !re=e1 z t ( an equal s]ies resi/ance b is )\t ! objectionable features ( ! latt]4 ,s]ies resi/ance limits ! dis*>ge curr5t to su* an ext5t t an arre/] ) s]ies resi/ance fails to protect aga9/ de/ructive rises ( voltage :5 ! conditions are sev]e/4 ,grad$ %unt resi/ance responds to all frequ5cies & op5s a dis*>ge pa? = excessive voltage :5 ! frequ5cies are high z well z :5 !y are l[4 ,its fur!r effect 9 )hold+ ! l9e curr5t f ! gaps aft] ! reliev+ dis*>ge has occurr$1 is to aid ! non-arc+ quality ( ! metal cyl9d]s 9 quickly suppress+ ! arc t foll[s a dis*>ge4 ,! arc is ext+ui%$ at ! end ( ! half cycle ( l9e curr5t 9 :i* ! dis*>ge takes place4 ,sp>k+ at ! ,gaps4--,! quantity ( electricity induc$ on ! second cyl9d] is great] ?an on any l[] cyl9d] & its gap has a great] pressure /ra9 across x z %[n 9 fig4 #b1ceg4 ,:5 ! voltage across ! fir/ gap is suffici5t to sp>k1 ! second cyl9d] is *>g$ to l9e voltage & ! second gap receives ! /atic /ra9 & breaks d[n4 ,! successive action is simil> to ov]turn+ a r[ ( t5-p9s by pu%+ ! fir/ p9 aga9/ ! second4 ,?is ph5om5on expla9s :y a giv5 l5g? ( air gap conc5trat$ 9 "o gap requires m voltage to sp>k across x ?an ! same total l5g? made up ( a r[ ( multi-gaps4 ,illu/ration3 ,,fig4 #b1ceb4--;,g5]al ,electric #b1bjj volt arre/] 9 ! act ( dis*>g+1 & %unt+ ! l9e curr5t4 ,! figure %[s an actual dis*>ge tak+ place4 ,x w be se5 t ! heavy l9e curr5t passes across only f\r ( ! gaps1 & !n goes ?r\gh ! resi/ance rods2 :ile ! /atic dis*>ge passes /raight across ! entire s]ies ( ?irte5 gaps4 ,:5 ! gaps ( an arre/] are %unt$ by ev5 a l[ resi/ance1 dis*>ges ( v high frequ5cy f9d x relatively difficult to pass ?r\gh ! resi/ance rods1 ow+ to ! imp$ance ( ! rods1 b comp>atively easy to pass across all ! gaps1 ow+ to ! capacity effect 9 break+ d[n ! gaps4 ,! high] ! frequ5cy1 ! m pron\nc$ is ?is effect1 h5ce ! dis*>ges select diff]5t pa?s ?r\gh gaps & resi/ances dep5d+ ^u ! frequ5cy4 ,by frequ5cy is meant1 n ! frequ5cy ( ! l9e curr5t b ! lightn+ frequ5cy1 :i* may run into hundr$s ( ?\s&s1 or into millions ( cycles4 ,! equival5t ne$le gap = ?is arre/] is %[n by te/s to be ne>ly ! same = all frequ5cies & quantities ( dis*>ge2 t is1 ! arre/] is equally responsive to all frequ5cies4 ,illu/ration3 ,,figs4 #b1cec to #b1cee4--,oscillograph record ( ! ph5om5a t take place 9 ! diff]5t circuits or selective pa?s ( a multi-gap arre/] dur+ a dis*>ge su* z %[n 9 fig4 #b1ceb4 ,z ! sp>k crosses ea* successive gap1 ! voltage gradi5t along ! rema9d] readju/s itself4 ,h[ ! ,arc is ,ext+ui%$4--,:5 ! sp>ks ext5d across all ! gaps ! l9e curr5t w foll[ if1 at t in/ant1 ! l9e pressure be suffici5t4 ,on acc\nt ( ! relatively great] l9e curr5t1 ! di/ribution ( pressure along ! gaps becomes equal1 & has ! value necess>y to ma9ta9 ! l9e curr5t arc on a gap4 ,! l9e curr5t cont9ues to fl[ until ! voltage ( ! g5]ator passes ?r\gh z]o to ! next half cycle1 :5 ! arc ext+ui%+ quality ( ! metal cyl9d]s comes into action4 ,illu/ration3 ,,figs4 #b1cef & #b1ceg4--;,diagram %[+ cond5s] action ( cyl9d]s & pressure gradi5t = /atic /ress4 ,! alloy conta9s a metal ( l[ boil+ po9t :i* prev5ts ! rev]sal ( ! l9e curr5t4 ,x is a rectify+ effect1 & be=e ! pressure aga9 rev]ses1 ! arc vapor 9 ! gaps has cool$ to a non-conduct+ /ate4 ,effect ( ,frequ5cy4--,! high] ! frequ5cy ( ! lightn+ oscillation1 ! m readily w ! multi-gap respond to ! pressure4 ,briefly /at$1 ! problem is to prop]ly limit ! l9e curr5t s t ! arc may be ext+ui%$2 to arrange a %unt circuit s t ! s]ies resi/ance w be automatically cut out if safety dem& x on acc\nt ( a heavy lightn+ /roke &1 :ile reta9+ ^! prop]ties1 to make ! arre/] s5sitive to a wide range ( frequ5cy4 ,x %\ld be not$ t s]ies resi/ance limits ! rate ( dis*>ge ( ! lightn+ z well z ( ! l9e curr5t4 ,! great] ! value ( ! l9e curr5t1 ! great] ! numb] ( gaps requir$ to ext+ui% ! arcs4 ,grad$ ,%unt ,resi/ances4--,any arc is un/able & c be ext+ui%$ by plac+ a prop]ly proportion$ resi/ance 9 p>allel ) x4 ,all ! m9or dis*>ges !n pass ov] ! resi/ances & ! un%unt$ sp>k gaps1 ! resi/ance assi/+ 9 op5+ ! l9e curr5t aft] ! dis*>ge4 ,v heavy dis*>ges pass ov] all ! sp>k gaps1 z a pa? )\t resi/ance1 b ^? sp>k gaps :i* are %unt$ by ! resi/ance1 op5 aft] ! dis*>ge4 ,! l9e curr5t1 aft] ! fir/ dis*>ge is accord+ly deflect$ ov] ! resi/ances1 & limit$ !reby1 ! circuit be+ f9ally op5$ by ! un%unt$ sp>k gaps4 ,! arrangem5t ( %unt$ resi/ances is %[n 9 fig4 #b1ceh4 ,illu/ration3 ,,fig4 #b1ceh4--;,arrangem5t ( grad$ resi/ances on multi-gap arre/]4 ,! ,cumulative or ,break+ ,back ,effect4--,! grad$ %unt resi/ance gives a valuable effect1 :]e ! arre/] is consid]$ z f\r sep>ate arre/]s4 ,?is is ! cumulative or break+ back action4 ,:5 a lightn+ /ra9 betwe5 l9e & gr\nd takes place1 ! pressure is c>ri$ d[n ! high resi/ance ,h 7figs4 #b1cfe & #b1cff71 to ! s]ies gaps ,,gs1 & ! s]ies gaps sp>k ov]4 ,al?\gh x may require sev]al ?\s& volts to sp>k across an air gap1 x requires relatively only a few volts to ma9ta9 ! arc :i* foll[s ! sp>k4 ,9 consequ5ce1 :5 ! gaps ,,gs sp>k ov]1 ! l[] end ( ! high resi/ance is r$uc$ practically to gr\nd pressure4 ,if ! high resi/ance c c>ry ! dis*>ge curr5t )\t giv+ an ohmic drop suffici5t to break d[n ! %unt$ gaps ,,gh1 no?+ fur!r occurs--! arc goes out4 ,if1 on ! contr>y1 ! lightn+ /roke be too heavy = ?is1 ! pressure /ra9 is ?r[n across ! %unt$ gaps1 ,,gh1 equal 9 numb] to ! previ\s set4 ,9 o!r words1 ! same voltage breaks d[n bo? ( ! gr\ps ( gaps1 ,,gs & ,,gh1 9 succession4 ,! lightn+ dis*>ge curr5t is n[ limit$ only by ! m$ium resi/ance ,m1 & ! pressure is conc5trat$ across ! gaps1 ,,gm4 ,if ! m$ium resi/ance _c dis*>ge ! lightn+1 ! gap ,,gm sp>k1 & ! dis*>ge is limit$ only by ! l[ resi/ance4 ,! l[ resi/ance %\ld take c>e ( mo/ cases b ) extraord9>ily heavy /rokes & high frequ5cies1 ! dis*>ge c break back f> en\gh to cut out all resi/ance4 ,9 ! la/ /eps1 ! resi/ance is relatively l[ 9 proportion to ! numb] ( %unt gaps1 ,,gl1 & is design$ to cut out ! l9e curr5t imm$iately f ! gap1 ,,gl4 ,?is break+ back effect is valuable 9 dis*>g+ lightn+ ( l[ frequ5cy4 ,illu/ration3 ,,figs4 #b1cei to #b1cfd4--,we/+h\se safety sp>k gaps4 ,fig4 #b1cei1 indoor type2 figs4 #b1cfj to #b1cfd1 outdoor type4 ,x is well kn[n t ) trans=m]s1 op]at+ on high voltage l9es & hav+ l>ge ratios ( trans=mation1 !re may occur1 on ! l[ t5sion side1 mom5t>y voltages to gr\nd greatly 9 excess ( ! normal4 ,^! mom5t>y increases 9 voltage betwe5 ! l[ t5sion circuits & gr\nd are commonly call$ /atic di/urbances4 ,9 g5]al !y are ! result ( a *ange 9 ! /atic balance ( ! high t5sion side & its connect+ circuits4 ,unless c]ta9 precautions are tak51 su* a /atic di/urbance on ! l[ t5sion side may cause s]i\s /resses 9 ! second>y insulation ( a trans=m] ) a high ratio ( trans=mation4 ,?is induc$ /atic voltage is indep5d5t ( ! ratio ( trans=mation4 ,! /atic /resses are m s]i\s 9 a high ratio trans=m] simply because ! insulation ( its second>y is less able to )/& !m4 ,a me?od ( reliev+ ?is di/urbance is to connect a dis*>ge sp>k gap betwe5 "s po9t ( ! l[ t5sion side ( ! trans=m] to be protect$ 7a middle or neutral po9t1 if "o be available7 & ! gr\nd4 ,! sp>k gap op5+ is su* t any voltage v mu* 9 excess ( ! maximum normal w cause a dis*>ge to gr\nd1 & ?us ! l[ t5sion side is practically ti$ to gr\nd dur+ su* di/urbance1 :ile at o!r times x is ungr\nd$4 ,! ,und]writ]s recomm5d ! gr\nd+ ( ! neutral po9t ( l[ t5sion circuits :5 ! conditions are su* t ! maximum normal voltage betwe5 ! po9t connect$ & gr\nd w n exce$ #bej volts4 ,! rule all[s "o side ( a #bej volt circuit or ! middle po9t ( a #eej volt circuit to be gr\nd$4 ,! sp>k gaps %[n above are design$ = use on trans=m] second>y circuits & = protect+ individual s]ies arc lamps4 ,^! sp>k gaps are s+le pole1 & consi/ ( two cyl9d]s ( non-arc+ metal ) an air gap betwe54 ,"o ( ! cyl9d]s is connect$ to ! gr\nd1 ! o!r to ! l9e4 ,illu/ration3 ,,figs4 #b1cfe & #b1cff4--;,grad$ %unt resi/ance arre/] connections4 ,fig4 #b1cfe1 connections = #cc1jjj volt ,y sy/em ) gr\nd$ neutral2 fig4 #b1cff1 connections = #cc1jjj volt delta or ungr\nd$ ,y sy/ems4 ,! type ( arre/] %[n above may be consid]$ z f\r arre/]s 9 "o4 ,fir/1 = small dis*>ges !re are a few gaps 9 s]ies ) a high %unt resi/ance4 ,?is "p ( ! arre/] w safely dis*>ge accumulat$ /atic & also all disruptive dis*>ges ( small amp]e capacity4 ,?is pa? is %[n ?r\gh ,h 7resi/ance7 & ,,gs 7gaps74 ,second1 !re are a numb] ( gaps 9 s]ies ) a m$ium %unt resi/ance :i* w dis*>ge disruptive /rokes ( m$ium amp]e capacity4 ,?is pa? is %[n ?r\gh ,m 7resi/ance7 & ,,gh plus ,,gs 7gaps74 ,?ird1 !re are a great] numb] ( gaps 9 s]ies ) a l[ %unt resi/ance :i* w dis*>ge heavy disruptive /rokes4 ,?is pa? is %[n ?r\gh ,l 7resi/ance7 & ,,gm plus ,,gh plus ,,gs 7gaps74 ,f\r?1 ! total numb] ( gaps has no s]ies resi/ance1 ?us enabl+ ! arre/] to freely dis*>ge ! heavie/ induc$ /rokes4 ,?is pa? is %[n ?r\gh z]o resi/ance & ,,gh plus ,,gm plus ,,gh plus ,,gs 7gaps74 ,9 ea* ( ! above circuits ! numb] ( gaps & ! resi/ance are s proportion$ z to ext+ui% ! l9e arc at ! end ( ! half cycle 9 :i* ! lightn+ dis*>ge takes place4 ,illu/ration3 ,,fig4 #b1cfg4--;,in/allation ( a ,g5]al ,electric #ab1ejj volt1 ?ree phase1 multi-gap lightn+ arre/] 9 ! ,g>field ,p>k sub-/ation ( ! ,we/ ,*icago p>k common4 ,! ,v unit multi-gap arre/]1 :i* is pla9ly se5 9 ! illu/ration1 is made up ( ,v units consi/+ ( gaps betwe5 knurl$ cyl9d]s & connect$ toge!r at _! ends by %ort metal /rips4 ,! base is ( porcela91 :i* ?or\ghly insulates ea* cyl9d]1 & insures ! prop] function+ ( ! multi-gaps4 ,! cyl9d]s are made ( an alloy t conta9s metal ( l[ boil+ po9t :i* gives ! rectify+ effect1 & metals ( high boil+ po9t :i* _c vaporize 9 ! pres5ce ( ! "o ( l[ boil+ po9t4 ,! cyl9d]s are heavily knurl$4 ,z ! arc plays on ! po9t ( a knurl x gradually burns back & :5 ! metal ( l[ boil+ temp]ature is us$ up1 ! gap is increas$ at t po9t4 ,! knurl+1 ?us1 insures long] life to ! cyl9d] by =c+ successive arcs to %ift to a new po9t4 ,:5 worn along ! entire face1 ! cyl9d] %\ld be slightly turn$4 ,! l[ resi/ance section ( ! grad$ %unt is compos$ ( rods ( a metallic alloy4 ,^! rods h l>ge curr5t c>ry+ capacity1 & practically z]o temp]ature coeffici5t up to r$ heat4 ,! m$ium & high resi/ance rods are ( ! same /&>d composition previ\sly us$4 ,! contacts are metal caps %runk on ! ends2 ! resi/ances are p]man5t 9 value & ! inductance is r$uc$ to a m9imum4 ,! rods are glaz$ to prev5t absorption ( moi/ure & surface arc+4 ,aft] ! sp>k passes1 ! arcs are ext+ui%$ 9 ! rev]s$ ord]4 ,! l[ resi/ance1 ,l1 is proportion$ s z to draw ! arcs imm$iately f ! gaps1 ,,gl4 ,! l9e curr5t cont9ues 9 ! next gr\p ( gaps1 ,,gm1 until ! end ( ! half cycle ( ! g5]ator wave4 ,illu/ration3 ,,figs4 #b1cfh to #b1cgj4--,multi-gap or l[ equival5t lightn+ arre/]4 ,x consi/s (3 #a1 a numb] ( gap units 9 s]ies2 #b1 a numb] ( gap units 9 %unt ) a resi/ance2 & #c1 a s]ies resi/ance4 ,all resi/ances are wire w\nd & ! s]ies resi/ance is non-inductive4 ,! %unt resi/ance & gap units are m\nt$ on m>ble4 ,:5 a dis*>ge occurs1 ! s]ies gaps are brok5 d[n1 & if ! dis*>ge be heavy en\gh1 x w meet opposition 9 ! %unt resi/ance & pass ov] ! %unt$ gaps1 ?r\gh ! s]ies resi/ance to ! gr\nd4 ,! arc :i* t5ds to foll[ ! dis*>ge is !n )drawn f ! %unt$ gaps by ! %unt resi/ance1 & aid$ by bo? resi/ances is suppress$ by ! s]ies gaps4 ,! pressure ( dis*>ge is det]m9$ by ! numb] ( s]ies gaps z suffici5t numb] is us$ to )/& ! normal voltage & yet give a prop] factor ( safety = ! sev]e/ s]vice4 ,at ?is in/ant ! m$ium resi/ance1 ,m1 aids ! rectify+ quality ( ! gaps1 ,,gm1 by %unt+ out ! l[ frequ5cy curr5t ( ! alt]nator4 ,on acc\nt ( ?is %unt+ effect ! curr5t dies out soon] 9 ! gaps1 ,,gm1 ?an x o!rwise w\ld4 ,9 ! same mann]1 b to a less degree1 ! high resi/ance1 ,h1 draws ! l9e curr5t f ! gaps1 ,,gh4 ,?is curr5t n[ be+ limit$ by ! high resi/ance1 ! arc is easily ext+ui%$ at ! end ( ! fir/ "o-half cycle ( ! alt]nator wave4 ,ques4 ,:at is ! diff]5ce betwe5 arre/] = gr\nd$ ,y & non-gr\nd$ neutral sy/ems8 ,ans4 ,! connections are %[n 9 figs4 #b1cfe & #b1cff4 ,! diff]5ce 9 design lies 9 ! use ( a f\r? arre/] leg betwe5 ! multiplex connection & gr\nd or ungr\nd$ sy/em4 ,ques4 ,:y is ! f\r? leg introduc$8 ,ans4 ,! arre/] is design$ to h two legs betwe5 l9e & l9e4 ,if "o l9e become accid5tally gr\nd$1 ! full l9e voltage w\ld be ?r[n across "o leg if ! f\r? or gr\nd leg 7 n pres5t4 ,illu/ration3 ,,fig4 #b1cga4--,we/+h\se ?ree pole or f\r pole arre/] 9 wea!r pro( wood5 case :i* protects ! arre/] units f ra9 & sn[ :5 !y are in/all$ 9 expos$ locations1 z on poles or build+s4 ,on a ,y sy/em ) a gr\nd$ neutral1 ! accid5tally gr\nd$ phase causes a %ort circuit ( ! phase & ! arre/] is reliev$ ( ! /ra9 by ! tripp+ ( ! circuit break]4 ,briefly /at$1 ! f\r? or gr\nd leg ( ! arre/] is us$ :51 = any reason1 ! sy/em c\ld be op]at$1 ev5 = a %ort "t ) "o phase gr\nd$4 ,ques4 ,describe ! multiplex connection4 ,ans4 ,x consi/s ( a common connection betwe5 ! phase legs ( ! arre/] above ! e>? connection & provides an arre/] bett] adapt$ to relieve high pressure surges betwe5 l9es ?an w\ld o!rwise be possible4 ,its use also economizes 9 space & mat]ial = delta & p>tially gr\nd$ or non-gr\nd$ ,y sy/ems4 ,illu/ration3 ,,figs4 #b1cgb & #b1cgc4--,we/+h\se multi-gap lightn+ arre/] & views %[+ p>ts4 ,9 con/ruction1 a s]ies ( gaps1 betwe5 non-arc+ metal cyl9d]s arrang$ 9 a r[1 is connect$ betwe5 l9e & gr\nd 9 s]ies ) a composition /ick resi/or hav+ a resi/ance ( some?+ betwe5 #hj & #abj ohms4 ,9 op]ation1 if an excessive pressure be develop$ on a l9e1 electric dis*>ge arcs =m betwe5 ! metal cyl9d]s1 & ! *>ge ( electricity fl[s to gr\nd1 reliev+ ! excessive /ress4 ,! resi/ance ( ! /ick resi/or limits ! fl[ s t an excessive p[] curr5t _c pass ?r\gh ! arre/]4 ,! t5d5cy = a de/ructive p[] arc to foll[ ! dis*>ge arc is ?us c\nt]act$4 ,! composition resi/ors & ! gap cyl9d]s are m\nt$ 9 pairs on a porcela9 base1 & complete units are arrang$ )9 wea!r pro( wood5 boxes z indicat$4 ,= two pole arre/]s1 "o unit is m\nt$ on ! back ( ! box4 ,= ?ree pole & f\r pole arre/]s1 two units are us$2 "o is secur$ on ea* side ( ! box4 ,illu/ration3 ,,figs4 #b1cgd to #b1cgf4--;,connections = ,we/+h\se multi-gap 7type ,g7 arre/]s4 ,^! arre/]s may be in/all$ outside on poles or build+s1 or indoors on /ation walls4 ,! wea!r pro( wood5 case 7z %[n 9 fig4 #b1cga7 protects ! arre/] units f ra9 & sn[ :5 in/all$ 9 expos$ places4 ,fig4 #b1cgd %[s s+le phase in/allation1 fig4 #b1cge1 two phase in/allation1 & fig4 #b1cgf1 ?ree phase in/allation4 ,on a two pole circuit "o l9e wire is connect$ to ! top ( ea* ( ! composition resi/ors ( ea* arre/] unit1 z %[n 9 fig4 #b1cgd1 & ! gr\nd wire is connect$ to ! middle po9t ( ! gap s]ies4 ,on f\r pole circuits1 fig4 #b1cge1 ! same s*eme ( connections is us$1 b two arre/] units are necess>y & ! connections ( bo? are ! same4 ,on ?ree pole circuits1 two arre/] units are us$1 ) ! same connections z = f\r pole circuits1 except t !re are b ?ree l9e connections in/ead ( f\r z 9 fig4 #b1cgf4 ,horn ,gap ,arre/]s4--,a horn gap arre/] consi/s ess5tially ( two horn %ap$ t]m9als =m+ an air gap ( v>iable l5g?1 "o horn be+ connect$ to ! l9e to be protect$ & ! o!r to ! gr\nd usually ?r\gh s]ies resi/ance z %[n 9 fig4 #b1cgh4 ,ques4 ,h[ does ! horn gap arre/] op]ate8 ,ans4 ,! arc due to ! l9e curr5t :i* foll[s a dis*>ge1 rises betwe5 ! div]g+ horn & becom+ m & m att5uat$ is f9ally ext+ui%$4 ,illu/ration3 ,,fig4 #b1cgg4--;,horn gap arre/]1 diagram %[+ arre/] & connections betwe5 l9e & gr\nd4 ,! horn type arre/] 0 inv5t$ by ,oels*laeg] = ! ,allgeme9e ,electricitaets ,gesells*aft1 & l ! ,?omson arc circuit arre/]1 its op]ation is bas$ on ! fact t a %ort circuit once />t$ at ! base1 ! heat g5]at$ by ! arc w cause x to travel upw>d until x becomes s att5uat$ t x is ruptur$4 ,on circuits ( high voltage ?is rupture sometimes takes a second or two1 b seems to act ) little di/urbance ( ! l9e4 ,sometimes a wat] resi/ance is us$1 a *oke coil be+ ins]t$ 9 ! circuit 9 s]ies4 ,9 "o in/allation = a #dj1jjj volt l9e1 ! horns 7 made ( ,no4 #j1jjj copp] wire ) gap knees #b to #c or #c in*es4 ,! capacity ( ! wat] resi/ance receptacle 0 #ae gallons4 ,us]s diff] z to :e!r ! wat] %\ld conta9 salt4 ,! *oke coil c be made ( ab\t #ah turns ( iron wire w\nd on a #f in* cyl9d]4 ,ques4 ,:at is ! objection to ! horn gap on alt]nat+ curr5t circuits8 ,ans4 ,! arc la/s too long = syn*ron\s app>atus to rema9 9 /ep4 ,ques4 ,:at provision 0 made to %ort5 ! duration ( ! arc8 ,ans4 ,a s]ies resi/ance 0 ins]t$ 9 ! arre/] circuit z %[n 9 fig4 #b1cgg4 ,ques4 ,:at difficulty 0 caus$ by ! s]ies resi/ance8 ,ans4 ,) suffici5t s]ies resi/ance to prev5t loss ( syn*ronism1 ! arre/] fail$ to protect ! sy/em "u sev]e conditions4 ,ques4 ,) ^! objections :at use 0 f\nd = ! horn gap arre/]8 ,ans4 ,x is us$ z an em]g5cy arre/] on "s ov]head l9es1 to op]ate only :5 a %ut d[n is unavoidable1 also = s]ies light+ circuits4 ,illu/ration3 ,,fig4 #b1cgh4--;,g5]al ,electric horn gap ) *>g+ resi/ance = cable sy/em4 ,arre/]s = cable sy/ems diff] f arre/]s = ov]head circuits only 9 ! con/ruction ( ! horn gaps4 ,! necessity = ?is diff]5ce is due to ! fact t a cable sy/em has a v mu* high] electro/atic capacity & mu* less inductance ?an an ov]head sy/em4 ,9 consequ5ce1 ! curr5ts :i* fl[ into ! arre/] dur+ *>g+ are some:at high]4 ,x is desirable to avoid ^! heavi] curr5ts1 especially dur+ ! "t ( break+ ! arc at ! horn gap4 ,?is is accompli%$ by us+ a special horn gap & resi/ance4 ,?is consi/s ( an auxili>y horn m\nt$ above & insulat$ f ! regul> horn 9 su* a mann] z to int]cept ! arc if x rise on ! regul> horns4 ,en\gh resi/ance is connect$ 9 s]ies ) ?is auxili>y horn s t ! curr5t fl[ & arc across ?is gap are always limit$ to a mod]ate value4 ,su* a device has sev]al advantages4 ,s9ce ! me*anism is s arrang$ t ! *>g+ is always done ?r\gh ! auxili>y horn ! curr5t ru% is limit$ dur+ ! *>g+ & ?us tr\bles f c>elessness or ignorance are avoid$4 ,x also gives a ne>] uni=m *>g+ curr5t4 ,9 ! use ( ?is auxili>y horn gap & resi/ance !re are ?ree successive /ages1 z foll[s3 #a1 light dis*>ges w pass across ! small] gaps to ! auxili>y horn & ?r\gh ! s]ies resi/ance to ! cells2 #b1 if ! dis*>ge be heavy1 ! resi/ance (f]s suffici5t imp$ance to cause ! sp>k to pass to ! ma9 horn4 ,?is is accompli%$ ) only a slight increase 9 pressure because ! gap is already ioniz$4 ,if ! cells be 9 normal condition1 ! sp>k at ! gap is imm$iately ext+ui%$1 )\t any fl[ ( l9e curr5t2 #c1 if ! cells be 9 poor =m1 ! l9e curr5t may foll[ ! dis*>ge across ! ma9 gap & ! arc w rise to ! safety horn & be ext+ui%$ ?r\gh a resi/ance4 ,= mix$ ov]head & cable sy/ems ! *oice ( arre/] w be a matt] ( judgm5t4 ,if !re be a comp>atively %ort l5g? ( cable1 ! usual practice = ov]head sy/ems may be adopt$4 ,= direct connection to busb>s1 arre/]s ) *>g+ resi/ance %\ld be us$4 ,illu/ration3 ,,figs4 #b1cgi & #b1chj4--;,diagram %[+ connections ( horn type lightn+ arre/]s on s]ies circuits4 ,! necessity ( s]vice requires t s]ies lightn+ sy/ems be fully equipp$ aga9/ damage by lightn+ & simil> tr\ble4 ,! mo/ common di/urbances occurr+ on s]ies circuits are ! surges set up by ! sudd5 op5+ ( ! load$ circuit4 ,^! di/urbances are especially sev]e :]e circuits are accid5tally gr\nd$1 due to contact ( ! wires :]e !y pass ?r\gh o!r circuits4 ,ques4 ,h[ are ! sp>k gaps adju/$8 ,ans4 ,!y are set to give a l[ sp>k pressure relative to ! voltage ( ! l9e4 ,illu/ration3 ,,fig4 #b1cha4--;,g5]al ,electric horn type arre/]1 m\nt$ = #ae light s]ies arc circuit4 ,! horn type arre/] consi/s ( a horn gap ) s]ies resi/ance betwe5 ea* l9e & gr\nd4 ,! resi/ances & horn gaps are m\nt$ on porcela9 bases & ! latt] on insulat+ wood5 supports4 ,! supports h asbe/os b>ri]s 7except = l[e/ voltages71 & backs to elim9ate liability ( damage f ! arc :i* =ms 9 ! horn gap at ! "t ( ! dis*>ge4 ,! sp>k gaps are adju/$ to give a l[ sp>k pressure relative to ! voltage ( ! circuit4 ,! numb] & ohmic value ( ! resi/ance rods us$ 9 ! v>i\s arre/]s dep5d ^u ! voltage & curr5t ( ! circuit4 ,ques4 ,:y are horn arre/]s well suit$ to protect s]ies light+ circuits aga9/ surges8 ,ans4 ,because ! surges are damp$ out be=e ! arc :i* =ms across ! horn gaps is int]rupt$4 ,^! arcs la/ = sev]al cycles1 s9ce ! l5g? ( ! "t ( action ( ! arre/] dep5ds ^u ! l5g!n+ ( ! arc betwe5 ! horn gaps1 limit$ by ! s]ies resi/ance4 ,s9ce practically all di/urbances on light+ circuits are ( l[ frequ5cy1 ! s]ies resi/ance c be us$ ) good results2 x aids ! horn 9 ext+ui%+ ! arc1 limits ! size ( ! arc & prev5ts %ort circuits occurr+ dur+ ! p]iod ( dis*>ge4 ,illu/ration3 ,,fig4 #b1chb4--;,g5]al ,electric horn arre/] = pole in/allation4 ,q frequ5tly s]ies circuits are run und]gr\nd 9 cables = "s di/ance f ! g5]at+ /ation4 ,9 ord] to protect ! cables x is advisable to place horn arre/]s at ! po9ts :]e ! cable jo9s ! ov]head wires4 ,! resi/ance units are m\nt$ 9 ! wood5 box4 ,?is design is us$ to economize space1 s9ce if ! horn gaps be plac$ 9 ! box ! latt] w\ld h to be made v l>ge to accommodate ! asbe/os b>ri]s & backs4 ,9 in/all+ ?is type ( arre/] x is advisable to place x z ne> z possible to ! top ( ! pole s t ! arc may rise unob/ruct$ & ?us avoid ! likelihood ( live wires com+ 9 contact ) ! horns :i*1 dur+ ! op]ation ( ! s]ies curr5t1 are alive4 ,electrolytic ,arre/]s4--,arre/]s ( ?is class are sometimes call$ alum9um arre/]s because ( ! prop]ty ( alum9um on :i* _! action dep5ds2 t is1 x dep5ds on ! ph5om5on t a non-conduct+ film is =m$ on ! surface ( alum9um :5 imm]s$ 9 c]ta9 electrolytes4 ,if h[ev]1 ! film be expos$ to a high] pressure1 x may be punctur$ by _m m9ute holes1 ?us s r$uc+ its resi/ance t a l>ge curr5t may pass4 ,:5 ! pressure is aga9 r$uc$ ! holes become reseal$ & ! film aga9 effective4 ,illu/ration3 ,,figs4 #b1chc & #b1chd4--;,elevation & plan ( ,g5]al ,electric horn gaps & op]at+ /& = high voltage arre/]s4 ,9 con/ruction1 ! alum9um arre/] consi/s ess5tially ( a sy/em ( ne/$ alum9um cup %ap$ trays1 support$ on porcela9 & secur$ 9 frames ( heat$ wood1 arrang$ 9 a /eel tank4 ,! sy/em ( trays is connect$ betwe5 ! l9e & gr\nd1 & betwe5 l9e & l9e1 a horn gap be+ ins]t$ 9 ! arre/] circuit :i* prev5ts ! arre/] be+ subject$ to ! l9e voltage except :5 9 action4 ,! electrolyte is p\r$ into ! cones & p>tly fills ! space betwe5 ! adjac5t ones4 ,! /ack ( cones ) ! electrolyte betwe5 !m is !n imm]s$ 9 a tank ( oil4 ,! electrolyte betwe5 adjac5t cones =ms an insulation4 ,! oil improves ?is insulation & prev5ts ! evaporation ( ! solution4 ,illu/ration3 ,,fig4 #b1che4--;,cross section ( ,g5]al ,electric alum9um 7electrolytic7 lightn+ arre/]4 ,a cyl9d] ( insulat+ mat]ial conc5tric ) ! cone /ack is plac$ betwe5 ! latt] & ! /eel tank1 ! object be+ to improve ! circulation ( ! oil & increase ! insulation betwe5 ! tank & ! cone /ack4 ,! arre/]1 z j describ$ consi/s ( a numb] ( cells connect$ 9 s]ies4 ,ques4 ,( :at does a s+le cell consi/ & :at are its *>act]i/ics8 ,ans4 ,x consi/s ( two ( ! cone %ap$ alum9ium trays or plates & an electrolyte1 :i* =ms a cond5s] t w /& ab\t #cej volts be=e break+ d[n4 ,:5 ?is voltage is exce$$ ! cell becomes a fairly good conductor ( electricity1 b z soon z ! voltage drops its resi/ance aga9 resumes a v high value4 ,ques4 ,:at is ! critical voltage8 ,ans4 ,! voltage at :i* ! curr5t beg9s to fl[ freely4 ,illu/ration3 ,,fig4 #b1chf to #b1cij4--,p>ts ( ,g5]al ,electric #ae1jjj volt alum9um lightn+ arre/]1 n includ+ horn gaps1 etc4 ,up to a c]ta9 voltage ! cell all[s an exce$+ly l[ curr5t to fl[1 b at a high] voltage ! curr5t fl[ is limit$ only by ! int]nal resi/ance ( ! cell1 :i* is v l[4 ,a close analogy to ?is action is f\nd 9 ! well kn[n safety valve ( ! /eam boil]1 by :i* ! /eam is conf9$ until ! pressure rises above a giv5 value1 :5 x is releas$4 ,on ! alum9um plates !re are myriads ( m9ute safety valves1 s t1 if ! electric pressure rise above ! critical voltage1 ! dis*>ge takes place equally ov] ! entire surface4 ,x is important to di/+ui% betwe5 ! valve action ( ?is hydroxide film & ! failure ( any dielectric sub/ance4 ,ques4 ,:5 a cell is connect$ p]man5tly to ! circuit :at two conditions are involv$8 ,ans4 ,! tempor>y critical voltage & ! p]man5t critical voltage4 ,= in/ance1 if ! cell h #cjj volts appli$ to x con/antly1 & ! pressure be sudd5ly increas$ to1 say #cbe volts1 !re w be a consid]able ru% ( curr5t until ! film ?ickness has be5 increas$ to )/& ! extra #be volts2 ?is usually requires sev]al seconds4 ,9 ?is case #cbe volts is ! tempor>y critical voltage ( ! cell4 ,simil> action w occur at any pressure up to ab\t ! p]man5t critical voltage1 or ! voltage at :i* ! film _c fur!r ?ick51 & !re=e all[s a free fl[ ( curr5t4 ,if ! voltage be aga9 r$uc$ to #cjj ! excess ?ickness ( film w be gradually dissolv$1 & if x v>y p]iodically betwe5 two values1 ea* ( :i* is less ?an ! p]man5t critical value1 ! tempor>y critical voltage w be ! high] value4 ,?is feature is ( great importance z x provides a means ( dis*>g+ abnormal surges1 ! in/ant ! pressure rises above ! impress$ value4 ,illu/ration3 ,,fig4 #b1cia4--,volt amp]e *>act]i/ic curve ( a ,g5]al ,electric alum9um 7electrolytic7 cell on alt]nat+ curr5t4 ,! p]man5t critical voltage is betwe5 #cce & #cfj volts4 ,) alt]nat+ curr5t1 ! cell acts z a fairly good cond5s]1 & !re is n only ! leakage ?r\gh ! film1 b also a capacity curr5t fl[+ into ! cell4 ,! phase ( ?is curr5t1 !n1 is ne>ly #ij degrees ahead ( ! pressure & repres5ts a v l[ en]gy factor4 ,ques4 ,h[ is ! numb] ( cells requir$ = a giv5 circuit det]m9$8 ,ans4 ,! numb] requir$ = a giv5 op]at+ voltage is det]m9$ by all[+ ab\t #bej to #cjj volts p] cell4 ,ques4 ,9 putt+ cells 9 commission h[ is ! electrolyte introduc$8 ,ans4 ,x is p\r$ into ! alum9um trays & ! ov]fl[ drawn (f at ! bottom ( ! tank4 ,ques4 ,describe ! fur!r op]ations 9 putt+ cells 9 commission4 ,ans4 ,aft] putt+ 9 ! electrolyte x is all[$ to /& = a few days until "p has evaporat$1 !n ! oil is p\r$ ov] ! surface to prev5t fur!r evaporation4 ,illu/ration3 ,,fig4 #b1cib4--,we/+h\se electrolytic lightn+ arre/]1 = ?ree phase ungr\nd$ neutral s]vice1 #be1jjj maximum voltage4 ,^! arre/]s are design$ = ! protection ( alt]nat+ curr5t circuits f all k9ds ( /atic di/urbances4 ,!y h be5 /&>diz$ = in/allation on ?ree phase circuits ( voltages ( #b1bjj to #aaj1jjj4 ,!y _c be us$ = voltages ( less ?an #ac1ejj4 ,= voltages bel[ ?is ! horn gaps _c1 ) safety1 be set close en\gh toge!r1 out ( doors1 to take advantage ( ! fre$om ( dis*>ge ( ! electrolytic elem5t4 ,if ! horn gaps be set too close toge!r !y may be %ort circuit$ by ra94 ,a %elt] %\ld be built = arre/]s ( #ac1ejj volts & bel[ = _! protection :5 in/all$ outside4 ,ques4 ,:at action takes place :5 ! trays /& 9 ! electrolyte & cell is disconnect$ f ! circuit8 ,ans4 ,"p ( ! film det]iorates4 ,ques4 ,:at is ! nature ( ! film8 ,ans4 ,! film is compos$ ( two p>ts1 "o ( :i* is h>d & insoluble1 & app>5tly acts z a skeleton to hold ! m soluble "p4 ,! action ( ! cell seems to indicate t ! soluble "p ( ! film is compos$ ( gases 9 a liquid =m4 ,ques4 ,:at action takes place :5 a cell :i* has /ood = "s "t disconnect$1 is reconnect$ to ! circuit8 ,illu/ration3 ,,figs4 #b1cic & #b1cid4--;,alum9um trays = ,we/+h\se electrolytic lightn+ arre/]s4 ,ans4 ,!re is a mom5t>y ru% ( curr5t :i* re=ms ! "p ( ! film :i* has dissolv$4 ,?is curr5t ru% w h increas+ values z ! int]vals ( re/ ( ! cell are made great]4 ,_m electrolytes h be5 /udi$1 b none has be5 f\nd :i* does n %[ ?is dissolution effect to a great] or less] ext5t4 ,if ! cell has /ood disconnect$ f ! circuit = "s "t1 especially 9 a w>m climate1 !re is a possibility t ! initial curr5t ru% w be suffici5t to op5 ! circuit break]s or oil swit*es4 ,?is curr5t ru% also raises ! temp]ature ( ! cell1 & if ! temp]ature rise be great1 x is objectionable4 ,:5 ! cells d n /& = m ?an a day1 h[ev]1 ! film dissolution & initial curr5t ru% are negligible4 ,ques4 ,:at is ! object ( us+ horn gaps on electrolytic arre/]s8 ,ans4 ,! use is ?reefold3 #a1 x prev5ts ! arre/] be+ subject$ cont9ually to ! l9e voltage2 #b1 acts z a disconnect+ swit* to disconnect ! arre/] f ! l9e = repairs1 etc41 & #c1 acts z a connect+ swit* = *>g+4 ,illu/ration3 ,,fig4 #b1cie4--;,horn gaps & transf] device ( ,g5]al ,electric alum9ium lightn+ arre/] = #ab1ejj volt non-gr\nd$ neutral circuit4 ,! object ( ! transf] device is to provide a means = int]*ang+ ! gr\nd /acks ) "o ( ! l9e /acks ( cones dur+ ! *>g+ op]ation s t ! films ( all ! cells w be =m$ to ! same value4 ,! transf] device consi/s ( a rotat+ swit* :i* may be turn$ #ahj degrees1 ?us int]*ang+ ! connections ( ! gr\nd /ack & "o ( ! l9e /acks4 ,= arre/]s up to #bg1jjj volts ! device is m\nt$ ) ?ree insulators on ! pipe frame "w1 & is op]at$ by a h& :eel2 = arre/]s ( high] voltage1 ! transf] device is m\nt$ directly ov] ! tanks & is op]at$ by bevel ge>s & h& :eel4 ,*>g+ ( ,electrolytic ,arre/]s4--,9 electrolytic arre/]s all electrolytes dissolve ! film :5 ! arre/] is on op5 circuit1 ! ext5t ( ! dissolution dep5d+ ^u ! l5g? ( "t ! film is 9 ! electrolyte1 & ^u its temp]ature4 ,x is !re=e necess>y to *>ge ! cells f "t to "t & ?us prev5t ! dissolution & consequ5t ru% ( curr5t :i* w\ld o!rwise occur :5 ! arre/] dis*>ges4 ,ques4 ,describe ! *>g+ op]ation = arre/]s ) gr\nd$ circuits4 ,ans4 ,x consi/s 9 simply clos+ simultane\sly ! ?ree horn gaps s t ! full pressure across ! cells causes a small *>g+ curr5t to fl[ & =m ! films to _! normal condition4 ,illu/ration3 ,,fig4 #b1cif4--,sectional view ( ,g5]al ,electric vacuum tube arre/] = railway signal circuits4 ,! arre/] is ess5tially a gap 9 a vacuum4 ,9 con/ruction1 ! gap is =m$ betwe5 ! inn] wall ( a drawn metal %ell & a disc electrode m\nt$ conc5tric ) x4 ,! electrode is support$ on a brass rod :i* s]ves z ! lead 9 connection1 & has ample curr5t c>ry+ capacity4 ,! electrode sy/em is insulat$ f ! tube & rigidly support$ 9 position by a bu%+ made ( vitre\s mat]ial4 ,! bu%+ does n =m ! vacuum seal1 t be+ made by a special comp\nd4 ,! op5 end ( ! tube is f9ally clos$ by a porcela9 bu%+4 ,! tube is exhau/$ 9 a special ma*9e :i* sold]s a small hole 9 ! end aft] ! vacuum has be5 e/abli%$4 ,! possibility ( sold] ent]+ ! active "p ( ! vacuum space is prev5t$ by a diaphragm pun*+1 & bo? ! electrode & ! l9+ ( ! tube are ( non-arc+ metal4 ,! arre/] has a sp>k pressure ( f #cej to #fjj volts direct curr5t1 & an equival5t ne$le gap ( ab\t 4#jje in*4 ,! arre/] w n /& a cont9u\s fl[ ( curr5t due to excessive heat+1 h5ce if !re be a possibility ( ?is due to high pressure crosses1 fuses %\ld be us$4 ,r4,r4,s4,a4 /&>d t]m9als are us$4 ,ques4 ,describe ! *>g+ op]ation = arre/]s = non-gr\nd$ circuits4 ,ans4 ,fir/1 ! horn gaps are clos$ = five seconds & op5$ aga9 to normal position1 ?us *>g+ ! cells ( ! ?ree l9e /acks4 ,second1 ) ! horn gaps /ill 9 normal position1 ! position ( ! transf] device is rev]s$ & ! horn gaps are aga9 clos$ = five seconds & return$ to ! normal position4 ,! complete *>g+ op]ation takes b a few mom5ts & %\ld be p]=m$ daily4 ,! op]ation is valuable1 n only 9 keep+ ! films 9 good condition1 b also 9 giv+ ! op]ator "s idea ( ! condition ( ! arre/] by enabl+ him to obs]ve ! size & color ( ! *>g+ sp>k4 ,illu/ration3 ,,fig4 #b1cig4--;,highl& ,p>k sub-/ation1 ,*>lotte1 ,n4,c41 %[+ old lightn+ arre/] t[] on ! left & ,g5]al ,electric alum9um 7electrolytic7 cell lightn+ arre/] & horn gaps 9 =egr\nd4 ,gr\nd$ & ,non-gr\nd$ ,neutral ,circuits4--,x is important to avoid ! mi/ake ( *oos+ an arre/] = a ?or\ghly gr\nd$ neutral :5 ! neutral is only p>tially gr\nd$1 t is1 gr\nd$ ?r\gh an appreciable resi/ance4 ,c>eful consid]ation ( ?is condition w make ! above /atem5t cle>4 ,9 an arre/] = a gr\nd$ neutral circuit1 ea* /ack ( cones normally receives ! neutral pressure :5 ! arre/] dis*>ges1 b if a phase become accid5tally gr\nd$1 ! l9e voltage is ?r[n across ea* ( ! o!r /acks ( cones until ! circuit break] op5s ! circuit4 ,! l9e voltage is #agc p] c5t4 ( ! neutral or normal op]at+ voltage ( ! cells & !re=e ab\t #aej p] c5t4 ( ! p]man5t critical voltage ( ea* cell4 ,?is means t :5 a gr\nd$ phase occurs1 ?is #ej p] c5t4 excess pressure is %ort circuit$ ?r\gh ! cells until ! circuit break] op5s4 ,illu/ration3 ,,fig4 #b1cih4--,we/+h\se electrolytic /ation lightn+ arre/] = direct curr5t up to #a1ejj volts consi/s ( a tank ( oil 9 :i* are plac$1 on prop]ly insulat$ supports1 a ne/ ( cup %ap$ alum9um trays4 ,! spaces betwe5 ! trays are fill$ ) electrolyte1 a suffici5t quantity = "o *>ge be+ furni%$ ) ea* arre/]4 ,! top tray is connect$ ) ! l9e ?r\gh a #fj amp]e fuse1 & ! bottom tray is connect$ to ! tank :i* is ?or\ghly gr\nd$ by means ( a lug4 ,! fuse is ( ! enclos$ type & m\nt$ on ! cov] ( ! arre/]4 ,a small *>g+ curr5t fl[s ?r\gh ! trays cont9u\sly & keeps ! films on ! trays built up1 s t no *>g+ is requir$4 ,?is *>g+ curr5t is n1 h[ev]1 ( suffici5t value to raise ! temp]ature appreciably4 ,! imm]s$ area ( ea* tray is #ajj squ>e in*es4 ,! %ape & ! arrangem5t ( ! trays is su* t any gases g5]at$ by ! dis*>ge c pass out readily )\t di/urb+ ! electrolyte betwe5 ! trays4 ,! am\nt ( en]gy to be dissipat$ 9 ! arre/] dep5ds ^u ! kil[att capacity ( ! g5]ator1 ! int]nal resi/ance ( ! cells1 & ! "t requir$ to op]ate ! circuit break]s4 ,x is evid5t t ! great] ! am\nt ( resi/ance 9 ! neutral1 ! long] w be ! "t requir$ = ! circuit break]s to op]ate4 ,!re=e1 9 cases :]e ! e>?+ resi/ance 9 ! neutral is great en\gh to prev5t ! automatic circuit break]s op5+ practically in/antane\sly1 an arre/] = a non-gr\nd$ neutral sy/em %\ld be in/all$4 ,illu/ration3 ,,figs4 #b1cii to #b1dja4--,we/+h\se gr\nd fitt+s4 ,fig4 #b1cii1 gr\nd plate2 fig4 #b1djj1 gr\nd po9t2 fig4 #b1dja1 cap4 ,! gr\nd plate consi/s ( a circul> piece ( ca/ iron1 #ab in*es 9 diamet]1 #a in*es ?ick ) a in* pipe tap 9 c5t] to connection to arre/]4 ,! surface is increas$ by means ( corrugations1 z %[n 9 ! accompany+ illu/rations1 to #dfa squ>e in*es1 af=d+ ample contact ) ! e>? & enabl+ x to take c>e ( all dis*>ges ?r\gh ! arre/]4 ,! plate %\ld pref]ably be buri$ at ! foot ( ! pole s t ! gr\nd wire runs to x 9 a /raight l9e f ! arre/]4 ,c>e %\ld1 ( c\rse1 be tak5 to see t ! e>? 9 :i* ! plate is buri$ is damp4 ,if ! gr\nd wire be plac$ )9 ! pipe lead+ to ! gr\nd plate x %\ld be sold]$ to a cap at ! top ( ! pipe to elim9ate ! inductive effect due to ! wire be+ surr\nd$ by iron4 ,a simple & effective me?od ( secur+ a good gr\nd is by means ( an iron pipe ) a malleable iron po9t hav+ a dipp$ galvaniz$ f9i%1 & a brass cap ) a lug = sold]+ ! gr\nd wire4 ,! pipe may be driv5 into ! e>?1 or if x be too h>d to p]mit driv+1 a hole may be dug & ! pipe plac$ !re94 ,x %\ld ext5d f eight to t5 feet above & bel[ ! e>? to secure1 respectively1 a good gr\nd & prev5t any tamp]+ ) ! gr\nd wire4 ,%\ld x be desir$ to make use ( a long] pipe :i* w\ld be inconv5i5t to drive into ! e>?1 two pieces c be us$ & connect$ toge!r by a c\pl+4 ,! brass cap & malleable iron po9t are tapp$ = use ) in* pipe4 ,gr\nd ,connections4--,9 all lightn+ arre/] in/allations x is ( ! utmo/ importance to make prop] gr\nd connections1 z _m lightn+ arre/] tr\bles c be trac$ to bad gr\nds4 ,x has be5 cu/om>y to gr\nd a lightn+ arre/] by means ( a l>ge metal plate buri$ 9 a b$ ( *>coal at a dep? ( six or eight feet 9 ! e>?4 ,a m satisfactory me?od ( mak+ a gr\nd is to drive a numb] ( "o in* iron pipes six or eight feet into ! e>? surr\nd+ ! /ation1 connect+ all ^! pipes toge!r by means ( a copp] wire or1 pref]ably1 by a ?9 copp] /rip4 ,a quantity ( salt %\ld be plac$ ar\nd ea* pipe at ! surface ( ! gr\nd & ! gr\nd %\ld be ?or\ghly moi/5$ ) wat]4 ,x is advisable to connect ^! pipes to ! iron framework ( ! /ation1 & also to any wat] ma9s1 metal flumes1 or trolley rails :i* are available4 ,illu/ration3 ,,figs4 #b1djb to #b1djd4--;,g5]al ,electric magnetic bl[ out arre/] = use on railways4 ,x consi/s ( an adju/able sp>k gap 9 s]ies ) a resi/ance4 ,"p ( ! resi/ance is 9 %unt ) a bl[ out coil1 betwe5 ! poles ( :i* is ! sp>k gap4 ,! p>ts are m\nt$ 9 a /rong1 porcela9 box1 :i*1 = c> & pole use1 is 9 turn m\nt$ 9 a sub/antial asbe/os l9$1 wood5 box4 ,9 op]ation1 :5 ! light+ pressure comes on ! l9e1 x causes ! sp>k gap to break d[n & a dis*>ge occurs ?r\gh ! gap & ! resi/ance rod to gr\nd4 ,"p ( ! curr5t %unts ?r\gh ! bl[ out coil produc+ a /rong magnetic field across ! sp>k gap4 ,! magnetic field bl[s out ! dis*>ge arc & re/ores normal conditions4 ,! resi/ance is only #fj ohms 7= #ejj volt rat+ "w71 & ! sp>k gap only "o-=tie? ( an in* 74#jbe 9474 ,! foll[+ sugge/ions are made = ! usual size /ation4 #a4 ,place ?ree pipes equally spac$ ne> ea* outside wall1 mak+ twelve altoge!r1 & place ?ree extra pipes spac$ ab\t six feet ap>t at a po9t ne>e/ ! arre/]4 #b4 ,:]e plates are plac$ 9 /reams ( runn+ wat]1 !y %\ld be buri$ 9 ! mud along ! bank 9 pref]5ce to be+ laid 9 ! /ream4 ,/reams ) rocky bottoms are to be avoid$4 #c4 ,:5ev] plates are plac$ at any di/ance f ! arre/]1 x is necess>y also to drive a pipe into ! e>? directly b5ea? ! arre/]1 ?us mak+ ! gr\nd connection z %ort z possible4 ,e>? plates at a di/ance _c be dep5d$ ^u4 ,long gr\nd wires 9 a /ation _c be dep5d$ ^u unless a lead is c>ri$ to ! p>allel gr\nd+ pipes in/all$ z describ$ above4 #d4 ,z x is advisable occasionally to exam9e ! und]gr\nd connections to see t !y are 9 prop] condition1 x is well to keep on file exact plans ( ! location ( gr\nd plates1 gr\nd wires & pipes1 ) a brief description1 s t ! data c be readily ref]r$ to4 ,illu/ration3 ,,fig4 #b1dje4--;,g5]al ,electric magnetic bl[ out arre/] = l9e use4 ,x consi/s ess5tially ( a small sp>k gap :i* is 9 s]ies ) a resi/ance1 & betwe5 ! poles ( a magnet4 ,! op]ation is simil> to t ( ! arre/] %[n 9 figs4 #b1djb to #b1djd1 b ! magnet is a p]man5t magnet in/ead ( an electromagnet4 ,! sp>k gap & ! magnet are m\nt$ )9 porcela9 blocks 9 su* a way t ! dis*>ge arc is bl[n by ! magnet ?r\gh an arc *ute & a cool+ grid :i* is also held by ! porcela94 ,! cool+ grid 9 ! arc *ute mat]ially assi/s ! magnet 9 ext+ui%+ ! dis*>ge arc1 giv+ ! arre/] a high arc ruptur+ quality4 ,! s]ies rod is c>borundum & is connect$ ext]nally to ! o!r portion ( ! arre/]4 ,! arre/] is self-conta9$4 #e4 ,f "t to "t ! resi/ance ( ^! gr\nd connections %\ld be measur$ to det]m9e _! condition4 ,! resi/ance ( a s+le pipe gr\nd 9 good condition has an av]age value ( ab\t #ae ohms4 ,a simple & satisfactory me?od ( keep+ acc\nt ( ! condition ( ! e>? connections is to divide ! gr\nd+ pipes into two gr\ps & connect ea* gr\p to ! #aaj volt light+ circuit ) an ammet] 9 s]ies4 ,*oke ,coils4--,a lightn+ dis*>ge is ( an oscillatory "* & possesses ! prop]ty ( self-induction1 accord+ly x passes ) difficulty ?r\gh coils ( wire4 ,moreov]1 ! frequ5cy ( oscillation ( a lightn+ dis*>ge be+ mu* great] ?an t ( comm]cial alt]nat+ curr5ts1 a coil c readily be con/ruct$ :i* w (f] a relatively high resi/ance to ! passage ( lightn+ & at ! same "t all[ free passage to all ord9>y electric curr5ts4 ,op9ions on ! design ( *oke coils = use ) lightn+ arre/]s v>y consid]ably4 ,"s eng9e]s recomm5d ! use ( v l>ge *oke coils1 b :ile l>ge *oke coils ( high inductance d *oke back ! high frequ5cy curr5ts bett] ?an small] coils ( less inductance1 !y co/ m1 & "u _m conditions !y are a m5ace to ! insulation unless ! lightn+ arre/]s be in/all$ on bo? sides ( !m4 ,illu/ration3 ,,fig4 #b1djf4--,we/+h\se l9e susp5sion *oke coil4 ,x is s design$ t x c be ins]t$ directly 9 ! transmission l9e wire or 9 ! /ation wir+ & held 9 position !re9 by ! t5sion ( ! l9e or /ation wires4 ,because ( ! fact t no insulators are requir$1 solely to support ?is *oke coil1 & t x c be in/all$ 9 ei!r a v]tical or a horizontal position x c (t5 be utiliz$ effectively 9 p[] & sub-/ation lay\ts4 ,t]m9als1 ea* hav+ a in* r\nd hole1 to accommodate ! conductors are provid$ at ea* end ( ! coil4 ,?ree squ>e head$ b9d+ screws are suppli$ :i* clamp ! conductors 9 position4 ,! coil is provid$ ) a /ra9 insulator1 s arrang$ )9 ! coil at its axis1 t x assumes any me*anical t5sion transmitt$ f ! conductors4 ,no me*anical t5sion rea*es ! turns ( ! *oke coil prop]4 ,9 con/ruction1 ! *oke coil is made 9 b "o size hav+ a curr5t c>ry+ capacity ( #bjj amp]es & is suitable = a voltage ( #b1jjj to #bb1jjj4 ,= high] voltages ?an #bb1jjj1 sev]al *oke coils are connect$ 9 s]ies4 ,"o coil is us$ = ea* #bb1jjj volts or fraction !re(1 ( ! pressure betwe5 ! wires ( ! circuit4 ,application3 ,?is type ( *oke coil may be us$ = alt]nat+ curr5t s]vice = ! entire range f #bb1jjj to #aaj1jjj volts4 ,x may be us$ on trans=m]s1 b is n recomm5d$ = ! protection ( g5]ators4 ,"p ( ! functions ( ! *oke coil are p]=m$ by ! end turns ( a trans=m] & extra insulation is inv>iably in/all$ 9 all p[] trans=m]s built 9 rec5t ye>s4 ,! *oice ( *oke coils mu/ be influ5c$ by ! condition ( insulation 9 ! trans=m]s z well z by ! co/1 pressure regulation1 & nature ( ! lightn+ protection requir$4 ,ques4 ,:at are ! prim>y objects ( a *oke coil8 ,ans4 ,to hold back ! light+ di/urbance f ! circuit app>atus dur+ dis*>ge1 & to l[] ! frequ5cy ( ! oscillation s t :atev] *>ge gets ?r\gh ! *oke coil w be ( a frequ5cy too l[ to cause s]i\s pressure drop ar\nd ! fir/ turns ( ! end coil 9 ei!r alt]nator or trans=m]4 ,illu/ration3 ,,figs4 #b1djg to #b1dji4--;,g5]al ,electric *oke coils4 ,fig4 #b1djg1 h\r glass *oke coil1 #de1jjj volts2 fig4 #b1djh1 l[ voltage *oke coil1 #f1fjj volts2 fig4 #b1dji1 l[ voltage *oke coil1 #d1fjj volts4 ,if !re be no arre/]1 ! *oke coil _c p]=m ! fir/ function1 accord+ly a *oke coil is be/ consid]$ z an auxili>y to an arre/]4 ,ques4 ,:at is ! pr9cipal electrical condition to be avoid$ ) a *oke coil8 ,ans4 ,resonance4 ,! coil %\ld be s arrang$ t if cont9ual surges be set up 9 ! circuit1 a resonant voltage due to ! pres5ce ( ! *oke coil _c build up at ! trans=m] or g5]ator t]m9als4 ,?is factor is a m5ace to ! insulation4 ,ano!r way ( /at+ ! condition is z foll[s3 ,s arrange ! *oke coil z n to prev5t surges1 orig9at+ 9 a trans=m]1 pass+ to ! arre/]4 ,ques4 ,:at is ano!r electrical condition to be avoid$ & :y8 ,ans4 ,int]nal /atic capacity betwe5 adjac5t turns ,illu/ration3 ,,fig4 #b1daj4--,we/+h\se *oke coil = high pressure transmission circuits1 #b1bjj to #be1jjj volts4 ,*oke coils ( ?is type are w\nd )\t iron cores on circul> or elliptical c5t] blocks4 ,!y h a l>ge numb] ( lay]s & few turns p] lay] 7except ^? made = small curr5ts1 !y usually h "o turn p] lay]71 :i* give ! be/ condition = insulat+ & cool+4 ,!y are air cool$1 heavily insulat$ & h a l9e lead at ! top1 z %[n4 ,*oke coils are design$ to prev5t ! %ort circuits sometimes caus$ by ! local conc5tration ( pressure su* z may be produc$ by a lightn+ dis*>ge4 ,!y limit1 to "s ext5t1 an abnormal rise ( pressure on ! app>atus by delay+ ! advance ( a /atic wave f ! l9e & ?us give ! arre/] m "t to act4 ,! di/urbance caus$ by a lightn+ fla% passes along ! l9e 9 ! =m ( a surge or tidal wave4 ,if ?is wave pass a *oke coil1 x is flatt5$ out1 & if ! coil be ( suffici5t p[]1 becomes practically h>mless4 ,x is evid5t1 h[ev]1 t ! *oke coil receives ! full =ce ( ! wave1 & t1 consequ5tly1 x mu/ be heavily insulat$2 moreov]1 ! *oke coil mu/ n ov]heat "u load1 nor introduce into ! circuit excessive inductive resi/ance4 ( ! *oke coil1 because ?is l[]s ! effectiv5ess ( ! coil4 ,ques4 ,:at is ! object ( mak+ *oke coils 9 ! =m ( an h\r glass8 ,ans4 ,to prev5t sagg+ betwe5 ! supports4 ,illu/ration3 ,,fig4 #b1daa4--,we/+h\se air cool$ *oke coil p>ticul>ly suitable = outdoor use4 ,! me?od ( m\nt+ is su* t insulation = any desir$ voltage is readily obta9$ ) ! same type ( porcela91 & m\nt+ 9 any position is possible4 ,! coil is a helix ( alum9um rod1 ab\t #ae in*es 9 diamet] & conta9+ ab\t #cj turns4 ,brac+ clamps are provid$ to give me*anical /r5g? to ! helix1 & ! rod us$ is ( suffici5t diamet] to c>ry #bjj amp]es4 ,! coil is support$ on two insulat+ columns made up ( porcela9 insulators1 :i*1 except = ! end pieces1 are int]*angeable4 ,! numb] ( insulators us$ 9 ! columns dep5ds on ! voltage ( ! circuit 9 :i* ! coil is to be us$4 ,! app>atus c be m\nt$ 9 any position conv5i5t = ! wir+1 on floor1 wall1 or ceil+4 ,x is int5d$ pr9cipally = ! protection ( trans=m]s4 ,:]e great] reactance ?an is af=d$ by a s+le coil is desir$ on ! high] voltage circuits1 x is recomm5d$ t two or m coils be connect$ 9 s]ies1 "o coil be+ us$ = ea* #bb1jjj l9e voltage4 ,?is coil %\ld n be us$ = g5]ators4 ,! insulat+ columns are support$ on sub/antial ca/ iron blocks on wood5 bases4 ,ques4 ,h[ are *oke coils cool$8 ,ans4 ,by air1 or by oil4 ,ques4 ,= :at s]vice are oil cool$ *oke coils us$8 ,ans4 ,on circuits ( pressures above #be1jjj volts1 *oke coils imm]s$ 9 oil1 z are trans=m] coils1 h advantages 9 t ! coil is amply insulat$ n only f ! gr\nd b aga9/ side fla%1 & t copp] ( comp>atively small section may be us$ )\t undue heat+4 ,illu/ration3 ,,fig4 #b1dab4--,we/+h\se air cool$ *oke coil1 = voltages ( f #b1bjj to #aaj1jjj4 ,9 con/ruction1 ! coils are made ( alum9um rod w\nd into a helix ( ab\t #ae in*es 9 diamet] & hav+ #bj turns4 ,! helix is support$ on two insulators4 ,= me*anical reasons x is necess>y to h ! alum9um rod ( suffici5t size to secure rigidity1 consequ5tly e coil has a capacity ( #bjj amp]es & may be us$ on any circuit up to t capacity4 ,! coils are insulat$ accord+ to ! /&>d practice = disconnect+ swit*es1 ! insulators be+ m\nt$ on wood5 p9s support$ by a wood5 base4 ,?is app>atus c be m\nt$ 9 any position4 ,! wir+ ( a /ation or sub-/ation is facilitat$ because ! protection may be plac$ s z to simply =m "p ( ! wir+4 ,! coils are symmetrical s t x is immat]ial :i* end is connect$ to ! l9e or to ! app>atus4 ,/atic ,int]rupt]s4--,a /atic int]rupt] is a comb9ation ( a *oke coil & a cond5s]1 ! two be+ m\nt$ toge!r & plac$ 9 a tank & oil insulat$4 ,x is us$ on high pressure circuits & its function is to s delay ! errone\sly call$ /atic wave 9 its entry into ! trans=m] coil1 t a consid]able portion ( ! latt] w become *>g$ be=e ! t]m9al w h rea*$ full pressure4 ,a *oke coil alone suffici5tly p[]ful to accompli% ?is w\ld be too l>ge & co/ly on v high pressure & w\ld int]f]e ) ! op]ation ( ! sy/em4 ,ques4 ,h[ is ! cond5s] & *oke coil connect$8 ,ans4 ,! cond5s] is connect$ betwe5 ! l9e & gr\nd beh9d ! *oke coil ne> ! app>atus to be protect$ z %[n 9 fig4 #b1dac4 ,illu/ration3 ,,fig4 #b1dac4--;,diagram %[+ connections ( /atic int]rupt] = protect+ a trans=m]4 ,ques4 ,:at is ! effect ( ! cond5s]8 ,ans4 ,! cond5s]1 :i* has a v small electro/atic capacity1 has no appreciable effect ^u ! normal op]ation1 b a v p[]ful effect ^u ! /atic wave on acc\nt ( its extremely high frequ5cy4 ,,*apt] ,,lx ,,regulat+ ,,devices ,regulation ( ,alt]nators4--,practically all ! me?ods employ$ = regulat+ ! voltage ( direct curr5t dynamos & circuits1 are applicable to alt]nators & alt]nat+ curr5t circuits4 ,= example3 9 ord] t !y %all automatically ma9ta9 a con/ant or ris+ voltage ) increase ( load1 alt]nators are provid$ ) composite w9d+ simil> to ! comp\nd w9d+ ( direct curr5t dynamos1 b s9ce ! alt]nat+ curr5t _c be us$ directly = excit+ ! field magnets1 an accessory app>atus is requir$ to rectify x or *ange x into direct curr5t be=e x is us$ = t purpose4 ,x is a fact1 h[ev]1 t composite w\nd alt]nators d n regulate prop]ly = inductive z well z non-inductive loads4 ,9 ord] to ov]come ?is defect comp5sat$ field alt]nators h be5 design$ :i* automatically adju/ ! voltage = all v>iations ( load & lag4 ,^! ma*9es h already be5 describ$4 ,alt]nat+ ,curr5t ,fe$] ,regulation4--,) slight modification1 ! v>i\s me?ods ( fe$] regulation employ$ ) direct curr5t1 may be appli$ to alt]nat+ curr5t di/ribution circuits4 ,= in/ance1 if a non-inductive resi/ance be introduc$ 9 any electric circuit1 ! consequ5t drop 9 voltage w be equal to ! curr5t multipli$ by ! resi/ance4 ,!re=e1 fe$] regulation by means ( rheo/ats is practically ! same 9 ! case ( alt]nat+ curr5t z 9 t ( direct curr5t4 ,9 ! case ( ! =m]1 h[ev]1 ! effect ( self-induction may also be utiliz$ to produce a drop 9 voltage4 ,9 practice1 ?is is accompli%$ by ! use ( self-induction coils :i* are commonly kn[n z reactance coils4 ,illu/ration3 ,,fig4 #b1dad4--;,diagram illu/rat+ ! pr9ciple ( induction voltage regulators4 ,! prim>y coil ,p1 consi/+ ( _m turns ( f9e wire1 is connect$ across ! ma9 conductors ,c & ,d1 com+ f ! alt]nator4 ,! second>y coil ,s1 consi/+ ( a few turns ( heavy wire1 is connect$ 9 s]ies ) ! conductor ,d4 ,! lam9at$ iron core ,e1 m\nt$ )9 ! coils1 is capable ( be+ turn$ into ! position %[n by ! dott$ l9es4 ,:5 ! core is v]tical1 ! magnetic l9es ( =ce produc$ 9 x by ! prim>y coil1 induces a pressure 9 ! second>y coil :i* aids ! voltage2 :5 turn$ to ! position indicat$ by ! dott$ l9es1 ! direction ( ! magnetic l9es ( =ce are rev]s$ ) respect to ! second>y coil & an oppos+ pressure w be produc$ !re94 ,?us1 by turn+ ! core1 ! pressure diff]5ce betwe5 ! l9e wires ,g & ,h1 c be v>i$ s z to be high] or l[] ?an t ( ! ma9 conductors ,c & ,d4 ,regulators op]at+ on ?is pr9ciple may be us$ = !atre dimm]s1 z controll]s = s]ies light+1 & also to adju/ ! voltage or ! bran*es ( unbalanc$ ?ree wire s+le phase & polyphase sy/ems4 ,application ( ,induction ,type ,regulators4--,9 supply+ light+ sy/ems1 :]e ! load & consequ5tly ! pressure drop 9 ! l9e increases or decreases1 x becomes necess>y to raise or l[] ! voltage ( an alt]nat+ curr5t1 9 ord] to regulate ! voltage deliv]$ at ! di/ant ends ( ! sy/em4 ,?is is usually accompli%$ by means ( alt]nat+ curr5t regulators or induction regulators4 ,a device ( ?is k9d is ess5tially a trans=m]1 ! prim>y ( :i* is excit$ by be+ connect$ directly across ! circuit1 :ile ! second>y is 9 s]ies ) ! circuit z %[n 9 fig4 #b1dad4 ,by ?is me?od ! circuit receives ! voltage g5]at$ 9 ! second>y4 ,illu/ration3 ,,fig4 #b1dae4--;,diagram ( induction regulator rais+ ! voltage #aj4 ,9 ! diagram an alt]nator is supply+ #ajj amp]es at #b1bjj volts4 ,! regulator raises ! fe$] pressure to #b1dbj volts1 ! curr5t be+ correspond+ly r$uc$ to #ia amp]es1 ! o!r #i amp]es fl[+ f ! alt]nator ?r\gh ! prim>y ( ! regulator1 back to ! alt]nator4 ,illu/ration3 ,,fig4 #b1daf4--;,diagram ( induction regulator l[]+ ! voltage #aj4 ,! diagram %[s ! regulator l[]+ ! fe$] pressure to #a1ihj volts ) an increase ( ! second>y curr5t to #aaa amp]es1 ! additional #aa amp]es fl[+ f ! fe$]1 ?r\gh ! prim>y back to ! fe$]4 ,ques4 ,"n two types ( pressure regulator4 ,ans4 ,! induction regulator1 & ! v>iable ratio trans=m] regulator4 ,ques4 ,( :at does an induction regulator consi/8 ,ans4 ,x consi/s ( a prim>y w9d+ or excit+ coil1 a second>y w9d+ :i* c>ries ! entire load curr5t4 ,illu/ration3 ,,fig4 #b1dag4--,mov+ elem5t or prim>y ( ,we/+h\se motor op]at$ s+le phase induction regulator4 ,x consi/s ( a core ( pun*+s built up directly on ! prim>y %aft & c>ry+ ! prim>y w9d+1 :i* is divid$ into f\r coils4 ,! prim>y coils are ma*9e w\nd & ! lay]s ( ! w9d+ are sep>at$ f ea* o!r by heavy insulat+ mat]ial 9 addition to ! cotton cov]+ ( ! inductors4 ,! complete coils are insulat$ & impregnat$ ) insulat+ comp\nd be=e be+ plac$ 9 ! slots4 ,! coils are held 9 position by fibre w$ges4 ,! prim>y is w\nd = ! full transmission voltage1 & is connect$ across ! l9e1 :ile ! second>y is connect$ 9 s]ies ) ! l9e4 ,ques4 ,:at is its pr9ciple ( op]ation8 ,ans4 ,:5 ! prim>y coil is turn$ to v>i\s positions ! magnetic flux s5t ?r\gh ! second>y coil v>ies 9 value1 !reby caus+ correspond+ v>iation 9 ! second>y voltage1 ! "* ( :i* dep5ds ^u ! value & direction ( ! flux4 ,ques4 ,:at is ! effect ( turn+ ! second>y coil to a position at "r angles ) ! prim>y coil8 ,ans4 ,! prim>y w n induce any voltage 9 ! second>y1 & accord+ly x has no effect on ! fe$] voltage4 ,ques4 ,:at is ?is position call$8 ,ans4 ,! neutral position4 ,ques4 ,:at are ! effects ( revolv+ ! prim>y coil f ! neutral position fir/ 9 "o direction !n 9 ! o!r8 ,ans4 ,turn+ ! prim>y 9 "o direction increases ! voltage induc$ 9 ! second>y1 ?us increas+ ! fe$] voltage l ! action ( a boo/] on a direct curr5t circuit :ile turn+ ! prim>y 9 ! opposite direction f ! neutral position1 correspond+ly decreases ! fe$] voltage4 ,illu/ration3 ,,fig4 #b1dah4--,mov+ elem5t or prim>y ( ,we/+h\se motor op]at$ polyphase induction regulator4 ,ques4 ,x 0 /at$ t = neutral position ! prim>y _h no effect on ! second>y2 does ! second>y h any effect on ! fe$] voltage8 ,ans4 ,! second>y t5ds to create a magnetic field ( its own self-induction1 & has ! effect ( a *oke coil4 ,ques4 ,h[ is ?is t5d5cy ov]come8 ,ans4 ,! prim>y is provid$ ) a %ort circuit$ w9d+1 plac$ at "r angles to ! excit+ w9d+4 ,9 ! neutral position ( ! regulator1 ?is %ort circuit$ w9d+ acts l ! %ort circuit$ second>y ( a s]ies trans=m]1 ?us prev5t+ a *ok+ effect 9 ! second>y ( ! regulator4 ,ques4 ,:at w\ld be ! effect if ! %ort circuit$ w9d+ 7 n employ$8 ,illu/ration3 ,,fig4 #b1dai4--,top end ( /ation>y elem5t or second>y ( ,we/+h\se polyphase induction regulator2 view %[+ leads4 ,! second>y is built up 9 a %ort skeleton frame ) brackets = ! rotor be>+s bolt$ to ! frame & ! top cov] bolt$ to ! top brackets4 ,9 assembl+ ! second>y1 ! pun*+s are /ack$ loosely 9 ! skeleton frame & an exp&+ build+ m&rel plac$ inside ! pun*+s & exp&$1 !reby tru+ up ! latt] be=e !y are f9ally compress$ & ! end plates key$ 9 position4 ,!n1 prior to remov+ ! m&rel a f9i%+ cut is tak5 on ! surface ( ! frame to :i* ! be>+ brackets are atta*$1 & z ! top cov] & brackets are also accurately ma*9$ ! alignm5t ( ! prim>y ) ! second>y is almo/ p]fect1 ?us r$uc+ to a m9imum ! t5d5cy to develop vibration & noise4 ,ans4 ,! voltage requir$ to face ! full load curr5t ?r\gh ! second>y w\ld increase z ! prim>y is turn$ away f ei!r ! position ( maximum or m9imum regulation1 rea*+ its highe/ value at ! neutral position4 ,! %ort circuit$ w9d+ s cuts d[n ?is voltage ( self-induction t ! voltage necess>y to =ce ! full load curr5t ?r\gh ! second>y :5 ! regulator is 9 ! neutral position is v little m ?an t necess>y to ov]come ! ohmic resi/ance ( ! second>y4 ,ques4 ,:at effect is noticeable 9 ! op]ation ( a s+le phase induction regulator8 ,ans4 ,x has a t5d5cy to vibrate simil> to t ( a s+le phase magnet or trans=m]4 ,illu/ration3 ,,fig4 #b1dbj4--;,bottom end ( /ation>y elem5t or second>y ( ,we/+h\se polyphase induction regulator4 ,ques4 ,:y8 ,ans4 ,x is due to ! action ( ! magnetiz+ field v>y+ 9 /r5g? f z]o to maximum value ) ea* alt]ation ( ! excit+ curr5t1 ?us caus+ a pulsat+ =ce to act across ! air gap1 :i* t5ds to cause vibration :5 ! mov+ "p is n 9 p]fect alignm5t4 ,ques4 ,expla9 ! effect produc$ by bad alignm5t8 ,ans4 ,if ! be>+s ( ! prim>y be n 9 p]fect alignm5t ) ! bore ( ! second>y1 !reby mak+ ! air gap on "o side small] ?an t on ! o!r1 ! cr[d+ ov] ( ! flux to ! small] air gap w cause an int]mitt5t pull 9 t direction1 :i* w develop vibration unless ! prim>y be>+s are tight & ! %aft suffici5tly /iff to )/& ! pull4 ,ques4 ,^u :at does ! regulator capacity = any giv5 s]vice dep5d8 ,illu/ration3 ,,fig4 #b1dba4--,we/+h\se two kw41 h& op]at$1 air cool$ induction regulator = te/+ purposes4 ,ans4 ,x dep5ds ^u ! range ( regulation requir$ & ! total load on ! fe$]4 ,ques4 ,h[ is ! capacity /at$8 ,ans4 ,9 p]c5tage ( ! full load ( ! fe$]4 ,= in/ance1 on a #ajj kil[att circuit1 a #aj kw4 regulator w give #aj p] c5t4 regulation1 & a #e kw4 regulator1 #e p] c5t4 regulation4 ,polyphase ,induction ,regulators4--,! polyphase induction regulator is simil> to ! s+le phase regulator except t bo? ! prim>y & second>y elem5ts are w\nd ) z _m sets ( coil z !re are phases 9 ! circuit4 ,9 con/ruction ^! w9d+s are di/ribut$ ?r\gh\t ! complete circumf]5ce ( ! /ation>y & mov+ elem5ts & closely resemble ! w9d+s ( an induction motor4 ,illu/ration3 ,,fig4 #b1dbb4--,we/+h\se polyphase motor op]at$ induction regulator %[+ op]at+ me*anism4 ,! prim>y %aft is turn$ by means ( a bronze worm :eel engag+ a =g$ /eel worm1 provid$ ) a ball be>+ end ?ru/4 ,?is worm ge> is h\s$ 9 a sep>ate ca/+ bolt$ to ! cov]4 ,! ca/+ is made sep>ate 9 ord] to p]mit close adju/m5t betwe5 ! worm :eel & ! worm to aid 9 c\nt]act+ ! t5d5cy to vibration4 ,f9i%$ surfaces on ! worm ge> ca/+ are provid$ = m\nt+ ! motor & ! brake4 ,on ! automatic regulator1 ! worm %aft is connect$ to ! motor ?r\gh a spur ge> & p9ion1 :i* con/itutes a compact driv+ device hav+ v little friction4 ,provision is made = ei!r alt]nat+ curr5t or direct curr5t motor drive4 ,:5 a motor driv5 regulator is op]at$ by h&1 ! brake mu/ be held 9 ! release position1 o!rwise x w be impossible to op]ate ! regulator4 ,9 ! h& op]at$ regulator ! spur ge> is replac$ by a h& :eel & ! regulator is driv5 directly f ! worm %aft4 ,polyphase regulators h b little t5d5cy to vibrate because ! field across ! air gap is ! resultant ( two or m s+le phase fields & is ( a con/ant value at all times4 ,?is field rotates at a rate dep5d+ ^u ! numb] ( poles & ! frequ5cy ( ! circuit4 ,?is produces a me*anical pull ( con/ant value :i* rotates ) ! magnetic field v>y+ its position f in/ant to in/ant4 ,x is evid5t t ?is pull is ( an entirely diff]5t "* f t produc$ by ! s+le phase field & t !re is no t5d5cy to set up ! vibration t ! me*anical pull ( ! s+le phase regulator t5ds to e/abli%4 ,illu/ration3 ,,fig4 #b1dbc4--;,g5]al ,electric adju/able comp5sation %unt4 ,x is us$ z ! comp5sat+ %unt = direct curr5t voltage regulators4 ,9 op]ation1 ! %unt may be adju/$ s z to comp5sate = any desir$ l9e drop up to #ae p] c5t4 ,x is pref]ably plac$ 9 ! pr9cipal light+ fe$] b may be connect$ to ! bus b>s s t x w take ! total curr5t4 ,! latt] me?od is sometimes undesirable1 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 %[n at ! c5t] ( ! %unt4 ,?is contact may be clamp$ at any desir$ po9t & x det]m9es ! pressure across ! comp5sat+ w9d+ ( ! regulator's control magnet4 ,:]e pressure wires are run back to ! c5tral /ation f ! c5t] ( di/ribution1 !y may be connect$ directly to ! pressure w9d+ ( ! ma9 control magnet1 & x is unnecess>y to use ! comp5sat+ %unt4 ,!re is1 h[ev]1 consid]able torque develop$1 & ! device = revolv+ ! mov+ elem5t mu/ be lib]ally design$ s z to )/& ! excess torque caus$ by tempor>y ov]loads or %ort circuits4 ,ques4 ,9 :at respects d polyphase induction regulators diff] 9 pr9ciple f s+le phase regulators8 ,ans4 ,! induc$ voltage 9 ! second>y has a con/ant value1 & ! regulation is effect$ by v>y+ ! phase relation betwe5 ! l9e voltage & ! regulator voltage4 ,ques4 ,h[ is ! prim>y w\nd8 ,ans4 ,x is w\nd ) z _m sep>ate w9d+s z !re are phases 9 ! circuit1 & ^! prim>y or %unt w9d+s are connect$ to ! correspond+ phases ( ! fe$]4 ,illu/ration3 ,,fig4 #b1dbd4--;,g5]al ,electric direct curr5t 7=m ,s7 voltage regulator4 ,x consi/s ( a ma9 control magnet1 relay1 cond5s] & rev]s+ swit*1 z %[n 9 ! diagram fig4 #b1dbh4 ,?is regulator _c be us$ = comp5sation ( l9e drop z ! curr5t coil is omitt$2 x is n a swit*bo>d in/rum5t1 b is design$ = inexp5sive in/allations su* z = regulat+ ! voltage ( motor g5]ator sets :5 ! curr5t is tak5 f a trolley l9e or "s o!r fluctuat+ s\rce4 ,! regulat+ outfit comprises1 besides ! regulator1 "o or m cond5s] sections accord+ to field dis*>ge1 set ( iron brackets :5 regulator _c be m\nt$ on front ( swit*bo>d1 "o comp5sat+ %unt1 :5 x is desir$ to comp5sate = l9e drop4 ,field rheo/ats hav+ suffici5t resi/ance to r$uce ! voltage ! prop] am\nt mu/ be us$ ) voltage regulator in/allations4 ,to prev5t undue decay at ! relay contacts1 all[ "o section = ea* #ae kw4 capacity ( dynamo ) lam9at$ poles1 & "o = ea* #bb kw4 capacity ) solid /eel poles4 ,ques4 ,:at k9d ( magnetiz+ flux is produc$ by ! prim>y w9d+s8 ,ans4 ,a practically con/ant flux :i* v>ies 9 direction4 ,ques4 ,h[ is ! second>y w\nd8 ,ans4 ,!re is a sep>ate w9d+ = ea* phase4 ,ques4 ,:y is ! voltage induc$ 9 ! second>y con/ant8 ,ans4 ,because ( ! con/ant magnetiz+ flux4 ,ques4 ,h[ is ! l9e voltage v>i$ by a polyphase regulator8 ,ans4 ,:5 ! regulator is 9 ! position ( maximum boo/1 ! l9e ,,ab1 fig4 #b1dbe repres5ts ! normal busb> voltage1 ,,bc ! regulator voltage1 & ,,ac ! resultant fe$] voltage4 ,:5 ! regulator voltage is displac$ #ahj degrees f ?is position1 ! regulator is 9 ! position to deliv] m9imum voltage to ! fe$]1 ! regulator voltage be+ !n repres5t$ by ,,bd1 & ! resultant fe$] voltage by ,,ad4 ,:5 ! regulator voltage is displac$ angul>ly 9 ! direction ,,bf1 s t ! resultant fe$] voltage ,,af becomes equal to ! normal busb> voltage ,,ab1 ! regulator is 9 ! neutral position4 ,int]m$iate resultant voltages = comp5sat+ ! voltage v>iations 9 ! fe$]s may be obta9$ by rotat+ ! mov+ elem5t or prim>y 9 ei!r direction f ! neutral position4 ,= example1 by rotat+ ! prim>y ?r\gh ! angle ,,fbe1 ! resultant voltage may be made equal to ,,ae or ,,aj1 !reby increas+ ! fe$] voltage by an am\nt ,,bj2 or by rotat+ x 9 ! opposite direction ?r\gh ! angle ,,fbg1 ! fe$] voltage may be r$uc$ by an am\nt ,,bh4 ,illu/ration3 ,,fig4 #b1dbe4--;,diagram illu/rat+ op]ation ( polyphase induction regulator4 ,ques4 ,h[ are induction regulators op]at$8 ,ans4 ,by h& or automatically4 ,ques4 ,h[ is automatic op]ation secur$8 ,ans4 ,by means ( a small motor1 controll$ by voltage regulat+ relays4 ,ques4 ,h[ is ! control app>atus arrang$8 ,ans4 ,two relays are employ$ ) ea* regulator1 a prim>y relay connect$ to ! fe$] circuit & op]at+ "u *anges ( voltage !re91 & a second>y relay connect$ betwe5 ! prim>y relay & ! motor1 & op]at$ by ! contacts ( ! =m]1 = />t+1 /opp+ & rev]s+ ! motor 9 accordance ) *anges 9 ! fe$] voltage1 !reby caus+ ! regulator to ma9ta9 t voltage at its pr$et]m9$ normal value4 ,illu/ration3 ,,fig4 #b1dbf4--,we/+h\se voltage regulat+ prim>y relay2 view ( me*anism ) case remov$4 ,?is relay is practically a voltmet] arrang$ = mak+ & break+ contacts ) fluctuations ( voltage4 ,z %[n 9 ! figure1 x consi/s ess5tially ( a sol5oid & a balance beam c>ry+ two movable contact po9ts on "o end & atta*$ to ! sol5oid core at ! o!r4 ,! oscillation ( ! core causes ! contact c>ry+ end ( ! beam to move betwe5 two /ation>y contact po9ts connect$ to ! auxili>y or second>y relay circuit4 ,! /ation>y contact po9ts are fitt$ ) adju/+ screws = ei!r increas+ or decreas+ ! di/ance betwe5 !m1 to ! am\nt ( *ange 9 ! voltage requir$ = mak+ or break+ contact2 9 o!r words1 = v>y+ ! s5sitiv5ess ( ! relay4 ,means = v>y+ ! normal voltage :i* x is desir$ to ma9ta9 are provid$ 9 ! spr+ atta*$ to ! balance beam & controll$ by ! micromet] adju/+ screw4 ,increas+ ! t5sion ( ! spr+ results 9 l[]+ ! normal voltage position4 ,! relay is w\nd = a normal voltage ( #aaj volts1 & has a range ( adju/m5t f #ij to #acj volts4 ,! total en]gy requir$ = its op]ation is ab\t #ej watts at normal voltage4 ,voltage trans=m]s hav+ at lea/ #ej watts capacity are1 !re=e1 requir$4 ,! p>ts are3 ,a1 sol5oid2 ,b1 sol5oid core2 ,c1 end ( balance beam2 ,d1 pivots1 be>+s2 ,e1 movable contact arm2 ,f1 upp] /ation>y contact po9t2 ,g1 l[] /ation>y contact po9t2 ,h1 adju/+ screw2 ,k1 adju/+ spr+2 ,l1 fe$] b9d+ po/s2 ,m1 auxili>y circuit & second>y relay b9d+ po/s4 ,illu/ration3 ,,fig4 #b1dbg4--,we/+h\se voltage regulat+ second>y relay2 view %[+ relay remov$ f oil tank4 ,! second>y relay is practically a motor />t+ swit* ( ! d\ble pole d\ble ?r[ type1 electrically op]at$ ?r\gh ! contacts ( ! prim>y relay4 ,x is provid$ ) contact po9ts ( "o-half in* rod4 ,! relay is suitably connect$ = />t+1 /opp+ & rev]s+ ! motor & = prop]ly op]at+ ! motor brake4 ,! p>ts are3 ,a1 sol5oid2 ,b1 lam9at$ field2 ,c1 movable contact arm2 ,d1 /ation>y contact arms2 ,e1 removable brass contact po9ts2 ,f1 t]m9al block2 ,g1 t]m9als4 ,ques4 ,:y are two relays us$8 ,ans4 ,= ! reason t a prim>y relay1 ( suffici5t accuracy & fre$om f errors due to temp]ature & frequ5cy v>iations1 c\ld n be made suffici5tly p[]ful to c>ry ! relatively l>ge curr5t requir$ = op]at+ ! motor4 ,ques4 ,:at names are giv5 to ! relays8 ,ans4 ,prim>y & second>y4 ,ques4 ,:at difficulties 7 enc\nt]$ 9 ! op]ation ( relays8 ,illu/ration3 ,,fig4 #b1dbh4--;,diagram ( connections ( ,g5]al ,electric direct curr5t 7=m ,s7 voltage regulator1 = #abe1 #bej1 & #eej volts4 ,! range ( voltage is giv5 9 ! foll[+ table3 ----------------------------------- ,regulator,range ( voltage ------------------------ #af #ag #ah #ai #bj ----------------------------------- #abe #aje #aaj #aae #abj #abe #bej #baj #bbj #bcj #bdj #bej #eej #eej ----------------------------------- ,ans4 ,vibration or *att]+ at ! contacts ( bo? relays & t5d5cy ( ! movable contact arm ( ! prim>y relay to hug clos] to "o ( ! /ation>y contact po9ts ?an to ! o!r1 !reby op]at+ too (t54 ,ques4 ,:at causes vibration or *att]+ at ! contacts8 ,ans4 ,?is is due to ! voltage frequ5tly approximat+ ! value requir$ = clos+ a contact1 !reby caus+ ! contact po9ts to b>ely t\* & make sev]al poor contacts 9 succession4 ,ques4 ,:at objectionable action is produc$ by vibration at ! contacts8 ,ans4 ,arc+1 burn+ & pitt+ ( ! contacts1 ev5 :5 alloys ( ! r>] metals are us$1 su* z ^? ( ! plat9um gr\p1 hav+ extreme h>dness & high melt+ po9ts4 ,illu/ration3 ,,fig4 #b1dbi4--;,diagram ( connections ( automatic induction regulator & auxili>y app>atus on s+le phase circuit4 ,ques4 ,:at effect is produc$ by poor contact ( ! prim>y relay8 ,ans4 ,x causes *att]+ 9 ! second>y relay2 :i* burns out & we>s away its contact po9ts1 increas+ ! heat+ ( ! motor1 creat+ objectionable noise & entail+ we> & te> on ! :ole outfit4 ,ques4 ,:y does ! movable contact arm ( ! prim>y relay t5d to rema9 ne>] "o ( ! /ation>y contact po9ts ?an ! o!r8 ,ans4 ,?is is due to ! t5d5cy ( ! relay to op5 ! contact :5ev] ! voltage equals t at :i* ! contact closes4 ,illu/ration3 ,,fig4 #b1dcj4--;,diagram ( connections ( automatic induction regulator & accessory app>atus on ?ree phase fe$] circuit4 ,ques4 ,:at provision is made 9 ! prim>y relay to prev5t vibration or *att]+8 ,ans4 ,two auxili>y w9d+s are provid$3 "o 9 s]ies ) ea* ( ! /ation>y contact po9ts & s arrang$ z to assi/ 9 mak+ ! contact by increas+ ! pressure on ! contact po9ts at ! in/ant ( closure4 ,! be/ effect ( ! comp\nd+ action ( ! auxili>y coils is obta9able :5 arrang$ = p] c5t4 ( ! torque ( ! ma9 coil4 ,illu/ration3 ,,fig4 #b1dca4--,we/+h\se drum type v>iable trans=m] voltage regulator4 ,x consi/s ( a drum & f+] type swit*4 ,a prev5tive resi/ance is us$ betwe5 ! diff]5t contacts1 mak+ x unnecess>y to op5 ! circuit :5 mov+ f "o tap ( ! regulat+ trans=m] to ! next tap4 ,a spr+ actuat$1 quick mov+1 c5tral /opp+ me*anism is us$ to prev5t burn+ ! resi/ances4 ,! regulator is arrang$ to give #dj po9ts ( regulation4 ,9 _m cases ?is l>ge numb] ( po9ts is n absolutely necess>y1 b x is desirable to use !m because ! voltage p] /ep is ?us r$uc$ to a small value1 & a correspond+ increase 9 ! life ( ! contacts results because ( ! r$uc$ sp>k+ at ! l[] voltage4 ,two drums are employ$4 ,! fir/ drum has t5 contacts & a correspond+ numb] ( f+]s1 ! latt] be+ m\nt$ ^u an insulat$ b>4 ,^! f+]s are connect$ to ! float+ coils ( ! regulat+ trans=m]1 & z ! drum is rotat$1 ! f+] connect$ to ! l9e is br\ght into contact successively ) ea* ( ! t5 taps4 ,! second drum is ( simil> con/ruction & consi/s ( a *ang+ & rev]s+ swit*4 ,x connects ! two float+ coils to ! v>i\s taps on ! ma9 second>y coil ( ! regulat+ trans=m] at ! prop] "t1 & also rev]ses ! trans=m] s t ! total w9d+ c be us$ = ei!r rais+ or l[]+ ! voltage4 ,all ! po9ts ( regulation are obta9$ by a cont9u\s motion ( ! h&le1 ! v>i\s connections produc$ 9 ! mann] are %[n 9 ! diagram1 fig4 #b1dcc4 ,! top & base ( ! regulator are made ( ca/ iron & ! top is support$ by /eel b>s1 two ( :i* are insulat$1 & us$ to support ! metallic bases f+] to :i* ! cable leads are atta*$4 ,! drums consi/ ( metal ca/+s m\nt$ ^u insulat$ %afts4 ,! fir/ drum1 :i* is ! only "o ^u :i* arc+ c take place1 is provid$ ) removable copp] contact tips4 ,! ma9 ca/+s are made ( alum9um to secure l[ in]tia ( ! drum4 ,a %eet iron cov] is us$ to enclose ! regulator1 & ! leads are br\ght out ?r\gh ! bottom ( ! controll]4 ,a non-inductive resi/ance plac$ 9 p>allel ) ea* coil ( ! second>y relay1 takes curr5t approximately 9 phase ) ! curr5t 9 ! ma9 coil ( ! prim>y relay1 & ( prop] /r5g? to make ! numb] ( amp]e turns 9 ! auxili>y coil ?ree-f\r?s p] c5t4 ( ! numb] 9 ! ma9 coil4 ,! resi/ances h ! additional effect ( absorb+ ! dis*>ge f ! ma9 coils ( ! second>y relay :5 ! contacts are brok51 !reby obviat+ sp>k+ at ! prim>y contact po9ts4 ,illu/ration3 ,,fig4 #b1dcb4--;,diagram %[+ connections ( ! ,/illwell regulator4 ,illu/ration3 ,,fig4 #b1dcc4--;,diagram %[+ position ( ! float+ coil on diff]5t /eps ( ,we/+h\se drum type v>iable ratio trans=m] regulator4 ,! upp] half ( ! diagram %[s ! connections ( ! v>i\s coils = ea* position ( ! regulator h&le4 ,?is arrangem5t applies to a regulator us$ 9 connection ) an indep5d5t regulat+ trans=m]4 ,:5 regulators are us$ 9 connection ) l>ge p[] trans=m]s1 ! regulat+ trans=m] c be omitt$ & auxili>y coils c be plac$ on ! ma9 trans=m] to provide ! necess>y taps = regulat+ purposes4 ,! l[] half ( ! diagram %[s ! connections us$ :5 auxili>y coils are add$ to a l>ge trans=m]4 ,! diagram %[s connections = a s+le phase regulator4 ,:]e polyphase regulators are requir$1 ! connections consi/ ess5tially ( two sets ( s+le phase connection1 & ! controll] is ext5d$ 9 l5g? s z to conta9 d\ble sets ( drum & contact4 ,v>iable ,ratio ,trans=m] ,voltage ,regulators4--,! pr9ciple ( op]ation ( ?is class ( regulator is virtually ! same z t ( ! induction type regulator2 t is to say1 bo? consi/ ( regulat+ trans=m]s1 b 9 ! v>iable ratio me?od ! prim>y or s]ies coil is divid$ into a numb] ( sections :i* may be successively cut 9 or out ( ! circuit to be regulat$1 in/ead ( v>y+ ! flux ?r\gh ! entire coil1 z 9 ! induction type4 ,!re are two di/9ct me*anical =ms ( v>iable ratio regulator3 #a4 ,drum type2 #b4 ,dial type4 ,drum ,type ,regulators4--,?is =m ( v>iable ratio trans=m] consi/s ess5tially ( a drum & f+] type swit*1 simil> to a railway controll]4 ,!re are _m contacts1 giv+ a l>ge numb] ( po9ts ( regulation1 obta9$ by ! use ( *ang+ swit*es & float+ coils4 ,! float+ coil is a "p ( ! second>y w9d+ ( ! regulat+ trans=m] :i* is insulat$ f ! ma9 portion ( ! w9d+1 & is sub-divid$ by taps into a numb] ( equal sections4 ,! sub-divisions ( ! ma9 second>y w9d+ are mu* l>g]1 ea* "o be+ equival5t to ! :ole ( ! float+ coil4 ,illu/ration3 ,,fig4 #b1dcd4--;,diagram ( connections ( ,g5]al ,electric high voltage cut out relay 7=m ,a7 = voltage regulators4 ,its use 9 connection ) ! regulator protects ! sy/em f any sudd5 rise 9 voltage due to "s accid5t to ! regulator :i* might cause ! relay contacts to /ick1 ?us produc+ full field on ! excit]4 ,9 con/ruction1 ! control magnet is connect$ 9 s]ies ) ! alt]nat+ curr5t control magnet on ! regulator & ! contacts are connect$ 9 s]ies ) ! rheo/at %unt circuit4 ,!n1 %\ld ! voltage rise beyond a c]ta9 value1 pr$et]m9$ by ! sett+ ( ! ?umb screw support+ ! plung] ( ! control magnet1 ! contacts ( ! relay are tripp$ op5 :i*1 by ins]t+ all ! resi/ance 9 ! excit] field1 r$uces ! excit] voltage :i* 9 turn r$uces ! alt]nat+ curr5t voltage4 ,?is relay has to be reset by h&4 ,ques4 ,describe ! op]ation ( a drum regulator4 ,ans4 ,! float+ coil & ma9 w9d+s are fir/ connect$ 9 s]ies ) ea* o!r & ) ! l9e to be regulat$4 ,! float+ coil is !n cut out ( ! circuit /ep by /ep4 ,:5 entirely cut out x is transf]r$ to ! next l[] tap on ! ma9 w9d+1 aft] :i* x is aga9 cut out /ep by /ep & !n transf]r$ aga94 ,by cont9u+ ?is process a l>ge numb] ( /eps are provid$ ) b comp>atively few actual taps on ! trans=m]4 ,ques4 ,h[ _m float+ coils are us$ & :y8 ,ans4 ,two float+ coils are includ$ 9 ea* regulator s t "o c be transf]r$ :ile ! o!r is supply+ ! curr5t to ! l9e4 ,dial ,type ,regulators4--,?is =m ( v>iable ratio trans=m] regulator consi/s ( a regulat+ trans=m] & a dial type swit* z %[n 9 ! accompany+ illu/rations4 ,! regulat+ trans=m] is simil> to a /&>d trans=m] except t ! second>y w9d+ is provid$ ) a numb] ( taps lead+ to ! contact ( ! dial swit* z %[n 9 ! diagram fig4 #b1dcg4 ,illu/ration3 ,,fig4 #b1dce4--;,dial ( ,we/+h\se dial type v>iable ratio voltage regulator4 ,! dial consi/s ( a m>ble slab1 ^u :i* ! contacts are m\nt$ 9 a circle z %[n4 ,! contact arm is arrang$ to move f contact to contact4 ,! alt]nate small contacts are dummies1 s]v+ to prev5t ! contact arm spr++ d[n betwe5 contacts :5 mov+ f "o to ano!r4 ,! panel conta9s a *ang+ swit* :i* makes x possible to d\ble ! range ( a regulator1 s9ce ! trans=m] connections c be *ang$ to bo? raise & l[] to an ext5t equal to ! full range ( ! trans=m]4 ,! total range 9 voltage f a c]ta9 p] c5t4 bel[ to a c]ta9 p] c5t4 above ! l9e voltage c be obta9$ 9 a numb] ( /eps equal to twice ! numb] ( divisions into :i* ! second>y w9d+ ( ! trans=m] is divid$4 ,ques4 ,:at modification is made to adapt dial regulators = heavy curr5t8 ,ans4 ,a dial ) a s]ies trans=m]1 & a %unt or auto-trans=m] are employ$ z %[n 9 fig4 #b1dcf4 ,ques4 ,:y is su* modification desirable8 ,ans4 ,because1 ! additional co/ ( a s]ies trans=m] is small 9 comp>ison ) ! co/ ( build+ a dial ) a l>ge curr5t c>ry+ capacity1 & ! co/ ( br++ out a numb] ( heavy leads f a small trans=m]4 ,illu/ration3 ,,fig4 #b1dcf4--;,diagram ( connections = ,we/+h\se #aa po9t dial1 s]ies trans=m] & auto-trans=m]4 ,! auto-trans=m] has a numb] ( taps connect$ across ! l9e1 ! s]ies trans=m] is plac$ 9 s]ies ) "o side ( ! l9e1 & connect$ to a dial1 z %[n4 ,ques4 ,h[ are dial regulators modifi$ = high voltage8 ,ans4 ,/&>d dials may be us$ ) s]ies & %unt trans=m]s simil> to ! me?od us$ = heavy curr5t circuits4 ,ques4 ,describe ! connections4 ,ans4 ,! prim>y ( ! %unt trans=m] is connect$ across ! l9e & ! second>y has a numb] ( taps :i* are connect$ to contacts on ! dial4 ,! prim>y ( ! s]ies trans=m] is connect$ 9 s]ies ) ! l9e & two leads f ! second>y w9d+ are connect$ to ! dial4 ,! connections are simil> to ^? %[n 9 fig4 #b1dcg1 except t %unt trans=m]s are us$ in/ead ( auto-trans=m]s4 ,illu/ration3 ,,fig4 #b1dcg4--;,diagram ( connections = ,we/+h\se dial type v>iable ratio voltage trans=m]4 ,9 con/ruction ! second>y w9d+ ( ! trans=m] is divid$ into #aj1 #ad1 or #bj p>ts giv+ #aa1 #ae1 or #ba taps :i* are br\ght out f ! second>y w9d+ & connect$ to ! v>i\s po9ts ( ! dial4 ,! diagram %[s connections = an #aa po9t dial & regulat+ trans=m]4 ,s9ce !re is a diff]5ce ( voltage betwe5 adjac5t contacts1 ! contact arm mu/ n t\* ! contact t[>d :i* x is mov+ until aft] x has left ! contact ^u :i* x 0 re/+4 ,moreov]1 x is undesirable to op5 ! circuit ea* "t 9 mov+ f "o contact to ! next4 ,^! conflict+ requirem5ts are met by ! use ( arc+ tips :i* are plac$ on ! contact arm s t a v close adju/m5t c be obta9$1 & s arrang$ t ! contacts are n %ort circuit$ b always h a gap ( f "o-sixte5? to "o-eigh? in* 9 ! circuit dur+ ! "t ( *ang+ f "o contact to ! next4 ,! air gaps =m a prev5tive resi/ance4 ,a quick mov+ me*anism is us$ to accel]ate ! movem5t f "o contact to ! next1 a v quick movem5t be+ necess>y to avoid undue arc+4 ,! capacity ( ! regulator is #bjj amp]es at #b1bjj volts1 be+ arrang$ to give a maximum increase 9 voltage ( #djj volts4 ,! maximum pressure betwe5 contacts is #be volts4 ,illu/ration3 ,,fig4 #b1dch4--;,diagram ( connections ( ,g5]al ,electric pole type regulator4 ,! op]ation ( ! regulator is obta9$ by means ( a small s+le phase motor :i* is 9 cont9u\s op]ation1 & :i* by me*anical means may be connect$ to ! regulator %aft4 ,! control ( ! me*anism is obta9$ by means ( a voltage relay4 ,! op]at+ motor1 :i* is ( ! drawn %ell type1 is provid$ ) a />t+ clut* & w consequ5tly />t up ) full load4 ,"u actual op]at+ conditions x w1 ( c\rse1 be comp>atively seldom t ! motor w be call$ ^u to />t up4 ,a non-inductive resi/ance1 made up f /&>d units1 is connect$ 9 s]ies ) ! relay w9d+ & sev]al taps are provid$1 s t ! relay c be adju/$ = any voltage f #aj p] c5t4 bel[ normal4 ,9 ord] to readily dissipate ! heat develop$ 9 ! resi/ance1 x has be5 m\nt$ 9 a pocket on ! back ( ! tank1 op5+s be+ provid$ = natural air v5tilation4 ,! relay plung] is h+$ to "o end ( a balance arm1 :i* arm is provid$ ) two trip p9s to control ! me*anism4 ,an adju/able helical spr+ is atta*$ to ! o!r end ( ! arm to assi/ ! magnetic pull ( ! coil 9 balanc+ ! plung] & also = adju/m5t4 ,! relay is n provid$ ) s]ies w9d+ = l9e drop comp5sation1 b x may be us$ ) a /&>d l9e drop comp5sator1 :i* !n has to be in/all$ outside ( ! regulator4 ,! voltage relay mu/ be connect$ to ! fe$] side ( ! regulator1 ! necess>y l[ voltage to be obta9$ f a di/ribut+ trans=m]1 or if ?is %\ld n be available 9 ! imm$iate vic9ity1 a #bjj watt /ep d[n trans=m] w be satisfactory4 ,! motor is design$ to op]ate 9 p>allel ) ! relay1 ! normal connections be+ z %[n4 ,! spe$ ( ! motor & ! ratio ( ! ge>+ is su* t x requires ab\t #ij seconds to op]ate ! regulator f limit to limit1 b1 z ?is regulator is n int5d$ to take c>e ( sudd5 voltage fluctuations1 ! comp>atively long "t ( op]ation w n be objectionable4 ,illu/ration3 ,,figs4 #b1dci to #b1ddc4--;,g5]al ,electric pole type regulator remov$ f tank4 ,x consi/s ess5tially ( a prim>y & second>y coil1 op]at+ motor1 & voltage relay me*anism4 ,! regulator & me*anism is susp5d$ 9 a ca/ iron tank1 ! l[] "p1 conta9+ ! regulator core & coils1 be+ fill$ ) oil4 ,! leads = ! regulator are br\ght out at ! upp] "p ( ! tank4 ,! outgo+ leads are compress$ into bu%+s & connect$ to ! leads ( ! regulator by means ( t]m9als1 ! arrangem5ts be+ su* t ! regulator ) me*anism c be remov$ f ! tank )\t difficulty4 ,besides ! cov]1 ! tank is also provid$ ) a h+$ door on ! front side s z to give access to ! me*anism4 ,! door is provid$ ) a gasket & ! con/ruction is practically ra9 & du/ pro(4 ,h[ev] z !re is always dang] ( ! door n be+ clamp$ d[n p]fectly1 ?us mak+ x possible = wat] to ent] ! tank1 a pocket has be5 provid$ inside ! tank & und]nea? ! door to collect ! wat]4 ,capacity up to #b4c kw41 to control #b1cjj volts1 #fj cycle1 #aj amp]e fe$]s1 & = a voltage range ( #aj p] c5t4 above or bel[ normal1 ! op]at+ motor & relay be+ design$ = #aaj or #bbj volts4 ,no provision is made = l9e drop comp5sation1 al?\gh ?is c be obta9$ by in/all+ a curr5t trans=m] & a l9e drop comp5sator ext]nally to ! regulator4 ,x w be se5 t ! circuit compris+ ! dial1 ! second>y ( ! %unt1 trans=m] & ! second>y ( ! s]ies trans=m] =m a circuit :i* is n electrically connect$ to ! ma9 circuit4 ,x c !re=e be gr\nd$ )\t di/urb+ ! ma9 circuit z a safegu>d to r5d] x impossible = ! pressure ( ! dial to be high] above ! gr\nd ?an ! second>y voltage ( ! %unt trans=m]4 ,illu/ration3 ,,figs4 #b1ddd to #b1ddf4--,sectional views ( ,g5]al ,electric pole type regulator w9d+ & core4 ,! second>y core has only two slots conta9+ a s+le coil1 :ile ! rotor or prim>y core has f\r slots4 ,two ( ^! slots are occupi$ by a s+le prim>y coil1 & ! two circul> slots 9 quadrature !reto conta9 ! comp5sat+ or %ort circuit w9d+4 ,?is w9d+ also s]ves to hold ! prim>y pun*+s toge!r1 & x consi/s ( two copp] rods rivet$ to ! two ca/ brass flanges4 ,! second>y coil is =m w\nd1 :ile ! prim>y coil is w\nd directly on ! core4 ,! rotor flanges1 bo? top & bottom1 are provid$ ) discs :i* are turn$ 9 alignm5t ) ! pun*+s1 & ^! discs be> aga9/ ! top & bottom flanges betwe5 :i* ! second>y pun*+s are clamp$4 ,^! second>y flanges are also turn$ 9 alignm5t ) ! second>y pun*+s1 s t an ev5 air gap betwe5 ! prim>y & ! second>y is assur$4 ,! second>y coil is w\nd ) an op5+ 9 ! upp] horizontal "p :i* af=ds passage = ! op]at+ %aft ( ! rotor4 ,a be>+ = ?is %aft is provid$ 9 ! table :i* supports ! me*anism & f :i* ! regulator is susp5d$4 ,flexible leads are br\ght out f ! rotor & twi/$ ar\nd ! %aft z 9 /&>d regulator practice4 ,! regulator be+ two pole1 ! rotor is turn$ ?r\gh an angle ( #ahj deg4 to obta9 ! full range ( ! regulator4 ,small ,fe$] ,voltage ,regulators4--,9 "s g5]at+ /ations ! voltage is ma9ta9$ con/ant at ! busb>s & ! l9e drop comp5sat$ by automatically op]at$ regulators connect$ 9 ! ma9 fe$]s4 ,x is possible 9 ?is way to obta9 con/ant voltage at all loads at ! v>i\s di/ribution c5t]s1 t is1 at ^? po9ts on ! fe$]s :]e ! l9es ( ! majority ( consum]s are connect$ z %[n 9 fig4 #b1ddg4 ,illu/ration3 ,,figs4 #b1ddg & #b1ddh4--,sy/ems ( di/ribution illu/rat+ use ( small fe$] or pole type voltage regulators4 ,x is evid5t1 h[ev]1 t1 :ile ! voltage at ! c5t] ( di/ribution c be ma9ta9$ con/ant1 no acc\nt c be tak5 ( ! drop 9 ! l9es betwe5 ?is c5t] & ! consum]s4 ,?is drop is g5]ally negligible1 except 9 "s p>ticul>ly long l9es1 z1 = example1 consum] ,b 9 fig4 #b1ddg4 ,9 ord] to obta9 p]fect regulation at ,b1 x w\ld be necess>y to in/all a sep>ate regulator 9 t l9e1 ?is regulator to be in/all$ ei!r at ! c5t] ,c or pref]ably at ,b4 ,9 a great _m cases ! p[] di/ribution is n z ideal z indicat$ 9 fig4 #b1ddg1 b r z %[n 9 fig4 #b1ddh1 t is1 ! consum]s are connect$ all along ! fe$]4 ,9 ?is case !re is no def9ite c5t] ( di/ribution1 & ! automatic regulator in/all$ 9 ! /ation c be adju/$ to give only approximately con/ant voltage at an imag9>y c5t] ( di/ribution ,c2 t is1 ! voltage _c be held con/ant at any def9ite po9t dur+ *anges ( load di/ribution4 ,illu/ration3 ,,fig4 #b1ddi4--;,g5]al ,electric pole type regulator 9 s]vice2 its con/ruction is %[n 9 fig4 #b1dej4 ,! majority ( ! consum]s may1 h[ev]1 obta9 suffici5tly good voltage :ile a few may h reason = criticism4 ,to ov]come ?is difficulty x is necess>y ei!r to increase ! copp] 9 ! fe$] or else to in/all small automatic regulators4 ,!re are also cases :]e a small am\nt ( p[] is transmitt$ a long di/ance ?r\gh a fe$] direct f ! /ation4 ,! am\nt ( copp] requir$ to r$uce ! l9e drop is usually too great to be consid]$ & ! co/ ( ! ord9>y automatic regulator is also comp>atively high4 ,9 su* cases small pole type regulators z %[n 9 fig4 #b1ddi are desirable4 ,ques4 ,describe ! op]ation ( ! regulator me*anism %[n 9 fig4 #b1dej4 ,ans4 ,assum+ ! voltage to be normal1 ! balance arm ( ! relay w be held horizontal1 ! trips ,f w n engage ) ! trigg]s ,e1 & no movem5t is !re=e transmitt$ to ! rat*et :eel ,c4 ,if ! voltage drops bel[ normal1 ! left h& trip w desc5d until x f9ally gets 9 ! way ( ! left h& trigg] j be=e x rea*es ! limit ( its c\nt]clockwise travel4 ,?is trigg] w !re=e release ! left pawl ,d1 :i* w engage ) ! rat*et :eel & w consequ5tly turn x clockwise until ! rock] arm rea*es its "r h& limit4 ,be=e ! rock] arm rea*es ! left h& limit1 ! releas$ pawl mu/ be lock$ by its trigg]1 s t if ! voltage has rea*$ its normal value1 fur!r movem5t ( ! rat*et :eel w n take place1 :]eas if ! voltage be /ill too l[1 ! trigg] w aga9 release ! pawl by /rik+ ! trip ( ! relay4 ,illu/ration3 ,,fig4 #b1dej4--,me*anism ( ,g5]al ,electric pole type regulator4 ,! op]at+ motor 7describ$ 9 fig4 #b1dch7 is direct connect$ to a worm & ge>1 ! %aft ( :i* is provid$ ) a bell crank4 ,a rod ,a1 connects ! crank ) ! rock] arm ,b1 :i* ?us may be caus$ to oscillate ov] a rat*et :eel ,c4 ,! rock] arm is provid$ ) two pawls ,d1 :i* c engage ) ! tee? ( ! rat*et :eel1 s t ?is :eel c be rotat$ "o way or ! o!r4 ,! rat*et :eel is m\nt$ on ! same %aft z a worm1 :i* engages ) ! ge> segm5t c>ri$ by ! regulator %aft1 s t ! movem5t ( ! rat*et :eel is directly transmitt$ to ! regulator4 ,besides ! two l>ge pawls ,d1 ! rock] arm also c>ries two small] ones ,e1 call$ ! trigg]s4 ,^! trigg]s usually hold ! pawls lock$ 9 su* positions z n to engage ) ! rat*et :eel1 b ! pawls w be releas$ :5 ! trigg]s /rike ! trips ,f ( ! relay arm4 ,a limit+ device = ! movem5t ( ! rat*et :eel & ! regulator segm5t is provid$1 z %[n4 ,?is device consi/s ( two cams ,k1 m\nt$ on a common arm1 :i* c turn on ! %aft ( ! rat*et :eel4 ,normally ^! cams are n )9 rea* ( ! pawls1 b ?r\gh a lev] arrangem5t1 controll$ by ! regulator segm5t1 ! arm hold+ ! cams may be rotat$ s t1 if ! trigg] has be5 rais$1 s z to release ! pawl1 ! tip ( ! pawl w be> on ! cam ( ! limit+ device1 & be=e ! pawl c engage ) ! rat*et :eel x has already be5 lock$ by its trigg]4 ,a fur!r movem5t ( ! rat*et :eel 9 t p>ticul> direction is !re=e impossible1 :ile x is free to be mov$ ! o!r way4 ,a positive /op = ! ge> segm5t is also provid$4 ,! motor is provid$ ) oil r+ be>+s1 & ! ge> = ! motor worm runs 9 oil1 ! support+ ca/+ =m+ a well !re=4 ,illu/ration3 ,,fig4 #b1dea4--;,diagram ( connections ( ,g5]al ,electric direct curr5t voltage regulator 7=m ,t7 ) two dynamos & "o excit]4 ,9 cases :]e sev]al %unt or comp\nd w\nd direct curr5t ma*9es are op]at+ 9 p>allel1 ei!r on two wire or ?ree wire sy/ems1 a good arrangem5t = voltage regulation & l9e drop comp5sation is obta9$ by us+ ?is regulator & a sep>ate excit]4 ,! comp5sat+ %unt z well z pressure wires c be us$ to ma9ta9 a con/ant pressure at ! c5t] ( di/ribution4 ,ques4 ,h[ is ?is automatic lock+ ( ! pawl obta9$8 ,ans4 ,by hav+ a lip ,g on ! "u side ( ! pawl /rike a f+] ,h fa/5$ to ! be>+s 9 front ( ! rat*et :eel4 ,! pawl is ?us rais$ j be=e x rea*es ! limit ( its clockwise travel suffici5t to be lock$ by its trigg]4 ,illu/ration3 ,,fig4 #b1deb4--;,cond5s] sections & me?od ( assembl+ same ) tripod4 ,! tripod bolts are made ( extra l5g? to accommodate ! addition ( extra cond5s] sections if necess>y4 ,! illu/ration %[s ?ree sections 9 position4 ,ques4 ,h[ does ! me*anism op]ate :5 ! voltage rises above normal8 ,ans4 ,z describ$ above1 ) ! exception t ! "r h& trip causes a rotation ( ! regulator 9 ! opposite direction4 ,ques4 ,h[ is adju/m5t made = v>i\s voltages8 ,ans4 ,taps are provid$ on ! resi/ance 9 s]ies ) ! relay1 & f9] adju/m5t c be obta9$ by means ( ! helical spr+ on ! "r h& end ( ! balance arm4 ,9 ord] to adju/ ! s5sitiv5ess ( regulation1 ! be>+ = ! balance arm c be rais$ or l[]$ by means ( a /ud ,j1 fig4 #b1dej1 connect+ ?is be>+ ) ! be>+ ( ! op]at+ %aft1 & ! regulator c be made to ma9ta9 ! voltage )9 #a p] c5t4 above or bel[ normal4 ,illu/ration3 ,,fig4 #b1dec4--,we/+h\se unit swit* type pressure regulator1 design$ = h&l+ heavy curr5ts :]e a v>iable ratio trans=m] type ( regulator is desir$4 ,! regulator consi/s ( a numb] ( electrically op]at$ swit*es controll$ f a ma/] swit*4 ,^! swit*es are arrang$ to p]=m practically ! same cycle ( op]ation z previ\sly describ$ = ! drum type regulators4 ,! trans=m] w9d+s are divid$ into sections1 & two float+ coils are provid$ :i* are connect$ to v>i\s taps on ! ma9 auto-trans=m]4 ,^! float+ coils h int]m$iate /eps1 & ! successive op]ation ( ! swit*es connects ! float+ coils 9 prop] sequ5ce to ! ma9 auto-trans=m]1 & transf]s ! l9e connection f "o po9t ( ! float+ coil to ! next4 ,9 ?is way a #bc po9t regulator ) sixte5 swit*es1 & a #ga po9t regulator ) #ba swit*es may be suppli$4 ,! ma/] swit*es are arrang$ ) an automatic lock to prev5t _! be+ op]at$ too rapidly4 ,! magnet swit*es !mselves are s int]lock$ t ! prop] sequ5ce ( op]ation is insur$4 ,! electrically op]at$ swit*es may be ( ! op5 type1 m\nt$ on a slate or m>ble swit*bo>d1 :5 ! :ole control outfit is plac$ 9 a room :i* is comp>atively free f du/ or dirt ( any k9d1 & :]e !re is no dang] ( employees com+ 9 contact ) ! swit*es4 ,! o!r type ( swit* is entirely enclos$1 ! ma9 contacts be+ oil imm]s$4 ,! frames ( ^! swit*es are gr\nd$ & ! :ole design is arrang$ to op]ate "u ord9>y dirty conditions4 ,all ( ^! swit*es1 h[ev]1 %\ld receive ! necess>y inspection & att5tion4 ,! contacts h a long life & are easily r5ew$4 ,regulators ( ?is type are adapt$ = metallurgical purposes :]e ! regulation is effect$ 9 ! prim>y circuit & ! second>y circuit is ( v l[ voltage b l>ge curr5t capacity & is us$ = supply+ p[] to ! furnaces4 ,^! regulators h be5 built 9 capacities up to #hjj amp]es at #c1cjj volts4 ,ques4 ,:at provision is made = conv5i5t inspection8 ,ans4 ,a snap swit* is provid$ by means ( :i* ! p[] to ! motor & relay c be disconnect$4 ,illu/ration3 ,,figs4 #b1ded & #b1dee4--;,front & re> views ( ,g5]al ,electric automatic voltage regulator4 ,! regulator has a direct curr5t control magnet1 an alt]nat+ curr5t control magnet1 & a relay4 ,! direct curr5t control magnet is connect$ to ! excit] bus b>s4 ,?is magnet has a fix$ /op core 9 ! bottom & a movable core 9 ! top :i* is atta*$ to a pivot$ lev] hav+ at ! opposite end a flexible contact pull$ d[nw>d by f\r spiral spr+s4 ,= cle>ness1 h[ev]1 only "o spr+ is %[n 9 ! figure4 ,opposite ! direct curr5t control magnet is ! alt]nat+ curr5t control magnet :i* has a pressure w9d+ connect$ by means ( a pressure trans=m] to ! alt]nator or bus b>s4 ,!re is an adju/able comp5sat+ w9d+ on ! alt]nat+ curr5t magnet connect$ ?r\gh a curr5t trans=m] to ! pr9cipal light+ fe$]4 ,! object ( ?is w9d+ is to raise ! voltage ( ! alt]nat+ curr5t bus b>s z ! load increases4 ,! alt]nat+ curr5t control magnet has a movable core & a lev] & contacts simil> to ^? ( ! direct curr5t control magnet1 & ! two comb9$ produce :at is kn[n z ! float+ ma9 contacts4 ,! relay consi/s ( a ,u %ap$ magnet core hav+ a diff]5tial w9d+ & a pivot$ armature controll+ ! contacts :i* op5 & close ! %unt circuit across ! excit] field rheo/at4 ,"o ( ! diff]5tial w9d+s ( ! relay is p]man5tly connect$ across ! excit] bus b>s & t5ds to keep ! contacts op52 ! o!r w9d+ is connect$ to ! excit] bus b>s ?r\gh ! float+ ma9 contacts & :5 ! latt] are clos$1 neutralizes ! effect ( ! fir/ w9d+ & all[s ! relay contacts to %ort circuit ! excit] field rheo/at4 ,cond5s]s are connect$ across ! relay contacts to prev5t sev]e arc+ & possible injury4 ,automatic ,voltage ,regulators = ,alt]nators4--,! accurate regulation ( voltage on any alt]nat+ curr5t sy/em is ( importance4 ,! desir$ voltage may be ma9ta9$ con/ant at ! alt]nator t]m9als by rapidly op5+ & clos+ a %unt circuit across ! excit] field rheo/at4 ,illu/ration3 ,,fig4 #b1def4--;,diagram ( connections ( ,g5]al ,electric contact mak+ ammet] = op]at+ on alt]nat+ curr5t circuits4 ,! in/rum5t is design$ to indicate ) ! aid ( a curr5t trans=m]1 c]ta9 values ( curr5t 9 an alt]nat+ curr5t sy/em4 ,?is value dep5ds ^u ! sett+ ( ! regulat+ rheo/at 9 p>allel ) ! pressure coil ( ! ammet]4 ,x is also possible ) ?is in/rum5t1 toge!r ) ! necess>y control app>atus1 to hold c]ta9 values ( curr5t4 ,by us+ a diff]5t magnet coil ?is met] may be connect$ to a %unt in/ead ( a curr5t trans=m] & us$ on a direct curr5t sy/em4 ,ques4 ,describe 9 m detail ?is me?od ( regulation4 ,ans4 ,! rheo/at is fir/ turn$ 9 until ! excit] voltage is greatly r$uc$ & ! regulator circuit is !n clos$4 ,?is %ort circuits ! rheo/at ?r\gh contacts 9 ! regulator & ! voltage ( ! excit] & alt]nator imm$iately rise4 ,at a pr$et]m9$ po9t1 ! regulator contacts are automatically op5$ & ! field curr5t ( ! excit] mu/ aga9 pass ?r\gh ! rheo/at4 ,! result+ r$uction 9 voltage is arre/$ at once by ! clos+ ( ! regulator contacts :i* cont9ue to vibrate 9 ?is mann] & keep ! g5]ator voltage )9 ! desir$ limits4 ,! connections are %[n 9 fig4 #b1deg4 ,illu/ration3 ,,fig4 #b1deg4--;,diagram ( ,g5]al ,electric automatic voltage regulator connections ) alt]nator & excit]4 ,9 op]ation1 ! circuit %unt+ ! excit] field rheo/at ?r\gh ! relay contacts is op5$ by means ( a s+le pole swit* at ! bottom ( ! regulator panel & ! rheo/at turn$ 9 until ! alt]nat+ curr5t voltage is r$uc$ #fe p] c5t4 bel[ normal4 ,?is weak5s bo? ( ! control magnets & ! float+ ma9 contacts are clos$4 ,?is closes ! relay circuit & demagnetizes ! relay magnet1 releas+ ! relay armature1 & ! spr+ closes ! relay contacts4 ,! s+le pole swit* is !n clos$ & z ! excit] field rheo/at is %ort circuit$1 ! excit] voltage w at once rise & br+ up ! voltage ( ! alt]nator4 ,?is w /r5g!n ! alt]nat+ curr5t & direct curr5t control magnets1 & at ! voltage = :i* ! c\nt]weight has be5 previ\sly adju/$1 ! ma9 contacts w op54 ,! relay magnet w !n attract its armature & by op5+ ! %unt circuit at ! relay contacts w ?r[ ! full resi/ance into ! excit] field circuit t5d+ to l[] ! excit] & alt]nator voltage4 ,! ma9 contacts w !n be aga9 clos$1 ! excit] field rheo/at %ort circuit$ ?r\gh ! relay contacts & ! cycle repeat$4 ,?is op]ation is cont9u$ at a high rate ( vibration due to ! s5sitiv5ess ( ! control magnets & ma9ta9s a /eady excit] voltage4 ,l9e ,drop ,comp5sators4--,9 ord] t ! actual voltage at a di/ant po9t on a di/ribution sy/em may be read at ! /ation "s provision mu/ be made to comp5sate = ! l9e drop1 t is to say1 = ! diff]5ce 9 voltage betwe5 ! alt]nator & ! c5t] ( di/ribution4 ,9 ord] to d ?is a device :i* is kn[n z a l9e drop comp5sator is plac$ 9 ! voltmet] circuit z %[n 9 ! diagram1 fig4 #b1deh4 ,ques4 ,:at are ! ess5tial p>ts ( a l9e drop comp5sator8 ,ans4 ,! elem5ts ( a l9e drop comp5sator are a v>iable resi/ance1 & a v>iable inductance4 ,ques4 ,describe ! connections4 ,ans4 ,! second>y ( a pressure trans=m] is connect$ 9 s]ies ) ! comp5sator inductance & resi/ance1 & ! second>y ( a curr5t trans=m] z %[n 9 ! diagram1 fig4 #b1deh4 ,illu/ration3 ,,fig4 #b1deh--;,diagram %[+ ess5tial p>ts & connections = a l9e drop comp5sator4 ,! comp5sator corrects ! voltmet] indication at ! supply end ( a fe$] = ! ohmic & inductive drop 9 pressure betwe5 t po9t & ! po9t ( consumption1 s t ! read+ ( ! /ation voltmet] corresponds ) ! actual voltage at ! po9t ( consumption1 indep5d5t ( ! p[] factor & curr5t4 ,x is especially useful = adju/+ pressure regulators4 ,ques4 ,h[ are ! inductance & resi/ance w\nd8 ,ans4 ,!y are w\nd s t any proportion ( ! w9d+ ( ei!r c be put 9 or out ( ! voltmet] circuit4 ,illu/ration3 ,,fig4 #b1dei4--;,g5]al ,electric l9e drop comp5sator4 ,x has two dial swit*es ) _m taps to ! resi/ance & reactance 9 ! box s t x c be adju/$ to comp5sate accurately = l9e losses ) loads ( v>y+ p[] factor4 ,dial ,r *anges resi/ance1 & dial ,x1 reactance4 ,illu/ration3 ,,fig4 #b1dfj4--;,g5]al ,electric l9e drop comp5sator4 ,?is comp5sator conta9s besides resi/ance & inductance1 a curr5t trans=m]1 ! second>y ( ! trans=m] be+ connect$ 9 s]ies ) ! resi/ance & inductance2 ! prim>y ( ! conta9$ curr5t trans=m] is connect$ to an ext]nal curr5t trans=m]4 ,! reactance & resi/ance are bo? s w\nd t any proportion ( ! w9d+ c be cut 9 or out ( ! voltmet] circuit4 ,bo? elem5ts h #ab po9ts ( adju/m5t ( "o volt ea*1 giv+ a total comb9$ drop at maximum sett+ ( ab\t #ag volts4 ,ques4 ,h[ c ! voltmet] indicate ! pressure at ! c5t] ( di/ribution8 ,ans4 ,if ! am\nt ( inductance & resi/ance be prop]ly adju/$1 !re w be produc$ a local circuit correspond+ exactly 9 all its *>act]i/ics to ! ma9 circuit4 ,h5ce1 any *ange 9 ! ma9 circuit produces a correspond+ *ange 9 ! local circuit1 & causes ! voltmet] to always indicate ! pressure at ! end ( ! l9e or c5t] ( di/ribution or at any po9t = :i* ! adju/m5t is made4 ,illu/ration3 ,,fig4 #b1dfa4--,we/+h\se l9e drop comp5sator4 ,= s+le phase circuits1 "o comp5sator & "o s]ies trans=m]1 t is ! in/rum5t z li/$ ) trans=m]s1 w give correct indications = a s+le phase circuit4 ,! same voltage trans=m] s]ves = bo? voltmet] & comp5sator4 ,= balanc$ two phase circuits "o comp5sator & "o trans=m] connect$ 9 "o ( ! phases is suffici5t4 ,two s+le phase comp5sators %\ld be us$ = unbalanc$ two phase circuits4 ,= ?ree phase circuits ! comp5sator %\ld be connect$ by means ( two s]ies trans=m]s4 ,ques4 ,h[ %\ld ! adju/m5t be made8 ,ans4 ,x is advisable to calculate ! ohmic drop = full load & set ! resi/ance arm at ! po9t :i* w give ! requir$ comp5sation & !n adju/ ! inductance arm until ! voltmet] read+ corresponds to ! voltage at ! po9t on ! l9e select$ = normal voltage4 ,illu/ration3 ,,fig4 #b1dfb4--;,diagram ( automatic voltage regulator1 us+ l9e drop comp5sator4 ,= ord9>y in/allations ! comp5sat+ w9d+ on ! alt]nat+ curr5t control magnet is connect$ to a curr5t trans=m] 9 ! ma9 fe$]4 ,a dial swit* is provid$ by :i* ! /r5g? ( ! alt]nat+ curr5t control magnet c be v>i$ & ! regulator made to comp5sate = any desir$ l9e drop up to #ae p] c5t4 accord+ to ! l9e requirem5ts4 ,:]e ! p[] factor ( ! load has a wide range ( v>iation1 a special l9e drop comp5sator1 su* z %[n 9 fig4 #b1dei1 adapt$ to ! regulator w\ld be desirable4 ,! connections are readily und]/ood by ! diagram4 ,! numb] ( cond5s] sections :i* w prev5t undue arc+ at ! relay contacts dep5ds on ! *>act]i/ics ( ! excit]4 ,!y may be r\ghly e/imat$ by all[+ "o section = ea* #ae kw4 capacity = excit]s ) lam9at$ poles1 & "o = ea* #bb kw4 capacity = excit]s ) solid /eel poles4 ,x is necess>y ?\gh to h "o cond5s] section = ea* pair ( relay contacts1 & at times x becomes necess>y to apply a d\ble section = ea* pair ( contacts4 ,9 ! l[] "p ( ! figure ! l9e drop comp5sation & connections is reproduc$ 9 m detail on a l>g] scale4#b #b ,,note4--,x is desirable1 9 any sy/em ( di/ribution1 to read ! active voltage at ! po9t ( di/ribution1 by means ( ! voltmet]s 9 ! /ation4 ,a comp5sator prop] consi/s ( a v>iable resi/ance & a v>iable inductance1 & sometimes a curr5t trans=m]4 ,9 wir+1 ! voltmet]1 in/ead ( be+ connect$ directly across ! second>ies ( a pressure trans=m]1 has ins]t$ 9 s]ies ) x1 portions ( ! resi/ance & inductance ( ! comp5sator4 ,^! are s connect$ t ! drop 9 pressure across !m w be comb9$ ) t ( ! pressure trans=m]1 s t ! voltmet] read+ indicates ! pressure at ! c5t] ( di/ribution or end ( ! l9e4 ,/>t+ ,comp5sators4--,^! are us$ = />t+ induction motors & consi/ ( inductive w9d+s 7"o = ea* phase7 ) a numb] ( taps connect+ ) swit* contacts z %[n 9 fig4 #b1dfc4 ,a />t+ comp5sator is simil> to a rheo/at except t inductive w9d+s are us$ 9 place ( ! resi/ance grids4 ,illu/ration3 ,,fig4 #b1dfc4--;,diagram ( connections ( ,g5]al ,electric two phase />t+ comp5sator ) no voltage release & fuses4 ,ques4 ,describe ! inductive w9d+s4 ,ans4 ,! comp5sator w9d+ consi/s ( an inductive coil 9 ea* phase ) ea* coil plac$ on a sep>ate leg ( a lam9at$ iron core4 ,ea* coil is provid$ ) sev]al taps s locat$ t a numb] ( sub-voltages may be obta9$4 ,ques4 ,are />t+ comp5sators necess>y = small motors8 ,:y8 ,ans4 ,no1 because ! full voltage />t+ curr5t tak51 al?\gh equal to sev]al times ! load curr5t1 is nev]!less s small1 comp>$ ) ! capacity ( ! /ation alt]nators or fe$]s1 t x does n mat]ially affect ! regulation ( ! circuit4 ,illu/ration3 ,,fig4 #b1dfd4--;,diagram ( connections ( ,g5]al ,electric ?ree phase />t+ comp5sator ) l[ voltage release & fuses4 ,illu/ration3 ,,fig4 #b1dfe4--;,diagram ( connections ( ,g5]al ,electric two phase />t+ comp5sator ) no voltage release & ov]load relays = #a1jdj to #b1ejj volt circuits4 ,motors l>g] ?an ab\t #g horse p[] cause an objectionably heavy ru% ( curr5t if ?r[n directly on ! l9e4 ,/>t+ comp5sators obviate su* sudd5 v>iations ( l9e load & are accord+ly recomm5d$ = motors above #g horse p[] except 9 cases :]e voltage v>iations & excessive />t+ curr5ts are n objectionable4 ,illu/ration3 ,,figs4 #b1dff & #b1dfg4--;,g5]al ,electric ?ree phase h& op]at$ />t+ comp5sator4 ,fig4 #b1dff1 comp5sator 9 case2 fig4 #b1dfg1 comp5sator ) case remov$4 ,! comp5sator consi/s ( a core & w9d+s1 a cable clamp1 & a swit*1 assembl$ 9 a sub/antial metal case ) ext]nal op]at+ h&le & release lev]4 ,! w9d+s consi/ ( coils w\nd on sep>ate legs ( a lam9at$ core1 & tapp$ at sev]al po9ts1 ! connections t]m9at+ at ! swit* contacts4 ,! %aft ( ! swit* ext5ds ?r\gh ! sides ( ! comp5sator case1 & is op]at$ by a lev] at ! "r1 be+ held 9 ! runn+ position by a lev] at ! left4 ,x is provid$ ) wip+ contacts4 ,! swit* is imm]s$ 9 oil1 & is int5d$ to be us$ z a l9e swit* z well z = />t+ ! motor4 ,! lev] has ?ree positions3 (f1 />t+1 & runn+4 ,9 ! (f position1 bo? comp5sator & motor w9d+s are disconnect$ f ! l9e4 ,9 ! />t+ position1 ! swit* connects ! l9e to ! ends & ! motor to ! taps ( ! comp5sator w9d+ )\t ov]load relays or fuses 9 circuit4 ,9 ! runn+ position1 ! comp5sation w9d+ is cut out & ! motor is connect$ to ! l9e ?r\gh suitable fuses or ov]load relays m\nt$ directly above ! comp5sator4 ,to prev5t ! att5dant ?r[+ ! motor directly on ! l9e1 & !reby caus+ a ru% ( curr5t :i* x is ! object ( ! comp5sator to avoid1 an automatic lat* is provid$ & s arrang$ t ! lev] at (f position c be ?r[n only into ! />t+ position 7backw>d72 & c be ?r[n !nce into ! runn+ position 7=w>d7 only by a quick ?r[ ( ! lev]1 :]eby any appreciable drop 9 spe$ & consequ5t increase 9 curr5t 9 pass+ f ! />t+ into ! runn+ position is avoid$4 ,ques4 ,:at %\ld be not$ ) respect to ! comp5sator w9d+ taps8 ,ans4 ,! *oice ( a tap giv+ s l[ a voltage z to require ov] "o m9ute = />t+ %\ld be avoid$ s z to prev5t ! ov]heat+ to :i* />t+ comp5sators1 9 common ) o!r motor />t+ devices1 are liable if left 9 circuit unnecess>ily long1 or if ! motor be />t$ sev]al times 9 rapid succession4 ,illu/ration3 ,,fig4 #b1dfh4--;,diagram ( connections ( ,g5]al ,electric ?ree phase />t+ comp5sator ) no voltage release & ov]load relays4 ,x %\ld also be not$ t ! />t+ curr5t dim9i%es rapidly z full spe$ is approa*$4 ,x is1 !re=e1 important t ! swit* be kept 9 ! />t+ position until ! motor has f9i%$ accel]at+ to prev5t any unnecess>y ru% ( curr5t :5 ! swit* is ?r[n to ! runn+ position4 ,illu/ration3 ,,fig4 #b1dfi4--;,g5]al ,electric />t+ comp5sator ) l[ voltage release & ov]load relays4 ,on ! swit* %aft !re are m\nt$ two lev]s1 held toge!r ) a /rong spr+ :i* op]ates 9 ei!r direction & prev5ts ! swit* be+ left on ! />t+ position4 ,on ! runn+ side x is held by ! ext]nal l[ voltage release lev] until releas$ ei!r by h& or by ! action ( a l[ voltage relay4 ,! l[ voltage release consi/s ( a ca/ iron frame op5 at ! bottom & totally enclos+ ! coil4 ,a lam9at$ plung] is us$ to hold ! tripp+ lev]1 ! latt] engag+ ) ! lev] m\nt$ on ! swit* %aft4 ,! comp5sator _c be ?r[n into ! runn+ position )\t fir/ go+ to ! />t+ position & x _c be left on ! />t+ position4 ,ques4 ,:at is ! usual arrangem5t ( />t+ comp5sators = l>ge motors8 ,ans4 ,/>t+ comp5sators may be w\nd = any voltage or curr5t = :i* x is practicable to build motors4 ,= v l>ge motors ! swit*+ device is g5]ally sep>ate f1 ! comp5sator itself & consi/s ( triple & f\r pole swit*es = ?ree phase & two phase motors respectively4 ,"o d\ble ?r[ swit* or two int]lock$ s+le ?r[ swit*es are requir$ = ! motor & a s+le ?r[ swit* = en]giz+ ! comp5sator1 ! runn+ side ( ! motor circuit be+ provid$ ) fuses or automatic circuit break]s1 or ! swit*es provid$ ) l[ voltage & ov]load release atta*m5ts4 ,/> ,delta ,swit*es4--,^! are />t+ swit*es1 design$ = use ) small ?ree phase squirrel cage motors hav+ _! w9d+s s arrang$ t !y may be connect$ 9 /> = />t+ & 9 delta = runn+4 ,ques4 ,describe ! op]ation ( a /> delta swit*4 ,ans4 ,9 />t+ ! motor1 ! drum lev] is ?r[n 9 ! />t+ direction :i* connects ! field w9d+s ( ! motor 9 />4 ,:5 ! motor has accel]at$ & has come p>tially up to spe$ ! />t+ lev] is quickly ?r[n to ! runn+ position 9 :i* position ! field w9d+s are connect$ 9 delta4 ,! effect ( connect+ ! field w9d+ 9 /> at />t+ is to r$uce ! voltage appli$ to ea* phase w9d+1 :ile 9 ! runn+ position ea* phase ( ! field w9d+ has full l9e voltage impress$ ^u x4 ,illu/ration3 ,,figs4 #b1dgj to #b1dgd4--;,g5]al ,electric "t limit ov]load relay = />t+ comp5sator4 ,9 case ( ov]load1 ! relay armature is rais$ & at ! end ( its travel1 op5s ! small swit* at ! top :i* 9 turn op5s ! circuit ( ! l[ voltage release coil caus+ ! comp5sator swit* to return to ! (f position4 ,! oil da% pot provides a c]ta9 "t elem5t & c be adju/$ to op]ate imm$iately ^u ov]load or at any int]val up to five m9utes4 ,ea* relay has five calibrat+ po9ts1 ! l[e/ be+ ! normal full load curr5t ( ! motor1 ! highe/ #cjj p] c5t4 full load curr5t4 ,! scale on ! calibration tube reads direct & %[s v>i\s values ( curr5t at :i* ! relay may be set to op]ate4 ,to *ange ov]load sett+3 #a1 loos5 set screw2 #b1 turn relay plung] on pi/on rod until :ite m>k comes opposite requir$ value ( curr5t2 #c1 tight5 set screw4 ,"t elem5t adju/m5t3 ,remov+ oil da% pot by turn+ to ! left w expose ! cup %ap$ pi/on1 made ( :i* are two conc5tric discs 7,b & ,c7 held toge!r by a mill$ lock nut1 ,a4 ,!re is a hole 9 ea* disc ?r\gh :i* ! oil mu/ pass :5 ! plung] ( ! relay is rais$4 ,! "t elem5t may be v>i$ by *ang+ ! size ( ! op5+ betwe5 ^! discs1 t is1 to h ! relays op]ate 9 a %ort] p]iod ( "t1 increase ! size ( ! op5+ & vice-v]sa4 ,to *ange ! "t sett+3 #a1 remove ! oil da% pot2 #b1 raise ! discs ,b & ,c on ! pi/on rod2 #c1 loos5 ! lock nut ,a2 #d1 *ange ! op5+ betwe5 ,b & ,c1 giv+ a l>g] op5+ = %ort] "t ( op]ation1 & a small] op5+ = long] "t2 #e1 tight5 lock nut ,a2 #f1 replace discs 9 pi/on ,d2 #g1 replace oil da% pot4 ,illu/ration3 ,,figs4 #b1dge1 & #b1dgf4--;,front & side views 7oil tank remov$7 ( ,cutl]-,hamm] /> delta swit* = />t+ small ?ree phase squirrel cage motors4 ,9 con/ruction1 ! swit* consi/s ( "o set ( /ation>y f+]s & a rotat+ wood5 cyl9d]1 c>ry+ two sets ( contacts4 ,^! p>ts are support$ f ! swit* frame ca/+ & are enclos$ 9 a /eel tank :i* conta9s an insulat+ oil4 ,flexible oil pro( cable leads are br\ght out ?r\gh insulat$ bu%+s 9 ! top ( ! swit* & tagg$ = conv5i5ce 9 connect+ to ! l9es & motor4 ,to prev5t seepage ( oil1 ! leads are seal$ into ! top ( ! cov] ) an oil pro( seal+ wax4 ,! lev] ( ! /> delta swit* is arrang$ ) an int]lock :i* prev5ts its be+ ?r[n directly into ! runn+ position f ! (f position4 ,x is necess>y to ?r[ ! lev] fir/ into ! />t+ position & !n ) an un9t]rupt$ movem5t to ! runn+ position4 ,! circuit ( ! motor is brok5 only = an in/ant 9 *ang+ f /> to delta & no heavy inru% curr5t occurs4 ,no voltage release protection is provid$ by a lat*+ sol5oid :i* holds ! spr+ c5t]$ drum cyl9d] 9 ! runn+ position4 ,! no voltage release coil is m\nt$ 9 ! l[] "p ( ! />t+ swit*1 imm]s$ 9 ! oil tank1 & is protect$ aga9/ me*anical injury & gr\nd+4 ,! coil is 9 circuit dur+ ! runn+ p]iod only & requires n m ?an #h to #ae watts to hold ! swit* 9 ! runn+ position4 ,! op]ation ( ?is protective device is su* t on failure ( voltage ! /> delta swit* w imm$iately be return$ to ! (f position4 ,ov]load release protection consi/s ( two relays on a small slate panel1 :i* is m\nt$ directly on ! side ( ! /> delta swit*4 ,! swit* contacts ( ! ov]load release are connect$ 9 s]ies ) ! connections to ! no voltage release coil s t :5 an ov]load occurs ! ov]load relay op]ates to op5 ! circuit to ! no voltage release coil1 ?us p]mitt+ ! swit* lev] to return to ! (f position4 ,! ov]load relays d n af=d ov]load protection dur+ ! />t+ p]iod1 & :5 su* protection is desir$ />t+ fuses %\ld be in/all$4 ,^! fuses1 if us$1 %\ld h a capacity ( #bej to #cjj p] c5t4 ( ! normal full load curr5t ( ! motor4 ,illu/ration3 ,,fig4 #b1dgg4--;,diagram ( connections ( ,g5]al ,electric ?ree phase />t+ comp5sator ) l[ voltage release & ov]load relays = #a1jdj-b1ejj volt circuits4 ,,*apt] ,,lxi ,,syn*ron\s ,,cond5s]s ,syn*ron\s ,cond5s]s4--,a syn*ron\s motor :5 suffici5tly excit$ w produce a lead+ curr5t1 t is1 :5 ov] excit$ x acts l a great cond5s]1 & :5 ?us op]at$ on circuits conta9+ induction motors & simil> app>atus = ! purpose ( improv+ ! p[] factor x is call$ a syn*ron\s cond5s]4 ,al?\gh ! motor p]=ms ! duty ( a cond5s] x possesses almo/ none ( ! prop]ties ( a /ation>y cond5s] o!r ?an produc+ a lead+ curr5t1 & is free f _m ( ! inh]5t defects ( a /ation>y cond5s]4 ,! relation ( p[] factor to ! size & effici5cy ( prime mov]s1 g5]ators1 conductors1 etc41 & ! value ( syn*ron\s cond5s]s = improv+ ! p[] factor is g5]ally recogniz$4 ,induction motors & o!r inductive app>atus take a compon5t ( curr5t :i* lags beh9d ! l9e pressure1 & !reby l[]s ! p[] factor ( ! sy/em1 :ile a non-inductive load1 su* z inc&esc5t lamps1 takes only curr5t 9 phase ) ! voltage & op]ates at unity p[] factor4 ,s9ce trans=m]s require ! magnetiz+ curr5t1 !y may s]i\sly affect ! p[] factor :5 unload$ or p>tially load$1 b :5 op]at+ at full load _! effect is practically negligible4 ,! relative effect ( fully load$ & lightly load$ induction motors on ! p[] factor is indicat$ by ! diagram1 fig4 #b1dgh4 ,! magnetiz+ curr5t is ne>ly con/ant at all loads & is wattless1 lagg+ #ij degrees beh9d ! impress$ pressure1 or at "r angles to ! curr5t :i* is utiliz$ = p[]4 ,9 ! figure1 ,,ab is ! magnetiz+ compon5t1 :i* is always wattless1 & ,,cb ! p[] compon5t4 ,! angle ,,acb gives ! phase relation betwe5 voltage & curr5t2 ! cos9e ( ?is angle ,,cb ,,ac is ! p[] factor4 ,illu/ration3 ,,fig4 #b1dgh4--;,diagram %[+ relative effect ( fully load$ & lightly load$ induction motors on p[] factor4 ,x is evid5t f ! diagram t if ! load be r$uc$1 ! side ,,cb is %ort5$1 & z ,,ab is practically con/ant1 ! angle ( lag ,,acb is increas$4 ,x !re=e foll[s t ! cos9e ( ?is angle1 or ! p[] factor is r$uc$4 ,! figure cle>ly %[s ! reason = ! l[ p[] factor ( induction motors on fractional loads & also %[s t s9ce ! magnetiz+ curr5t is practically con/ant 9 value1 ! induction motor c nev] op]ate at unity p[] factor4 ,) no load1 ! side ,,cb 7real p[]7 is j suffici5t to supply ! friction & w9dage4 ,if ?is be repres5t$ by ,,db1 s9ce ,,ab rema9s con/ant1 ! p[] factor is r$uc$ to #aj or #ae p] c5t4 & ! motor takes f ! l9e ab\t #cj p] c5t4 ( full load curr5t4 ,x !re=e foll[s t a gr\p ( lightly load$ induction motors c take f ! sy/em a l>ge curr5t at exce$+ly l[ p[] factor4 ,! syn*ron\s motor :5 us$ z a cond5s]1 z be=e /at$1 has ! prop]ty ( alt]+ ! phase relation betwe5 pressure & curr5t1 ! direction & ext5t ( ! displacem5t be+ dep5d5t on ! field excitation ( ! cond5s]4 ,x c be run at unity p[] factor & m9imum curr5t input1 or x c be ov] excit$ & !reby deliv] lead+ curr5t :i* comp5sates = ! inductive load on o!r p>ts ( ! sy/em4 ,! syn*ron\s cond5s]1 !re=e1 c supply magnetiz+ curr5t to ! load on a sy/em :ile ! p[] compon5t is suppli$ by ! g5]ators4 ,illu/ration3 ,,fig4 #b1dgi4--;,g5]al ,electric #djj kw41 #eej volt1 #fjj ,r4,p4,m41 syn*ron\s cond5s] ) direct connect$ excit] in/all$ 9 sub-/ation ,no4 #a ( ! ,colorado ,light ,p[] ,co41 ,cripple ,creek1 ,colo4 ,! ma*9e is design$ = alt]nat+ curr5t />t+ by means ( a comp5sator4 ,! field is provid$ ) a /&>d syn*ron\s motor w9d+1 &1 9 addition1 an amortisseur w9d+ :i* assi/s 9 />t+ & s]ves z a damp+ device to m9imize hunt+4 ,illu/ration3 ,,fig4 #b1dhj4--;,diagram %[+ relative location ( alt]nators & syn*ron\s motors 9 plant ( ,)]bee ,%]man ,co41 ,m9eville ,n4 ,y4 ,! di/ribution sy/em ( ! ,company is provid$ ) ?ree syn*ron\s motors1 z %[n4 ,! sy/em includes two hydro-electric1 "o turb9e driv51 & "o eng9e driv5 g5]ator plants2 f ?ree ( ^!1 curr5t is transmitt$ to ! f\r?1 :i* is locat$ 9 ,m9eville1 at ! po9t ,a1 ! curr5t be+ di/ribut$ to ! motor circuits f ! po9ts ,a & ,b4 ,! transmission to ! c5tral /ation at ,m9eville is ov] ?ree phase circuits at #f1fjj volts4 ,= op]at+ ! m9e at ,*eev]1 curr5t is transmitt$ direct f ! g5]at+ /ation at ,port ,h5ry4 ,! di/ribution f ,a & ,b is all at #c1cjj volts1 be+ /epp$ d[n to #ddj volts = ! op]ation ( ! motors1 :i* h a total rat$ capacity ( #d1gfb horse p[]4 ,except+ ?ree syn*ron\s motors1 ! load is practically all inductive1 !re be+ less ?an #aj kw4 requir$ = light+4 ,! actual p[] dem& ranges f #fj to #fe p] c5t4 ( ! rat$ motor capacity1 & prior to ! in/allation ( ! syn*ron\s motors1 ! p[] factor 0 approximately #fh p] c5t41 ! cond5s] effect ( ^! motors mak+ x possible to ma9ta9 an av]age ( ab\t #ij p] c5t4 p[] factor 9 spite ( ! fact t a consid]able portion ( ! induction motor load is v widely di/ribut$4 ,! ?ree syn*ron\s motors are p>tially load$1 ea* motor driv+ an air compressor ?r\gh belt+4 ,! #ahj kva4 motor at ,*eev] takes ab\t #aej kw4 = ! op]ation ( a #a1bej cubic foot compressor1 :ile ! two #cfj kva4 ma*9es take ab\t #cjj kw4 ea*1 = ! op]ation ( two #b1ejj cu4 ft4 sets4 ,! op]ation ( ^! compressors af=ds a me?od ( utiliz+ a portion ( ! motor capacity me*anically1 inasmu* z ! load on ! motors is practically con/ant dur+ ! "t ! m9es are 9 op]ation1 & !reby p]mit ! motors to be run at approximately #hj p] c5t4 p[] factor4 ,effects ( ,l[ ,lagg+ ,p[] ,factors4--,trans=m]s are rat$ 9 kva4 output2 t is1 a #ajj kva4 trans=m] is suppos$ to deliv] #ajj kw4 at unity p[] factor at normal voltage & at normal temp]atures2 b1 if ! p[] factor %\ld be1 say 4#f lagg+1 ! rat$ en]gy output ( ! trans=m] w\ld be only #fj kw4 & yet ! curr5t &1 consequ5tly1 ! heat+ w\ld be approximately ! same z :5 deliv]+ #ajj kw4 at unity p[] factor4 ,illu/ration3 ,,fig4 #b1dha4--;,field ( a syn*ron\s cond5s]4 ,note ! amortisseur w9d+1 errone\sly call$ squirrel cage w9d+1 consi/+ ( two end r+s :i* s]ve to %ort circuit spokes pass+ ?r\gh ! pole tips z %[n4 ,! amortisseur w9d+ assi/s 9 />t+ & s]ves also z a damp+ device to m9imize hunt+4 ,! regulation ( trans=m]s is inh]5tly good1 be+ = small light+ trans=m]s ab\t #a to #b p] c5t4 = a load ( unity p[] factor1 & ab\t #d to #e p] c5t4 at 4#g p[] factor4 ,l>g] trans=m]s ) a regulation ( #a p] c5t4 or bett] at a unity p[] factor load1 w\ld h ab\t #c p] c5t4 regulation at 4#g p[] factor4 ,alt]nators also are rat$ 9 kva4 output1 usually at any value ( p[] factor betwe5 unity & 4#h4 ,! delet]i\s effects ( l[ p[] factor loads on alt]nators are ev5 m m>k$ ?an on trans=m]s4 ,^! are1 decreas$ kw4 capacity1 ! necessity = increas$ excit] capacity1 decreas$ effici5cy1 & impair$ regulation4 ,assume ! case ( a #ajj kva4 4#f p[] factor1 #fj kw4 output4 ,x is probable t normal voltage c\ld be obta9$ only ) difficulty1 unless ! alt]nator 0 especially design$ = l[ p[] factor s]vice4 ,! lagg+ p[] factor curr5t 9 ! armature sets up a flux :i* opposes ! flux set up by ! fields1 & 9 consequ5ce t5ds to demagnetize !m1 result+ 9 l[ armature voltage4 ,x is (t5 impracticable1 )\t ! in/allation ( new excit]s1 to raise ! alt]nator voltage by a fur!r increase ( ! excit+ voltage & curr5t4 ,! field losses1 & !re=e ! field heat+ ( ! alt]nator1 :5 x is deliv]+ rat$ voltage & curr5t1 are great] at lagg+ p[] factor ?an at unity4 ,increas$ en]gy input & decreas$ en]gy output bo? cause a r$uction 9 effici5cy4 ,illu/ration3 ,,fig4 #b1dhb4--;,diagram ( a section ( ! ,nor!rn ,cali=nia ,p[] ,co4's transmission sy/em1 %[+ relative location ( alt]nators & syn*ron\s cond5s]4 ,! syn*ron\s cond5s] is in/all$ at ,k5nett1 :i* is s]v$ by g5]at+ /ations at ,kil>c & ,volta1 locat$ respectively #bh & #ch miles f ! po9t at :i* ! cond5s] is op]at$4 ,! local dem& am\nts to ab\t #f1ejj kw41 & be=e ! in/allation ( ! syn*ron\s cond5s]1 ! p[] factor 0 ab\t #gi p] c5t4 & aft] in/all+1 ab\t #if p] c5t4 :ile ! voltage at ! po9t :]e ! syn*ron\s cond5s] is in/all$ is rais$ approximately #aj p] c5t4 dur+ ! *ange f no load to full load4 ,9 ord] to obta9 close voltage regulation1 a regulator is us$ 9 connection ) ! syn*ron\s cond5s] & holds ! voltage1 at ! c5t] ( di/ribution1 )9 #b p] c5t4 ,! regulator is m\nt$ on ! side ( ! control panel & connect$ 9 ! field ( ! syn*ron\s cond5s] to automatically *ange ! excitation & comp5sate = voltage v>iations4 ,a graphic demon/ration ( ! improvem5t 9 voltage regulation1 :i* has be5 secur$ 9 ?is case1 is giv5 by ! curve draw+ voltmet] records reproduc$ 9 fig4 #b1dhc4 ,! regulation at unity p[] factor ( mod]n alt]nators capable ( c>ry+ #be p] c5t4 ov]load1 is usually ab\t #h p] c5t4 ,_! regulation at 4#g p[] factor lagg+ is ab\t #be p] c5t4 ,! effect ( l[ p[] factor on ! l9es c be/ be %[n by ! foll[+ example3 ,,example4--,assum+ a di/ance ( five miles & a load ( #a1jjj kw4 & desir+ to deliv] ?is load at a pressure ( ab\t #f1jjj volts1 ?ree phase1 ) an en]gy loss ( #aj p] c5t41 ea* conductor at unity p[] factor w\ld h to be #gi1bjj c4m41 at 4#i p[] factor1 #ig1ecc c4m41 & at 4#f p[] factor1 #bah1jjj c4m4 ,9 o!r words1 at ! l[] p[] factor ( 4#f1 ! inve/m5t 9 copp] alone w\ld be #b4h times z mu*4 ,illu/ration3 ,,fig4 #b1dhc4--;,curve draw+ voltmet] records at ,k5nett1 ,cal4 ,! upp] curve %[s voltage regulation ) syn*ron\s cond5s] out ( s]vice1 & ! l[] curve1 ) syn*ron\s cond5s] 9 op]ation4 ,if ! same size ( wire 7 us$ at bo? unity & 4#f p[] factor lagg+1 ! en]gy loss w\ld be ab\t #b4h times ! loss at unity p[] factor1 or ab\t #bh p] c5t4 ,l[ lagg+ p[] factor on a sy/em1 !re=e1 w g5]ally mean limit$ output ( prime mov]s2 greatly r$uc$ kil[att capacity ( g5]ator1 trans=m] & l9e2 & increas$ en]gy losses4 ,! regulation ( ! entire sy/em w also be poor4 ,co/ ( ,syn*ron\s ,cond5s] vs4 ,co/ ( ,copp]4--,ref]r+ to ! example giv5 9 ! prec$+ p>agraph1 & calculat+ ! necess>y extra inve/m5t 9 copp] ) ! 4#f p[] factor load1 & copp] at #ag c5ts p] p\nd1 ! result is t #bi1bib p\nds m copp] is requir$ ?an ) ! p[] factor ( 4#i :i* means a total extra inve/m5t 9 copp] alone ( #e1jjj 7#bi1bib 4#ag74 ,a syn*ron\s cond5s] ( suffici5t capacity to accompli% ! same result w\ld co/ ab\t ! same am\nt4 ,x w\ld !re=e co/ less to in/all ! cond5s] because at ! same "t a consid]ably increas$ capacity w\ld be obta9$ f ! alt]nators1 trans=m]s1 etc4 ,illu/ration3 ,,fig4 #b1dhd4--;,diagram %[+ ! field curr5t tak5 by a syn*ron\s motor ( normal design :5 op]at+ at normal kva4 input at v>i\s p[] factors4 ,x w be not$ t a slight dep>ture f unity p[] factor necessitates a consid]able *ange 9 field curr5t4 ,z ! field curves increase ) ! squ>e ( ! curr5t1 !re is a rapid increase 9 temp]ature ) lead+ curr5t4 ,?is action ( lead+ or lagg+ curr5t s]ves automatically to keep ! flux con/ant 9 ! armature ) *anges 9 field excitation4 ,:5 ! motor is runn+ at unity p[] factor1 an increase 9 field excitation causes a lead+ curr5t to fl[1 & at ! same "t ?is lead+ curr5t demagnetizes ! field until ! d5sity ( ! armature is re/or$ to its normal value4 ,if ! field be decreas$ a lagg+ curr5t fl[s :i* 9 turn magnetizes ! field br++ ! d5sity back to its orig9al value4 ,!re=e1 ) a con/ant l9e voltage1 ! iron losses 9 a syn*ron\s motor are approximately con/ant irrespective ( ! field excitations ) ! exception t ! int]nal voltage w v>y slightly due to ! armature ,i ,r drop1 ! d5sity be+ a trifle l[] at full load ?an at no load4 ,syn*ron\s ,cond5s] ,calculations4--,9 figur+ on ! in/allation ( a cond5s] = correct+ p[] factor tr\bles1 a c>eful survey ( ! conditions %\ld be made ) a view ( det]m9+ j :at ^! tr\bles are & to :at ext5t !y c be rem$i$ by ! pres5ce ( a lead+ curr5t 9 ! sy/em4 ,illu/ration3 ,,fig4 #b1dhe4--;,diagram %[+ a set ( phase *>act]i/ic curves tak5 f a ,g5]al ,electric syn*ron\s motor4 ,^! curves %[ ! curr5t input to ! motor at v>i\s loads ) con/ant voltage & v>y+ field excitation4 ,!re is a c]ta9 field curr5t at ea* load t causes a m9imum curr5t4 ,any increase or decrease ( field f ! value increases ! curr5t & causes x to lead or lag ) respect to ! l9e voltage4 ,by ref]r+ to ! m9imum input curve1 x w be not$ t if ! ma*9e be runn+ at full load m9imum input curr5t & load is tak5 (f1 ! curr5t w be lead+ or vice v]sa4 ,9 ea* case ! phase *>act]i/ic curve 0 run back on ! lagg+ side to ! break d[n po9t4 ,at no load & "o qu>t] load ! motor /ill ran 9 /ep :5 ! field 0 r$uc$ to z]o & ev5 tak5 (f altoge!r1 & x 0 necess>y to rev]se ! field curr5t 9 ord] to back d[n ! motor4 ,! motor runs )\t slip1 z a syn*ron\s motor1 9 ?is condition1 obta9+ its excitation f ! lagg+ curr5t & runn+ z a reaction ma*9e4 ,! am\nt ( load a ma*9e w c>ry )\t field v>ies ) ! design1 ! av]age be+ ab\t #dj ( full load4 ,x w be not$ f ! limit ( /ability curve t ! light] ! load on ! ma*9e :5 x breaks d[n f lack ( suffici5t excitation1 ! great] ! curr5t input at ?is po9t4 ,! no load *>act]i/ic rises %>ply on ea* side ) slight *ange 9 field curr5t1 :ile x flatt5s out ) increase 9 load until at ov]load ! curr5t input is practically ! same ?r\gh\t a l>ge range ( field curr5t4 ,illu/ration3 ,,fig4 #b1dhf4--;,comp>ison ( ! spe$ curr5t curves & spe$ p[] factor curves ( a typical syn*ron\s1 & induction motor4 ,x w be not$ t ! p[] factor ( ! syn*ron\s motor at />t is high] ?an t ( ! induction motor ow+ to ! high] resi/ance ( ! squirrel cage w9d+4 ,z ! ma*9e approa*es syn*ronism1 h[ev]1 ! magnetiz+ curr5t ( ! induction motor drops to a v mu* l[] value ?an 9 ! syn*ron\s motor & ! p[] factor is consequ5tly mu* high]4 ,! magnetiz+ curr5t ( ! induction motor at full spe$ is usually #be p] c5t4 ( full load curr5t :ile t ( ! syn*ron\s motor is f #bjj to #bej p] c5t4 ( full curr5t1 or ev5 high] :5 runn+ full spe$ & normal voltage4 ,?is ( c\rse is due to ! l>ge air gap on ! syn*ron\s ma*9e4 ,! curr5t at />t ) full voltage appli$ is usually high] 9 an induction motor ow+ to ! fact t ! total imp$ance ( ! /ator & rotor are less due to ! great] di/ribution ( ! w9d+s & ! l[] resi/ance ( ! squirrel cage4 ,! high magnetiz+ curr5t ( a syn*ron\s motor %\ld n be lo/ sight ( z x is a v important consid]ation 9 />t+ ! ma*9e4 ,ev5 ?\gh ! motor c be br\ght practically to syn*ron\s spe$ :ile /ill on ! comp5sator1 if l9e voltage be ?r[n on1 !re w be a v heavy ru% ( curr5t4 ,! obvi\s ?+ to d is to get ! field on ! motor :ile /ill on ! comp5sator1 :5ev] possible1 to avoid ! high magnetiz+ curr5t4 ,?is magnetiz+ curr5t is obvi\sly equal to ! circuit curr5t ( ! ma*9e at no load field4 ,9 "s cases additional torque ne> syn*ronism c be obta9$ by %ort circuit+ ! field w9d+ ?r\gh ! field rheo/at4 ,?is has ! effect ( r$uc+ ! resi/ance ( ! rotor w9d+ to "s ext5t & caus+ ! motor to h less slip ) a giv5 load4 ,! ga9 f ?is s\rce is small1 h[ev]1 9 mo/ cases1 z ! self-inductance ( ! field w9d+ is s high z to all[ v little curr5t to fl[ ev5 if ! field be %ort circuit$ s t ! total effective resi/ance ( ! rotor w9d+ is n mat]ially r$uc$4 ,9 "s cases :]e ! torque is ne>ly suffici5t1 h[ev]1 en\gh ga9 may be obta9$ to take c>e ( ! conditions4 ,if ! field be %ort circuit$ be=e ! motor is />t$ !re w be a r$uction 9 />t+ torque & an increase 9 curr5t f ! l9e1 h5ce if ?is me?od be resort$ to1 arrangem5ts mu/ be made to %ort circuit ! field aft] ! motor has come to con/ant spe$4 ,x is necess>y to possess a ?or\gh k ( ! sy/em1 cov]+ ! g5]at+ capacity 9 en]gy & kva41 av]age & maximum load1 & p[] factor on ! alt]nators1 av]age & maximum load1 & p[] factor on ! fe$]s1 sy/em ( di/ribution1 etc4 ,illu/ration3 ,,fig4 #b1dhg4--;,curves %[+ am\nt ( wattless compon5t requir$ to raise ! p[] factor ( a giv5 kw4 load to requir$ high] value4 ,! wattless compon5ts are express$ z p]c5tages ( ! orig9al kw4 load4 ,! numb]s at ! "r :i* indicate ! po9ts ( tang5cy ( ! p[] factor curves to ! #ajj p] c5t4 l9e1 %[ ! am\nt ( wattless compon5t requir$ to raise a giv5 kw4 load ( giv5 lagg+ p[] factor to unity p[] factor4 ,obvi\sly ! addition ( fur!r wattless compon5t 9 a giv5 case w\ld result 9 a lead+ p[] factor less ?an unity4 ,! desirable location ( a cond5s] is1 ( c\rse1 ne>e/ ! inductive load 9 ord] to avoid ! transmission ( ! wattless curr5t1 b x (t5 happ5s t a sy/em is s int]connect$ t "o l>ge cond5s] _c economically meet ! conditions1 9 :i* case x may be bett] to in/all two or m small] ones4 ,! "q ( suitable att5dance %\ld also be consid]$ &1 = ?is reason1 x may be necess>y to compromise on ! location4 ,:5 ! location ( ! cond5s] has be5 decid$ ^u & ! load & p[] factor )9 its zone det]m9$1 ! prop] size ( cond5s] to raise ! p[] factor to a giv5 value c be f\nd z foll[s3 ,! me?od ( proc$ure c be/ be expla9$ by ref]5ce to a concrete case4 ,assume a load ( #dej kw4 at 4#fe p[] factor4 ,x is desir$ to raise ! p[] factor to 4#i4 ,:at w be ! rat+ ( ! cond5s]8 ,illu/ration3 ,,fig4 #b1dhh4--;,diagram = syn*ron\s cond5s] calculations4 ,ref]r+ to ! diagram1 fig4 #b1dhh1 x is necess>y to />t ) #dej kw4 ,at 4#fe p[] factor1 or #fib kva41 ?is has a wattless lagg+ compon5t ( 7#fib - #dej7 #ebe kva4 ,) ! load un*ang$ & ! p[] factor rais$ to 4#i1 !re w be #ejj app>5t kva41 :i* w h a wattless compon5t ( 7#ejj - #dej7 #bah kva4 ,x is obvi\s t ! cond5s] mu/ supply ! diff]5ce betwe5 #ebe kva4 & #bah kva41 or #cjg kva4 ,a #cjj kva4 cond5s] w\ld1 !re=e1 meet ! requirem5ts4 ,if x be desir$ to drive "s en]gy load ) ! cond5s] & /ill br+ ! total p[] factor to 4#i1 proce$ z indicat$ 9 fig4 #b1dhi4 ,assume a total load ( #aej kw4 on ! motor4 ,z be=e1 #dej kw4 at 4#fe p[] factor1 or #fib kva41 ) a wattless compon5t ( #ebe kva4 ,! en]gy load w be increas$ f #dej to #fjj kw4 z indicat$1 & ) ! p[] factor rais$ to 4#i !re w be a kva4 ( #ffg ) a wattless compon5t ( 7#ffg - #fjj7 #bia4 ,!re mu/ be suppli$ #ebe - #bia #bcd 9 lead+ kva4 ,! syn*ron\s motor !n mu/ supply #aej kw4 en]gy & #bcd kva4 wattless1 :i* w\ld give x a rat+ ( 7#aej #bcd7 #bgh kva4 at 4#fh p[] factor4 ,illu/ration3 ,,fig4 #b1dhi4--;,diagram = syn*ron\s cond5s] calculation = cases :]e x is desir$ to drive "s en]gy load ) ! cond5s] & /ill br+ ! total p[] factor to 4#i4 ,! /&>d #cjj kva4 cond5s] w\ld evid5tly raise ! p[] factor slightly above 4#i p[] factor lead+4 ,by ref]5ce to ! *>t1 fig4 #b1dij1 ! size ( ! requir$ cond5s] c be obta9$ direct )\t ! use ( ! above calculation4 ,! me?od ( us+ ?is curve is z foll[s3 ,assume a load ( say #c1jjj kw4 at 4#g p[] factor & t x be desir$ to raise ! p[] factor to 4#i4 ,run up ! v]tical l9e at #c1jjj kw4 to ! 4#g p[] factor l9e1 & f !re along ! horizontal l9e to ! m>g9 & f9d a wattless compon5t at ?is p[] factor ( #c1jjj kva41 approximately4 ,aga9 run up ! #c1jjj kw4 v]tical l9e to ! 4#i p[] factor l9e & f !re along ! horizontal l9e to ! m>g9 & f9d a wattless compon5t ( #a1ejj kva4 ,! rat+ ( ! cond5s] w !n be #c1jjj kva4 - #a1ejj kva4 #a1ejj kva4 ,?is table ( c\rse c be us$ = hundr$s ( kil[atts z well4 ,illu/ration3 ,,fig4 #b1dij4--;,curve %[+ ! relation ( en]gy load to app>5t load & wattless compon5ts at diff]5t p[] factors4 ,= det]m9+ ! rat+ ( a syn*ron\s motor to drive an en]gy load ?is curve is n s valuable1 al?\gh x c be us$ 9 det]m9+ ! wattless compon5t direct 9 all cases :]e ! en]gy compon5t & p[] factor are kn[n4 ,kn[+ ?is en]gy compon5t & p[] factor or wattless compon5t1 ! en]gy load c obvi\sly be f\nd by ref]r+ to ! curv$ l9es on ! diagrams1 ! curve t crosses ! junction ( ! v]tical en]gy l9e & ! p[] factor or wattless compon5t l9e giv+ ! total app>5t kva4 ,,*apt] ,,lxii ,,indicat+ ,,devices ,alt]nat+ curr5t ammet]s or voltmet]s indicate ! virtual values ( ! curr5t or pressure respectively1 t is to say1 !y indicate1 ! squ>e root ( ! mean squ>e ( a v>iable quantity4 ,illu/ration3 ,,fig4 #b1dia4--,l9e curve ( alt]nat+ curr5t1 illu/rat+ v>i\s curr5t or pressure values4 ,! virtual value1 or 4#gjg maximum value1 is ! value indicat$ by an ammet] or voltmet]4 ,?us1 if ! maximum value ( ! curr5t be #ajj volts1 ! virtual value z indicat$ by an ammet] is #ajj 4#gjg #gj4g amp]es4 ,! virtual value ( an alt]nat+ curr5t or pressure is equival5t to t ( a direct curr5t or pressure :i* w\ld produce ! same effect4 ,= in/ance an alt]nat+ curr5t ( #aj virtual amp]es w produce ! same heat+ effect z #aj amp]es direct curr5t4 ,! relation ( ! virtual value ( an alt]nat+ curr5t to ! o!r values is %[n 9 fig4 #b1dia4 ,:5 ! curr5t foll[s ! s9e law1 ! squ>e root ( ! mean squ>e1 value ( ! s9e functions is obta9$ by multiply+ _! maximum value by #a #b or 4#gjg4 ,illu/ration3 ,,fig4 #b1dib4--,wagn] tubul> alum9um po9t]4 ,! ^w effective is commonly us$ errone\sly = virtual1 ev5 among ! be/ writ]s & ! practice _c be too /rongly condemn$#c4d ,! diff]5ce betwe5 ! two is illu/rat$ 9 ,guide ,no4 #e1 page #a1jac1 fig4 #a1bcg1 ! me*anical analogy "h giv5 may make ! di/9ction m m>k$4 #c ,,note4--,i adh]e to ! t]m virtual1 z x 0 9 use be=e ! t]m efficace :i* 0 recomm5d$ 9 #ahhi by ! ,p>is ,congress to d5ote ! squ>e root ( mean squ>e value4 ,! correspond+ ,engli% adjective is efficaci\s1 b "s eng9e]s mi/ranslate x ) ! ^w effective4 ,i adh]e to ! t]m virtual ma9ly because effective is requir$ 9 its usual mean+ 9 k9ematics to repres5t ! resolv$ "p ( a =ce :i* acts obliquely to ! l9e ( motion1 ! effective =ce be+ ! :ole =ce multipli$ by ! cos9e ( ! angle at :i* x acts ) respect to ! direction ( motion4--,s4 ,p4 ,?ompson4 #d ,,note4--,! au?or adh]es to ! t]m virtual because 9 me*anics ! adjective effective is us$ to d5ote ! diff]5ce ( two oppos+ =ces2 = in/ance1 at any in/ant 9 ! op]ation ( a /eam eng9e1 effective pressure =w>d pressure - back pressure1 h5ce1 to be consi/5t 9 nom5clature1 ! t]m effective _c be us$ = ! =w>d or virtual pressure1 t is1 ! pressure impress$ on an electric circuit4 ,9 ! op]ation ( a /eam eng9e1 !re are two pressures act+ on ! pi/on3 #a4 ,! =w>d pressure2 #b4 ,! back pressure4 ,! =w>d pressure on "o side ( ! pi/on is t due to ! live /eam f ! boil]1 & ! back pressure1 on ! o!r side1 t due to ! resi/ance or opposition enc\nt]$ by ! /eam z x exhau/s f ! cyl9d]4 ,9 ord] t ! eng9e may run & d ext]nal "w1 x is evid5t t ! =w>d pressure mu/ be great] ?an ! back pressure1 & x foll[s t ! pressure available to run ! eng9e is ! diff]5ce betwe5 ^! two pressures1 ?is pressure diff]5ce be+ kn[n z ! effective pressure1 t is to say effective pressure =w>d pressure - back pressure ,?us1 electrically speak+1 ! effective voltage is t voltage :i* is available = driv+ electricity ar\nd ! circuit1 t is1 effective volts virtual volts - back volts virtual pressure - 7virtual pressure - drop7 ,9 ! case ( ! /eam eng9e1 ! =w>d pressure absolute1 t is1 measur$ f a p]fect vacuum is ! virtual pressure 7n consid]+ ! s\rce74 ,! back pressure may v>y widely = diff]5t conditions ( op]ation z illu/rat$ 9 figs4 #b1dic & #b1did4 ,illu/ration3 ,,figs4 #b1dic & #b1did4--,/eam eng9e indicator c>ds1 illu/rat+ 9 me*anical analogy1 ! misuse ( ! t]m effective z appli$ to ! pressure ( an alt]nat+ curr5t4 ,! c>d fig4 #b1dic1 repres5ts ! p]=mance ( a /eam eng9e tak+ /eam at #fj lbs4 7gauge7 pressure & exhau/+ into ! atmosph]e4 ,! exhau/ l9e be+ above ! atmosph]ic l9e %[s t ! friction enc\nt]$ by ! /eam 9 fl[+ ?r\gh ! exhau/ pipe produces a back pressure ( two lbs4 ,h5ce at ! in/ant repres5t$ by ! ord9ate y1 ! effective pressure is #fj - #b #eh lbs41 or us+ absolute pressures1 #gd4g - #af4g #eh lbs41 ! virtual pressure be+ #fj lbs4 gauge1 or #gd4g lbs4 absolute4 ,n[1 ! back pressure may be consid]ably r$uc$ by exhau/+ into a cond5s] z repres5t$ by ! c>d1 fig4 #b1did4 ,"h1 mo/ ( ! pressure ( ! atmosph]e is remov$ f ! exhau/1 & at ! in/ant y1 ! back pressure is only #f lbs41 & ! effective pressure #gd4g - #f #fh4g lbs4 ,?us1 9 ! two cases = ! same virtual pressure ( #fj lbs4 gauge or #gd4g lbs4 absolute1 ! effective pressures are #eh lbs4 & #fh4g lbs4 respectively4 ,9 ! measurem5t ( alt]nat+ curr5t1 x is n ! av]age1 or maximum value ( ! curr5t wave t def9es ! curr5t comm]cially1 b ! squ>e root ( ! mean squ>e value1 because ?is gives ! equival5t heat+ effect ref]r$ to direct curr5t4 ,!re are sev]al types ( in/rum5t = measur+ alt]nat+ curr5t1 & !y may be classifi$ z #a4 ,electromagnetic 7mov+ iron72 #b4 ,hot wire2 #c4 ,induction2 #d4 ,dynamomet]4 ,electromagnetic or ,mov+ ,iron ,in/rum5ts4--,?is type ( in/rum5t dep5ds = its action ^u ! pull ( flux 9 endeavor+ to r$uce ! reluctance ( its pa?4 ,?is pull is proportional to ! product ( ! flux & ! curr5t1 & s long z no "p ( ! magnetic circuit becomes saturat$1 ! flux is proportional to ! curr5t1 h5ce ! pull is proportional to ! squ>e ( ! curr5t to be measur$4 ,illu/ration3 ,,fig4 #b1die4--;,a calibrat$ scale4 ,?is means t pr9t$ scales are n employ$1 b ea* in/rum5t has its scale divisions plott$ by actual comp>ison ) /&>ds1 aft] :i* ! division l9es are ink$ 9 by a draughtsman4 ,!re are makes ( direct curr5t in/rum5ts employ+ pr9t$ scales 9 :i* ! scale deflections are fairly accurate1 ev5 ?\gh ! scales are pr9t$1 b pr9t$ scales %\ld n be us$ on alt]nat+ curr5t in/rum5ts4 ,ques4 ,:at are "s objections to mov+ iron in/rum5ts8 ,ans4 ,in/rum5ts ( ?is type are n indep5d5t ( ! frequ5cy1 wave =m1 or temp]ature & ext]nal magnetic fields may affect ! read+s tempor>ily4 ,illu/ration3 ,,fig4 #b1dig4--,plung] =m ( electromagnetic or mov+ iron type ( ammet]4 ,!re are sev]al =ms ( mov+ iron ammet]s1 :i* may be classifi$ z #a4 ,plung]2 #b4 ,incl9$ coil2 #c4 ,magnetic vane4 ,ques4 ,describe ! plung] type4 ,ans4 ,?is type ( ammet] consi/s ( a s]ies coil & a s(t iron plung] =m+ a sol5oid1 ! plung] is s susp5d$ t ! magnetic pull due to ! curr5t fl[+ ?r\gh ! coil is balanc$ by gravity1 z %[n 9 fig4 #b1dig4 ,ques4 ,h[ %\ld ! plung] be con/ruct$ to adapt x to alt]nat+ curr5t1 & :y8 ,ans4 ,x %\ld be lam9at$ to avoid eddy curr5ts4 ,illu/ration3 ,,fig4 #b1dig4--,"o =m ( plung] in/rum5t z made by ,siem5s4 ,x has gravity control1 is dead beat1 & is %ield$ f ext]nal magnetic influ5ce4 ,! mov+ sy/em consi/s ( a ?9 s(t iron pe> %ap$ plate ,i pivot$ on a horizontal sp9dle ,s runn+ 9 jewell$ c5t]s4 ,to ?is sp9dle ,s is also atta*$ a light po9t] ,p & a light wire ,w1 b5t z %[n1 & c>ry+ a light pi/on ,d1 :i* works 9 a curv$ air tube ,t4 ,?is tube ,t is clos$ at ! end ,b b fully op5 at ! o!r ,a1 & con/itutes ! air damp+ device = mak+ ! in/rum5t dead beat4 ,ques4 ,:at is ! "* ( ! scale & h[ %\ld x be con/ruct$8 ,ans4 ,! scale is n uni=m & %\ld be h& made & calibrat$ "u ! conditions :i* x is to be us$4 ,ques4 ,:at is ! objection to mov+ iron ammet]s8 ,ans4 ,s9ce ! coil c>ries ! entire curr5t !y are l>ge & exp5sive4 ,ques4 ,:at precaution %\ld be tak5 9 in/all+ mov+ iron ammet]s8 ,ans4 ,s9ce gravity is ! controll+ =ce1 ! in/rum5t %\ld be c>efully levell$4 ,ques4 ,describe an incl9$ coil in/rum5t4 ,ans4 ,x consi/s ( a coil m\nt$ at an angle to a %aft c>ry+ ! vane & po9t]1 z %[n 9 fig4 #b1dih4 ,a spr+ =ms ! controll+ =ce & holds ! po9t] at z]o :5 no curr5t is fl[+4 ,illu/ration3 ,,fig4 #b1dih4--;,incl9$ coil =m ( electromagnetic or mov+ iron in/rum5t4 ,ques4 ,:at is ! pr9ciple ( op]ation ( ! incl9$ coil in/rum5t8 ,ans4 ,:5 a curr5t is pass$ ?r\gh ! coil1 ! iron t5ds to take up a position ) its longe/ sides p>allel to ! l9es ( =ce1 :i* results 9 ! %aft be+ rotat$ & ! po9t] mov$ on ! dial1 ! am\nt ( movem5t dep5d+ ^u ! /r5g? ( ! curr5t 9 ! coil4 ,ques4 ,describe a magnetic vane in/rum5t4 ,ans4 ,x consi/s ( a small piece ( s(t iron or vane m\nt$ ,illu/ration3 ,,fig4 #b1dii4--,magnetic vane =m ( electromagnetic or mov+ iron in/rum5t4 ,illu/ration3 ,,fig4 #b1ejj4--,magnetic vane movem5t ( a ,wagn] in/rum5t2 x is us$ bo? = voltmet]s & ammet]s4 ,?is type diff]s f ! dynamomet] movem5t 9 t a vane ( v s(t iron replaces ! mov+ coil4 ,! magnetic vane movem5t makes use ( its controll+ spr+ only = ! purpose ( resi/+ ! pull on ! vane & ! return+ ( ! ne$le to z]o4 ,! spr+ does n c>ry any curr5t4 on a %aft t is pivot$ a little (f ! c5t] ( a coil z %[n 9 fig4 #b1dii1 & c>ry+ a po9t] :i* moves ov] a scale4 ,ques4 ,h[ does x "w8 ,ans4 ,its pr9ciple ( op]ation is t a piece ( s(t iron plac$ 9 a magnetic field & free to move1 w move into su* position z to conduct ! maximum numb] ( l9es ( =ce4 ,! curr5t to be measur$ is pass$ ar\nd ! coil1 produc+ a magnetic field ?r\gh ! c5t] ( ! coil4 ,! magnetic field inside ! coil is /ronge/ ne> ! inn] edge1 h5ce1 ! vane w move aga9/ ! re/ra9+ =ce ( a spr+ s t ! di/ance betwe5 x & ! inn] edge ( ! coil w be z small z possible4 ,illu/ration3 ,,fig4 #b1eja4--,sol5oid & plung] illu/rat+ ! op]ation ( mov+ iron in/rum5ts4 ,:5 a curr5t fl[s ?r\gh ! coil1 a field is set up z indicat$ by ! dott$ l9es ( =ce4 ,! curr5t fl[+ 9 ! direction indicat$ by ! arr[ induces a nor? pole at ,n1 :i* 9 turn induces a s\? pole 9 ! plung] at ,s1 ?us attract+ ! plung]4 ,! effect ( ! field ^u ! plung] may also be /at$ by say+ t x t5ds to cause ! plung] to move 9 a direction s z to conduct ! maximum numb] ( l9es ( =ce1 t is1 t[>d ! sol5oid4 ,?us if ,,abcd be ! initial position ( ! plung] only five l9es ( =ce pass ?r\gh x3 %\ld x move to ! position ,a,b,c,d1 ! numb] ( l9es pass+ ?r\gh x w !n be #i1 assum+ ! field to rema9 un*ang$4 ,! op]ation ( mov+ iron in/rum5ts ( ! plung] type may be expla9$ by say+ t ! curr5t fl[+ 9 ! coil produces a pole at its end & induces an unlike pole at ! end ( ! plung] ne>e/ ! coil1 ?us attract+ ! plung]1 z illu/rat$ 9 fig1 #b1eja above4 ,illu/ration3 ,figs1 #b1ejb & #b1ejc4--,wagn] s]ies trans=m]s4 ,fig4 #b1ejb1 w\nd prim>y s]ies trans=m]2 fig4 #b1ejc1 op5 prim>y trans=m]4 ,wagn] s]ies trans=m]s are made 9 ?ree g5]al types3 ,"o = swit*bo>d m\nt+ ) w\nd prim>y2 "o = swit*bo>d m\nt+ ) op5 prim>y1 & "o ) op5 prim>y suitable = slipp+ ov] bus b>s or swit* /ud4 ,^! trans=m]s h #e amp]e second>y w9d+1 & are int5d$ = use 9 connection ) in/rum5t ( scale capacity #j-e1 al?\gh ! scale %\ld be calibrat$ to indicate ! prim>y curr5t4 ,! capacities are f #b watts to #ej watts1 be+ suitable = op]ation on circuits ( #gej to #ff1jjj volts4 ,hot ,wire ,in/rum5ts4--,in/rum5ts ( ?is class dep5d = _! op]ation on ! expansion & contraction ( a f9e wire c>ry+ ei!r ! curr5t to be measur$ or a def9ite proportion ( t curr5t4 ,! expansion or contraction ( ! wire is caus$ by temp]ature *anges1 :i* 9 turn are due to ! heat+ effect ( ! curr5t fl[+ ?r\gh ! wire4 ,s9ce ! v>iations 9 ! l5g? ( ! wire are extremely small1 consid]able magnification is necess>y4 ,pulleys or lev]s are sometimes us$ to multiply ! motion1 & sometimes ! d\ble sag arrangem5t %[n 9 fig4 #b1ejd4 ,z %[n "h1 ,a is ! active wire c>ry+ ! curr5t to be measur$ & /ret*$ betwe5 ! t]m9als ,t & ,t4 ,x is pull$ taut at its middle po9t by ano!r wire ,c1 :i* c>ries no curr5t1 & is1 9 its turn1 kept tight by a ?read pass+ r\nd ! pulley ,d atta*$ to ! po9t] sp9dle1 ! :ole sy/em be+ kept 9 t5sion by ! spr+ ,e4 ,hot wire in/rum5ts are equally accurate ) alt]nat+ or direct curr5t1 b h cramp$ scales 7s9ce ! deflection is proportional to ! squ>e ( ! curr5t71 & are liable to creep ow+ to unequal expansion ( ! p>ts4 ,!re is also ! dang] t !y may be burnt out ) ev5 comp>atively small ov]loads4 ,!y are n affect$ by magnetic fields b consume m curr5t ?an ! o!r types1 ^! read+s are inaccurate ne> ei!r end ( ! scale4 ,illu/ration3 ,,fig4 #b1ejd4--;,diagram illu/rat+ ! pr9ciple ( hot wire in/rum5ts4 ,! ess5tial p>ts are ! active wire ,a1 /ret*$ betwe5 t]m9als ,t & ,t1 t5sion wire ,c1 ?read ,e1 & pulley ,d to :i* is atta*$ ! po9t]4 ,induction ,in/rum5ts4--,^! 7 inv5t$ by ,f]r>is1 & are sometimes call$ aft] him4 ,!y are = alt]nat+ curr5t only1 & !re are two =ms3 #a4 ,%ield$ pole type2 #b4 ,rot>y field type4 ,ques4 ,describe ! %ield$ pole type ( induction in/rum5t4 ,ans4 ,z %[n 9 figs4 #b1eje1 & #b1ejf x consi/s1 ess5tially ( a disc ,a1 or sometimes a drum & a lam9at$ magnet ,b4 ,cov]+ "s two-?irds ( ! pole faces are two copp] plates or %ields ,c1 & a p]man5t magnet ,d4 ,illu/ration3 ,,figs4 #b1eje & #b1ejf4--,plan & elevation ( %ield$ pole type ( induction in/rum5t4 ,ques4 ,h[ does x "w8 ,ans4 ,eddy curr5ts are induc$ 9 ! two copp] plates or %ields ,c1 :i* attract ^? 9 ! disc1 produc+ 9 consequ5ce a torque 9 ! direction %[n by ! arr[1 aga9/ ! oppos+ action ( a spr+4 ,magnet ,d damps ! oscillations4 ,illu/ration3 ,,fig4 #b1ejg4--;,diagram %[+ con/ruction & op]ation ( ,hosk9s in/rum5t4 ,x is ( ! modifi$ induction type 9 :i* ! torque is produc$ f ! direct repulsion betwe5 a prim>y & a second>y1 or induc$ curr5t4 ,z %[n 9 ! diagram1 ! in/rum5t embodies ! pr9ciple ( a %ort circuit$ trans=m]1 consi/+ ( a prim>y or excit+ coil ,a1 a second>y or clos$ coil ,b1 l9k$ 9 inductive relation to ! prim>y by a lam9at$ iron core ,c1 con/ruct$ to give a completely clos$ magnetic circuit1 t is1 )\t air gap4 ,! second>y is s m\nt$ ) respect to ! prim>y z to h a movem5t "u ! influ5ce ( _! mutual repulsion :5 ! prim>y is trav]s$ by an alt]nat+ curr5t4 ,?is movem5t ( ! second>y ,b is oppos$ by a spiral spr+1 s t ! ext5t ( movem5t w be dep5d5t ^u & w indicate ! /r5g? ( ! prim>y curr5t4 ,to increase ! s5sitiv5ess ( ! in/rum5t & also to adju/ ! cont\r ( ! scale1 an adju/able second>y ,d1 :i* has an attraction effect ^u ! coil ,b1 is provid$ ^u ! core4 ,! effect ( ?is coil is inv]sely proportional to its di/ance f ! end ( ! sw+ ( ! coil ,b4 ,! vane1 ,e1 :i* is a "p ( ! /amp+ ,b1 is adju/$ to sw+ freely & ) a l>ge am\nt ( cle>ance1 betwe5 ! poles ( a p]man5t magnet ,f1 :i* acts z a damp] on ! oscillation ( ! mov+ elem5t1 b does n cause any friction or affect ! accuracy ( ! calibration4 ,! prim>y1 l t ( a trans=m]1 is an indep5d5t electrical circuit & may be highly insulat$4 ,?is met] w )/& sev]al hundr$ p] c5t4 ov]load = "s "t because ( ! v high value ( ! self-induction & ! fact t ! controll+ spr+ is n 9 ! circuit & !re=e _c burn (f4 ,illu/ration3 ,,figs4 #b1ejh to #b1eaa4--;,hosk9s in/rum5ts4 ,fig4 #b1ejh1 voltmet]1 small patt]n2 fig4 #b1eji1 ammet]1 l>ge patt]n2 fig4 #b1eaj1 voltmet]1 horizontal edgewise patt]n2 fig4 #b1eaa1 illum9at$ dial voltmet]4 ,ques4 ,describe ! rot>y field type ( induction in/rum5t4 ,ans4 ,! p>ts are arrang$ simil> to ^? ( wattmet]s1 ! necess>y split phase be+ produc$ by divid+ ! curr5t into two circuits1 "o inductive & ! o!r non-inductive4 ,illu/ration3 ,,fig4 #b1eab4--;,hosk9s in/rum5t ) case remov$4 ,x has a v %ort magnetic circuit :i* is compos$ ( silicon /eel1 p]mitt+ l[ magnetic d5sities to be us$4 ,dynamomet]s4--,?is type ( in/rum5t is us$ to measure volts1 amp]es1 or watts1 & its op]ation dep5ds on ! reaction betwe5 two coils :5 ! curr5t to be measur$ is pass$ ?r\gh !m4 ,"o ( ! coils is fix$ & ! o!r movable4 ,illu/ration3 ,,fig4 #b1eac4--;,diagram ( ,siem5s' dynamomet]4 ,x consi/s ( two coils on a common axis b set 9 planes at "r angles to ea* o!r 9 su* a way t a torque is produc$ betwe5 ! two coils :i* measures ! product ( _! curr5ts4 ,?is torque is measur$ by twi/+ a spiral spr+ ?r\gh a measur$ angle ( su* degree t ! coils %all resume _! orig9al relative positions4 ,:5 con/ruct$ z a voltmet]1 bo? coils are w\nd ) a l>ge numb] ( turns ( f9e wire1 mak+ ! in/rum5t s5sitive to small curr5ts4 ,!n by connect+ a high resi/ance 9 s]ies ) ! in/rum5t x c be connect$ across ! t]m9als ( a circuit ^: voltage is to be measur$4 ,:5 con/ruct$ z a wattmet]1 "o coil is w\nd s z to c>ry ! ma9 curr5t & ! o!r made ) _m turns ( f9e wire ( high resi/ance suitable = connect+ across ! circuit4 ,illu/ration3 ,,fig4 #b1ead4--,wagn] dynamomet] movem5t4 ,9 ?is type ( in/rum5t ! deflection is proportional to ! squ>e ( ! curr5t1 produc+ a con/antly decreas+ s5sitiv5ess z ! pressure appli$ is decreas$4 ,! dynamomet] movem5t is1 = any indication1 m accurate ?an ! magnetic vane1 b _c readily be employ$ = ! indication ( curr5t1 z requir$ 9 ammet]s4 ,ques4 ,describe ! con/ruction ( a dynamomet]4 ,ans4 ,x consi/s1 z %[n 9 fig4 #b1eac1 ( a fix$ coil1 compos$ ( a numb] ( turns ( wire1 & fa/5$ to a v]tical support4 ,! fix$ coil is surr\nd$ by a movable coil compos$ ( a few numb] ( turns or (t5 ( only "o turn ( wire4 ,! movable coil is susp5d$ by a ?read & a spiral spr+ atta*$ to a tortive head :i* passes ?r\gh ! c5t] ( a dial4 ,! ends ( ! movable coil dip into m]cury cups1 :i* act z pivots & electrical contacts1 mak+ connection ) "o end ( ! fix$ coil & "o t]m9al ( ! in/rum5t z %[n4 ,! tortion head c be turn$ s z to place ! planes ( ! coils at "r angles to ea* o!r & to apply tortion to ! spr+ to oppose ! deflection ( ! movable coil = ?is position :5 a curr5t is pass$ ?r\gh ! coils4 ,a po9t] atta*$ to ! movable coil indicates its position on ! graduat$ dial betwe5 ! two /ops4 ,ano!r po9t] atta*$ to ! tortion head p]=ms a simil> function4 ,illu/ration3 ,,fig4 #b1eae4--;,armature ( ,wagn] dynanomet] movem5t4 ,great] accuracy is claim$ = ?is movem5t ?an ! magnetic vane1 b x _c readily be employ$ = ! indication ( curr5t fl[1 z requir$ 9 ammet]s4 ,! magnetic vane movem5t is us$ on ! ,a4 ,c4 ammet]1 & c be us$ also 9 ! ,a4 ,c4 voltmet]s2 x makes use ( its controll+ spr+ only = ! purpose ( resi/+ ! pull on ! vane & ! return+ ( ! po9t] to z]o4 ,! dynanomet] movem5t is recomm5d$ = voltmet]s4 ,illu/ration3 ,,fig4 #b1eaf4--,wagn] #be watt pressure trans=m] = use ) v>i\s alt]nat+ curr5t in/rum5ts1 su* z voltmet]s1 wattmet]s1 etc4 ,!y are made 9 capacities #be1 #ej1 #ajj1 & #bjj watts1 & are built = pressures ( #gej to #fj1jjj volts4 ,ques4 ,h[ does ! dynamomet] op]ate8 ,ans4 ,:5 curr5t is pass$ ?r\gh bo? coils1 ! movable coil is deflect$ aga9/ "o ( ! /op p9s1 !n ! tortion head is turn$ to oppose ! movem5t until ! deflection has be5 ov]come & ! coil br\ght back to its orig9al position4 ,illu/ration3 ,,fig4 #b1eag4--,mov+ elem5t ( ,key/one dynamomet] in/rum5t4 ,! illu/ration %[s ! movable coil1 po9t]1 alum9um air vane = damp+ ! oscillations1 controll+ spr+s1 & c\nt] weights4 ,illu/ration3 ,,fig4 #b1eah4--,key/one dynamomet] movem5t4 ,s9ce ! law gov]n+ ?is type ( in/rum5t is ! law ( curr5t squ>es1 x foll[s t 9 ! case ( voltmet]s1 equally divid$ scales _c be obta9$4 ,9 ! case ( wattmet]s1 ! scale is approximately equally divid$1 due to ! fact t ! movem5t ( ! mov+ coil is proportional to ! product ( ! curr5t 9 ! fix$ & mov+ coils4 ,! mov+ p>ts h be5 made z light 9 weight z is consi/5t ) me*anical /r5g?1 & ! entire mov+ sy/em is support$ on jewel$ be>+s4 ,! motion ( ! po9t] is r5d]$ ap]iodic by ! use ( an alum9um air vane mov+ 9 a p>tially enclos$ air *amb]4 ,?is me?od ( damp+ ! oscillations ( ! mov+ p>ts r5d]s unnecess>y ! use ( me*anical brakes or o!r frictional devices1 :i* t5d to impair ! accuracy ( ! in/rum5t4 ,! illu/ration %[s a voltmet]1 :i*1 h[ev]1 diff]s b little f a wattmet]4 ,9 ! case ( a wattmet] ! fix$ coils are connect$ 9 s]ies ) ! l9e1 ei!r directly or ?r\gh a curr5t trans=m]1 :ile ! mov+ coil is connect$ 9 %unt to ! l9e4 ,! angle ?r\gh :i* ! tortion head 0 turn$1 be+ proportional to ! squ>e root ( ! angle ( tortion1 ! curr5t /r5g? 9 amp]es is equal to ! squ>e root ( ! angle ( tortion multipli$ by a calculat$ con/ant1 furni%$ by ! mak] ( ! in/rum5t4 ,ques4 ,h[ is ! dynamomet] arrang$ to measure watts8 ,ans4 ,:5 measur+ watts1 ! in/rum5t %\ld be s arrang$ t "o coil c>ries ! ma9 curr5t1 & ! o!r a small curr5t :i* is proportional to ! pressure4 ,illu/ration3 ,,fig4 #b1eai4--,le$s & ,nor?rup electro-dynamomet]4 ,x is a reliable in/rum5t = ! measurem5t ( alt]nat+ curr5ts ( comm]cial frequ5cies4 ,:5 w\nd ) f9e wire & us$ 9 connection ) prop]ly w\nd resi/ances1 x is equally useful = measur+ alt]nat+ pressures1 & may ?us be employ$ to calibrate alt]nat+ curr5t voltmet]s z well z ammet]s4 ,to give accurate results ! in/rum5ts mu/ be c>efully con/ruct$ & design$ ) a view to avoid+ ! eddy curr5ts always set up by alt]nat+ curr5ts 9 masses ( metal ne>1 or 9 ! circuits4 ,! con/ant ( a dynamomet] may be obta9$ ) a pot5tiomet]1 b ?is is usually done ) precision by ! manufactur] & a c]tificate giv+ ! value ( ! con/ant is furni%$ ) ! in/rum5t4 ,! size & co/ ( dynamomet]s rapidly increase ) ! maximum curr5ts :i* !y are design$ to c>ry1 & :5 m ?an #ejj amp]es are to be measur$1 ! use ( o!r in/rum5ts & me?ods is recomm5d$4 ,ques4 ,9 ! con/ruction ( a dynamomet] :at mat]ial %\ld n be us$ & :y8 ,ans4 ,no iron or o!r magnetic mat]ial %\ld be employ$ because ( ! hy/]esis losses occasion$ !reby4 ,! frame %\ld be ( non-conduct+ mat]ial s z to avoid eddy curr5ts4 ,illu/ration3 ,,figs4 #b1ebj to #b1ebf4--,v>i\s types ( ,wagn] in/rum5ts4 ,fig4 #b1ebj1 small r\nd type2 fig4 #b1eba1 horizontal edgewise type2 fig4 #b1ebb1 smalle/ swit*bo>d type2 fig4 #b1ebc1 portable type2 fig4 #b1ebd1 comb9ation voltmet] & ammet] 9 "o case2 fig4 #b1ebe1 v]tical type2 fig4 #b1ebf1 polyphase type4 ,watt ,h\r ,met]s4--,a watt h\r met] is a watt met] t w regi/] ! watt h\rs exp5d$ dur+ an int]val ( "t4 ,watt h\r met]s are (t5 errone\sly call$ record+ or integrat+ watt met]s4 ,!re are sev]al types ( ! electromotor =m ( watt h\r met]1 :i* may be classifi$ z #a4 ,commutator type2 #b4 ,induction type2 #c4 ,f>aday disc type4 ,illu/ration3 ,,fig4 #b1ebg--;,int]ior ,we/on s+le phase wattmet]4 ,! g5]al appe>ance ( ! dynamomet] movem5t & ! relative positions ( ! v>i\s p>ts are cle>ly %[n4 ,! p>ts are assembl$ on "o base1 ! :ole movem5t be+ removable by unfa/5+ two bolts4 ,! fix$ w9d+ is made up ( two coils1 :i* toge!r produce ! field ( ! wattmet]4 ,! movable coil is w\nd to gauge ) silk cov]$ wire & treat$ ) cem5t4 ,:ile w9d+1 ! coil is spread at diametrical po9ts to all[ ! ins]tion ( ! /aff1 :i* is c5t]$ by means ( two curv$ plates cem5t$ to ! inside surface ( ! coil & =m+ a "p !re(4 ,! coil is held 9 a def9ite position by two t9y p9s :i* pass ?r\gh ! /aff & engage ) e>s on ! curv$ plates4 ,illu/ration3 ,,fig4 #b1ebh4--,we/+h\se s+le phase induction type watt h\r met] remov$ f case4 ,! friction comp5sation1 or light load adju/m5t1 is accompli%$ by slightly unbalanc+ ! two legs ( ! %unt magnetic circuit4 ,to d ?is a %ort circuit$ loop is plac$ 9 ea* air gap1 & means are provid$ = adju/+ ! position ( ! loops s t "o loop w enclose & *oke back m ( ! flux ?an ! o!r loop1 & ?us produce a slight torque4 ,x w be not$1 t ?is torque dep5ds on voltage alone1 :i* is practically con/ant1 & is entirely indep5d5t ( ! load4 ,adju/m5t is accompli%$ by means ( ei!r ( two screws :i* makes micromet] adju/m5t possible4 ,x is clamp$ :5 adju/$ by means ( a set screw1 :i* prev5ts *ange4 ,?is me?od makes possible an accuracy ( adju/m5t :i* effectively prev5ts creep+4 ,! p[] factor adju/m5t consi/s ( an adju/able comp5sat+ coil plac$ ar\nd ! %unt pole tip4 ,?is is adju/$ at ! factory by twi/+ toge!r ! leads ( ! comp5sat+ coil1 ?us alt]+ its resi/ance until ! desir$ lagg+ effect is _h4 ,frequ5cy adju/m5t4 #acc cycle met]s are fir/ calibrat$ on #fj cycles & ! leads !n untwi/$ to make !m correct on #acc cycles4 ,to *ange su* a met] = use on #fj cycles x is necess>y only to retwi/ ^! leads to ! po9t %[n by ! condition ( ! wire4 ,ques4 ,:at are ! ess5tial p>ts ( a watt h\r met]8 ,ans4 ,a motor1 g5]ator1 & c\nt+ me*anism4 ,illu/ration3 ,,fig4 #b1ebi4--,po9t] & movable sy/em ( ,we/on wattmet]4 ,! coil is describ$ 9 fig4 #b1ebg4 ,! po9t] consi/s ( a triangul> truss ) tubul> memb]s1 an index tip ( v ?9 metal be+ m\nt$ at its extremity4 ,! index tip is re9=c$ by a rib /amp$ into ! metal4 ,! po9t] is p]man5tly jo9$ to a balance cross1 consi/+ ( a flat c5t] web1 provid$ ) two %ort arms & "o long arm1 ea* arm c>ry+ a nut by means ( :i* ! balance ( ! sy/em may be adju/$4 ,! longe/ arm1 :i* is opposite ! po9t]1 c>ries a balance nut1 consi/+ ( a ?9 wall$ sleeve provid$ ) a relatively l>ge flange at its out] end4 ,! sleeve is tapp$ ) #bgb ?reads to ! in*1 ! int]nal diamet] ( ! sleeve be+ made slightly small] ?an ! outside diamet] ( ! screw1 & ! sleeve is split l5g?wise2 !re=e :5 sprung into place & prop]ly adju/$ x w rema9 p]man5tly 9 position4 ,a sleeve :i* is =c$ ov] ! end ( ! /aff c>ries ! po9t] firmly clamp$ betwe5 a flang$ %\ld] & a nut4 ,by p]=at+ ! web plate ( ! balance cross ) a hole hav+ two flat sides t fit snugly ov] a simil>ly %ap$ portion ( ! sleeve1 ! po9t] is giv5 a def9ite & p]man5tly fix$ angul> position4 ,! air damp]consi/s ( two v light symmetrically dispos$ vanes1 :i* are enclos$ 9 *amb]s made z ne>ly air tight z possible4 ,^! vanes are =m$ ( v ?9 metal /iff5$ by ribs1 /amp$ into !m & by ! edges1 :i* are b5t ov] to con=m to ! surface ( ! side walls ( ! *amb]s4 ,!y are atta*$ by metal eyelets to a cross b> c>ri$ on a sleeve simil> 9 con/ruction to ! "o at ! upp] end ( ! /aff4 ,?is cross b> is held 9 place by a nut1 & is provid$ at ! c5t] ) a hole hav+ two flat sides1 be+ simil> 9 %ape to ! "o 9 ! balance cross4 ,?is hole likewise fits ov] a sleeve & def9itely locates ! vanes ) ref]5ce to ! o!r p>ts ( ! sy/em4 ,! damp] box is ca/ 9 "o piece to =m ! base t c>ries ! field coils & ! movable sy/em4 ,ques4 ,:at is ! function ( ! motor8 ,ans4 ,s9ce ! motor runs at a spe$ proportional to ! en]gy pass+ ?r\gh ! circuit1 x drives ! c\nt+ me*anism at ! prop] spe$ to indicate ! am\nt ( en]gy consum$4 ,ques4 ,:at is ! object ( ! g5]ator8 ,ans4 ,x furni%es a suitable c\nt] torque or load = ! motor4 ,illu/ration3 ,,fig4 #b1ecj4--,we/+h\se polyphase induction type watt h\r met]1 cov]s remov$4 ,?is type is made = two phase ?ree wire & f\r wire1 & ?ree phase ?ree wire & f\r wire circuits4 ,met]s = circuits ( m ?an #cjj amp]es or #ejj volts require trans=m]s1 b1 l ! self-conta9$ met]s1 are calibrat$ to read directly 9 kil[att h\rs on ! dial1 )\t a multiply+ con/ant4 ,ques4 ,is !re any o!r resi/ance to be ov]come by ! motor8 ,ans4 ,x mu/ ov]come ! friction ( all ! mov+ p>ts4 ,ques4 ,is ! friction con/ant8 ,ans4 ,no4 ,illu/ration3 ,,figs4 #b1eca to #b1ecc4--;,diagram ( electromagnetic circuit ( ,we/+h\se induction type watt h\r met]1 & diagram %[+ rotation ( field4 ,! dott$ l9es %[ ! ma9 pa?s ( ! magnetic flux produc$ by ! two w9d+s1 ! directions1 h[ev]1 are con/antly rev]s+ ow+ to ! alt]nations ( ! curr5t 9 ! coils4 ,d5ot+ ! %unt & s]ies pole tips by ! lett]s z %[n1 a cle> /atem5t ( ! relation ( ! fields = ea* qu>t] p]iod may be giv54 ,! signs & - repres5t ! in/antane\s values ( ! poles indicat$4 ,?us1 at "o in/ant ! %unt pole tips ,a1 ,c1 & ,a are maximum 1 -1 & 1 respectively because ! in/antane\s value ( ! curr5t is maximum1 :ile ! value ( ! s]ies flux is z]o4 ,at p]iod lat] ! %unt curr5t is z]o1 giv+ z]o magnetic pressure at ! pole tips1 :ile ! s]ies curr5t has rea*$ a maximum value1 giv+ maximum-& at ! pole tips ,b & ,d4 ,at ! next p]iod ! %unt curr5t is aga9 maximum1 b 9 a direction opposite to :at x 0 at ! beg9n+1 mak+ ! pole tips ,a1 ,c1 & ,a 1 -1 & 1 respectively1 :ile ! s]ies curr5t aga9 is z]o1 etc41 ! values = ! complete cycle be+ giv5 9 fig4 #b1ecc4 ,x w be obs]v$ f ! table t bo? ! & - signs move con/antly 9 ! direction f ,a to ,a1 indicat+ a %ift+ ( ! field 9 ?is direction1 ! process be+ repeat$ dur+ ea* cycle4 ,ques4 ,:at provision is made to correct ! error due to friction8 ,ans4 ,! met] is comp5sat$ by excit+ an adju/able auxili>y field f ! %unt or pressure circuit4 ,ques4 ,:at is ! con/ruction ( ! g5]ator8 ,ans4 ,9 ne>ly all met]s x consi/s ( a copp] or alum9um disc c>ri$ on ! same %aft ) ! motor & rotat$ 9 a magnetic field ( con/ant value4 ,ques4 ,h[ is ! c\nt] torque produc$8 ,ans4 ,:5 ! disc is rotat$ 9 ! magnetic field1 eddy curr5ts are induc$ 9 ! disc 9 a direction to oppose ! motion :i* produces !m4 ,ques4 ,= :at s]vices is ! commutator type met] us$8 ,ans4 ,x is us$ on bo? direct & alt]nat+ curr5t circuits4 ,illu/ration3 ,,figs4 #b1ecd & #b1ece4--;,cross section ( be>+s ( ,we/+h\se induction type watt h\r met]4 ,! l[] be>+ consi/s ( a v highly poli%$ & h>d5$ /eel ball re/+ betwe5 two sapphire cup jewels1 "o fix$ 9 ! end ( ! be>+ screw & ! o!r m\nt$ 9 a removable sleeve on ! end ( ! %aft4 ,ow+ to ! m9ute gyrations ( ! %aft ! ball has a roll+ action1 :i* n only makes a l[] friction coeffici5t ?an ! usual rubb+ action1 b pres5ts con/antly new be>+ surfaces & ?us produces long life4 ,! upp] be>+ is only a guide be>+ to keep ! %aft 9 a v]tical position1 & is subject to virtually no pressure1 & consequ5tly little friction4 ,x consi/s ( a /eel p9 fa/5$ to a removable screw & project+ d[n into a bu%+ 9 a recess drill$ 9 ! %aft4 ,! bottom ( ?is recess is fill$ ) billi>d clo? saturat$ ) wat* oil4 ,a film ( oil is ma9ta9$ ar\nd ! p9 by capill>y action4 ,ques4 ,:at is ! objection to ! commutator met]8 ,ans4 ,! complication ( commutator & bru%es1 & ! fact t ! friction ( ! bru%es is likely to affect ! accuracy ( ! met]4 ,illu/ration3 ,,fig4 #b1ecf4--;,diagram ( ,=t ,wayne1 induction watt h\r met]4 ,x is design$ to regi/] ! en]gy ( alt]nat+ curr5t circuits reg>dless ( ! p[] factor1 & embodies ! usual induction motor1 eddy curr5t g5]ator & regi/]+ me*anism4 ,! electrical arrangem5t ( ! met] consi/s ( a curr5t circuit compos$ ( two coils connect$ 9 s]ies ) ea* o!r & 9 s]ies ) ! l9e to be measur$1 & a pressure circuit consi/+ ( a reactance coil & a pressure coil connect$ 9 s]ies ) ea* o!r & across ! l9e to be measur$4 ,9 addition1 ! pressure circuit conta9s a light load coil w\nd ov] a lam9at$ %eet /eel memb]1 adju/ably arrang$ 9 ! core ( ! pressure coil & connect$ across a small numb] ( turns ( ! reactance coil s z to give a field sub/antially 9 phase ) ! impress$ pressure4 ,! light load w9d+ is fur!r provid$ ) a s]ies adju/able resi/ance furni%$ = ! purpose ( regulat+ ! curr5t fl[+ 9 ! light load w9d+1 !reby provid+ a means ( lagg+ ! met] on high frequ5cies1 su* z #abe or #adj cycle circuits4 ,! pressure circuit also comprises a lag coil w\nd ov] ! upp] limb ( ! core ( ! pressure circuit & provid$ ) an adju/able resi/ance = obta9+ a held compon5t 9 quadrature ) ! %unt field4 ,ques4 ,:at are its *>act]i/ics8 ,ans4 ,x is indep5d5t ( p[] factor1 wave =m1 & frequ5cy :5 no iron is us$ 9 ! motor4 ,ques4 ,:at met] is *iefly us$ on ,a4 ,c4 circuits8 ,ans4 ,! induction met]4 ,illu/ration3 ,,fig4 #b1ecg4--;,=t ,wayne multiphase induction watt h\r met]4 ,! con/ruction ( ! me*anism is ess5tially two s+le phase motor elem5ts1 "o at ! bottom ( ! met] 9 a suitable position1 ! o!r inv]t$ & plac$ at ! top ( ! met]4 ,ea* elem5t acts on a sep>ate cup1 b bo? cups are m\nt$ on a s+le %aft s t ! regi/ration is due to ! resultant torque ( ! two elem5ts4 ,! met] is provid$ ) ?ree support+ lugs1 ! "o at ! top be+ keyhol$ & "o ( ! bottom two1 slott$ to facilitate level+4 ,! regi/]+ me*anism is m\nt$ on a ca/ iron bracket at ! middle ( ! met] betwe5 ! two motor elem5ts4 ,! support+ bracket is atta*$ to ! met] base by two screws & align$ by two d[el p9s4 ,! regi/] is ( ! f\r dial type1 read+ 9 kil[att h\rs4 ,ea* division ( ! "r h& circle1 or t pass$ ov] by ! mo/ rapidly mov+ po9t]1 equals "o kil[att h\r 9 met]s )\t a dial con/ant4 ,9 met]s ( l>g] capacities1 dial con/ants ( #aj1 #ajj & #a1jjj are us$1 9 :i* case x is only necess>y to add "o1 two or ?ree ciph]s to ! obs]v$ read+4 ,pr9ciples ( ,induction ,watt ,h\r ,met]s4--,e comm]cial met] ( ?is type is made up ( a numb] ( elem5ts1 describ$ bel[4 ,ea* ( ^! elem5ts & p>ts has c]ta9 functions1 & ea* is !re=e necess>y to ! successful op]ation ( ! met]2 moreov]1 ea* elem5t1 unless correctly design$1 may introduce a s\rce ( inaccuracy4 ,^! elem5ts are3 #a4 ,! field produc+ elem5t2 #b4 ,! mov+ elem5t2 #c4 ,! ret>d+ elem5t2 #d4 ,! regi/]+ elem5t2 #e4 ,! m\nt+ frame & be>+s2 #f4 ,! friction comp5sator2 #g4 ,! p[] factor adju/m5t2 #h4 ,frequ5cy adju/m5t2 #i4 ,! case & cov]4 ,illu/ration3 ,,figs4 #b1ecc to #b1eda4--;,connections ( ,=t ,wayne multiphase watt h\r met]s 7type k--=ms ,,mab & ,,mak71 = #ajj-fbe volt circuits1 #e-aej amp]es4 ,fig4 #b1ech two & ?ree phase1 ?ree wire circuit1 #be-cf cycles2 fig4 #b1eci two & ?ree phase1 #c wire circuit1 #cf cycles & above2 fig4 #b1edj1 two phase #d wire circuit1 #be-cf cycles2 fig4 #b1eda two phase1 #d wire circuit #cf cycles & above4 ,illu/ration3 ,,fig4 #b1edb4--;,=t ,wayne s+le phase induction wat?\r met] ) cov] remov$4 ,! rotat+ p>ts consi/ ( an alum9um disc m\nt$ on a %ort %aft ( small diamet]4 ,! l[] end has ins]t$ 9 x a h>d5$ /eel pivot :i* re/s 9 a cup %ap$ jewel be>+4 ,! top ( ! met] %aft is drill$ & provid$ ) a small wa%] hav+ ! c5tral hole ( v small diamet]4 ,into ?is hole !re ext5ds a /eel p9 ar\nd :i* ! %aft turns4 ,two micromet] screws are provid$ = load adju/m5t--"o = ! full load & ! o!r = ! light load adju/m5t4 ,! adju/m5t = accuracy on full load is secur$ by v>y+ ! position ( ! p]man5t magnets1 slid+ !m ei!r 9 or out f ! c5t] ( ! rotat+ disc ( ! met] dep5d+ on :e!r x is desir$ to increase or decrease ! spe$ ( ! disc4 ,! micromet] screw %[n 9 ! figure s]ves to v>y ! position ( ! p]man5t magnets1 caus+ ! %oe 9 :i* ! two magnets are firmly clamp$ to slide on ! mill$ magnet support :i* is ca/ z an integral "p ( ! met] frame4 ,:5 ! prop] position ( ! magnets has be5 accurately det]m9$ by adju/m5t & te/1 ! %oe :i* holds ! two magnets is clamp$ firmly to ! mill$ magnet support by two screws1 "o ( :i* is %[n 9 ! figure4 ,! adju/m5t = accuracy on light load is secur$ by v>y+ ! position ( a metal pun*+1 kn[n z ! />t+ plate1 lat]ally "u ! pressure pole 9 ! pa? ( ! pressure flux4 ,?is lat]al movem5t is accompli%$ by means ( ! micromet] screw4 ,:5 ! prop] position ( ?is pun*+ has be5 accurately det]m9$ by adju/m5t & te/1 x is secur$ 9 place by tight5+ ! two brass screws :i* s]ve to clamp x to ! met] frame4 #a4 ,! ,field ,produc+ ,elem5t4--,?is consi/s ( ! electromagnetic circuit & ! measur+ coils4 ,"o ( ^! coils1 connect$ 9 s]ies ) ! circuit to be met]$1 is w\nd ( few turns & is !re=e ( l[ inductance4 ,! curr5t ?r\gh x is 9 phase ) ! curr5t 9 ! met]$ circuit4 ,! o!r coil1 connect$ across ! circuit1 is highly inductive1 & !re=e ! curr5t 9 x is ne>ly #ij degrees out ( phase )1 & proportional to ! voltage ( ! met]$ circuit across its t]m9als4 ,!re=e1 :5 ! curr5t 9 ! circuit is 9 phase ) ! voltage 7#ajj p] c5t4 p[] factor7 ! curr5ts 9 ! met] coils are displac$ almo/ #ij degrees ) respect to ea* o!r4 ,ques4 ,h[ is ?is angle made exactly #ij degrees8 ,ans4 ,by means ( ! p[] factor adju/m5t4 ,illu/ration3 ,,fig4 #b1edc4--,re> view ( ,=t ,wayne s+le phase induction wat?\r met] ) back cov] plate remov$4 ,! pressure & curr5t coils & _! respective cores lie beh9d ! ma9 frame ( ! met]4 ,?is complete electromagnetic unit c be remov$ z a :ole f its m\nt+ 9 ! case4 ,! pressure coil is w\nd f enamel$ wire1 ! numb] ( turns be+ v high4 ,! curr5t coils h b few turns ea* & are w\nd f cotton cov]$ wire4 ,all coils are treat$ ) insulat+ comp\nd be=e assembl+ 9 ! met]s4 ,! lam9at$ iron cores plac$ )9 ^! coils are built up f magnetic /eel4 ,! magnetic circuits =m$ by ! cores ( ! pressure & curr5t coils are s arrang$ t !y ex]t a high torque ^u ! disc ( ! rotat+ elem5t 9 ord] t m9ute v>iations 9 ! friction ( ! mov+ p>ts1 :i* are likely to occur w n cause any appreciable error 9 ! regi/ration ( ! met]4 ,! iron case surr\nd+ ! electrical elem5ts protect t "p ( ! met] f ! effects ( ext]nal /ray fields1 :ile ! a/atic arrangem5t ( ! p]man5t magnets t5ds to prev5t any influ5ce on ! damp+ sy/em4 ,! fact t ! iron frame ( ! met] lies betwe5 ! p]man5t magnets & ! curr5t coils protects ! magnets f ! effects ( %ort circuits :i* create a /rong magnetic field )9 ! met] itself4 ,ques4 ,h[ are ! coils m\nt$8 ,ans4 ,!y are s m\nt$ on ! core t ! curr5ts 9 !m produce a rotat+ or %ift+ field 9 ! air gap1 9 some:at ! same mann] t ! curr5ts 9 ! prim>y w9d+s ( an induction motor produce a rotat+ field4 ,illu/ration3 ,,fig4 #b1edd4--;,=t ,wayne s+le phase induction wat?\r met] ) cov] regi/] & p]man5t magnets remov$ to %[ solid met] frame4 ,a heavy /eel back plate held 9 place by two screws ins]t$ f ! front ( ! c5tral ca/+ encloses ! back "p ( ! completely assembl$ met]4 ,a felt gasket ly+ on a suitable l$ge seals ! jo9t aga9/ ! entrance ( du/ or moi/ure :5 ! back plate is drawn d[n firmly by ! screws4 ,! cov] :i* encloses ! back "p ( ! met] is a non-magnetic metallic /amp+4 ,x is held 9 place by w+ nuts on ! two light brass /uds ext5d+ =w>d f ! met] frame4 ,?is jo9t betwe5 ! ma9 frame & ! cov] is also seal$ aga9/ ! entrance ( du/ & moi/ure by ! use ( a suitable felt gasket4 ,two glass w9d[s are provid$ 9 ?is cov]1 "o to p]mit ! read+ ( ! regi/] dials1 ! o!r to p]mit obs]vation ( ! disc's rotation4 ,! cov] is seal$ 9 place 9 ! usual way by pass+ a seal+ wire ?r\gh a hole drill$ 9 ! cov] seal+ /ud & !nce ?r\gh a hole provid$ 9 ! w+ ( ! seal nut4 ,! t]m9al *amb] is an ext5sion ( ! ca/+ :i* supports all ! inn] p>ts ( ! met]4 ,! heavy brass t]m9als us$ = connect+ ! met] 9 circuit are held p]man5tly by a non-combu/ible insulat+ comp\nd :i* is m\ld$ 9 place ar\nd !m4 ,?is con/ruction gives excell5t insulation & is a safegu>d aga9/ accid5tal %ort circuits across t]m9als4 ,a pun*$ t]m9al cov] :i* fits ov] ! t]m9al *amb] is h+$ at ! upp] left h& corn] s t x w ( its own accord sw+ out ( ! way :5 ! t]m9al cov] seal+ screw is remov$4 ,?is h+$ /yle ( cov] w be f\nd conv5i5t :5 in/all+ & connect+ ! met] 9 circuit4 ,:5 ?is cov] is swung back into clos$ position x is fa/5$ 9 place by pass+ a seal "r ?r\gh ! seal screw & ?r\gh a lug provid$ on ! cov]4 ,ques4 ,:at is ! /r5g? ( ! rotat+ field ) #ij degrees phase diff]5ce betwe5 ! curr5ts8 ,ans4 ,x is proportional to ! product ( ! curr5ts 9 ! two coils & !re=e proportional to ! product ( curr5t & voltage 9 ! met]$ circuit4 ,at any o!r p[] factor ! field is proportional to ?is product multipli$ by ! s9e ( ! angle ( phase diff]5ce betwe5 ! two met] curr5ts4 ,if ! curr5t 9 ! voltage coil be 9 quadrature ) ! voltage ( ! met]$ circuit1 at any p[] factor ! s9e ( ! angle ( phase diff]5ce betwe5 ! curr5ts 9 ! met] circuits w be equal to ! cos9e ( ! angul> displacem5t betwe5 ! curr5t & voltage 9 ! met]$ circuit4 ,"u ^! conditions !re=e ! /r5g? ( ! %ift+ field is proportional also to ! p[] factor ( ! circuit4 ,9 o!r words1 ! /r5g? ( ! rotat+ field is proportional to ! product ( ! volts1 amp]es & p[] factor & is !re=e a measure ( ! actual p[]4 ,illu/ration3 ,,fig4 #b1ede4--,sangamo s+le phase induction watt h\r met]2 view ) cov] remov$ %[+ me*anism4 ,ques4 ,9 :at "p ( ! met] is en]gy consum$8 ,ans4 ,9 ! field produc+ elem5t4 ,illu/ration3 ,,fig4 #b1edf4--,ma9 grid or support+ frame ( ,sangamo s+le phase induction watt h\r met]4 ,! grid is ( ca/ iron & its design is su* t ! weight ( ! p]man5t magnets1 s]ies lam9at$ elem5t & return plate are c>ri$ on ! ma9 portion1 ! small] project+ brackets c>ry+ no weight except t ( ! mov+ sy/em4 ,! support+ grid is remov$ by tak+ out ! ?ree screws locat+ & hold+ x 9 position1 to ! iron base1 also remov+ at ! same "t ! screws connect+ ! leads ( ! s]ies coils to ! b9d+ po/s at ! bottom4 ,! met]s are all built ) f\r b9d+ po/s s t !y may be connect$ ei!r ) two s]ies leads & a tap = ! pressure connection or ) bo? sides ( ! circuit c>ri$ ?r\gh ! met]4 ,! wire met]s employ a #bbj volt %unt coil1 connect$ across ! b9d+ po/s )9 ! met]1 "o s]ies coil be+ 9 ea* ( ! out] l9es ( ! ?ree wire sy/em4 ,?is r5d]s unnecess>y ! use ( a pressure tap4 ,x is ^u ! design ( ?is elem5t t ! losses 9 ! met] dep5d4 ,curr5t is fl[+ ?r\gh ! %unt coil cont9u\sly1 ev5 :5 no en]gy is be+ tak51 & ! high] ! inductance ( ?is coil1 ! small] w be ! en]gy compon5t ( ! con/ant fl[4 ,! s]ies coil causes a loss ( en]gy proportional to ! squ>e ( ! curr5t fl[+4 ,x also causes a drop 9 voltage1 bo? inductive & resi/ive1 h5ce1 ! resi/ance & inductance ( ! s]ies coil ( ! met] %\ld be z l[ z possible4 ,ques4 ,h[ %\ld ! magnetic circuit be design$8 ,ans4 ,! design %\ld be su* t ! increase ( magnetic flux ) high voltage or high curr5t w n h a ret>d+ action b w act only to increase ! torque4 ,if ! ret>d+ effect be n prev5t$1 ! met] w1 ( c\rse1 run sl[ at ov]loads4 ,a comp>ative te/ ( met]s at v>y+ load & at v>y+ voltage w reveal ! *>act]i/ics ( ! magnetic circuit4 #b4 ,! ,mov+ ,elem5t4--,?is usually consi/s ( a light metal disc revolv+ ?r\gh ! air gap 9 :i* ! rotat+ field is produc$4 ,illu/ration3 ,,fig4 #b1edg4--,mov+ elem5t ( ,sangamo s+le phase induction watt h\r met]4 ,x consi/s ( a light alum9um disc m\nt$ on a h>d brass %aft1 ! entire sy/em weigh+ #ae4f grams4 ,! disc is swag$ "u heavy pressure1 to r5d] x /iff4 ,! arrangem5t ( ! disc1 %aft1 & be>+s is %[n 9 fig4 #b1edh4 ,by unscrew+ ! upp] & l[] be>+s ! disc & %aft c be remov$ )\t di/urb+ ! magnets or adju/m5ts4 ,ques4 ,:at is ! action ( ! disc8 ,ans4 ,x acts l ! squirrel cage armature ( an induction motor1 develop+ ! motive torque = ! met]4 ,ques4 ,h[ is ?is torque c\nt] balanc$8 ,ans4 ,by ! ret>d+ elem5t s t ! spe$ is proportional to ! torque4 ,ques4 ,h[ %\ld ! disc be made & :y8 ,ans4 ,z light z possible to r$uce we> on ! be>+s to a m9imum4 ,illu/ration3 ,,fig4 #b1edh4--;,be>+ sy/em ( ,sangamo s+le phase induction wat?\r met]4 ,! upp] pivot1 or be>+ is made ( temp]$ /eel wire & ( suffici5tly small diamet] to be q flexible 9 ! l5g? betwe5 ! top ( ! brass %aft & ! guide r+ 9 :i* x rotates4 ,! guide r+1 made ( phosphor bronze1 has ! heavy hole l9$ & burni%$4 ,! upp] be>+ screw1 9 :i* ! bronze bu%+ is c>ri$1 is s con/ruct$ t a long brass sleeve closely surr\nds ! upp] pivot ( ! sp9dle4 ,any bl[ aga9/ ! mov+ sy/em1 caus$ by accid5t or %ort circuit1 w slightly deflect ! %aft until ! /eel pivot t\*es aga9/ ! side ( ! %ell1 ?us prev5t+ dang] ( break+ (f or b5d+ ! upp] pivot4 ,at ! same "t a cu%ion+ or flexible action betwe5 ! %aft & ! be>+ %ell is secur$1 ?us elim9at+ ! effect ( vibration 9 ! mov+ sy/em1 :i* w\ld t5d to produce rattl+4 ,! l[] be>+ consi/s ( a cup sapphire jewel1 support$ 9 a ?read$ pill>1 ! upp] end ( :i* is provid$ ) a sleeve s locat$ t x prev5ts ! mov+ elem5t dropp+ out dur+ %ipm5t4 ,?is protect+ sleeve is held friction tight on ! %aft & c be remov$ if x be desir$ to inspect ! jewel4 #c4 ,! ,ret>d+ ,elem5t4--,?is "p acts z a load on ! induction motor & enables ! adju/m5t ( its spe$ to normal limits4 ,9 ord] t ! spe$ %all be proportional to ! driv+ torque1 :i* v>ies ) ! watts 9 ! circuit1 x is necess>y t ! torque ( ! ret>d+ device be proportional to ! spe$4 ,= ?is reason a %ort circuit$ con/ant field g5]ator1 consi/+ ( a metal disc rotat+ betwe5 p]man5t magnet poles1 has be5 g5]ally adopt$4 ,ques4 ,h[ is ! ret>d+ torque produc$8 ,ans4 ,eddy curr5ts are induc$ 9 ! disc 9 rotat+ ?r\gh ! magnetic field :i*1 accord+ to ,l5z's law1 oppose ! =ce t produces !m1 ?us develop+ a ret>d+ torque4 ,ques4 ,h[ is ! con/ant field = ! ret>d+ disc produc$8 ,ans4 ,by p]man5t magnets4 ,! ret>d+ disc may be ! same disc us$ = ! mov+ elem5t1 9 :i* case ! met] field acts on "o edge :ile ! p]man5t magnet field acts on ! edge diametrically opposite4 ,?is arrangem5t simplifies ! numb] ( p>ts & saves space & weight ( mov+ elem5t4 ,ques4 ,:at error is likely to be introduc$ by ! ret>d+ elem5t8 ,ans4 ,if ! /r5g? ( ! p]man5t magnets *ange f any cause1 ! ret>d+ torque w be *ang$ & ! calibration ( ! met] r5d]$ inaccurate4 ,ques4 ,h[ may ! /r5g? ( ! p]man5t magnets be *ang$8 ,ans4 ,!y may become weak ) age1 or affect$ by ! proximity ( o!r magnetic fields4 ,! s]ies coil ( ! met] may1 "u %ort circuit s affect ! /r5g? ( ! p]man5t magnets z to r5d] ! met] inaccurate4 ,ques4 ,:at precautions are tak5 to keep ! /r5g? ( ! p]man5t magnets con/ant8 ,ans4 ,weak5+ ) age is prev5t$ by ! process ( ,ag+4 ,! effect ( neighbor+ fields is ov]come by iron %ields2 ?is prev5ts ! electromagnets affect+1 ?r\gh ov]loads1 ! /r5g? ( ! p]man5t magnets4 #d4 ,! ,regi/]+ ,elem5t4--,?is me*anism comprises ! dials1 po9t]s1 & ge> tra9 necess>y to secure ! requir$ r$uction 9 spe$4 ,?is ge> tra9 is driv5 directly by ! rotor & !re=e its friction %\ld be l[ & con/ant4 ,! dials %\ld be easily read & %\ld regi/] directly 9 kil[att h\rs4 ,if a con/ant be us$ to r$uce ! read+ to kil[att h\rs1 x %\ld be "s multiple ( #aj1 to avoid errors 9 multiplication4 ,by means ( suitable ge>s 9 ! met]s ?is is easily accompli%$4 ,illu/ration3 ,,fig4 #b1edi4--,regi/] dial ( ,sangamo s+le phase induction watt h\r met] 7full size74 ,! dial circles read #aj1 #ajj1 #a1jjj1 & #aj1jjj kil[att h\rs f "r to left4 #e4 ,! ,m\nt+ ,frame & ,be>+s4--,^! p>ts h an important influ5ce on ! accuracy ( ! met]1 z x is 9 ! be>+s t mo/ ( ! friction 9 ! met] occurs4 ,! frame %\ld be rigid & free f vibration1 s t ! be>+s w be at all times 9 p]fect alignm5t4 ,initial friction is unavoidable 9 any met] con/ruction & c be easily comp5sat$ =4 ,a *ange 9 ! initial friction1 h[ev]1 due to we> ( be>+s1 makes readju/m5t necess>y4 ,9 select+ a met] ! special att5tion %\ld !re=e be giv51 to ! con/ruction ( ! be>+s1 p>ticul>ly ! l[]1 or /ep be>+ :i* supports ! weight ( ! mov+ elem5t4 ,illu/ration3 ,,fig4 #b1eej4--;,canadian dial ( ,sangamo s+le phase induction watt h\r met]4 ,x has a small te/ circle indicat+ "o kil[att h\r p] revolution 9 all sizes :]e ! fir/ regul> circle indicates #aj4 ,?is is provid$ to con=m ) ! requirem5ts ( ! ,canadian gov]nm5t & x is int5d$ t ! h& on ! te/ circle %all make n less ?an revolution 9 "o h\r ) full load on a met]4 ,9 ! case ( a #aj amp]e met]1 x w make "o complete revolution 9 "o h\r & = a #bj amp]e1 two revolutions1 & s on4 ,! tra9 or indicat+ me*anism is c>ri$ on a rigidly =m$ & swag$ brass bracket accurately locat$ by two d[el p9s set 9 ! top face ( ! ma9 grid1 & is held to ! grid ) two screws easily accessible :5 x is desir$ to remove ! tra9 = any purpose4 ,all indicat+ tra9s us$ on type ,h met]s are m>k$ ) symbols on ! back ( ! tra9 & on ! comp\nd atta*m5t to indicate ! ge> ratio ( ea* comb9ation2 ?is ratio be+ diff]5t = met]s ( diff]5t capacities 9 ord] to obta9 a direct read+ 9 kil[att h\rs on ! dial4 ,ques4 ,describe a good con/ruction = ! /ep be>+4 ,ans4 ,a desirable con/ruction w\ld consi/ ( a v highly poli%$ & h>d5$ ball ) jewel seats4 #f4 ,! ,friction ,comp5sator4--,! object ( ?is device is to ov]come ! initial friction ( ! mov+ p>ts4 ,x is evid5t t if ?is initial friction 7 n comp5sat$ "s ( ! driv+ torque ( ! met] w\ld be us$ 9 ov]com+ x1 & ! met] w\ld !re=e n rotate at v light load1 & n fa/ en\gh at o!r loads1 ?us r5d]+ ! regi/ration inaccurate1 especially at light loads4 ,illu/ration3 ,,fig4 #b1eea4--;,base & %unt coil ( ,sangamo s+le phase induction watt h\r met]4 ,s9ce ! %unt or pressure coil sometimes breaks d[n or burns out1 due to abnormal l9e conditions or accid5t1 provision is made = easy replacem5t4 ,! %unt magnet ) its coil is held to ! base by two d[el p9s & f\r screws1 enabl+ x to be remov$ z a unit z %[n4 ,a new core & coil may !n be sub/itut$ )\t ! necessity ( remov+ & replac+ lam9ations4 ,! %unt coil 9 #be cycle met]s is wid] & conta9s m /eel ?an ! #fj & #acc cycle coils1 ! w9d+ also be+ correspond+ly increas$4 ,! return plate & s]ies coil lam9ations are also *ang$ 9 proportion to correspond to ! increas$ wid? ( ! %unt magnet4 ,! lam9ations =m+ ! core are lac$ into ! %unt coil1 & subject$ to enorm\s hydraulic pressure1 ! rivets be+ set at ! same "t1 to =m a compact unit & elim9ate humm+4 ,! lam9at$ core ( ! %unt elem5t has b a s+le air gap 9 :i* ^! discs rotate4 ,s9ce met]s are usually run at light loads x is important t an effici5t light load adju/m5t or friction comp5sator %\ld be provid$4 ,ques4 ,:at important po9t %\ld be consid]$ 9 ! design ( ! friction comp5sator8 ,ans4 ,! comp5sat+ torque mu/ n cause ! mov+ elem5t to rotate or creep )\t curr5t 9 ! s]ies coil4 ,! rotation ( a met] is caus$ by two di/9ct torques1 ! v>y+ met] torque1 dep5d5t on ! p[] 9 ! circuit1 & ! con/ant torque adju/$ to comp5sate ! initial friction4 ,! friction at all spe$s is n exactly ! same z ! initial friction1 & !re=e ! friction comp5sat+ torque may be 9 error a few p] c5t4 at high spe$s4 ,illu/ration3 ,,figs4 #b1eeb ,,& #b1eec4--;,arrangem5t ( magnetic circuit ( ,sangamo s+le phase induction met]4 ,fig4 #b1eeb1 front view2 fig4 #b1eec1 re> & side view4 ,z %[n1 ! gap ( ! %unt held 9 :i* ! disc rotates1 projects 9 betwe5 ! poles ( ! s]ies magnet1 ! return plate b5d+ ar\nd s z to cle> ! upp] leg ( ! %unt magnet4 ,?is gives ! desir$ proximity ( %unt & s]ies fields ) a maximum radius ( action = bo? sets ( field4 ,9 all capacities up to & includ+ #fj amp]es1 #b wire & #c wire1 r\nd wire & tap$ s]ies coils are us$1 & 9 capacities ( #hj & #ajj amp]es1 /rap w9d+s4 ,met]s exce$+ #ajj amp]e capacity h five amp]e coils & are op]at$ f ext]nal curr5t trans=m]s hav+ #e amp]e second>ies4 ,! s]ies w9d+s or coils are m\nt$ on a lam9at$ iron ,u %ap$ magnet hav+ a lam9at$ return pa? above ! disc ( ! met]1 ?us =m+ air gaps 9 :i* ! disc rotates4 ,! s]ies coils 9 all capacities n hav+ /rap w9d+s are held firmly 9 position on ! yoke s t !y _c slip up f ! l[e/ position4 ,?is is accompli%$ by means ( a pair ( spr+ brass clips slipp$ ?r\gh ! coils on ! re> face ( ! yoke1 ! clips be+ held by ! two screws :i* fa/5 ! s]ies magnet to ! ma9 grid4 ,z an additional precaution1 spr+ /eel lock wa%]s are put b5ea? ! heads ( ! hold+ screws1 ?us elim9at+ any *ance ( ! s]ies magnet loos5+ & *ang+ position4 ,if ! comp5sat+ torque be small comp>$ ) ! driv+ torque1 ?is small error p]c5tage is negligible 9 its effect on accuracy4 ,! small] x is1 ! great] w be ! accuracy at all loads1 & !re=e1 z ! comp5sat+ torque is adju/$ to balance ! initial friction1 ! initial friction %\ld be small comp>$ ) ! driv+ torque4 ,a high driv+ torque & l[ initial friction are !re=e desirable1 b any increase 9 ! driv+ torque :i* necessitates an increase 9 friction1 is obvi\sly useless4 ,! desirable feature ( a met] is high ratio ( torque to friction4 ,z ! friction is practically proportional1 to ! weight ( ! mov+ elem5t1 9 met]s hav+ ! same =m ( be>+1 ! ratio ( torque to weight ( rotor gives an approximation to ! ratio ( torque to friction1 b ! design ( be>+ %\ld n be ov]look$4 ,a met] hav+ a high torque obta9$ by us+ a ?ick & consequ5tly heavy disc1 (t5 has a l[] ratio ( torque to weight ?an ano!r ) l[] torque1 & is consequ5tly likely to be less accurate ov] a giv5 range4 ,fur!rmore1 ! heavy disc is a di/9ct disadvantage because x produces m we> on ! be>+s & ?us r$uces ! life4 ,illu/ration3 ,,figs4 #b1eed ,,& #b1eee4 ,connections ( ,sangamo s+le phase induction met]4 ,fig4 #b1eed1 #b wire met]1 #e-ajj amp]e capacity2 fig4 #b1eee1 #c wire met]1 #e-ajj amp]e capacity4 #g4 ,! ,p[] ,factor ,adju/m5t4 ,?is adju/m5t is necess>y to make ! phase angle betwe5 ! %unt & s]ies field compon5ts #ij ) unity p[] factor 9 ! met]$ circuit4 ,ow+ to ! resi/ance & iron loss 9 ! %unt field circuit1 t field is n %ift$ q #ij ) respect to ! voltage4 ,yet exact quadrature is necess>y to make ! /r5g? ( ! resultant field1 & consequ5tly ! rotor spe$1 proportional to ! p[] factor1 z expla9$ 9 ! discussion ( ! field produc+ elem5t4 ,ques4 ,:at is ! usual con/ruction ( ! p[] factor adju/m5t8 ,ans4 ,x usually consi/s ( a %ort circuit$ loop enclos+ "p or all ( ! %unt field flux4 ,ques4 ,h[ does ?is loop act8 ,ans4 ,x acts l ! second>y ( a trans=m]4 ,! flux induces a curr5t 9 x :i*1 act+ ) ! curr5t 9 ! %unt coil1 produces a slightly lagg+ field4 ,by %ift+ ! position ( ! resi/ance ( ! %ort circuit$ loop1 ! lag may be s adju/$ t ! %unt field flux is 9 exact quadrature ) ! voltage4 ,x %\ld be not$1 h[ev]1 t ?is adju/m5t makes ! met] correct at or ne> "o frequ5cy only4 ,?is feature is n objectionable if reasonable accuracy be ma9ta9$ )9 ! limits ( normal v>iation ( frequ5cy4 ,illu/ration3 ,,figs4 #b1eef ,,& #b1eeg4 ,connections ( ,sangamo s+le phase induction met]4 ,fig4 #b1eef1 #b wire met] exce$+ #ajj amp]es2 fig4 #b1eeg1 #c wire met] exce$+ #ajj amp]es4 #h4 ,frequ5cy ,adju/m5t4--,?is is (t5 desirable1 p>ticul>ly = sy/ems op]at+ at #acc cycles4 ,mo/ makes ( met] are provid$ ) means = *ang+ ! adju/m5t f #acc to #fj cycles 9 case ( *ange 9 ! sy/em4 #i4 ,! ,case & ,cov]4--,^! p>ts %\ld be du/ & bug pro(1 to avoid damage to ! be>+s1 insulation & mov+ p>ts1 & %\ld ( c\rse be provid$ ) means = seal+4 ,t]m9al *amb]s s arrang$ t ! cov] ( ! met] elem5t ne$ n be remov$ 9 connect+ up1 are an important feature1 p>ticul>ly 9 met]s t require no adju/m5t at in/allation1 z !y prev5t entrance ( du/ into ! ma9 met] *amb]4 ,a w9d[ ?r\gh :i* ! rotation ( ! disc c be obs]v$ 9 *eck+1 %\ld be provid$ = ! same reason4 ,illu/ration3 ,,fig4 #b1eeh4--;,f>aday disc1 or m]cury motor amp]e h\r met]2 view %[+ electric & magnetic circuits4 ,! ,f>aday ,disc1 or ,m]cury ,motor ,amp]e ,h\r ,met]4--,on ?is type ( met] ! m]cury motor consi/s ess5tially ( a copp] disc float$ 9 m]cury betwe5 ! poles ( a magnet & provid$ ) leads to & f ! m]cury at diametrically opposite po9ts4 ,! !oretical relations ( ! v>i\s p>ts are %[n 9 fig4 #b1eeh4 ,illu/ration3 ,,fig4 #b1eei4--;,diagram %[+ relative direction ( curr5t1 magnetic flux1 & motion ( disc 9 ,f>aday disc1 or m]cury motor amp]e h\r met]4 ,ques4 ,expla9 its op]ation4 ,ans4 ,! electric curr5t1 z %[n 9 fig4 #b1eeh1 ent]s ! contact ,c1 passes ?r\gh ! comp>atively high resi/ance m]cury ,h to ! edge ( ! l[ resi/ance copp] disc ,d across ! disc to ! m]cury ,h & out ( contact ,c'4 ,! magnetic flux cuts across ! disc on ea* side f ,n to ,s1 mak+ a complete circuit ?r\gh ,m & ,m'4 ,! relative directions ( ! magnetic flux & ! curr5t ( electricity z well z ! result+ motion are %[n 9 fig4 #b1eei4 ,accord+ to ! laws ( electromagnetic induction1 if a curr5t c>ry+ conductor cut a magnetic field ( flux at "r angles1 a =ce is ex]t$ ^u ! conductor1 t5d+ to pu% x at "r angles to bo? ! curr5t & ! flux4 ,:5 connect$ to an eddy curr5t damp] or g5]ator :i* requires a driv+ =ce directly proportional to ! spe$ ( rotation1 ! m]cury motor g5]ator becomes a met]4 ,! spe$ ( su* a met] is a measure ( ! curr5t or rate ( fl[ ( ! electricity ?r\gh ! motor elem5t1 & ea* revolution ( ! motor corresponds to a giv5 quantity ( electricity4 ,!n1 by connect+ a revolution c\nt] to ?is motor g5]ator1 a means is provid$ = indicat+ ! total quantity ( electricity 9 amp]e h\rs t is pass$ ?r\gh ! met]4 ,illu/ration3 ,,fig4 #b1efj4--,sectional view ( ,f>aday disc or m]cury motor amp]e h\r met] z made by ,sangamo ,electric ,co4 ,! illu/ration does n %[ ! magnets & indicat+ me*anism4 ,ques4 ,h[ is ! flux produc$ 9 ! alt]nat+ curr5t =m ( ,f>aday disc met]8 ,ans4 ,by ! second>y curr5t ( a s]ies trans=m]4 ,frequ5cy ,indicators4--,a frequ5cy indicator or met] is an in/rum5t us$ = det]m9+ ! frequ5cy1 or numb] ( cycles p] second ( an alt]nat+ curr5t4 ,!re are sev]al =ms ( frequ5cy indicator1 ^: pr9ciple ( op]ation diff]s1 & accord+ to :i*1 !y may be class$ z #a4 ,syn*ron\s motor type2 #b4 ,resonance type2 #c4 ,induction type4 ,illu/ration3 ,,fig4 #b1efa4--;,circuit diagram ( simple %unt ,sangamo amp]e h\r met]4 ,x is rat$ at #aj amp]es1 l>g] curr5ts be+ measur$ by us+ %unts4 ,9 op]ation1 ! ma9 or l9e curr5t to be measur$ passes ?r\gh ! %unt1 :ile a "p proportional to ! drop across ! %unt1 is %unt$ ?r\gh ! met] & measur$4 ,! only effect ( rev]s+ ! curr5t w be to rev]se ! direction ( rotation ( ! met]4 ,9 batt]y in/allations x is nev] possible to take ! same numb] ( amp]e h\rs f a batt]y z are put into x1 h5ce1 if ! simple %unt amp]e h\r met] be us$ = repeat$ & successive *>ges & dis*>ges1 x w be necess>y to reset ! po9t] to z]o ea* "t ! batt]y is fully *>g$4 ,:5 ! %unt met] is equipp$ ) a *>ge /opp+ device1 ! po9t] is reset :ile *>g+1 to all[ = a pr$et]m9$ ov]*>ge4 ,illu/ration3 ,,fig4 #b1efb4--;,circuit diagram ( ,sangamo diff]5tial %unt type amp]e h\r met] = use 9 batt]y *>g+4 ,s9ce a batt]y absorbs m en]gy on *>ge ?an x w give out on dis*>ge1 at its work+ voltage1 x is usually giv5 a c]ta9 am\nt ( ov]*>ge4 ,?is makes desirable a met] t automatically all[s = ! prop] am\nt ( ov]*>ge4 ,su* a met] indicates at all times ! am\nt ( electricity available = useful "w )\t resett+ ! po9t] e "t ! batt]y is *>g$4 ,9 o!r words1 ! batt]y & ! met] w\ld keep 9 /ep = consid]able p]iods ( "t )\t readju/m5t4 ,! ,sangamo diff]5tial %unt met] is design$ to meet ^! requirem5ts1 & x consi/s ess5tially ( a ,sangamo met] ) two %unts connect$ z %[n4 ,! relative value ( %unt resi/ance is adju/able by means ( slid] ,g1 s t ! met] c be made to run sl[ on *>ge or fa/ on dis*>ge1 :i*ev] may be desir$4 ,! usual me?od is to all[ ! met] to regi/] less ?an ! true am\nt on *>ge & ! exact am\nt on dis*>ge1 ! diff]5ce repres5t+ ! loss 9 ! batt]y1 or ! ov]*>ge4 ,if ! met] be provid$ ) a *>ge /opp+ device1 ! batt]y c be giv5 an am\nt ( ov]*>ge pr$et]m9$ by ! sett+ ( ! slid] ,g4 ,!re=e ! am\nt ( ov]*>ge c be fix$ 9 advance by a skill$ man & ! actual *>g+ done by any unskill$ p]son1 s9ce all !re is to d is to make ! connection4 ,ques4 ,h[ is a syn*ron\s motor employ$ z a frequ5cy indicator8 ,ans4 ,a small syn*ron\s motor is connect$ 9 ! circuit ( ! curr5t ^: frequ5cy is to be measur$4 ,aft] det]m9+ ! revolutions p] m9ute by us+ a revolution c\nt]1 ! frequ5cy is easily calculat$ z foll[s3 frequ5cy 7revolutions p] second numb] ( poles7 #b4 ,illu/ration3 ,,figs4 #b1efc & #b1efd4--;,frahm resonance type frequ5cy met]4 ,fig1 #b1efc1 portable met]2 fig4 #b1efd1 swit*bo>d met]4 ,! read+s are correct 9 ei!r ! v]tical or horizontal position4 ,! en]gy consumption at #ajj volts is ab\t #a to #b volt amp]es1 & is approximately proportional = o!r pressures4 ,! regul> portable met]s are arrang$ = pressures ( f #ej to #cjj volts1 & = ?is purpose !y are fitt$ ) t]m9als = #fe1 #ajj1 #acj1 #ahj1 & #bej volts4 ,9 ord] to obta9 full amplitude at int]m$iate pressures1 a mill$ head$ screw is provid$ = adju/+ ! base piece me*anically1 & !reby p]mitt+ ( regulat+ ! pressure range )9 #bj p] c5t2 ?is insures indications ( maximum cle>ness4 ,%\ld x be desir$ to ext5d ! /&>d pressure range ( #ej to #cjj volts1 up to #fjj volts1 two fur!r t]m9als = #cej & #ejj volts are necess>y1 s t ^! in/rum5ts are provid$ ) eight fix$ t]m9als 9 addition to ! me*anical regulat+ device4 ,in/rum5ts :i* are int5d$ = connect+ to "o specific supply or to ! second>y ( a pressure trans=m]1 require only a s+le pressure range1 say #ajj volts1 ) ! a=em5tion$ regulat+ device4 ,! frequ5cy range is f #g4e to #fjj cycles p] second4 ,9 ord] to obta9 easily readable indications1 "o re$ is provid$ = e qu>t] p]iod = frequ5cies bel[ #cj1 = e half p]iod = frequ5cies betwe5 #cj & #hj1 & = e :ole p]iod = frequ5cies betwe5 #hj & #adj4 ,! use ( a small] numb] ( re$1 t is to say1 ( l>g] int]vals betwe5 ! p]iods ( vibration ( adjo9+ re$s1 is only recomm5d$ = circuits hav+ v v>iable frequ5cies1 z o!rwise no re$ might respond to ! vibrations caus$ by int]m$iate frequ5cies4 ,! arrangem5t ( ! sep>ate re$s on a common base piece1 p]mits supply+ any comb9ation ( int]val t may be requir$4 ,x is (t5 desirable to secure two ranges ) "o set ( re$4 ,to d ?is a second electromagnet is suppli$4 ,x is pol>iz$1 & op]ates on ! same base plate4 ,9 ! case ( alt]nat+ curr5t :5 ! unpol>iz$ magnet is us$ ! re$s receive two impulses dur+ ea* cycle1 :ile ) ! pol>iz$ magnet !y receive b "o impulse p] cycle4 ,a commutator is provid$ to easily make ! *ange f "o range to ! o!r4 ,if !re be two sets ( re$1 ! "o commutator may be connect$ to *ange bo?4 ,?is device is only applicable :5 alt]nat+ curr5t is measur$4 ,in/rum5ts ) unpol>iz$ magnets are made ) frequ5cies ( #ae to #cjj cycles p] second4 ,ques4 ,describe ! resonance me?od ( obta9+ ! frequ5cy4 ,ans4 ,9 con/ruction1 ! app>atus consi/s ( a p5dulum1 or re$1 ( giv5 l5g?1 :i* responds to p]iodic =ces hav+ ! same natural p]iod z itself4 ,! in/rum5t comprises a numb] ( re$s ( diff]5t l5g?s1 m\nt$ 9 a r[1 & all simultane\sly subject$ to ! oscillatory attraction ( an electromagnet excit$ by ! supply curr5t t is be+ measur$4 ,! re$1 :i* has ! same natural "t p]iod z ! curr5t w vibrate1 :ile ! o!rs w rema9 practically at re/4 ,illu/ration3 ,,figs4 #b1efe & #b1eff4--,side & end views ( ,frahm resonance type frequ5cy met] re$s4 ,ow+ to ! pr9ciple employ$ 9 ! met] x is evid5t t ! indications are indep5d5t ( ! voltage1 *ange ( wave =m1 & ext]nal magnetic fields4 ,! con/ruction & op]ation ( ! in/rum5t may be bett] und]/ood f figs4 #b1efe & #b1eff1 :i* illu/rates ! indicat+ "p ( ! ,frahm met]4 ,?is consi/s ( "o or m r[s ( tun$ re$s rigidly m\nt$ side by side on a common & slightly flexible base4 ,! re$s are made ( spr+ /eel1 #c or #g mm4 wide1 ) a small portion ( _! free ends b5t ov] at "r angles z %[n 9 fig4 #b1eff & enamel$ :ite s t :5 view$ end on !y w be easily visible4 ,! re$s are ( adju/able l5g?1 & are weight$ at ! end4 ,a piece ( s(t iron1 rigidly fa/5$ on ! base plate :i* supports ! re$s1 =ms ! armature ( a magnet4 ,:5 ! magnet is excit$ by alt]nat+ curr5t1 or int]rupt$ direct curr5t1 ! armature is set 9 vibration1 & t gives a slight movem5t to ! base plate at "r angles to its axis1 !reby affect+ all ! re$s1 especially ^? :i* are almo/ 9 tune ) its vibrations4 ,! re$ :i* is 9 tune w vibrate ?r\gh an arc ( consid]able amplitude1 & s indicate ! frequ5cy ( ! excit+ curr5t4 ,ques4 ,= :at use is ! resonance type ( frequ5cy met] mo/ desirable8 ,ans4 ,= laboratory use4 ,illu/ration3 ,,fig4 #b1efg4--,we/+h\se induction type frequ5cy met]4 ,! normal frequ5cy is usually at ! top ( ! scale to facilitate read+4 ,! damp+ disc moves 9 a magnetic field1 ?us damp+ by ! me?od ( eddy curr5ts4 ,! /&>d met]s are design$ = circuits ( #ajj volts nom9al & c be us$ = voltages up to #abe volts4 ,= high] voltages1 trans=m]s ) nom9al #ajj volt second>y %\ld be us$4 ,ques4 ,describe ! induction type ( frequ5cy met]4 ,ans4 ,x consi/s ( two voltmet] electromagnets act+ 9 opposition on a disc atta*$ to ! po9t] %aft4 ,"o ( ! magnets is 9 s]ies ) an inductance1 & ! o!r ) a resi/ance1 s t any *ange 9 ! frequ5cy w unbalance ! =ces act+ on ! %aft & cause ! po9t] to assume a new position1 :5 ! =ces are aga9 balanc$4 ,! alum9um disc is s arrang$ t :5 ! %aft turns 9 "o direction ! torque ( ! magnet t5d+ to rotate x decreases1 :ile ! torque ( ! o!r magnet increases4 ,! po9t] !re=e comes to re/ :]e ! torques ( ! two magnets are equal1 ! po9t] indicat+ ! frequ5cy on ! scale4 ,illu/ration3 ,,fig4 #b1efh4--,langsdorf & ,begole frequ5cy met]4 ,! op]ation ( ?is met] is bas$ on ! fact t if an alt]nat+ pressure ( ,e ,volts be impress$ on a cond5s] ( capacity ,c1 9 f>ads1 ! curr5t 9 amp]es w be equal to #b ,,ec1 provid$ ! pressure be con/ant4 ,9 con/ruction1 ! scale is m\nt$ on ! same axis z ! pressure coil1 across ! ma9s s z to r5d] ! in/rum5t indep5d5t ( v>iation ( voltage4 ,= a discussion ( ?is met]1 see ,electrical ,review1 vol4 ,,lviii1 page #aad4 ,illu/ration3 ,,fig4 #b1efi4--;,g5]al ,electric horizontal edgewise1 induction type frequ5cy indicator4 ,x is provid$ ) an ext]nal inductance & resi/ance plac$ 9 a v5tilat$ cage = m\nt+ on ! back ( ! swit*bo>d4 ,means are provid$ = adju/+ ! in/rum5t = ! *>act]i/ics ( ! circuit on :i* x is in/all$4 ,/&>d in/rum5ts are w\nd = #ajj to #abe volt circuits only1 b c be w\nd = circuits up to & includ+ #fej volts4 ,in/rum5ts = use on circuits 9 excess ( #fej volts are always provid$ ) pressure trans=m]s4 ,! normal op]at+ po9t is m>k$ at approximately ! c5t] ( ! scale1 ?us giv+ ! advantage ( v op5 divisions4 ,! /&>d frequ5cies are #be1 #dj1 #fj1abe & #acc4 ,ques4 ,:at is ! object ( ! alum9um disc8 ,ans4 ,its function is to damp ! oscillations ( ! po9t]4 ,illu/ration3 ,,fig4 #b1egj4--,we/+h\se rot>y type ( syn*roscope or syn*ronism indicator4 ,! indication is by means ( a po9t] :i* assumes at e in/ant a position correspond+ to ! phase angle betwe5 ! pressures ( ! busb>s & ! incom+ ma*9e1 & !re=e rotates :5 ! incom+ ma*9e is n 9 syn*ronism4 ,! direction ( rotation indicates :e!r ! ma*9e be fa/ or sl[1 & ! spe$ ( rotation dep5ds on ! diff]5ce 9 frequ5cy4 ,! po9t] is cont9u\sly visible1 dur+ bo? ! d>k & light p]iods ( ! syn*roniz+ lamps4 ,syn*ronism ,indicators4--,^! devices1 sometimes call$ syn*roscopes1 or syn*roniz]s indicate ! exact diff]5ce 9 phase angle at e in/ant1 & ! diff]5ce 9 frequ5cy1 betwe5 an incom+ ma*9e & ! sy/em to :i* x is to be connect$1 s t ! c\pl+ swit* c be clos$ at ! prop] in/ant4 ,!re are sev]al types ( syn*roniz]1 su* z #a4 ,lamp or voltmet]2 #b4 ,resonance or vibrat+ re$2 #c4 ,rotat+ field4 ,! simple/ arrangem5t consi/s ( a lamp or pref]ably a voltmet] connect$ across "o pole ( a two pole swit* connect+ ! incom+ ma*9e to ! busb>s1 ! o!r pole ( ! swit* be+ already clos$4 ,if ! ma*9es be out ( /ep1 ! lamps w fluctuate 9 brightness1 or ! voltmet] po9t] w oscillate1 ! pulsation becom+ less & less z ! incom+ ma*9e approa*es syn*ron\s spe$4 ,syn*ronism is %[n by ! lamp rema9+ out1 or ! voltmet] at z]o4 ,illu/ration3 ,,fig4 #b1ega4--;,g5]al ,electric syn*ronism indicator4 ,! syn*ronism indicator is a motor ^: field is suppli$ ) s+le phase curr5t f "o ( ! ma*9es to be syn*roniz$1 & its armature f ! o!r4 ,! armature c>ries two inductance coils plac$ at a l>ge angle1 "o suppli$ ?r\gh a resi/ance1 ! o!r ?r\gh an inductance4 ,?is arrangem5t g5]ates a rotat+ field 9 ! armature1 :ile ! /ation>y field is alt]nat+4 ,! armature t5ds to assume a position :]e ! two fields co9cide :5 ! alt]nat+ field passes ?r\gh its maximum2 h5ce1 ! armature & po9t] move =w>d or backw>d at a rate correspond+ to ! diff]5ce ( frequ5cy1 & ! position :5 /ation>y dep5ds on ! phase relation4 ,:5 ! ma*9es are runn+ at ! same frequ5cy & 9 phase ! po9t] is /ation>y at ! m>k$ po9t4 ,9 con/ruction1 x is l a small1 two phase1 bipol> syn*ron\s motor1 ! field be+ suppli$ ) alt]nat+ in/ead ( direct curr5t4 ,! armature is m\nt$ 9 ball be>+s 9 ord] to make x suffici5tly s5sitive & smoo? 9 op]at+4 ,! armature coils are n exactly #ij degrees ap>t1 s9ce x is n possible to get ! curr5t 9 ! two coils exactly 9 quadrature )\t introduc+ cond5s]s on o!r complicat$ con/ruction4 ,/&>d rat+s are = #aaj & #bbj volt circuits4 ,syn*ronism indicators %\ld be ord]$ = ! frequ5cy ( ! circuit on :i* !y are to be op]at$1 al?\gh ! in/rum5ts may be us$ on circuits v>y+ #aj p] c5t to #ae p] c5t f ! normal4 ,! words ,fa/ & ,sl[ on ! dial indicate t ! frequ5cy on b9d+ po/s ,e & ,f is respectively high] or l[] ?an t on ,a & ,b2 or1 9 o!r words1 clockwise rotation ( ! po9t] means t ! incom+ ma*9e is runn+ at too high spe$1 c\nt] clockwise rotation indicat+ too l[ spe$4 ,ques4 ,h[ does ! resonance type ( syn*ronism indicator op]ate8 ,ans4 ,on ! same pr9ciple z ! resonance type ( frequ5cy indicator1 already describ$4 ,ques4 ,:at is ! pr9ciple ( ! rotat+ field type ( syn*ronism indicator8 ,ans4 ,its op]ation dep5ds on ! production ( a rotat+ field by ! curr5ts ( ! met]$ circuits 9 angul>ly plac$ coils1 "o = ea* phase 9 ! case ( a polyphase indicator4 ,9 ?is field is provid$ a movable iron vane or armature1 magnetiz$ by a /ation>y coil ^: curr5t is 9 phase ) ! voltage ( "o phase ( ! circuit4 ,z ! iron vane is attract$ or repell$ by ! rotat+ field1 x takes up a position :]e ! z]o ( ! rotat+ field occurs at ! same in/ant z ! z]o ( its own field4 ,9 ! s+le phase met] ! positions ( voltage & curr5t coils are int]*ang$ & ! rotat+ field is produc$ by means ( a split phase w9d+ connect$ to ! voltage circuit4 ,illu/ration3 ,,fig4 #b1egb4--;,g5]al ,electric ext]nal resi/ance & inductance = #aaj volt syn*ronism indicator4 ,bo? ! resi/ance & inductance are int5d$ to be plac$ beh9d ! swit*bo>d4 ,illu/ration3 ,,figs4 #b1egc to #b1egf4--;,connections ( ,g5]al ,electric syn*ronism indicator4 ,fig4 #b1egc1 connections ) gr\nd$ second>ies on pressure trans=m]s2 fig4 #b1egd1 connections ) ungr\nd$ second>ies on pressure trans=m]s2 fig4 #b1ege1 connections = #bjj to #bdj volt circuits1 ) six po9t receptacles2 fig4 #b1egf1 connections = *eck+ location ( ne$le4 ,! v>i\s lett]s ref]r$ to 9 ! diagrams w be f\nd m>k$ on ! ends ( ! in/rum5t /uds & back ( reactance coil box4 ,x is important t ! in/rum5t be connect$ 9 circuit 9 ! prop] mann] s t ! ne$le w come to ! m>k on ! upp] "p ( ! scale :5 syn*ronism is obta9$4 ,9 case ! po9t] become mov$ or a *ange 9 its position be necess>y1 x is advisable to make a *eck on ! indication be=e relocat+ ! ne$le4 ,?is te/ c be made z foll[s3 ,connect toge!r 7fig4 #b1egc7 /uds m>k$ ,b & ,e & connect /ud ,a to t]m9al ,f on ! ext]nal reactance box4 ,:5 ^! connections are made1 ! in/rum5t c be connect$ to a s+le phase circuit ( normal voltage & if ! in/rum5t be correct1 ! po9t] w /& v]tically at ! po9t ( syn*ronism4 ,if x d n1 ! ne$le c be mov$ & %\ld be fa/5$ 9 ! correct position4 ,! syn*roniz+ lamps :5 connect$ z illu/rat$ 9 ! diagrams1 %[ d>k :5 syn*ronism is rea*$4 ,?is is ! only connection possible :5 gr\nd$ second>ies are us$1 z 9 fig4 #b1egc1 & = ! high voltage indicators :5 us$ z 9 fig4 #b1ege1 b ) ungr\nd$ second>ies 7fig4 #b1egd7 ! lamps may be connect$ z indicat$1 :5 !y w %[ bright at ! mom5t ( syn*ronism4 ,! connections to ! syn*ronism indicator rema9 ! same z be=e4 ,p[] ,factor ,indicators4--,met]s ( ?is class indicate ! phase relation%ip betwe5 pressure & curr5t1 & are !re=e sometimes call$ phase indicators4 ,!re are two types3 #a4 ,wattmet] type2 #b4 ,disc1 or rotat+ field type4 ,illu/ration3 ,,fig4 #begg4--;,g5]al ,electric syn*roniz+ receptacle & plug = use ) syn*ronism indicator4 ,illu/ration3 ,,fig4 #b1egh4--,we/+h\se rotat+ field type p[] factor met]4 ,! rotat+ field is produc$ by ! curr5ts ( ! met]$ circuits 9 angul>ly plac$ coils1 "o = ea* phase ( ! sy/em1 9 ! case ( polyphase met]s4 ,9 ! ?ree phase met] ! rotat+ field is produc$ by ?ree coils spac$ #fj ap>t2 9 ! two phase met] by two coils spac$ #ij2 9 ! s+le phase met] ! positions ( voltage & curr5t coils are int]*ang$ & ! rotat+ field is produc$ by means ( a split phase w9d+1 connect$ to ! voltage circuit4 ,!re are no movable coils or flexible connections4 ,s+le phase met]s indicate ! p[] factor ( a s+le phase circuit1 or ( "o bran* ( any polyphase circuit4 ,special calibration is necess>y 9 ord] to use a s+le phase in/rum5t on a ?ree phase circuit unless ! voltage coil be connect$ f "o l9e to ! neutral4 ,polyphase met]s indicate ! av]age angle betwe5 ! curr5ts & voltages & are sup]ior = polyphase s]vice to met]s hav+ only "o curr5t coil4 ,9 ! wattmet] type1 ! phase relation betwe5 ! pressure & ! curr5t fluxes is su* t on a non-inductive load ! torque is z]o4 ,= in/ance1 9 a dynamomet] wattmet]1 ! pressure circuit is made highly inductive & ! in/rum5t !n indicates volts amp]es s9 in/ead ( volts amp]es cos 1 t is to say1 x w indicate ! wattless compon5t ( ! p[]4 ,a dynamomet] ( ?is type is sometimes call$ an idle curr5t wattmet]4 ,illu/ration3 ,,fig4 #b1egi4--,s+le phase p[] factor met] ( ! rotat+ field or disc type4 ,ques4 ,describe a s+le phase p[] factor met] ( ! disc or rotat+ field type4 ,ans4 ,x consi/s ( two pressure coils1 z %[n 9 fig4 #b1egi1 plac$ at "r angles to ea* o!r1 "o be+ connect$ ?r\gh a resi/ance1 & ! o!r ?r\gh an inductance s z to split ! phase & get ! equival5t ( a rotat+ magnetic field4 ,! coils are plac$ ab\t a common axis1 along :i* is pivot$ an iron disc or vane4 ,! magnetiz+ coils ,,fg are 9 s]ies ) ! load4 ,if ! load be v inductive1 ! coil ,m exp]i5ces v little torque & ! sy/em w set itself z %[n 9 ! figure4 ,z ! load becomes less inductive1 ! torque on ,s decreases & on ,m increases s t ! sy/em takes up a p>ticul> position = e angle ( lag or lead4 ,gr\nd ,detectors4--,in/rum5ts ( ?is "n are us$ = detect+ 7& sometimes measur+7 ! leakage to e>? or ! insulation ( a l9e or network & are sometimes call$ gr\nd or e>? indicators1 or leakage detectors4 ,= sy/ems n p]man5tly e>!d any:]e1 ^! in/rum5ts are ne>ly all bas$ on a measurem5t ( ! pressure diff]5ce betwe5 ea* pole & e>?1 two measurem5ts be+ requir$ = two wire sy/ems1 & ?ree = ?ree wire1 :e!r direct curr5t s+le phase1 or polyphase alt]nat+ curr5t4 ,9 ! case ( direct curr5t sy/ems1 ! insulation1 bo? ( ! network & ( ! individual l9es1 c be calculat$ f ! read+s1 b ) alt]nat+ curr5t1 ! di/urbance due to capacity effects is usually too great4 ,9 any case1 h[ev]1 ! ma9 %[+ ! smalle/ pressure diff]5ce to e>? mu/ be tak5 z be+ ! wor/ insulat$4 ,= l[ t5sion sy/ems mov+ coil 7= alt]nat+ curr5t7 or mov+ iron in/rum5ts 7= direct curr5t7 are ! mo/ us$1 :ile = high t5sion sy/ems electro/atic voltmet]s are to be pref]r$4 ,on sy/ems hav+ "s po9t p]man5tly e>!d at ! /ation1 z = in/ance ! neutral wire ( direct curr5t sy/em1 or ! neutral po9t ( a ?ree phase sy/em1 an ammet] connect$ 9 ! e>? wire w s]ve z a r\gh guide4 ,x %\ld indicate no curr5t s long z ! insulation is 9 a satisfactory /ate1 b on ! occurr5ce ( an e>? x w at once %[ a deflection4 ,! indications are1 h[ev]1 (t5 mislead+1 & s]ve m z a w>n+ ?an any?+ else4 ,illu/ration3 ,,fig4 #b1ehj4--,we/+h\se s+le phase electro/atic gr\nd detector4 ,illu/ration3 ,,fig4 #b1eha4--,we/+h\se ?ree phase electro/atic gr\nd detector4 ,illu/ration3 ,,fig4 #b1ehb4--,wallis-,jones automatic e>? leakage cut out4 ,x is an in/rum5t :i* s protects a direct curr5t circuit t ! circuit is brok5 :5ev] a leak occurs f ei!r ma9 to e>?1 & s t ! circuit _c be p]man5tly re-e/abli%$ until ! leak has be5 remov$4 ,! in/rum5t & its connections may be expla9$ by ! aid ( ! accompany+ diagram1 9 :i* ,t & ,t repres5t ! po9ts ( connection f ! ma9s1 & ,t & ,t1 ! po9ts ( connection to ! circuit to be protect$4 ,s ,s1 & ,s w pref]ably be ord9>y tumbl] swit*es1 b !y are diagrammatically repres5t$ z pla9 b> swit*es1 _! fix$ contacts be+ diagrammatically repres5t$ by dott$ circles4 ,:5 ! ?ree swit*es ,s1 ,s1 & ,s are clos$1 ! curr5t passes f ,t to ,t ?r\gh ! small resi/ance ,r1 ?r\gh circuit ,l to ,t1 & back ?r\gh ! resi/ance ,r to ,t4 ,9 %unt ) ,r & ,r1 are ! two mov+ coils ,c & ,c1 work+ 9 ! magnetic field ( ! magnets ,,ns1 ,,ns1 & rigidly fix$ on "o sp9dle1 :i* is brok5 electrically by an ebonite block ,e4 ,! po9ts ( connection to ! %unts are adju/$ s t :5 ! same curr5t passes out ?r\gh "o & back ?r\gh ! o!r1 ! effect on ! two coils is equal & opposite1 & !re is ?us no movem5t4 ,%\ld1 h[ev]1 any m9ute portion ( ! curr5t ?r\gh ,r leak to e>? in/ead ( return+ via ,r1 ! balance is di/urb$1 ,c becomes /rong] ?an ,c1 ! sy/em is deflect$1 & a contact is made by ! arm ,a at ,b1 no matt] 9 :i* direction ! coils deflect4 ,! sy/em is simil>ly deflect$ = a leak on ! o!r lead4 ,9 ! diagram ^! contacts are %[n at "r angles to _! normal plane4 ,z soon z ! contact is made1 ! electromagnet ,m is en]giz$1 ! arm ( ,s is releas$ & ! spr+ at once pulls x (f its contact1 at ! same "t break+ ,s4 ,! positions ( ! blades :5 ! swit*es are op5 are %[n dott$4 ,! only means ! us] has ( clos+ ! circuit is by putt+ on ,s by ! h&le ,h1 :i* is outside ! lock$ box4 ,! fir/ effect ( putt+ on ,s is to break its circuit2 x !n by means ( ! slott$ b> ,p beg9s to pull on ,s & ,s1 :i* c ?us be clos$ aga91 & held clos$ by ! trigg] z be=e4 ,! circuit1 is1 h[ev]1 /ill brok5 till ,s is pu%$ back4 ,!n if ! leak be /ill on1 ! slot 9 ,p all[s ,s & ,s to op5 at once z be=e4 ,x is !re=e impossible to keep ! circuit clos$ :ile ! leak exi/s4 ,! work+ condition ( ! in/rum5t c be te/$ at any "t by swit*+ a lamp on 9 ! circuit & depress+ "o ( ! keys ,k1 ,k4 ,?is %ort circuits ,r or ,r1 ?r[s ! coils out ( balance1 & ! swit* op5s4 ,! contact arm is clos$ 9 an inn] du/ tight case1 & x w be not$ t x makes contact only2 ! break occurs at ! swit*es1 ?us avoid+ any sp>k+4 ,s9ce ! two coils "w 9 ! two gaps ( "o & ! same field1 *anges 9 ! /r5g? ( ! magnets h no effect1 ! app>atus is enclos$ 9 a lock$ metallic box1 & ! only "p to :i* ! us] has access is ! h&le ,h1 &1 if desir$1 ! te/+ keys ,k ,k4 ,,hawk9s ,,practical ,,libr>y ,,( ,,electricity ,,9 ,,h&y ,,pocket ,,=m ,,price #a ,,ea* 99 99 99 99 99 ,!y are n only ! be/1 b ! *eape/ "w publi%$ 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? ,,av5ue1 ,,new ,,york ,,transcrib]',s ,,notes ,sil5tly correct$ simple spell+1 gramm>1 & typographical errors4 ,reta9$ ana*roni/ic & non-/&>d spell+s z pr9t$4 ,enclos$ italics m>kup 9 und]scores4 ,enclos$ bold m>kup 9 tildes4