,,! ,,?\ght ,,is ,,9 ,,! ,,"q ,,! ,,in=mation ,,is ,,9 ,,! ,,answ] ,illu/ration3 ,,hawk9s ,,electrical ,,guide ,,numb] ,,six ,,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$1 #aiad1 ,,by ,,!o4 ,,audel ,,co41 ,,new ,,york4 ,pr9t$ 9 ! ,unit$ ,/ates4 ,,table ,,( ,,cont5ts ,,guide ,,no4 #f4 ,,alt]nat+ ,,curr5t ,,motors #a1bfg to #a1cgf ,classification--syn*ron\s motors--ess5tial p>ts--syn*ron\s motor pr9ciples3 condition = />t+2 effective pressure2 dead c5t]s2 spe$2 limit ( lag2 effect ( load *anges--effect ( alt]+ ! field /r5g?--disadvantages ( syn*ron\s motors2 advantages--! ,v curve--adaptation--effici5cy--hunt+ ( syn*ron\s motors2 me*anical analogy--use z cond5s]--surg+--*>act]i/ics ( syn*ron\s motors3 />t+2 runn+2 /opp+2 effect ^u circuit2 p[] factor2 auxili>y app>atus2 adaptation--induction 7asyn*ron\s7 motors--ess5tial p>ts--types--oscillat+ magnetic field--rotat+ magnetic field--op]ation ( s+le phase motor2 :y n self />t+2 provision = />t+--op]ation ( polyphase induction motor2 :y call$ asyn*ron\s--spe$2 classification accord+ to spe$--! t]ms prim>y & second>y--:y polyphase induction motors are expla9$ be=e s+le phase--polyphase induction motors--features--ess5tial p>ts--pr9ciples--production ( rotat+ field--,tesla's rotat+ field--me?od ( obta9+ resultant flux ( ,tesla's field--,arago's rotations2 explanation--,f>aday's exp]im5t--production ( two phase rotat+ field2 resultant poles--six & eight pole two phase rotat+ fields--physical conception ( two phase rotat+ field--production ( ?ree phase rotat+ field2 ) r+ w9d+--physical conception ( ?ree phase rotat+ field--?ree phase six pole w9d+--slip--copp] cyl9d] illu/rat+ pr9ciple ( op]ation ( induction motor--calculation ( slip--table ( syn*ron\s spe$s--v>iation ( slip2 :y s small2 v>iation ) load2 table ( v>iation--sector me?od ( measur+ slip--evolution ( ! squirrel cage armature2 con/ruction--! field magnets2 p>ts2 con/ruction--field w9d+s = induction motors--calculation = revolutions ( rotat+ field2 objection to high spe$ ( field--difficulty ) l[ frequ5cy curr5ts--g5]al "* ( field w9d+--=mation ( poles--gr\p+ ( coils--/>t+ ( induction motors3 ext]nal resi/ance1 auto-trans=m]1 int]nal resi/ance me?ods--int]nal resi/ance induction motors2 adaptation--h[ resi/ance is cut out--:y n desirable = l>ge sizes--ext]nal resi/ance or slip r+ motors--op]ation--armature connections--s+le phase induction motors--s]vice suitable =--disadvantage--p>ts--:y n self-/>t+--h[ />t$--phase splitt+2 production ( rotat+ field f oscillat+ field--me?ods--/>t+ coils--%ad+ coils--"* ( ! />t+ torque--modification ( armature = />t+ ) heavy load--clut* type ( s+le phase induction motor2 its action 9 />t+--commutator motors--classification--action ( clos$ coil rotat+ 9 alt]nat+ field--! trans=m] pressure--g5]at$ pressure--self-induction pressure--local armature curr5ts2 reason = sp>k+2 h[ r$uc$--high resi/ance connectors--effect ( l[ p[] factor--effect ( frequ5cy--s]ies motor--features--adaptation--neutraliz$ s]ies motor--conductive me?od--inductive me?od--%unt motors--repulsion motors--difficulty ) e>ly motors--means employ$ to /op sp>k+--ess5tials ( s+le repulsion motors--! t]m repulsion induction motor--comp5sat$ repulsion motor--p[] factor ( induction motors--its importance--false ideas 9 reg>d to p[] factor--spe$ & torque ( motors4 ,,trans=m]s #a1cgg to #a1def ,_! use--ess5tial p>ts--basic pr9ciples--! prim>y w9d+--! second>y w9d+--magnetic leakage--! induc$ voltage--no load curr5t--magnetiz+ curr5t--action ( trans=m] ) load--classification--/ep up trans=m]s--use--con/ruction--copp] economy--/ep d[n trans=m]s--use--con/ruction--core trans=m]s--con/ruction--advantages--%ell trans=m]s--comp>ison ( core & %ell types--*oice--comb9$ core & %ell trans=m]s--economy ( con/ruction--s+le & polyphase trans=m]s--features ( ea* type--*oice ( types = polyphase curr5ts--op]ation ( ?ree phase trans=m] ) "o phase damag$--trans=m] losses--hy/]esis--:at gov]ns ! loss--h[ r$uc$--eddy curr5ts--lam9ation--?ickness ( lam9--importance ( iron losses--h[ to r$uce iron losses--copp] losses--h[ caus$--effect on p[] factor--effect ( resi/ance--cool+ ( trans=m]s--cool+ m$iums employ$--heat+ ( trans=m]s--objection to heat+--dry trans=m]s--air cool$ trans=m]s--natural draught type--=c$ draught or air bla/ type--con/ruction ( coils = air cool+--requirem5ts ) respect to air supply--quantity ( air us$--oil cool$ trans=m]s--circulation ( ! oil--action ( ! oil--objection to oil--k9d ( oil us$--oil requirem5ts--moi/ure 9 oil--wat] cool$ trans=m]s--int]nal coil type--ext]nal coil type--!rmo-circulation--quantity ( circulat+ wat] requir$--trans=m] insulation--! major & m9or insulation--mica--outdoor trans=m]s = irrigation s]vice--oil insulat$ trans=m]s--effici5cy ( trans=m]s--effici5cy curve--all day effici5cy ( trans=m]s--trans=m] fuse blocks--auto-trans=m]s--con/ant curr5t trans=m]s = s]ies arc light+2 elem5t>y diagram illu/rat+ pr9ciples--regulation--trans=m] connections--s+le phase connections--comb9+ trans=m]s--precautions--op]at+ second>ies 9 p>allel--connections = diff]5t voltages--precautions--two phase connections--?ree phase connections3 delta1 />1 delta />1 />-delta--comp>ison ( /> & delta connections--?ree phase trans=m]s--comp>ison ( air bla/1 wat] cool$1 & oil cool$ trans=m]s--/&>d trans=m] connections--h[ to te/ trans=m]s--trans=m] op]ation ) gr\nd$ second>y--trans=m] capacity = motors--trans=m] connections = motors--arc lamp trans=m]--trans=m] in/all$ on pole--/atic boo/] or regulat+ trans=m]4 ,,conv]t]s #a1deg to #a1did ,:]e us$--k9ds ( conv]t]--,a4,i4,e4,e4 classification--rot>y conv]t]s--op]ation--spe$--pr9ciples--rel ation betwe5 input & output pressures--s+le & polyphase types--advantage ( polyphase conv]t]s--armature connections ( polyphase conv]t]--pressure relation--voltage v>iation--advantage ( unity p[] factor--effect ( field too /rong--comp\nd+ ( rot>y conv]t]s--ratio ( conv]sion--voltage regulation--split pole me?od--regulat+ pole me?od--be/ location ( regulat+ poles--reactance me?od--multi-tap trans=m] me?od--syn*ron\s boo/] me?od--w9d+ connections--field connections--adaptation--motor g5]ator sets--classification--/&>d practice--behavior ( rot>y :5 hunt+2 comp>ison ) motor g5]ator sets--rac+--frequ5cy *ang+ sets--p>allel op]ation ( frequ5cy *ang]s--cascade conv]t]--spe$--action 9 motor armature w9d+--advantages--h[ />t$--comp>ison ( cascade conv]t] ) syn*ron\s conv]t]4 ,,rectifi]s #a1die to #a1ecj ,classification--me*anical rectifi]s--ess5tial features--con/ruction--application--elec trolytic rectifi]s--pr9ciples ( op]ation--,mohawk rectifi]--! t]m valve--metals = electrodes--electrolyte--,nodon valve--,audion valve--,buttn] valve--,*ur*] valve--,de ,f>ia valve--,flem+ oscillation valve--,grisson valve--,pawl[ski valve--,giles electric valve--,buttn] valve--m]cury vapor rectifi]s--pr9ciples--! t]ms arc & vapor--?ree phase m]cury vapor rectifi]--con/ruction--auxili>y app>atus--s]ies m]cury arc rectifi]--dissipation ( heat f bulb--replacem5t ( bulb--advantages ( rectifi]--precautions 9 in/all+--electromagnetic rectifi]s--con/ruction & op]ation4 ,,*apt] ,,li ,,alt]nat+ ,,curr5t ,,motors ,! almo/ univ]sal adoption ( ! alt]nat+ curr5t sy/em ( di/ribution ( electrical en]gy = light & p[]1 & ! _m inh]5t advantages ( ! alt]nat+ curr5t motor1 h creat$ ! wide field ( application n[ cov]$ by ?is type ( app>atus4 ,z _m c5tral /ations furni% only alt]nat+ curr5t1 x has become necess>y = motor manufactur]s to p]fect types ( alt]nat+ curr5t motor suitable = all classes ( indu/rial drive & :i* are adapt$ = use on ! k9ds ( alt]nat+ circuit employ$4 ,?is has naturally result$ 9 a multiplicity ( types & a classification1 to be compreh5sive1 mu/1 z 9 ! case ( alt]nators1 divide ! motors into gr\ps z reg>d$ f sev]al po9ts ( view4 ,accord+ly1 alt]nat+ curr5t motors may be classifi$3 #a4 ,) respect to _! pr9ciple ( op]ation1 z a4 ,,syn*ron\s ,,motors2 b4 ,,asyn*ron\s ,,motors3 #a4 ,induction motors2 s]ies2 #b4 ,commutator motors comp5sat$2 %unt2 repulsion4 #b4 ,) respect to ! curr5t z a4 ,s+le phase2 b4 ,polyphase2 ,illu/ration3 ,,figs4 #a1ehe to #a1ehh4--,syn*ron\s motor pr9ciples3 ,i4 ,a s+le phase syn*ron\s motor is n self-/>t+4 ,! figures %[ an elem5t>y alt]nator & an elem5t>y syn*ron\s motor1 ! con/ruction ( ea* be+ id5tical z %[n4 ,if ! alt]nator be />t$1 dur+ ! fir/ half ( a revolution1 beg9n+ at ! initial position ,,abcd1 fig4 #a1ehe1 curr5t w fl[ 9 ! direction indicat$ by ! arr[s1 pass+ ?r\gh ! ext]nal circuit & armature ( ! motor1 fig4 #a1ehf1 induc+ magnetic poles 9 ! latt] z %[n by ! v]tical arr[s4 ,^! poles are attract$ by unlike poles ( ! field magnets1 :i* t5d to turn ! motor armature 9 a c\nt]-clockwise direction4 ,n[1 be=e ! torque ?us set up has "t to ov]come ! in]tia ( ! motor armature & cause x to rotate1 ! alt]nator armature has complet$ ! half revolution1 & beg9n+ ! second half ( ! revolution1 z 9 fig4 #a1ehg1 ! curr5t is rev]s$ & consequ5tly ! induc$ magnetic poles 9 ! motor armature are rev]s$ also4 ,?is t5ds to rotate ! armature 9 ! rev]se direction1 z 9 fig4 #a1ehh4 ,^! rev]sals ( curr5t occur ) su* frequ5cy t ! =ce does n act long en\gh 9 ei!r direction to ov]come ! in]tia ( ! armature2 consequ5tly x rema9s at re/1 or to be exact1 x vibrates4 ,h5ce1 a s+le phase syn*ron\s motor mu/ be />t$ by "s ext]nal =ce & br\ght up to a spe$ t gives ! same frequ5cy z ! alt]nator be=e x w op]ate4 ,a s+le phase syn*ron\s motor1 !n1 is n self-/>t+1 :i* is "o ( its disadvantages2 ! reason x w op]ate aft] be+ spe$$ up to syn*ronism ) ! alt]nator & !n connect$ 9 ! circuit is expla9$ 9 figs4 #a1ehi to #a1eib4 #c4 ,) respect to spe$1 z a4 ,con/ant spe$2 b4 ,v>iable spe$4 #d4 ,) respect to /ructural features1 z a4 ,enclos$2 b4 ,semi-enclos$2 c4 ,op52 d4 ,pipe v5tilat$2 e4 ,back ge>$2 f4 ,skeleton frame2 g4 ,rivet$ frame2 h4 ,v5tilat$2 etc4 ,( ! above divisions & sub-divisions "s are self-def9+ & ne$ little or no explanation2 ! o!rs1 h[ev]1 w be consid]$ 9 detail1 ) explanations ( ! pr9ciples ( op]ation & con/ruction4 ,syn*ron\s ,motors4--,! t]m syn*ron\s means 9 unison1 t is1 9 /ep4 ,a s call$ syn*ron\s motor1 !n1 z g5]ally def9$1 is "o :i* rotates 9 unison or 9 /ep ) ! phase ( ! alt]nat+ curr5t :i* op]ates x4 ,/rictly speak+1 h[ev]1 x %\ld be not$ t ?is condition ( op]ation is only approximately realiz$ z w be lat] %[n4 ,any s+le or polyphase alt]nator w op]ate z a syn*ron\s motor :5 suppli$ ) curr5t at ! same pressure & frequ5cy z x produces z a g5]ator1 ! ess5tial condition1 9 ! case ( a s+le phase ma*9e1 be+ t x be spe$$ up to s call$ syn*ronism be=e be+ put 9 ! circuit4 ,9 con/ruction1 syn*ron\s motors are almo/ id5tical ) ! correspond+ alt]nator1 & consi/ ess5tially ( two elem5ts3 #a4 ,an armature1 #b4 ,a field4 ,illu/ration3 ,,figs4 #a1ehi to #a1eib4--,syn*ron\s motor pr9ciples3 ,,ii4 ,! condition necess>y = syn*ron\s motor op]ation is t ! motor be spe$$ up until x rotates 9 syn*ronism1 t is1 9 /ep ) ! alt]nator4 ,?is means t ! motor mu/ be run at ! same frequ5cy z ! alt]nator 7n necess>ily at ! same spe$74 ,9 ! figures x is assum$ t ! motor has be5 br\ght up to syn*ronism ) ! alt]nator & connect$ 9 ! circuit z %[n4 ,9 figs4 #a1ehi & #a1eij ! arr[s indicate ! direction ( ! curr5t = ! armature position %[n4 ,! curr5t fl[+ ?r\gh ! motor armature induces magnetic poles :i* are attract$ by ! field poles1 ?us produc+ a torque 9 ! direction 9 :i* ! armature is rotat+4 ,aft] ! alt]nator coil passes ! v]tical position1 ! curr5t rev]ses z 9 fig4 #a1eia1 & ! curr5t fl[s ?r\gh ! motor armature 9 ! opposite direction1 ?us rev]s+ ! induc$ poles z 9 fig4 #a1eib4 ,?is br+s l poles ne> ea* o!r1 & s9ce ! motor coil has rotat$ beyond ! v]tical position ! repell+ action ( ! l poles1 & also ! attraction ( unlike poles1 produces a torque act+ 9 ! direction 9 :i* ! motor is rotat+4 ,h5ce1 :5 ! two armatures move syn*ron\sly1 ! torque produc$ by ! action ( ! induc$ poles ^u ! field poles is always 9 ! direction 9 :i* ! motor is runn+1 & accord+ly1 t5ds to keep x 9 op]ation4 ei!r ( :i* may revolve4 ,! field is sep>ately excit$ ) direct curr5t4 ,illu/ration3 ,,figs4 #a1eic & #a1eid4--,syn*ron\s motor pr9ciples3 ,,iii4 ,! curr5t :i* fl[s ?r\gh ! armature ( a syn*ron\s motor is t due to ! effective pressure4 ,s9ce ! motor rotates 9 a magnetic field1 a pressure is induc$ 9 its armature 9 a direction opposite to t induc$ 9 ! armature ( ! alt]nator1 & call$ ! rev]se pressure1 z di/+ui%$ f ! pressure g5]at$ by ! alt]nator call$ ! impress$ pressure4 ,at any in/ant1 ! pressure available to cause curr5t to fl[ ?r\gh ! two armatures1 call$ ! effective pressure1 is equal to ! diff]5ce betwe5 ! pressure g5]at$ by ! alt]nator or impress$ pressure & ! rev]se pressure induc$ 9 ! motor4 ,n[ if ! motor be p]fectly free to turn1 t is1 )\t load or friction1 ! rev]se pressure w equal ! impress$ pressure & no curr5t w fl[4 ,?is is ! case ( real syn*ron\s op]ation1 t is1 n only is ! frequ5cy ( motor & alt]nator ! same1 b ! coils rotate )\t phase diff]5ce4 ,9 figs4 #a1eic & #a1eid1 ! impress$ & rev]se pressures are repres5t$ by ! dott$ arr[s ,p & ,pr1 respectively4 ,s9ce 9 ?is case ^! oppos+ pressures are equal1 ! resultant or effective pressure is z]o2 h5ce1 !re is no curr5t4 ,9 actual ma*9es ?is condition is impossible1 because ev5 if ! motors h no ext]nal load1 !re is always m or less friction pres5t2 h5ce1 9 op]ation !re mu/ be m or less curr5t fl[+ ?r\gh ! motor armature to induce magnetic poles s z to produce suffici5t torque to c>ry ! load4 ,! action ( ! motor 9 automatically adju/+ ! effective pressure to suit ! load is expla9$ 9 figs4 #a1eie & #a1eif4 ,! pr9ciples ^u :i* su* motors op]ate may be expla9$ by consid]+ ! action ( two elem5t>y alt]nators connect$ 9 circuit1 z illu/rat$ 9 ! accompany+ illu/rations1 "o alt]nator be+ us$ z a g5]ator & ! o!r z a syn*ron\s motor4 ,suppose ! motor1 z 9 figs4 #a1ehe & #a1ehf1 be at re/ :5 x is connect$ 9 circuit ) ! alt]nator4 ,! alt]nat+ curr5t w fl[ ?r\gh ! motor armature & produce a reaction ^u ! field t5d+ to rotate ! motor armature fir/ 9 "o direction1 !n 9 ano!r4 ,illu/ration3 ,,figs4 #a1eie & #a1eif4--,syn*ron\s motor pr9ciples3 ,,iv--,a syn*ron\s motor adju/s itself to *anges ( load by *ang+ ! phase diff]5ce betwe5 curr5t & pressure4 ,if !re be no load & no friction1 ! motor :5 spe$$ up & connect$ 9 ! circuit1 w run 9 true syn*ronism ) ! alt]nator1 t is1 at any in/ant1 ! coils ,a ,b ,c ,d & ,a,b,c,d w be 9 p>allel planes4 ,:5 ?is condition obta9s1 no curr5t w fl[ & no torque w be requir$ 7z expla9$ 9 figs4 #a1eic & #a1eid74 ,if a load be put on ! motor1 ! effect w be to cause ,a,b,c,d to lag beh9d ! alt]nator coil to "s position ,a,b,c,d & curr5t to fl[4 ,! rev]se pressure w lag beh9d ! impress$ pressure equally ) ! coil1 & ! curr5t :i* has n[ />t$ w ord9>ily take an int]m$iate phase s t x is beh9d ! impress$ pressure b 9 advance ( ! rev]se pressure4 ,^! phase relations may be repres5t$ 9 ! figure by ! armature positions %[n1 viz43 #a1 ! syn*ron\s position ,a,b,c,d repres5t+ ! impress$ pressure1 #b1 ! int]m$iate position ,a',b',c',d'1 ! curr5t1 #c1 ! actual position ,a,b,c,d 7correspond+ to me*anical lag71 ! rev]se pressure4 ,f ! figure x w be se5 t ! curr5t phase repres5t$ by ,a',b',c',d' is 9 advance ( ! rev]se pressure phase repres5t$ by ,a,b,c,d4 ,h5ce1 by armature reaction1 ! curr5t lead+ ! rev]se pressure weak5s ! motor field & r$uces ! rev]se pressure1 ?us e/abli%+ equilibrium betwe5 curr5t & load4 ,z ! load is increas$1 ! me*anical lag ( ! alt]nator coil becomes great] & likewise ! curr5t lead ) respect to ! rev]se pressure1 :i* int5sifies ! armature reaction & all[s m curr5t to fl[4 ,9 ?is way equilibrium is ma9ta9$ = v>iations 9 load )9 ! limits ( z]o & #ij me*anical lag4 ,! effect ( armature reaction on motors is j ! rev]se to its effect on alt]nators1 :i* results 9 m>k$ automatic adju/m5t betwe5 ! ma*9es especially :5 a s+le motor is op]at$ f an alt]nator ( ab\t ! same size4 ,9 o!r words1 ! curr5t :i* weak5s or /r5g!ns ! motor field1 /r5g!ns or weak5s respectively ! alt]nator field z ! load is v>i$4 ,because ( ! v rapid rev]sals 9 direction ( ! torque ?us set up1 !re is n suffici5t "t to ov]come ! in]tia ( ! armature be=e ! curr5t rev]ses & produces a torque 9 ! opposite direction1 h5ce1 ! armature rema9s /ation>y or1 /rictly speak+1 x vibrates4 ,illu/ration3 ,,figs4 #a1eig & #a1eih4--,syn*ron\s motor pr9ciples3 ,v4 ,! effectiv5ess ( armature reaction 9 weak5+ ! field is proportional to ! s9e ( ! angle by :i* ! curr5t lags beh9d ! impress$ pressure4 ,if a motor be )\t load or friction1 its armature w revolve syn*ron\sly 79 p>allel planes7 ) ! alt]nator armature4 ,9 ! figures let ,,abcd repres5t an in/antane\s position ( ! motor armature :5 ?is condition obta9s2 x w !n repres5t ! phase relation%ip ( impress$ & rev]se pressures = ! same condition ( no load1 no friction1 op]ation4 ,n[1 if a light load be plac$ on ! motor = ! same in/antane\s position ( alt]nator armature1 ! motor coil w drop beh9d to "s position z ,a1 fig4 #a1eig 7"p ( ! coil only be+ %[n74 ,! rev]se pressure w also lag an equal am\nt & its phase ) respect to ! impress$ pressure w be repres5t$ by ,a4 ,! armature curr5t w ord9>ily take an int]m$iate phase1 repres5t$ by coil position ,a',b',c',d'1 induc+ a field /r5g? correspond+ to ! #i l9es ( =ce ,,(1 ,o',f'1 etc4 ,! curr5t be+ 9 advance ( ! phase ( ! rev]se pressure ,a1 ! armature reaction weak5s ! field1 ?us r$uc+ ! rev]se pressure & all[+ ! prop] curr5t to fl[ to balance ! load4 ,! am\nt by :i* ! field is weak5$ may be det]m9$ by resolv+ ! induc$ magnetic l9es ,,(1 ,o',f'1 ,o,f1 etc41 into compon5ts ,,og1 ,,gf1 ,o',g'1 ,g',f'1 ,o,g1 ,g,f1 etc41 respectively p>allel & at "r angles to ! l9es ( =ce ( ! ma9 field4 ,( ^! compon5ts1 ! field is weak5$ only by ,,og1 ,o',g'1 ,o,g1 etc4 ,s9ce by con/ruction1 angle ,,(g ,,aoa'1 & call+ ,,( unity l5g?1 ,,og s9e ( angle by :i* ! curr5t lags beh9d ! impress$ pressure4 ,! con/ruction is %[n bett] 9 ! enl>g$ diagram4 ,= a heavi] load ! armature coil w drop back fur!r to "s position z ,a'1 fig4 #a1eih1 & ! lag ( ! curr5t increase to "s int]m$iate phase z ,a,b,c,d4 ,by simil> con/ruction x is se5 t ! compon5t ,,og 7fig4 #a1eig7 has increas$ to ,,oj 7fig4 #a1eih71 ?is compon5t ?us fur!r weak5+ ! ma9 field1 by an am\nt proportional to ! s9e ( ! angle by :i* ! curr5t lags beh9d ! impress$ pressure4 ,! increas$ curr5t :i* is n[ p]mitt$ to fl[1 causes ! induc$ field to be /r5g!n$ 7z indicat$ by ! dott$ magnetic l9es ,m1 ,m'1 ,m1 etc471 ?us increas+ ! torque to balance ! additional load4 ,n[ if ! motor armature be fir/ br\ght up to a spe$ correspond+ 9 frequ5cy to t ( ! alt]nator be=e connect+ ! motor 9 ! circuit1 ! armature w cont9ue revolv+ at ! same frequ5cy z ! alt]nator4 ,! armature cont9ues revolv+1 because1 at syn*ron\s spe$1 ! field flux & armature curr5t are always 9 ! same relative position1 produc+ a torque :i* always pulls ! armature ar\nd 9 ! same direction4 ,a polyphase syn*ron\s motor is self />t+1 because1 be=e ! curr5t has di$ out 9 ! coils ( "o phase1 x is increas+ 9 ^? ( ! o!r phase or phases1 s t !re is always "s turn+ ef=t ex]t$ on ! armature4 ,! spe$ ( a syn*ron\s motor is t at :i* x w\ld h to run1 if driv5 z an alt]nator1 to deliv] ! numb] ( cycles :i* is giv5 by ! supply alt]nator4 ,illu/ration3 ,,figs4 #a1eii & #a1fjj4--,syn*ron\s motor pr9ciples3 ,,vi4 ,a s+le phase syn*ron\s motor has dead c5t]s1 j ! same z a "o cyl9d] /eam eng9e4 ,two diagrams ( ! motor are "h %[n illu/rat+ ! effect ( ! curr5t 9 bo? directions4 ,:5 ! plane ( ! coil is p]p5dicul> to ! field1 ! poles induc$ 9 ! armature are p>allel to field = ei!r direction ( ! curr5t2 t is to say1 ! field l9es ( =ce & ! induc$ l9es ( =ce act+ 9 p>allel or opposite directions1 no turn+ effect is produc$1 j z 9 analogy :5 an eng9e is on ! dead c5t]1 ! pi/on rod 7field l9e ( =ce7 & connect+ rod 7induc$ l9e ( =ce7 be+ 9 a /raight l9e1 ! =ce ex]t$ by ! /eam on ! pi/on produces no torque4 ,= in/ance a #ab pole alt]nator runn+ at #fjj revolutions p] m9ute w deliv] curr5t at a frequ5cy ( #fj cycles a second2 an #h pole syn*ron\s motor suppli$ f t circuit w run at #ijj revolutions p] m9ute1 :i* is ! spe$ at :i* x w\ld h to be driv5 z an alt]nator to give #fj cycles a second--! frequ5cy ( ! #ab pole alt]nator4 ,illu/ration3 ,,figs4 #a1fja to #a1fjd4--,syn*ron\s motor pr9ciples ,,vii4 ,an ess5tial condition = syn*ron\s motor op]ation is t ! me*anical lag be less ?an #ij4 ,figs4 #a1fja & #a1fjb repres5t ! conditions :i* prevail :5 ! lag ( ! motor armature ,a',b',c',d' is any?+ less ?an #ij4 ,z %[n1 ! lag is almo/ #ij4 ,! direction ( ! curr5t & induc$ poles are indicat$ by ! arr[s4 ,! incl9ation ( ! motor coil is su* t ! repulsion ( l poles produces a torque 9 ! direction ( rotation1 ?us t5d+ to keep motor 9 op]ation4 ,n[1 9 figs4 #a1fjc & #a1fjd1 = ! same position ( ! alt]nator coil ,,abcd1 if ! lag be great] ?an #ij1 ! incl9ation ( ! motor coil ,a',b',c',d' is su* t at ?is in/ant ! repulsion ( l poles produces a torque 9 a direction opposite to t ( ! rotation1 ?us t5d+ to /op ! motor4 ,9 actual op]ation ?is quickly br+s ! motor to re/1 hav+ ! same effect z a /rong brake 9 ov]com+ ! mom5tum ( a revolv+ :eel4 ,illu/ration3 ,,figs4 #a1fje to #a1fjh4--,syn*ron\s motor pr9ciples3 ,,viii4 ,if ! torque & curr5t ?r\gh ! motor armature be kept con/ant1 /r5g!n+ ! field w increase ! me*anical lag1 & ! lead ( ! curr5t ) respect to ! rev]se pressure4 ,9 ! figures1 let ,a be an in/antane\s position ( ! alt]nator coil1 ,a1 syn*ron\s position ( motor coil1 ,a'1 position correspond+ to curr5t phase1 ,a1 actual position or me*anical lag ( motor coil beh9d alt]nator coil necess>y to ma9ta9 equilibrium4 ,9 fig4 #a1fjf1 let ,a' & ,a repres5t respectively ! relation ( curr5t phase & me*anical lag correspond+ to a c]ta9 load & field /r5g?4 ,= ^! conditions ,,og1 ,o',g'1 ,o,g1 etc41 w repres5t ! compon5ts ( ! induc$ l9es ( =ce 9 opposition to ! motor field1 t is1 !y indicate ! int5sity ( ! armature reaction at ! in/ant depict$4 ,n[1 assume ! field /r5g? to be d\bl$1 z 9 fig4 #a1fjh1 ! motor load & curr5t be+ ma9ta9$ con/ant4 ,"u ^! conditions1 ! armature reaction mu/ be d\bl$ to ma9ta9 equilibrium2 t is1 ! compon5ts ,,og1 ,o',g'1 etc41 fig4 #a1fjh1 mu/ be twice ! l5g? ( ,,og1 ,o',g'1 etc41 fig4 #a1fje4 ,also s9ce ! curr5t is ma9ta9$ con/ant1 ! induc$ magnetic l9es ,,(1 ,o',f' are ( same l5g? 9 bo? figures4 ,h5ce1 9 fig4 #a1fjh ! plane ( ^! compon5ts is su* t _! extremities t\* p]p5dicul>s f ,g1 ,g'1 etc41 giv+ ! o!r compon5ts ,,fg1 ,f',g'1 etc4 ,! plane ,a'1 normal to ,,(1 ,o',f'1 etc41 gives ! curr5t phase4 ,by con/ruction1 ! phase diff]5ce betwe5 ,a & ,a' is su* t s9 ,a,,oa' 7fig4 #a1fjh7 #b s9 ,a,,oa' 7fig4 #a1fjf74 ,t is1 d\bl+ ! field /r5g? causes an increase ( curr5t lag su* t ! s9e ( ! angle ( ?is lag is d\bl$4 ,s9ce ! int5sity ( ! armature reaction dep5ds on ! lead ( ! curr5t ) respect to ! rev]se pressure1 ! me*anical lag ( ! coil mu/ be increas$ to "s position z ,a 7fig4 #a1fjh71 su* z w give an armature reaction ( an int5sity indicat$ by ! compon5ts ,,og1 ,o',g'1 etc4 ,! foll[+ simple =mula gives ! spe$ relations betwe5 g5]ators & motors connect$ to ! same circuit & hav+ diff]5t numb]s ( poles4 ,p ,s s ----- p 9 :i* s4 ,revolutions p] m9ute ( ! motor2 p4 ,numb] ( poles ( ! motor2 ,s4 ,revolutions p] m9ute ( ! alt]nator2 ,p4 ,numb] ( poles ( ! alt]nator4 ,"q4 ,if ! field /r5g? ( a syn*ron\s motor be alt]$1 :at effect does ?is h on ! spe$1 & :y8 ,ans4 ,! spe$ does n *ange 7save = a mom5t>y v>iation to e/abli% ! phase relation correspond+ to equilibrium71 because ! motor has to run at ! same frequ5cy z ! alt]nator4 ,ques4 ,h[ does a syn*ron\s motor adju/ itself to *anges ( load & field /r5g?8 ,ans4 ,by *ang+ ! phase diff]5ce betwe5 ! curr5t & pressure4 ,if1 on connect+ a syn*ron\s motor to ! ma9s1 ! excitation be too weak1 s t ! voltage is l[] ?an t ( ! supply1 ?is phase diff]5ce w appe> result+ 9 wattless curr5t1 s9ce ! miss+ magnetization has1 z x 71 to be suppli$ f an ext]nal s\rce4 ,a phase diff]5ce also appe>s :5 ! magnetization is too /rong4 ,ques4 ,/ate ! disadvantages ( syn*ron\s motors4 ,ans4 ,a syn*ron\s motor requires an auxili>y p[] = />t+1 & w /op if1 = any reason1 ! syn*ronism be de/roy$2 collector r+s & bru%es are requir$4 ,= "s purposes syn*ron\s motors are n desirable1 z = driv+ %afts 9 small work%ops hav+ no o!r p[] available = />t+1 & 9 cases :]e frequ5t />t+1 or a /rong torque at />t+ is necess>y4 ,a syn*ron\s motor has a t5d5cy to hunt#a & requires intellig5t att5tion2 also an excit+ curr5t :i* mu/ be suppli$ f an ext]nal s\rce4 #a ,,note4--,see ,hunt+ ( syn*ron\s motors1 page #a1bhj4 ,ques4 ,/ate ! advantage ( syn*ron\s motors4 ,ans4 ,! syn*ron\s motor is desirable = l>ge p[]s :]e />t+ "u load is n necess>y4 ,its p[] factor may be controll$ by v>y+ ! field /r5g?4 ,! p[] factor c be made unity &1 fur!r1 ! curr5t c be made to lead ! pressure4 ,illu/ration3 ,,fig4 #a1fji4--;,diagram illu/rat+ me?od ( repres5t+ ! p]=mance ( syn*ron\s motors4 ,! ,v %ap$ curve is obta9$ by plott+ ! curr5t tak5 by motor "u diff]5t degrees ( excitation1 ! p[] develop$ by ! motor rema9+ con/ant4 ,! curr5t may be made to lag or lead :ile ! load rema9s con/ant1 by v>y+ ! excitation4 ,by v>y+ ! excitation1 a c]ta9 value may be rea*$ :i* w give a m9imum curr5t 9 ! armature2 ?is is ! condition ( unity p[] factor4 ,if n[ ! excitation be dim9i%$ ! curr5t w lag & increase 9 value to obta9 ! same p[]2 if ! excitation be increas$ ! curr5t w lead & increase 9 value to obta9 ! same p[]4 ,! results plott$ = sev]al values ( ! excitation curr5t w give ! ,v curve z %[n4 ,?is is an actual curve obta9$ by ,mordey on a #ej kw4 ma*9e runn+ unload$ z a motor4 ,o!r curves situat$ above ?is "o may be obta9$ = v>i\s load+s ( ! motor4 ,a syn*ron\s motor is frequ5tly connect$ 9 a circuit solely to improve ! p[] factor4 ,9 su* cases x is (t5 call$ a cond5s] motor = ! reason t its action is simil> to t ( a cond5s]4 ,! design ( syn*ron\s motors proce$s on ! same l9es z t ( alt]nators1 & ! "q ( voltage regulation 9 ! latt] becomes a "q ( p[] factor regulation 9 ! =m]4 ,ques4 ,= :at s]vice are !y especially suit$8 ,ans4 ,= high pressure s]vice4 ,high voltage curr5t suppli$ to ! armature does n pass ?r\gh a commutator or slip r+s2 ! field curr5t :i* passes ?r\gh slip r+s be+ ( l[ pressure does n give any tr\ble4 ,illu/ration3 ,,fig4 #a1faj4--,we/+h\se self-/>t+ syn*ron\s motor4 ,motors ( ?is type are suitable = con/ant spe$ s]vice :]e />t+ conditions are mod]ate1 su* z driv+ compressors1 pumps1 & l>ge bl[]s4 ,syn*ron\s motors c be made to op]ate n only z motors b z syn*ron\s cond5s]s to improve ! p[] factor ( ! circuit4 ,! field is provid$ ) a comb9$ />t+ & damp] or amorlisseur w9d+ s proportion$ t ! necess>y />t+ torque is develop$ by ! m9imum curr5t consi/5t ) satisfactory syn*ron\s runn+ )\t hunt+4 ,! armature slots are op5 & ! coils =m w\nd1 impregnat$1 & int]*angeable4 ,malleable iron f+] plates at ea* end ( ! core support ! tee?4 ,v5tilat+ f+] plates assembl$ ) ! lam9ations =m air ducts4 ,! frames are ( ca/ iron1 box section ) op5+s = v5tilation2 %oes & slide rails p]mit adju/m5t ( position4 ,! bru% hold]s are ( ! /&>d slid+ %unt type4 ,two or m bru%es are provid$ = ea* r+4 ,ques4 ,h[ d syn*ron\s & induction motors comp>e z to effici5cy8 ,ans4 ,syn*ron\s motors are usually ! m effici5t4 ,illu/ration3 ,,fig4 #a1faa4--,me*anical analogy illu/rat+ hunt+4 ,! figure repres5ts two fly:eels connect$ by a spr+ susceptible to torsion 9 ei!r direction ( rotation4 ,if ! :eels ,a & ,b be rotat+ at ! same spe$ & a brake be appli$1 say to ,b1 its spe$ w dim9i% & ! spr+ w coil up1 & if fairly flexible1 m ?an ! necess>y am\nt to balance ! load impos$ by ! brake2 because :5 ! position ( prop] torque is rea*$1 ,b is /ill rotat+ slightly sl[] ?an ,a1 & an additional torque is requir$ to ov]come ! in]tia ( ,b & br+ its spe$ up to syn*ronism ) ,a4 ,n[ be=e ! spr+ /ops coil+ up ! :eels mu/ be rotat+ at ! same spe$4 ,:5 ?is occurs ! spr+ has rea*$ a position ( too great torque1 & !re=e ex]t+ m turn+ =ce on ,b ?an is necess>y to drive x aga9/ ! brake4 ,accord+ly ,b is accel]at$ & ! spr+ uncoils4 ,! velocity ( ,b ?us oscillates above & bel[ t ( ,a :5 a load is put on & tak5 (f4 ,ow+ to friction1 ! oscillations gradually die out & ! second :eel takes up a /eady spe$4 ,a simil> action takes place 9 a syn*ron\s motor :5 ! load is v>i$4 ,hunt+ ( ,syn*ron\s ,motors4--,s9ce a syn*ron\s motor runs practically 9 /ep ) ! alt]nator supply+ x ) curr5t :5 !y bo? h ! same numb] ( poles1 or "s multiple ( ! ratio ( ! numb] ( poles on ea* ma*9e1 x w take an increas+ curr5t f ! l9e z its spe$ drops beh9d ! alt]nator1 b w supply curr5t to ! l9e z a g5]ator if = any reason ! spe$ ( ! alt]nator %\ld drop beh9d t ( ! motor1 or ! curr5t wave lag beh9d1 :i* produces ! same effect1 & due to additional self-induction or inductance produc$ by />t+ up or ov]load+ "s o!r motor or rot>y conv]t] 9 ! circuit4 ,:5 ! motor is fir/ tak+ curr5t1 !n giv+ curr5t back to ! l9e1 & ?is action is cont9u$ p]iodically1 ! motor is said to be hunt+4 ,illu/ration3 ,,fig4 #a1fab4--;,diagram illu/rat+ ! use ( a syn*ron\s motor z a cond5s]4 ,if a syn*ron\s motor be suffici5tly excit$ ! curr5t w lead4 ,h5ce1 if x be connect$ across an inductive circuit z 9 ! figure & ! field be ov] excit$ x w comp5sate = ! lagg+ curr5t 9 ! ma91 ?us increas+ ! p[] factor4 ,if ! motor be suffici5tly ov] excit$ ! p[] factor may be made unity1 ! m9imum curr5t be+ ?us obta9$ t w suffice to transmit ! p[] 9 ! ma9 circuit4 ,a syn*ron\s motor us$ 9 ?is way is call$ a rot>y cond5s] or syn*ron\s comp5sator4 ,?is is especially useful on long l9es conta9+ trans=m]s & induction motors4 ,ques4 ,:at t]m is appli$ to describe ! behavior ( ! curr5t :5 hunt+ occurs8 ,ans4 ,! t]m surg+ is giv5 to describe ! curr5t fluctuations produc$ by hunt+4 ,! me*anical analogy ( hunt+ illu/rat$ 9 fig4 #a1faa w help to an und]/&+ ( ?is ph5om5on4 ,9 alt]nat+ curr5t circuits a precisely simil> action takes place betwe5 ! alt]nators & syn*ron\s motors1 or ev5 betwe5 ! alt]nators !mselves4 ,,*>act]i/ics ,,( ,,syn*ron\s ,,motors ,/>t+4--,! motor mu/ be br\ght up to syn*ron\s spe$ )\t load1 a />t+ comp5sator be+ us$4 ,if provid$ ) a self-/>t+ device1 ! latt] mu/ be cut out ( circuit at ! prop] "t4 ,! />t+ torque ( motor ) self-/>t+ device is v small4 ,runn+4--,! motor runs at syn*ron\s spe$4 ,! maximum torque is sev]al times full load torque & occurs at syn*ron\s spe$4 ,/opp+4--,if ! motor receive a sudd5 ov]load suffici5t to mom5t>ily r$uce its spe$1 x w /op2 ?is may be br\ght ab\t by mom5t>y int]ruption ( ! curr5t1 suffici5t to cause a loss ( syn*ronism4 ,effect ^u ,circuit4--,9 case ( %ort circuit 9 ! l9e ! motor acts z a g5]ator & ?us increases ! int5sity ( ! %ort circuit4 ,! motor impresses its own wave =m ^u ! circuit4 ,ov] excitation w give to ! circuit ! effect ( capacity1 & "u excitation1 t ( inductance4 ,p[] ,factor4--,?is dep5ds ^u ! field curr5t1 wave =m & hunt+4 ,! p[] factor may be controll$ by v>y+ ! field excitation4 ,necess>y ,auxili>y ,app>atus4--,p[] = />t+1 or if self-/>t+1 means ( r$uc+ ! voltage :ile />t+2 also1 field excit]1 rheo/at1 friction clut*1 ma9 swit* & excit] swit*1 in/rum5ts = indicat+ :5 ! field curr5t is prop]ly adju/$4 ,adaptation4--,if induction motors be connect$ to ! same l9e ) a syn*ron\s motor t has a /eady load1 !n ! field ( ! syn*ron\s motor c be ov] excit$ to produce a lead+ curr5t1 :i* w c\nt]act ! effect ( ! lagg+ curr5ts induc$ by ! induction motors4 ,ow+ to ! weak />t+ torque1 skill$ att5dance requir$1 & ! liability ( ! motor to /op "u abnormal work+ conditions1 ! syn*ron\s motor is n adapt$ to g5]al p[] di/ribution1 b r to l>ge units :i* op]ate "u a /eady load & d n require frequ5t />t+ & /opp+4 ,illu/ration3 ,,figs4 #a1fac to #a1fbe4--;,disassembl$ view ( ,we/]n ,electric ?ree phase squirrel cage skeleton frame induction motor4 ,induction 7,asyn*ron\s7 ,motors4-- ,an induction motor consi/s ess5tially ( an armature & a field magnet1 !re be+1 9 ! simple/ & mo/ usual types1 no electrical connection betwe5 ^! two p>ts4#b #b ,,note4--,! au?or pref]s ! t]ms armature & field magnet1 in/ead ( prim>y1 second>y1 /ator1 rotor1 etc41 z us$ by o!r writ]s1 ! armature be+ ! "p 9 :i* curr5ts are induc$ & ! field magnet 7or magnets7 t "p furni%+ ! field 9 :i* ! induction takes place4 ,accord+ to ! k9d ( curr5t t an induction motor is design$ to op]ate on1 x may be classifi$ z3 #a4 ,s+le phase2 #b4 ,polyphase4 ,! op]ation ( an induction motor dep5ds on ! production ( a magnetic field by pass+ an alt]nat+ curr5t ?r\gh field magnets4 ,! "* ( ?is field is ei!r #a4 ,oscillat+#c1 or #b4 ,rotat+1 accord+ z s+le phase or polyphase curr5t is us$4 #c ,,note4--,! ^w oscillat+ is becom+ specializ$ 9 its application to ^? curr5ts & fields ^: oscillations are be+ damp$ out1 z 9 electric 'oscillations4' ,b = ?is1 we %\ld h spok5 ( an oscillat+ field4--,s4 ,p4 ,?ompson4 ,! au?or believes ! ^w oscillat+1 not)/&+ its o!r usage1 be/ describes ! s+le phase field1 & %\ld be "h us$4 ,illu/ration3 ,,figs4 #a1fbf to #a1fbh4--;,g5]al ,electric base con/ruction = polyphase induction motors4 ,! base is made ( ca/ iron4 ,adju/+ ge> is provid$ to slide ! motor along ! base z %[n 9 ! illu/rations1 ! movem5t be+ f #f to #ab in*es accord+ to size4 ,) ?is design ( base1 motors are securely held 9 position "u all conditions & may be run ) an upw>d pull on ! belt4 ,close fitt+ guides mov+ 9 an accurately ma*9$ slot on ! base pres]ve a correct alignm5t ( ! motor :5 adju/m5t ( ! latt] is requir$4 ,! same base c be us$ :e!r ! motor be support$ f ! wall or ceil+ or locat$ on ! floor4 ,a s+le adju/+ screw is plac$ "u ! c5t] l9e ( ! motor frame1 :i* produces an ev5 & balanc$ draw 9 ei!r direction on all p>ts ( ! motor :5 ! belt t5sion is alt]$4 ,?is screw c be locat$ at ei!r end ( ! base4 ,! base c be omitt$ :5 ! motor is direct connect$ or :5 provision = belt adju/m5t is n requir$4 ,ques4 ,describe briefly ! op]ation ( a s+le phase motor4 ,ans4 ,a s+le phase curr5t be+ suppli$ to ! field magnets1 an oscillat+ field is set up4 ,a s+le phase motor is n self-/>t+2 b :5 ! armature has be5 set 9 motion by ext]nal means1 ! reaction betwe5 ! magnetic field & ! induc$ curr5ts 9 ! armature be+ no long] z]o1 a torque is produc$ t5d+ to turn ! armature4 ,! curr5t fl[+ ?r\gh ! armature produces an alt]nat+ pol>ity su* t ! attraction betwe5 ! unlike armature & field poles is always 9 "o direction1 ?us produc+ ! torque4 ,illu/ration3 ,,fig4 #a1fbi4--,ri*mond ?ree phase induction motor on base fitt$ ) screw adju/+ ge> = %ift+ ! position ( ! motor on ! base to take up slack ( belt4 ,ques4 ,:y is a s+le phase induction motor n self-/>t+8 ,ans4 ,:5 ! armature is at ! re/1 ! curr5ts induc$ !re9 are at a maximum 9 a plane at "r angles to ! magnetic field1 h5ce !re is no initial torque to />t ! motor4 ,ques4 ,:at provision is made = />t+ s+le phase induction motors8 ,ans4 ,app>atus is suppli$ = splitt+ ! phase 7lat] describ$ 9 detail7 ( ! s+le phase curr5t furni%$1 conv]t+ x tempor>ily into a two phase curr5t1 s z to obta9 a rotat+ field :i* is ma9ta9$ till ! motor is br\ght up to spe$4 ,! phase splitt+ device is !n cut out & ! motor op]at$ ) ! oscillat+ field produc$ by ! s+le phase curr5t4 ,illu/ration3 ,,figs4 #a1fcj to #a1fda4--,t]m9als = ,g5]al ,electric polyphase induction motors4 ,9 ord] to prev5t any me*anical /ra9 on ! leads be+ transmitt$ to ! motor w9d+s1 ! t]m9al cables are clamp$ 9 insulat$ bu%+s ) a connector = ea* cable4 ,ques4 ,describe briefly ! op]ation ( a polyphase induction motor4 ,ans4 ,its op]ation is due to ! production ( a rotat+ magnetic field by ! polyphase curr5t furni%$4 ,?is field rotat+ 9 space ab\t ! axis ( ! armature induces curr5ts 9 ! latt]4 ,! reaction betwe5 ^! curr5ts & ! rotat+ field creates a torque :i* t5ds to turn ! armature1 :e!r ! latt] be at re/ or 9 motion4 ,illu/ration3 ,,figs4 #afdb & #afdc4--,we/]n ,electric end flange rivets & pun*+s ( rivet$ frame induction motor4 ,! rivet$ frame is con/ruct$ ( two ca/ iron flanges betwe5 :i* ! /ator lam9ations ( %eet /eel are securely clamp$ & rivet$ "u hydraulic pressure4 ,?is con/ruction exposes ! lam9ations directly to ! air & improves ! radiation1 ?us insur+ high ov]load capacity & l[ op]at+ temp]atures4 ,! field slots are ov]hung or p>tially clos$1 af=d+ me*anical protection to ! coils4 ,ques4 ,:y are induction motors call$ asyn*ron\s8 ,ans4 ,because ! armature does n turn 9 syn*ronism ) ! rotat+ field1 or1 9 ! case ( a s+le phase induction motor1 ) ! oscillat+ field 7consid]+ ! latt] 9 ! light ( a rotat+ field74 ,ques4 ,h[ does ! spe$ v>y8 ,ans4 ,x is sl[] 7m or less accord+ to load7 ?an ! field spe$1 t is1 ?an syn*ronism or ! syn*ron\s spe$4 ,illu/ration3 ,,figs4 #a1fdd to #a1fdi4--;,con/ruction ( ,g5]al ,electric drawn %ell fractional horse p[] motors4 ,! di/+ui%+ feature ( drawn %ell motors is ! field con/ruction :i* consi/s ( a /eel %ell or cyl9d] support+ & clamp+ toge!r ! /ator or field pun*+s4 ,?is me?od avoids ! ca/ frame "w outside ! active magnetic mat]ial4 ,a disc is fir/ pun*$ or blank$ out ( s(t /eel1 fig4 #a1fdd1 ?is disc be+ fac$ into ! %ape1 fig4 #a1fde1 ) "o end clos$4 ,! o!r end ( ! %ell is !n cut out1 leav+ ! small flange z 9 fig4 #a1fdf4 ,x is n[ ready to receive ! core pun*+s4 ,9 ! next op]ation a suitable numb] ( spac+ r+s1 fig4 #a1fdg1 are =c$ into ! %ell & seat$ aga9/ ! reta9+ lip1 :i* may be se5 9 fig4 #a1fdf4 ,! field pun*+s or lam91 fig4 #a1fdh1 are n[ assembl$1 aft] :i* a second & equal set ( spac+ r+s are put into place to c5t] ! active field iron4 ,! op5 edge ( ! %ell is !n roll$ ov] ! pun*+s "u heavy pressure1 ?us prep>+ ! field /ructure = ! ma*9+ & fitt+ ( ! end heads & base4 ,fig4 #a1fdi %[s a section ( ! completely assembl$ field /ructure1 ! p>ts be+ cut away to indicate ! relation betwe5 ! field pun*+s1 spac+ r+s & %ell4 ,aft] ! spac+ r+s at bo? frame ends h be5 turn$ true & groov$1 ! be>+ heads1 fig4 #a1fdi1 are ready = fa/5+ 9 place by f\r filli/] head$ screws4 ,a complete w\nd field is %[n 9 fig4 #a1heh1 ) flat base ca/+ atta*$4 ,ques4 ,:at is ! diff]5ce ( spe$ call$8 ,ans4 ,! slip4 ,?is is a vital factor 9 ! op]ation ( an induction motor1 s9ce !re mu/ be slip 9 ord] t ! armature inductors %all cut magnetic l9es to induce 7h5ce ! "n induction motor7 curr5ts !re9 s z to create a driv+ torque4 ,illu/ration3 ,,fig4 #a1fej4--;,ideal fifte5 horse p[] two phase induction motor4 ,! armature core is support$ by a ca/ iron frame c>ri$ on a base1 ) slid+ ways & screw adju/m5t = tight5+ ! belt4 ,! armature core is provid$ ) v5tilat+ ap]tures1 ) metal spac]s betwe5 ea* too?4 ,! revolv+ field is a /eel ca/+ ) radially project+ poles1 to :i* ! pole %oes are bolt$4 ,! ov]hang+ pole tips reta9 ! field coils4 ,all coils ( ! small] sizes are w\nd ) insulat$ copp] wire ( squ>e section1 & ( ! l>g] sizes1 ) flat copp]1 w\nd on edge1 ea* turn be+ insulat$ by %eet insulation4 ,motors ( ?is type are adapt$ = use 9 small p[] plants & isolat$ plants4 ,! relatively high spe$ = :i* !y are design$1 r$uces consid]ably ! weight & ov]all dim5sions1 & likewise ! co/4 ,! excit] is belt driv54 ,! normal kw4 capacity ( ! excit] usually exce$s ! kw4 requir$ = ! excitation "u normal load conditions to p]mit ( /ation light+4 ,all excit]s are built z comp\nd w\nd dynamos1 capable ( deliv]+ ! excit] curr5t up to #abe volts1 :i* is suffici5t m>g9 9 ! field to control ! alt]nat+ curr5t l9e voltage on circuits ( unusually l[ p[] factor4 ,ques4 ,:at is ! ext5t ( ! slip8 ,ans4 ,x v>ies f ab\t #b to #e p] c5t4 ( syn*ron\s spe$ dep5d+ ^u ! size4 ,ques4 ,:y are induction motors sometimes call$ con/ant spe$ motors8 ,ans4 ,!y are errone\sly & ill advis$ly1 yet conv5i5tly s call$ by build]s to di/+ui% !m f induction motors fitt$ ) special devices to obta9 widely v>y+ spe$s1 & :i* are kn[n z v>iable spe$ induction motors4 ,! t]m adju/able w\ld be bett]4 ,motor1 ,con/ant ,spe$4--,a motor 9 :i* ! spe$ is ei!r con/ant or does n mat]ially v>y2 su* z syn*ron\s motors1 induction motors ) small slip1 & ord9>y direct curr5t %unt motors4--,p>agraph #df ( #aijg ,/&>dization ,rules ( ! ,a4,i4,e4,e4 ,motor1 ,v>iable ,spe$4--,a motor 9 :i* provision is made = v>y+ ! spe$ z desir$4 ,! ,a4,i4,e4,e4 has un=tunately introduc$ ! t]m v>y+ spe$ motor1 to designate motors 9 :i* ! spe$ v>ies ) ! load1 decreas+ :5 ! load increases1 su* z s]ies motors4 ,! t]m is objectionable1 s9ce by ! expression v>iable spe$ motor a mu* m g5]al mean+ is int5d$4 ,illu/ration3 ,,fig4 #a1fea4--,we/]n ,electric core con/ruction & me?od ( w9d+ field ( skeleton frame induction motor4 ,! coils are w\nd on =ms to give !m exact %ape & dim5sions requir$4 ,!y are press$ into hot m\lds to remove any irregul>ities & !n ! coils are impregnat$ ) hot cem5t1 to b9d ! lay]s toge!r 9 _! p]man5t %ape4 ,! portion ( ! coil :i* fits into ! slot is wrapp$ ) v>ni%$ clo? & a lay] ( dry tape is w\nd ov] ! entire coil4 ,! coils are !n impregnat$ ) an insulat+ comp\nd & bak$1 ! process be+ repeat$ six times4 ,coils = #a1ajj & #b1bjj volt motors h an extra cov]+ ( insulation & d\ble ! am\nt ( impregnat+ & bak+4 ,! coils may be furni%$ ) special insulation & treatm5t = exceptionally sev]e s]vice conditions1 su* z exposure to excessive moi/ure1 extreme heat1 acid or alkal9e fumes1 etc4 ,! coils are accessible & = ! f9al f9i% are spray$ ) black v>ni%4 ,ques4 ,:y d "s writ]s call ! field magnets & armature ! prim>y & second>y1 respectively8 ,ans4 ,because1 9 "o s5se1 ! induction motor is a species ( trans=m]1 t is1 x acts 9 _m respects l a trans=m]1 ! prim>y w9d+ ( :i* is on ! field & ! second>y w9d+ on ! armature4 ,9 ! motor ! function ( ! second>y circuit is to furni% en]gy to produce a torque1 in/ead ( produc+ light & heat z 9 ! case ( ! trans=m]4 ,su* comp>isons are ill advis$ :5 made = ! purpose ( supply+ names = motor p>ts4 ,!re c be no confusion by employ+ ! simple t]ms armature & field magnets1 rememb]+ t ! latt] is t "p t produces ! oscillat+ or rotat+ field 7accord+ z ! motor is s+le or polyphase71 & ! =m]1 t "p 9 :i* curr5ts are induc$4 ,illu/ration3 ,,fig4 #a1feb4--;,armature ( ,allis-,*alm]s squirrel cage induction motor4 ,! frame ca/+ is ( ! box type & has l>ge cor$ op5+s = v5tilation4 ,lugs are ca/ on ! int]ior surface ( ! frame to support ! core1 leav+ a l>ge air space betwe54 ,ques4 ,:y are polyphase induction motors usually pres5t$ 9 text books be=e s+le phase motors8 ,ans4 ,because ! latt] mu/ />t ) a rotat+ field & come up to spe$ be=e ! oscillat+ field c be employ$4 ,a k !n ( ! production ( a rotat+ field is necess>y to und]/& ! action ( ! s+le phase motor at />t+4 ,polyphase ,induction ,motors4--,z _m c5tral /ations put out only alt]nat+ curr5t circuits1 x has become necess>y = motor build]s to p]fect types ( alt]nat+ curr5t motor suitable = all classes ( indu/rial drive & :i* are adapt$ = use on ^! comm]cial circuits4 ,?ree phase induction motors are slightly m effici5t at all loads ?an two phase motors ( correspond+ size1 due to ! sup]ior di/ribution ( ! field w9d+s4 ,! p[] factor is high]1 especially at light loads1 & ! />t+ torque ) full load curr5t is also great]4 ,fur!rmore1 = giv5 requirem5ts ( load & voltage1 ! am\nt ( copp] requir$ 9 ! di/ribut+ sy/em is less2 consequ5tly1 :]ev] s]vice conditions w p]mit1 ?ree phase motors are pref]able to two phase4 ,illu/ration3 ,,fig4 #a1fec4--,sectional view %[+ p>ts ( ,reliance polyphase induction motor4 ,a special feature ( ! squirrel cage armature con/ruction is ! multiplicity ( %ort circuit+ r+s4 ,! holes 9 ! r+s are bor$ slightly small] ?an ! diamet] ( ! copp] rods1 & ! =ce fit gives good contact4 ,! r+s hav+ be5 =c$ 9 place are dip sold]$ 9 an alloy ( t9 ( high melt+ po9t4 ,! motor p>ts are3 #a1 end yoke2 #b1 %aft2 #c1 armature %ort circuit+ r+s2 #d1 oil r+2 #e1 self-align+ be>+ bu%+2 #f1 spid]2 #g1 armature b>s2 #h1 field coils2 #i1 field lam9ation end plate2 #aj1 field lam9ations2 #aa1 eye bolt2 #ab1 /ator lock+ key2 #ac1 armature lam9ations2 #ad1 armature lam9ation end plate2 #ae1 armature lock+ key2 #af1 du/ cap2 #ag1 oil well cov]2 #ah1 oil ?r[s2 #ai1 field frame2 #bj1 squirrel cage armature4 ,illu/ration3 ,,fig4 #a1fed4--,tesla's rotat+ magnetic field4 ,! figure is f "o ( ,tesla's pap]s z giv5 9 ,! ,electrician1 illu/rat+ h[ a rotat+ magnetic field may be produc$ ) /ation>y magnets & polyphase curr5ts4 ,! illu/ration %[s a lam9at$ iron r+ ov]w\nd ) f\r sep>ate coils1 ,,aa1 & ,,bb1 ea* occupy+ ab\t #ij ( ! p]iph]y4 ,! opposite pairs ( coils ,,aa & ,,bb respectively are connect$ 9 s]ies & jo9$ to ! leads f a two phase alt]nator1 ! pair ( coils ,,aa be+ on "o circuit & ! coils ,,bb on ! o!r4 ,! resultant flux may be obta9$ by comb9+ ! two fluxes due to coils ,,aa & ,,bb1 tak+ acc\nt ( ! phase diff]5ce ( ! two phase curr5t1 z 9 fig4 #a1fee4 ,! con/ruction ( an induction motor is v simple1 & s9ce !re are no slid+ contacts z ) commutator motors1 !re c be no sp>ks dur+ op]ation--a feature :i* adapts ! motor = use 9 places :]e fire haz>ds are prom95t4 ,! motor consi/s1 z already m5tion$1 simply ( two p>ts3 an armature & field magnets1 )\t any electrical connection betwe5 ^! p>ts4 ,its op]ation dep5ds ^u3 #a4 ,! production ( a rotat+ field2 #b4 ,induction ( curr5t 9 ! armature2 #c4 ,reaction betwe5 ! revolv+ field & ! induc$ curr5ts4 ,illu/ration3 ,,fig4 #a1fee4--,me?od ( obta9+ resultant flux ( ,tesla's rotat+ magnetic field4 ,! eight small diagrams "h se5 %[ ! two compon5ts & resultant = eight equival5t successive in/ants ( "t dur+ "o cycle4 ,at #a1 ! v]tical flux is at maximum & ! horizontal is z]o4 ,at #b1 ! v]tical flux is /ill b decreas+1 & ! horizontal is & increas+1 ! resultant is ! ?ick l9e slop+ at #de upw>ds to ! "r4 ,at #c1 ! v]tical flux is z]o1 & ! horizontal is at its maximum1 & simil>ly = ! o!r diagrams4 ,?us at #h1 ! v]tical flux is & increas+1 :ile ! horizontal is-& decreas+1 ! resultant is ! ?ick l9e slop+ at #de upw>ds to ! left4 ,at po9ts #b1 #d1 #f1 & #h ! increas+ fluxes are d5ot$ by full & ! decreas+ by dott$ l9es4 ,! lam9at$ iron ( ! r+ is indicat$ by ! circles1 & ! result is t at ! in/ants *os5 ! flux across ! plane ( ! r+ is direct$ inw>ds f ! po9ts #a1 #b1 #c1 #d1 etc41 on ! inn] p]iph]y ( ! iron4 ,!re w1 !re=e1 appe> successively at ^! po9ts effective nor? poles1 ! correspond+ s\? poles be+ simultane\sly develop$ at ! po9ts diametrically opposite4 ,^! poles travel cont9u\sly f "o position to ! next1 & ?us ! magnetic flux across ! plane ( ! r+ sw+s r\nd & r\nd1 complet+ a revolution )\t *ange ( int5sity dur+ ! cycle "t ( ! curr5t4 ,production ( a ,rotat+ ,field4--,x %\ld at once be und]/ood t ! t]m rotat+ field does n signify t "p ( ! app>atus revolves1 ! expression m]ely ref]s to ! magnetic l9es ( =ce set up by ! field magnets )\t reg>d to :e!r ! latt] be ! /ation>y or rotat+ memb]4 ,a rotat+ field !n may be def9$ z ! resultant magnetic field produc$ by a sy/em ( coils symmetrically plac$ & suppli$ ) polyphase curr5ts4 ,a rotat+ magnetic field c1 ( c\rse1 be produc$ by sp9n+ a horse %oe magnet ar\nd its longitud9al axis1 b ) polyphase curr5ts1 z w be lat] %[n1 ! rotation ( ! field c be produc$ ,)\t any movem5t ( ! me*anical p>ts ( ! electro magnets4 ,illu/ration3 ,,fig4 #a1fef4--;,arago's rotations4 ,! app>atus necess>y to make ! exp]im5t consi/s ( a copp] disc ,m1 arrang$ to rotate ar\nd a v]tical axis & op]at$ by belt drive1 z %[n4 ,by turn+ ! l>ge pulley by h&1 ! disc ,m may be rotat$ ) great rapidity4 ,above ! disc is a glass plate on :i* is a small pivot support+ a magnetic ne$le ,n4 ,if ! disc n[ be rotat$ ) a sl[ & uni=m velocity1 ! ne$le is deflect$ 9 ! direction ( ! motion1 & /ops at an angle ( f #bj to #cj ) ! direction ( ! magnetic m]idian1 accord+ to ! velocity ( ! rotation ( ! disc4 ,if ! velocity increase1 ! ne$le is ultimately deflect$ m ?an #ij & !n cont9ues to foll[ ! motion ( ! disc4 ,! orig9al rotat+ magnetic field dates back to #ahbc1 :5 ,francois ,jean ,arago1 an assi/ant 9 ,davy's laboratory1 discov]$ t if a magnet be rotat$ be=e a metal disc1 ! latt] _h a t5d5cy to foll[ ! motion ( ! magnet1 z %[n 9 fig4 #bij1 page #bgj & also 9 fig4 #a1fef4 ,?is exp]im5t l$ up to ! discov]y :i* 0 made by ,arago 9 #ahbd1 :5 he obs]v$ t ! numb] ( oscillations :i* a magnetiz$ ne$le makes 9 a giv5 "t1 "u ! influ5ce ( ! e>?'s magnetism1 is v mu* less5$ by ! proximity ( c]ta9 metallic masses1 & especially ( copp]1 :i*1 may r$uce ! numb] 9 a giv5 "t f #cjj to #d4 ,illu/ration3 ,,fig4 #a1feg4--;,explanation ( ,arago's rotations4 ,"p ( fig4 #a1fef is "h reproduc$ 9 plan4 ,f>aday 0 ! fir/ to give an explanation ( ! ph5om5a ( magnetism by rotation 9 attribut+ x to ! induction ( curr5ts :i* by _! electro-dynamic action1 oppose ! motion produc+ !m2 ! action is me*anically analog\s to friction4 ,9 ! figure1 let ,,ab be a ne$le oscillat+ ov] a copp] disc1 & suppose t 9 "o ( its oscillations x goes 9 ! direction ( ! arr[ f ,m to ,s4 ,9 approa*+ ! po9t ,s1 = in/ance1 x develops !re a curr5t 9 ! opposite direction1 & :i* !re=e repels x2 9 mov+ away f ,m x produces curr5ts :i* are ( ! same k9d1 & :i* !re=e attract1 & bo? ^! actions concur 9 br++ x to re/4 ,aga91 suppose ! metallic mass turn f ,m t[>ds ,s1 & t ! magnet be fix$2 ! magnet w repel by induction po9ts su* z ,m :i* are approa*+ ,a1 & w attract ,s :i* is mov+ away2 h5ce ! motion ( ! metal /ops1 z 9 ,f>aday's exp]im5t4 ,if 9 ,arago's exp]im5t ! disc be mov+ f ,m to ,s1 ,m approa*es ,a & repels x1 :ile ,s1 mov+ away1 attracts x2 h5ce ! ne$le moves 9 ! same direction z ! disc4 ,if ?is explanation be true1 all circum/ances :i* favor induction w increase ! dynamic action2 & ^? :i* dim9i% ! =m] w also less5 ! latt]4 ,! explanation ( ,arago's rotations is t ! magnetic field cutt+ ! disc produces eddy curr5ts !re9 & ! reaction betwe5 ! latt] & ! field causes ! disc to foll[ ! rotations ( ! field4 ,! induction motor is a logical developm5t ( ! exp]im5t ( ,arago1 :i* s int]e/$ ,f>aday :ile an assi/ant 9 ,davy's laboratory & :i* l$ him to ! discov]y ( ! laws ( electromagnetic induction1 :i* are giv5 9 ,*apt] ,x4 #d;,9 #ahhe1 ,pr(essor ,f]r>is1 ( ,tur9 discov]$ t a rotat+ field c\ld be produc$ f /ation>y coils by means ( polyphase curr5ts4 #d ,,note4--,walmsley attributes ! fir/ production ( rotat+ fields to ,walt] ,bailey 9 #ahgi1 :o exhibit$ a model at a meet+ ( ! ,physical ,society ( ,london1 b v little 0 done1 x is /at$1 until ,f]r>is took up ! subject4 ,illu/ration3 ,,fig4 #a1feh4--;,exp]im5t made by ,f>aday be+ ! rev]se ( ,arago's fir/ obs]vation4 ,f>aday assum$ t s9ce ! pres5ce ( a metal at re/ /ops ! oscillations ( a magnetic ne$le1 ! neighborhood ( a magnet at re/ ought to /op ! motion ( a rotat+ mass ( metal4 ,he susp5d$ a cube ( copp] by a twi/$ ?read1 :i* 0 plac$ betwe5 ! poles ( a p[]ful electromagnet4 ,:5 ! ?read 0 left to itself1 x began to sp9 r\nd ) great velocity1 b /opp$ ! mom5t a p[]ful curr5t 0 pass$ ?r\gh ! electromagnet4 #e,?is discov]y 0 comm]cially appli$ a few ye>s lat] by ,tesla1 ,br[n1 & ,dobr[olsky4 #e ,,note4--,! ,tesla pat5ts 7 acquir$ 9 ! ,u4,s4 by ! ,we/+h\se ,co4 9 #ahhh1 & polyphase induction motors1 z !y 7 call$1 7 soon on ! m>ket4 ,br[n ( ! ,o]likon ,ma*9e ,works develop$ ! s+le phase sy/em & op]at$ a transmission plant ov] five miles 9 l5g? at ,kassel1 ,g]many1 :i* op]at$ at #b1jjj volts4 ,! pr9ciples ( polyphase motors c be be/ und]/ood by means ( elem5t>y diagrams illu/rat+ ! action ( polyphase curr5ts 9 produc+ a rotat+ magnetic field1 z expla9$ 9 ! p>agraphs foll[+4 ,production ( a ,rotat+ ,magnetic ,field by ,two ,phase ,curr5ts4--,fig4 #a1fei repres5ts an iron r+ w\nd ) coils ( insulat$ wire1 :i* are suppli$ ) a two phase curr5t at ! f\r po9ts ,a1 ,b1 ,c1 ,d1 ! po9ts ,a & ,b1 & ,c & ,d1 be+ electrically connect$4 ,illu/ration3 ,,fig4 #a1fei4--,production ( a rotat+ magnetic field by two phase curr5ts4 ,! figure repres5ts an iron r+1 w\nd ) coils ( insulat$ wire1 & suppli$ ) two phase curr5ts at ! f\r po9ts ,a1 ,b1 ,c1 & ,d4 ,! action ( ! two phase curr5t on ! r+ 9 produc+ a rotat+ magnetic field is expla9$ 9 ! accompany+ text4 ,accord+ to ! pr9ciples ( electromagnetic induction1 if only "o curr5t a ent]$ ! r+ at ,a1 & ! direction ( ! w9d+ be suitable1 a negative pole 7-7 w be produc$ at ,a & a positive pole 77 at ,b1 s t a magnetic ne$le pivot$ 9 ! c5t] ( ! r+ w\ld t5d to po9t v]tically upw>d t[>ds ,a4 ,n[ suppose t at ?is in/ant1 correspond+ to ! beg9n+ ( an alt]nat+ curr5t cycle1 a second curr5t b1 diff]+ 9 phase f ! fir/ by #ij degrees1 is all[$ to ent] ! r+ at ,c4 ,z %[n 9 fig4 #a1fei1 :5 ! pressure ( ! curr5t a is at its maximum1 t ( ! curr5t b is at its m9imum2 !re=e1 ev5 a two phase curr5t1 at ! beg9n+ ( ! cycle1 ! ne$le w po9t t[>d ,a4 ,illu/ration3 ,,fig4 #a1ffj4--,production ( rotat+ magnetic field 9 a two pole two phase motor4 ,! poles are numb]$ f #a to #d 9 a clockwise direction4 ,phase ,a w9d+ is ar\nd poles #a & #c1 & phase ,b w9d+1 ar\nd poles #b & #d4 ,9 ea* case ! poles are w\nd alt]nately1 t is1 if #a be w\nd clockwise1 #c w be w\nd c\nt] clockwise1 ?us produc+ unlike pol>ity 9 opposite poles4 ,n[ dur+ "o cycle ( ! two phase curr5t1 ! foll[+ *anges take place1 />t+ ) pole #a ( ,n pol>ity & #c1 ( ,s pol>ity3 ---------------------------------------- ---------------------- ,"o ,cycle ---------------------------------------- ------------------ ,degrees #j to #ij #ij to #ahj #ahj to #bgjbgj to #cfj ---------------------------------------- ------------------ ,pol>ity #a,n - #c,s #b,n - #d,s #c,n - #a,s #d,n - #b,s ---------------------------------------- ---------------------- ,illu/ration3 ,,fig4 #a1ffa4--;,diagram %[+ resultant poles due to two phase curr5t4 ,illu/ration3 ,,fig4 #a1ffb4--;,diagram ( two phase1 six pole field w9d+4 ,!re are six coils 9 ea* phase1 z %[n4 ,! coils ( ea* phase are connect$ 9 s]ies1 adjac5t coils be+ jo9$ 9 opposite s5ses1 ?us1 = ea* phase1 fir/ "o coil is w\nd clockwise1 & ! next c\nt] clockwise4 ,z ! cycle cont9ues1 h[ev]1 ! /r5g? ( a w dim9i% & t ( b increase1 ?us %ift+ ! induc$ pole t[>d ,c1 until b atta9s its maximum & a falls to its m9imum at #ij or ! end ( ! fir/ qu>t] ( ! cycle1 :5 ! ne$le w po9t t[>d ,c4 ,at #ij1 ! phase a curr5t rev]ses 9 direction & produces a negative pole at ,b1 & z its /r5g? increases f #ij to ! #ahj po9t ( ! cycle1 & t ( phase b dim9i%es1 ! resultant negative pole is %ift$ pa/ ,c t[>d ,b1 until a atta9s its maximum & b falls to its m9imum at #ahj1 & ! ne$le po9ts 9 ! direction ( ,b4 ,illu/ration3 ,,fig4 #a1ffc4--;,diagram ( two phase1 eight pole field w9d+4 ,! w9d+ is divid$ into #af gr\ps 7equal to ! product ( ! numb] ( poles multipli$ by ! numb] ( phases74 ,ea* gr\p su* z at ,a comprises a numb] ( coils 9 s]ies1 ea* coil be+ locat$ 9 a sep>ate pair ( slots1 ! end ( "o be+ connect$ to ! beg9n+ ( ! next4 ,:5 ! curr5ts are 9 ! same direction1 ! curr5ts circulate 9 ! same direction 9 two adjac5t gr\ps1 a pole !n ) ?is arrangem5t be+ =m$ by two gr\ps1 bo? phases contribut+ to ! =mation ( ! pole4 ,aft] cycle :5 ! curr5t 9 ea* phase rev]ses1 ! pole advances ! angul> di/ance1 cov]$ by two gr\ps2 h5ce ! field completes "o revolution 9 eight alt]nations ( curr5t4 ,illu/ration3 ,,figs4 #a1ffd to #a1fhc4--,s9e curves ( two phase curr5t & diagrams %[+ ! physical conception ( a two phase rotat+ magnetic field4 ,! alt]nat+ magnetiz+ curr5t is assum$ to be ( su* /r5g? t1 at its maximum /r5g?1 ! field produc$ may be repres5t$ by #aj l9es ( =ce z indicat$ by ! p>allel l9es4 ,at ! beg9n+ ( ! rotation1 fig4 #a1ffd1 phase ,a magnetization1 accord+ to s9e curve is z]o1 indicat$ by ! solid black poles1 :ile phase ,b is ( /r5g? #aj ) ,illu/ration3 curr5t 9 ! direction to produce a s\? pole at ,b4 ,simil>ly1 9 fig4 #a1ffe1 ! /r5g? ( ,a is #d l9es1 & ( ,b1 #i l9es1 ! resultant magnetization hav+ rotat$ #bb4 ,! direction ( ! resultant magnetization is indicat$ by ! arr[ 9 ea* figure4 ,x %\ld be not$ 9 fig4 #a1ffi1 t ! pol>ity ( ,b is rev]s$1 ! curr5t curve n[ be+ above ! z]o l9e4 ,by foll[+ ! arr[ ?r\gh ! successive positions ! rotation ( ! resultant magnetization is cle>ly se54 ,at ! #ahj po9t ( ! cycle1 b rev]ses 9 direction & produces a negative pole at ,d1 & z ! fluctuation ( ! pressure ( ! two curr5ts dur+ ! second half ( ! cycle1 f #ahj to #cfj1 be> ! same relation to ea* o!r z dur+ ! fir/ half1 ! resultant poles ( ! rotat+ magnetic field ?us produc$ c>ry ! ne$le ar\nd 9 cont9u\s rotation s long z ! two phase curr5t trav]ses ! w9d+s ( ! r+4 ,illu/ration3 ,,fig4 #a1fhd4--,mov+ picture me?od ( %[+ motion ( a rot>y magnetic field4 ,a numb] ( %eets ( pap] are prep>$1 ea* conta9+ a draw+ ( ! motor frame & a magnetic ne$le 9 successively advanc+ angul> positions1 indicat+ resultant directions ( ! magnetism4 ,! %eets are b\nd toge!r s t ! axis ( ! ne$le on ea* %eet co9cides4 ,:5 pass+ ! %eets 9 "o way ! revolv+ field w be se5 to rotate 9 "o direction1 :ile1 :5 mov+ ! %eets backw>d1 ! rotation ( ! magnetic field is 9 ! opposite direction1 %[+ t ! rev]sal ( ! ord] ( ! coils has ! effect ( rev]s+ ! rotation ( ! magnetic field4 ,production ( ,rotat+ ,magnetic ,field by ,?ree ,phase ,curr5t4--,a rotat+ magnetic field is produc$ by ! action ( a ?ree phase curr5t 9 a mann] q simil> to ! action ( a two phase curr5t4 ,fig4 #a1fhe %[s a r+ suitably w\nd & suppli$ ) a ?ree phase curr5t at ?ree po9ts ,a1 ,b1 ,c1 #abj ( a cycle ap>t4 ,illu/ration3 ,,fig4 #a1fhe4--,production ( a rotat+ magnetic field by ?ree phase curr5t4 ,a r+ w\nd z %[n is tapp$ at po9ts ,a1 ,b1 & ,c1 #abj ap>t1 & connect$ ) leads to a ?ree phase alt]nator4 ,z describ$ on page #a1cjd1 a rotat+ magnetic field is produc$ 9 a mann] simil> to ! two phase me?od4 ,illu/ration3 ,,fig4 #a1fhf4--;,diagram ( ?ree phase1 f\r pole ,y connect$ field w9d+4 ,at ! in/ant :5 ! curr5t a1 fl[+ 9 at ,a1 is at its maximum1 two curr5ts b & c1 ea* "o-half ! value ( a1 w fl[ out ,b & ,c1 ?us produc+ a negative pole at ,a & a positive pole at ,b & at ,c4 ,! resultant ( ! latt] w be a positive pole at ,e1 & consequ5tly1 ! magnetic ne$le w po9t t[>ds ,a4 ,illu/ration3 ,,fig4 #a1fhg4--,production ( a rotat+ magnetic field 9 a two pole ?ree phase motor4 ,9 ord] to obta9 a uni=mly rotat+ magnetic field1 x is necess>y to arrange ! phase w9d+s 9 ! direction ( rotation1 9 ! sequ5ce ,,acb1 n ,,abc z indicat$ on ! magnets4 ,?us poles #a & #d are connect$ 9 s]ies to phase ,a1 #b & #e 9 s]ies to phase ,c1 & #c & #f 9 s]ies to phase ,b4 ,! diff]5t phase w9d+s are diff]5tly l9$1 & x %\ld be not$ t !y h a common return wire1 ?\gh ?is is n absolutely necess>y4 ,s9ce ! phases ( ! ?ree curr5ts diff] f ea* o!r by "o-?ird ( a p]iod or cycle1 ea* ( ! phase w9d+s w !re=e set up a field betwe5 its poles1 :i* at any in/ant w diff]1 bo? 9 direction & magnitude1 f ! fields set up by ! o!r phase w9d+s4 ,h5ce1 ! ?ree phase w9d+s act+ toge!r w produce a resultant field1 & if plott$ out1 ! directions ( ?is field = v>i\s fractions ( ! p]iod is su* t 9 "o complete p]iod ! resultant field w make "o complete r\nd ( ! poles 9 a clockwise direction1 z indicat$ by ! curv$ arr[4 ,! positions ( ! resultant field dur+ "o complete p]iod may be tabulat$ z foll[s3 ---------------------------------------- ---------------------------- ,"o ,cycle ---------------------------------------- -------------- #j to #fj #fj to #abj to #ahj to #bdj to #cjj to #abj #ahj #bdj #cjj #cfj ---------------------------------------- -------------- ,pol>ity #a,n - #d,s #b,n - #e,s #c,n - #f,s #d,n - #a,s #e,n - #b,s #f,n - #c,s ---------------------------------------- ---------------------- ,z ! cycle advances1 h[ev]1 ! mutual relations ( ! fluctuations ( ! pressures ( ! ?ree curr5ts1 & ! "t ( _! rev]sals ( direction w be su*1 t :5 a maximum curr5t is fl[+ at any "o ( ! po9ts ,a1 ,b1 & ,c1 two curr5ts ea* ( "o-half ! value ( ! ent]+ curr5t w fl[ out ( ! o!r two po9ts1 & :5 two curr5ts are ent]+ at any two po9ts1 a curr5t ( maximum value w fl[ out ( ! o!r po9t4 ,?is action w produce "o complete rotation ( ! magnetic field dur+ ea* cycle ( ! curr5t4 ,illu/ration3 ,,fig4 #a1fhh4--,production ( ?ree phase rotat+ magnetic field ) w9d+ on lam9at$ iron r+4 ,! w9d+ is divid$ into twelve sections1 :i* are connect$ 9 ?ree gr\ps1 ,a1 ,b1 & ,c1 ( f\r sections ea*1 ! sections 9 ea* gr\p be+ ev5ly plac$ r\nd ! r+ ) ! sections ( ! two o!r gr\ps betwe5 !m4 ,"o end ( ea* gr\p is to be connect$ to ! l9e wire & ! o!r end to ! common junction ,j1 f :i* x foll[s t ! w9d+ giv5 is an example ( /> w9d+4 ,) ?ree phase curr5ts ! w9d+ w give at e in/ant f\r ,n poles & f\r ,s poles r\nd ! r+1 & 9 actual work+ ^! poles w be on ! inn] p]iph]y because ( ! pres5ce ( an inn] r+ or cyl9d] ( good magnetic iron plac$1 ) ! requisite cle>ance to all[ ( rotation1 z close z is me*anically possible to ! out] r+4 ,ea* "o ( ^! eight poles w make a complete revolution r\nd ! r+ 9 f\r times ! p]iodic "t ( ! curr5ts suppli$4 ,?us1 if ! supply curr5t has a frequ5cy ( #ej1 a complete revolution ( ! field w take place 9 4#jh 7_/7 ( a second1 :i* corresponds to an angul> velocity ( #gej revolutions p] m9ute 9 place ( #c1jjj revolutions p] m9ute1 :i* w\ld be ! angul> velocity ) a bipol> field at ?is p]iodicity4 ,simil>ly a cont9u\sly w\nd ,gramme r+ tapp$ at twelve po9ts1 jo9$ 9 ?ree gr\ps ( f\r ea* to ! supply ma9s1 w\ld give an eight pole rot>y field4 ,9 ?is case ! gr\p+ w\ld be a me% gr\p+1 ) ea* side ( ! me% =m$ ( f\r coils 9 p>allel4 ,illu/ration3 ,,figs4 #a1fhi to #a1gjh4--,s9e curves ( ?ree phase curr5t & diagrams %[+ ! physical conception ( a ?ree phase rotat+ magnetic field4 ,! diagrams are con/ruct$ 9 ! same mann] z expla9$ 9 figs4 #a1ffd to #a1fhc4 ,x %\ld be not$ t ! phase w9d+s are arrang$ 9 ! direction ( rotation 9 ! sequ5ce ,,acb1 phase ,c be+ w\nd 9 opposite ,illu/ration3 s5se to ,a & ,b1 z indicat$ by ! curves1 9 t nor? poles are produc$ at ,a & ,b :5 ! respective curves are above ! z]o l9e1 a s\? pole be+ produc$ at ,c :5 its curve is above ! z]o l9e4 ,! rotation ( ! resultant magnetization is cle>ly se5 by foll[+ ! arr[ ?r\gh its successive positions4 ,slip4--,in/ead ( ! magnetic ne$le z 0 us$ 9 ! prec$+ figures1 a copp] cyl9d] may be plac$ 9 a rotat+ magnetic field & x w be urg$ also to turn 9 ! same direction z ! rotation ( ! field4 ,illu/ration3 ,,fig4 #a1gji4--;,diagram ( ?ree phase1 six pole field w9d+4 ,!re are #ah gr\ps1 & ! sequ5ce ( phases is ,,abc 9 a c\nt] clockwise direction4 ,= a ,y connection1 ! middle phase is rev]s$1 s t a pole w be =m$ by ! ?ree consecutive phases :5 ! curr5t is 9 ! same direction 9 ,a & ,c1 & opposite 9 ,b4 ,! beg9n+ ( ! middle coil ,c1 & n ! end1 z ) ! o!r two1 is connect$ to ! common po9t ,o4 ,9 ?is case ! pole %ifts a di/ance equal to ?ree gr\ps = ea* alt]nation1 s t "o revolution ( ! field requires ?ree cycles4 ,! torque t5d+ to turn ! cyl9d] is due to ! induction ( curr5ts ( opposite pol>ity 9 ! cyl9d]4 ,= simplicity1 ! rotat+ magnetic field may be suppos$ to be produc$ by a pair ( magnetic poles plac$ at opposite sides ( ! cyl9d] & revolv$ ar\nd x z 9 fig4 #a1gaj4 ,n[1 = in/ance 9 />t+1 ! cyl9d] be+ at re/ any elem5t or section ( ! surface z ! %ad$ area ,,ab1 w1 z x comes into ! magnetic field ( ! rotat+ magnet1 cut ,illu/ration3 ,,fig4 #a1gaj4--;,copp] cyl9d] & rotat+ magnet illu/rat+ ! pr9ciple ( op]ation ( an induction motor4 ,! rotat+ magnetic field :i* is necess>y = induction motor op]ation is = simplicity "h produc$ by rotat+ a magnet z %[n4 ,9 />t+1 ! cyl9d] be+ at re/1 any elem5t z ,,ab1 z x is swept by ! field w cut magnetic l9es1 :i* w induce a curr5t upw>d 9 direction z det]m9$ by apply+ ,flem+'s rule 7fig4 #acb1 page #acc74 ,! inductive action is /ronge/ at ! c5t] ( ! field h5ce z ,,ab passes ! c5t] ! induc$ pressure along ,,ab is great] ?an along elem5ts m or less remote on ei!r side4 ,accord+ly a pair ( eddy curr5ts w result z %[n 7see fig4 #bia1 page #bga74 ,apply+ ! "r h& rule = pol>ity ( ^! eddy curr5ts 7see fig4 #aai1 page #aag7 x w be se5 t a ,s pole is induc$ by ! eddy on ! side ( ! cyl9d] rec$+ f ! magnet1 & a ,n pole by ! eddy on ! side t[>d :i* ! magnet is approa*+4 ,! cyl9d]1 !n1 is attract$ 9 ! direction ( rotation ( ! magnet by ! induc$ pole on ! rec$+ side1 & repell$ 9 ! same direction by ! induc$ pole on ! approa*+ side4 ,accord+ly1 ! cyl9d] beg9s to rotate4 ,! velocity ) :i* x turns dep5ds ^u ! load2 x mu/ always turn sl[] ?an ! magnet1 9 ord] t its elem5ts may cut magnetic l9es & induce poles to produce ! necess>y torque to balance ! load4 ,! diff]5ce 9 spe$ ( ! magnet & cyl9d] is call$ ! slip4 ,evid5tly ! great] ! load1 ! great] is ! slip requir$ to induce poles ( suffici5t /r5g? to ma9ta9 equilibrium4 ,! figure is drawn some:at di/ort$1 s t bo? eddies are visible4 magnetic l9es ( =ce induc+ a curr5t !re91 ^: direction is easily det]m9$ by apply+ ,flem+'s rule4#f #f ,,note4--,9 ord] to avoid confusion 9 apply+ ,flem+'s rule1 x may be well to reg>d ! pole z be+ /ation>y & ! cyl9d] z 9 motion2 =1 s9ce motion is purely a relative matt] 7see fig4 #a1cic71 ! inductive action w be ! same z if ! pole /ood /ill :ile ! cyl9d] revolv$ f left to "r1 t is1 c\nt] clockwise1 look+ d[n on x4 ,reg>d+ x ?us 7pole /ation>y & cyl9d] revolv+ c\nt] clockwise7 ,flem+'s rule 7see fig4 #acb1 page #acc7 is easily appli$ to asc]ta9 ! direction ( ! induc$ curr5t1 :i* is f\nd to fl[ upw>d 9 ! %ad$ area z %[n4 ,s9ce ! field is n uni=m1 b gradually weak5s1 z %[n1 on ei!r side ( ! %ad$ area 7:i* is j pass+ ! c5t]71 ! pressure induc$ on ei!r side w be less ?an t induc$ 9 ! %ad$ area1 giv+ rise to eddy curr5ts 7z illu/rat$ 9 fig4 #bia1 page #bga74 ,^! eddy curr5ts induce poles z indicat$ at ! c5t]s ( ! :orls1 ! pol>ity be+ det]m9$ by apply+ ! "r h& rule 7fig4 #aai1 page #aag74 ,illu/ration3 ,,figs4 #a1gaa to #a1gah4--,p>ts ( ,allis-,*alm]s polyphase induction motor ) squirrel cage armature4 ,by inspection ( fig4 #agaj1 x is se5 t ! induc$ pole t[>d :i* ! magnet is mov+ is ( ! same pol>ity z ! magnet2 !re=e x is repell$1 :ile ! induc$ pole f :i* ! magnet is rec$+1 be+ ( opposite pol>ity1 is attract$4 ,a torque is ?us produc$ t5d+ to rotate ! cyl9d]4 ,x mu/ be evid5t t ?is torque is greate/ :5 ! cyl9d] is at re/1 because ! magnetic l9es are cut by any elem5t on ! cyl9drical surface at ! maximum rate4 ,moreov]1 z cyl9d] is set 9 motion & br\ght up to spe$1 ! torque is gradually r$uc$1 because ! rate ) :i* ! magnetic l9es are cut is gradually r$uc$4 ,ques4 ,:at is ! ess5tial condition = ! op]ation ( an induction motor8 ,ans4 ,! armature1 or "p 9 :i* curr5ts are induc$1 mu/ rotate at a spe$ sl[] ?an t ( ! rotat+ magnetic field4 ,9 ! elem5t>y induction motor1 fig4 #a1gaj1 ! cyl9d] is ! armature1 & ! rotat+ magnets are ! equival5t ( a rotat+ magnetic field4 ,ques4 ,:at is ! diff]5ce ( spe$ call$8 ,ans4 ,! slip4 ,ques4 ,:y is slip necess>y 9 ! op]ation ( an induction motor8 ,ans4 ,if ! armature _h no weight & !re 0 no friction (f]$ by ! be>+s & air1 x w\ld revolve 9 syn*ronism ) ! rotat+ magnetic field1 t is1 ! slip w\ld be z]o2 b s9ce weight & friction are always pres5t & con/itute a small load1 its spe$ ( rotation w be a little less ?an t ( ! rotat+ magnetic field1 s t induction w take place1 9 am\nt suffici5t to produce a torque t w balance ! load4 ,illu/ration3 ,,fig4 #a1gai4--;,g5]al ,electric v]tical type induction motor2 sectional view %[+ oil+ sy/em4 ,x is provid$ ) ball ?ru/ be>+s & top & bottom guide be>+s1 & a cont9u\s fl[ ( oil is ma9ta9$ ?r\gh all ! be>+s by means ( a pump :i* is made integral ) ! motor4 ,! ball ?ru/ be>+s are design$ to support ! weight ( ! armature only4 ,9 cases :]e ! armature is direct connect$ a flexible c\pl+ %\ld be us$ to prev5t additional weight com+ on ! ?ru/ be>+s4 ,9 op]ation1 :5 ! motor />ts1 ! oil1 revolv+ ) ! pan1 fl[s aga9/ ! /ation>y nozzle & is =c$ by its velocity at a high pressure ?r\gh ! oil pipe into ! res]voir on top4 ,x !n fl[s d[n ?r\gh ! ball be>+ & upp] guide be>+1 ?r\gh a slot 9 ! armature spid] into ! l[] guide be>+ & !nce into ! oil pan4 ,?us a cont9u\s /ream ( oil is deliv]$ ?r\gh all be>+s4 ,ques4 ,h[ is slip express$8 ,ans4 ,9 t]ms ( syn*ronism1 t is1 z a p]c5tage ( ! spe$ ( ! rotat+ magnetic field4 ,! slip is obta9$ f ! foll[+ =mula3 ,slip 7rev4 p] sec47 ,sf - ,s or1 express$ z a p]c5tage ( syn*ronism1 t is1 ( ! syn*ron\s spe$1 7,sf - ,s7 #ajj ,slip 77 ----------------- ,sf :]e ,sf ,syn*ron\s spe$1 or ,r4,p4,m4 ( ! rotatory magnetic field2 ,s ,spe$ ( ! armature4 ,! syn*ron\s spe$ is det]m9$ ! same z = syn*ron\s motor by use ( ! foll[+ =mula3 #b;f ,sf ---- ,p :]e ,sf ,syn*ron\s spe$ or ,r4,p4,m4 ( ! rotat+ magnetic field2 ,p ,numb] ( poles2 f frequ5cy4 ,illu/ration3 ,,fig4 #agbj4--,triumph back ge>$ polyphase induction motor4 ,a great _m applications1 especially = direct atta*m5t1 require ! use ( ei!r a v sl[ or special spe$ motor4 ,z ^! are q co/ly1 ! pref]able arrangem5t1 & "o equally z satisfactory1 is ! use ( a /&>d spe$ motor comb9$ ) a back ge>$ atta*m5t4 ,ra:ide p9ions are furni%$ :5ev] possible1 insur+ smoo? runn+ ) a m9imum ( noise4 ,illu/ration3 ,,figs4 #a1gba to #a1gce4--,p>ts ( ,g5]al ,electric small polyphase induction motors4 ,a1 armature2 ,b1 key = armature %aft2 ,c1 oil r+2 ,d1 be>+ l9+2 ,e1 be>+ head1 pulley end2 ,f1 cap screw = be>+ heads2 ,g1 field1 complete ) w9d+1 t]m9al plate & leads2 ,h1 motor leads2 ,i1 t]m9al connector = motor leads2 ,j1 s(t rubb] bu%+ = motor leads2 ,k1 t]m9al plate2 ,l1 screw = t]m9al bo>d2 ,m1 field coils2 ,n1 wood5 top /icks = field coils2 ,o1 oil fill]2 ,p1 be>+ head opposite pulley end2 ,q1 screw = oil well cov]2 ,r1 oil well cov]2 ,s1 socket pipe plug = be>+ head2 ,u1 motor base2 ,v1 yoke = motor base2 ,w1 motor base adju/+ screw2 ,x1 bolt = motor base & frame 7%ort72 ,y1 cap screw = be>+ head2 ,z1 int]nal directive fan2 ,aa1 pulley4 ,! foll[+ table gives ! syn*ron\s spe$ = v>i\s frequ5cies & diff]5t numb]s ( poles3 ,table ( ,syn*ron\s ,spe$s ---------------------------------------- -------------- ,r4,p4,m4 ( ! rotat+ magnetic field1 :5 numb] ( poles is ,frequ5cy------------------------------- ------------- #b #f #aj #af #bj #bd ---------------------------------------- -------- #be #a1ejj #ejj #cjj #ahh #aej #abe #fj #c1fjj #a1bjj #gbj #dej #cfj #cjj #hj #d1hjj #a1fjj #ifj #fjj #dhj #djj #ajj #f1jjj #b1jjj #a1bjj #gej #fjj #ejj #abj #g1bjj #b1djj #a1ddj #ijj #gbj #fjj #abe #g1ejj #b1ejj #a1ejj #ich #gej #fbe ---------------------------------------- -------------- ,ques4 ,h[ does ! slip v>y8 ,ans4 ,x v>ies f ab\t #a p] c5t4 9 a motor design$ = v close regulation to #dj p] c5t4 9 "o badly design$1 or design$ = "s special purpose4 ,ques4 ,:y is ! slip ord9>ily s small8 ,ans4 ,because ( ! v l[ resi/ance ( ! armature1 v little pressure is requir$ to produce curr5ts !re91 ( suffici5t /r5g? to give ! requir$ torque4 ,h5ce1 ! necess>y rate ( cutt+ ! magnetic l9es to induce ?is pressure 9 ! armature is rea*$ ) v little diff]5ce betwe5 ! field spe$ & armature spe$1 t is1 ) v little slip4 ,ques4 ,h[ does ! slip v>y ) ! load8 ,ans4 ,! great] ! load ! great] ! slip4 ,9 o!r words1 if ! load increase1 ! motor w run sl[]1 & ! slip w increase4 ,) ! increas$ slip1 ! induc$ curr5ts & ! driv+ =ce w fur!r increase4 ,if ! motor be well design$ s t ! field /r5g? is con/ant & ! lag ( ! armature curr5ts is small1 ! driv+ =ce develop$ or torque w be proportional to ! slip1 t is ! slip w increase automatically z ! load is increas$1 s t ! torque w be proportional to ! load4 ,accord+ to ,we9]1 ! slip v>ies accord+ to ! foll[+ table3 ,,slip ,,( ,,induction ,,motors ---------------------------------------- ---------------------------- ,slip at full load ,slip at full load ,capacity p] c5t4 ,capacity p] c5t4 ( motor ------------------------ ( motor ------------------------ ,h4 ,p4 ,usual limits ,av]age ,h4 ,p4 ,usual limits ,av]age ---------------------------------------- -------------------------- #bj to #dj #cj #ae #e to #aa #h #aj #cj #bj #bj #d #aj #g #aj #bj #ae #cj #c #i #f #a #h #bj #ad #ej #b #h #e #b #h #ah #ac #ge #a #g #d #c #h #af #ab #ajj #a #f #c4e #e #g #ae #aa #aej #a #e #c #g #f #ad #aj #bjj #a #d #b4e #aj #g #ab #i #cjj #a #c #b ---------------------------------------- -------------------------- ,illu/ration3 ,,fig4 #a1gcf4--,sector me?od ( measur+ ! slip ( induction motors4 ,a black disc hav+ a numb] ( :ite sectors 7g5]ally ! same z ! numb] ( poles ( ! induction motor7 is fa/5$ ) wax to %aft ( ! induction motor1 & is obs]v$ ?r\gh ano!r disc hav+ an equal numb] ( sector %ap$ slits 7t is a simil> disc ) ! :ite sectors cut out7 & atta*$ to ! %aft ( a small self-/>t+ syn*ron\s motor1 :i* is fitt$ ) a revolution c\nt] t c be ?r[n 9 or out ( ge> at w2 !n ! slip 79 t]ms ( ,nr7 ,n 7,ns ,nr71 9 :i*3 ,n numb] ( passages ( ! sectors2 ,ns numb] ( sectors2 ,nr numb] ( revolutions record$ by ! c\nt] dur+ ! int]val ( obs]vation4 ,= l>ge values ( slip1 ! obs]vations may be simplifi$ by us+ only "o sector 7,ns #a71 !n ,n w equal ! slip 9 revolutions4 ,ques4 ,describe "o way ( measur+ ! slip4 ,ans4 ,a simple ?\gh r\gh way is to obs]ve simultane\sly ! spe$ ( ! armature & ! frequ5cy1 calculat+ ! slip f ! data ?us obta9$1 z on page #a1cae4 ,?is me?od is n accurate1 z1 ev5 ) ! mo/ c>eful read+s1 l>ge errors _c be avoid$4 ,a bett] way is %[n 9 fig4 #a1gcf4 ,illu/ration3 ,,fig4 #a1gcg4--;,detail ( ,we/+h\se squirrel cage armature = induction motor4 ,?is is an example ( ca/ on con/ruction simil> to t ( ,morse-,fairbanks 7see figs4 #a1geb1 #a1gec & #a1iae74 ,! inductors are emb$d$ 9 a special cem5t4 ,evolution ( ! ,squirrel ,cage ,armature4--,9 ! e>ly exp]im5ts ) rotat+ magnetic fields1 copp] discs 7 us$2 9 fact1 x 0 !n discov]$ t a mass ( copp] or any conduct+ metal1 if plac$ 9 a rotat+ magnetic field1 w be urg$ 9 ! direction ( rotation ( ! field4 ,f]r>is us$ a copp] cyl9d] z 9 figs4 #a1gaj & #a1gch1 :i* 0 ! fir/ /ep 9 ! evolution ( ! squirrel cage armature4 ,! tr\ble ) an armature ( ?is k9d is t !re is no def9ite pa? provid$ = ! induc$ curr5ts4 ,illu/ration3 ,,s ,,call$ ,,squirrel ,,cage ,illu/ration3 ,,figs4 #a1gch to #a1gdd4--;,evolution ( ! squirrel cage armature4 ,! e>ly exp]im5ts ( ,arago1 ,h]s*el1 ,babbage & ,baily demon/rat$ t a mass ( copp] or any conduct+ metal1 if plac$ 9 a revolv+ magnetic field1 w be urg$ to revolve 9 ! direction ( ! revolv+ field4 ,!y us$ discs1 b ,f]r>is us$ a copp] cyl9d] z %[n 9 figs4 #a1gaj & #a1gch2 ?is 0 ! fir/ squirrel cage armature4 ,figs4 #a1gci to #a1gdd %[ ! gradual developm5t ( ! primitive device %[n 9 fig4 #a1gch2 fig4 #a1gci1 ,f]r>is' cyl9d] ) slots re/rict+ ! pa? ( induc$ curr5ts2 fig4 #a1gdj1 ,dobr[olsky's s call$ squirrel cage :i* he emb$d$ 9 a solid iron core1 z 9 fig4 #a1gda2 fig4 #a1gdb1 design ) insulat$ b>s & lam9at$ core to prev5t eddy curr5ts 9 ! core2 fig4 #a1gdc1 lam9at$ core ) v5tilat+ ducts2 fig4 #a1gdd1 mod]n squirrel cage armature repres5t+ ! late/ practice z built by ,me*anical ,appliance ,co4 ,! core is built up ( discs pun*$ f ,no4 #bi gauge electrical %eet1 insulat$ f ea* o!r & firmly clamp$ betwe5 end plates lock$ on ! %aft4 ,! slots 9 ! discs are ( ! same g5]al =m z ^? 9 ! core4 ,heavy fibre end pieces1 pun*$ to mat* ! discs are plac$ at ea* end ( ! core1 to prev5t ! b>s com+ 9 contact ) ! %>p edges ( ! tee?4 ,! w9d+ is made up ( rectangul> copp] b>s1 pass+ ?r\gh slots 9 ! core1 & %ort circuit$ on ea* o!r by means ( copp] end r+s ( special design4 ,! b>s are press$ into holes pun*$ 9 ! end r+s1 & ! contact is !n protect$ f corrosion by be+ dipp$ 9 a sold] ba?4 ,! b>s are insulat$ f ! iron ( ! core by fibre cell project+ beyond ! end ( ! slot4 ,to secure v5tilation ! %ort circuit+ r+s are set "s di/ance f ! end ( ! core4 ,9 ?is way ! b>s betwe5 ! core & ! r+ act z ! vanes ( a pressure bl[]1 =c+ a l>ge volume ( air ?r\gh ! field coils & v5tilat+ op5+s4 ,illu/ration3 ,,fig4 #a1gde4--,me*anical ,appliance ,co4 solid core discs z us$ on small & m$ium size induction motors4 ,illu/ration3 ,,fig4 #a1gdf4--;,allis-,*alm]s squirrel cage armature con/ruction4 ,! core lam9 are m\nt$ on a ca/ iron spid] hav+ arms %ap$ to act z fan blades = =c+ air ?r\gh ! motor4 ,! spid] is press$ on to ! %aft4 ,9 ! smalle/ sizes ! pun*+s are m\nt$ directly on ! %aft1 :i* is prop]ly ma*9$ to hold !m firmly4 ,copp] b>s are us$ z inductors 9 ! l>g] sizes1 & copp] rods 9 ! small] sizes4 ,! ends ( ! inductors are turn$ d[n some:at small] ?an ! body & fit 9 holes 9 ! end r+s4 ,! %\ld] ?us =m$ fits firmly aga9/ ! end r+s4 ,good electrical contact is obta9$ by exp&+ ! inductors 9 ! end r+ holes4 ,9 l>ge armatures bo? b>s & end r+s are ( rectangul> cross section1 ! b>s & r+s be+ fa/5$ by ma*9e /eel cap screws4 ,obvi\sly1 a bett] result is obta9$ if1 9 fig4 #a1gch1 ! d[nw>d return+ curr5ts ( ! eddies are l$ into "s pa? :]e !y w return across a field ( opposite pol>ity f t across :i* !y asc5d$1 z 9 su* case1 ! turn+ effect w be d\bl$4 ,accord+ly ! design ( fig4 #a1gch 0 modifi$ by cutt+ a numb] ( p>allel slits :i* ext5d$ ne>ly to ! ends1 leav+ at ea* end an un9t]rupt$ r+ ( metal4 ,?is may be call$ ! fir/ squirrel cage armature1 & 9 ! lat] developm5t ,dobr[olsky 0 ! fir/ to employ a built-up con/ruction1 us+ a numb] ( b>s jo9$ toge!r by a r+ at ea* end1 z 9 fig4 #a1gdj1 & emb$d$ 9 a solid mass ( iron1 z 9 fig4 #a1gda2 he reg>d+ ! b>s m]ely z ve9s ( copp] ly+ buri$ 9 ! iron4 ,illu/ration3 ,,fig4 #a1gdg4--,triumph squirrel cage armature4 ,9 con/ruction ?9 %eet /eel lam9ations1 japann$1 are built up to =m ! core1 & are rigidly clamp$ toge!r by heavy malleable iron end plates4 ,semi-enclos$ slots are pun*$ 9 ! out] p]iph]y to receive ! w9d+s1 s t none ( ! c5trifugal =ce is c>ri$ by ! inductors4 ,^! inductors are set edge on1 & are rivet$ & sold]$ into resi/ance r+s4 ,^! r+s are pun*$ to receive ! inductors 9 su* a mann] t !re is an unbrok5 /rip ( metal completely surr\nd+ !m4 ,moreov]1 ! %ort circuit+ r+s are set "s di/ance f ! end ( ! core1 s t ! inductors betwe5 ! core & r+ act z vanes to =ce air ?r\gh ! coils = v5tilation4 ,illu/ration3 ,,fig4 #a1gdh4--;,g5]al ,electric sold]$ =m ( end r+ con/ruction on squirrel cage armatures4 ,! armature inductors or copp] b>s laid 9 ! core slots are %ort circuit$ by ^! end r+s1 :i* are also made ( copp]4 ,= ! small] sizes ! r+s are ?91 b ( consid]able radial dep? & are held ap>t by spac+ wa%]s4 ,!y h rectangul> holes pun*$ ne> _! out] p]iph]ies ?r\gh :i* ! b>s pass4 ,lips are =m$ on ! r+s1 z %[n1 to :i* ! b>s are sold]$4 ,illu/ration3 ,,fig4 #a1gdi4--;,g5]al ,electric weld$ =m ( end r+ con/ruction on squirrel cage armatures4 ,space limitations make x difficult to provide multiple sold]$ r+s ( suffici5t area = l>ge motors2 h5ce1 on su* ma*9es weld+ is resort$ to1 z %[n4 ,! r+ 9 weld$ con/ruction is plac$ b5ea? ! b>s at ea* end ( ! armature4 ,%ort radial b>s are weld$ to ! edges ( ^! r+s & to ! inductors or squirrel cage b>s1 !reby mak+ good electrical contact4 ,a solid cyl9d] ( iron w ( c\rse s]ve z an armature1 z x is magnetically excell5t2 b ! high specific resi/ance ( iron prev5ts ! fl[ ( induc$ curr5ts tak+ place suffici5tly copi\sly2 h5ce a solid cyl9d] ( iron is improv$ by surr\nd+ x ) a mantle ( copp]1 or by a squirrel cage ( copp] b>s 7l fig4 #a1gdj71 or by emb$d+ rods ( copp] 7%ort circuit$ toge!r at _! ends ) r+s7 9 holes j b5ea? its surface4 ,h[ev]1 s9ce all eddy curr5ts t circle r\nd1 z ^? sket*$ 9 fig4 #a1gch1 are n s effici5t 9 _! me*anical effect z curr5ts conf9$ to prop] pa?s1 & z !y consume p[] & sp5d x 9 heat+ effects1 ! core 0 !n con/ruct$ ) lam9ations lightly insulat$ f ea* o!r1 & fur!r ! squirrel cage copp] b> inductors 7 fully insulat$ f contact ) ! core4 ,tunnel slots 7 lat] replac$ by designs ) op5 tops4 ,illu/ration3 ,figs4 #a1gej & #a1gea4--;,built up core con/ruction ) discs pun*$ 9 "o piece4 ,! spid] prop] consi/s ( a hub provid$ ) f\r radial arms1 :i* fit ! inn] diamet] ( ! disc4 ,! hub is bor$ out s t x fits v tightly on ! %aft1 & a key is provid$ to avoid any *ance ( turn+4 ,! core disks are clamp$ firmly 9 place by two heavy ca/ iron end plates :i* are press$ up & held by ! bolts4 ,^! bolts pass "u ! discs1 s t !re is no dang] ( _! giv+ rise to eddy curr5ts4 ,! key n only prev5ts ! discs turn+ on ! spid] b also ensures ! al9em5t ( discs1 :i* is necess>y to make ! tee? =m smoo? slots :5 ! core is assembl$4 ,fig4 #a1gdd %[s a mod]n squirrel cage armature con=m+ to ! late/ practice1 o!r designs be+ illu/rat$ 9 ! num]\s accompany+ cuts4 ,9 ! small] sizes1 ! core lam9 are ( ! solid type z %[n 9 fig4 #a1gde1 b = l>g] motors ! core consi/s ( a spid] & segm5tal discs z %[n 9 figs4 #a1gej & #a1gea4 ,fig4 #a1gdh %[s a sold]$ =m ( end r+ con/ruction1 & figs4 #a1geb & #a1gec ! me?od ( weld+ ! end r+ to ! inductors4 ,! ,field ,magnets4--,! con/ruction ( ! field magnets1 :i*1 :5 en]giz$ ) alt]nat+ curr5t produce ! rotat+ magnetic field1 is 9 _m respects id5tical ) ! armature con/ruction ( revolv+ field alt]nators4 ,illu/ration3 ,,fig4 #a1geb4--;,fairbanks-,morse squirrel cage armature ) ca/-on r+s %[+ inspection grooves4 ,! me?od consi/s 9 fus+ ! ends ( ! inductors into an end r+ ( a special composition1 !reby produc+ a p]fect electrical & me*anically /rong jo9t4 ,9 ?is process ! armature ) its b>s 9 place is put into a m\ld & ! molt5 metal p\r$ ar\nd ! inductors1 melt+ _! ends & effectually fus+ !m into ! body ( ! r+4 ,! r+ is !n turn$ d[n to f9i%$ size & poli%$4 ,an inspection groove is cut z %[n to indicate t ! fusion is complete & ! jo9t p]fect4 ,illu/ration3 ,,fig4 #a1gec4--,section ( ,fairbanks-,morse ca/-on jo9t %[+ union ( end r+ & inductor4 ,! view %[s ! ,v-%ape inspection groove z describ$ 9 fig4 #a1geb4 ,broadly1 ! field magnets ( induction motors consi/s (3 #a4 ,yoke or frame2 #b4 ,lam91 or core /amp+s2 #c4 ,w9d+4 ,illu/ration3 ,,fig4 #a1ged4--,ri*mond field con/ruction = polyphase induction motors1 %[+ /yle ( w9d+ = use ) squirrel cage & w\nd armature types4 ,ques4 ,:at is ! con/ruction ( ! yoke & lam98 ,ans4 ,!y are 9 e way simil> to ! armature frame & core con/ruction ( revolv+ field alt]nators4 ,illu/ration3 ,,fig4 #a1gee4--,we/]n ,electric squirrel cage armature ( high spe$ induction motor = c5trifugal pump s]vice4 ,?is armature is an example ( heavy duty con/ruction4 ,! inductors are weld$ to ! %ort circuit+ end r+s1 ! latt] be+ locat$ b5ea? ! inductors1 z %[n4 ,fan vanes are provid$ at "o end = v5tilation4 ,9 ! field con/ruction1 ! core lam9ations are assembl$ 9 a clos$ box frame1 & clamp$ by heavy r+s :ile "u hydraulic pressure4 ,! /ator coils are =m w\nd & subject$ to a special insulat+ process1 :i* r5d]s !m especially imp]vi\s to moi/ure1 & capable ( op]at+ )\t breakd[n 9 locations :i* are too damp = ord9>y motors4 ,! be>+ brackets are ( rigid me*anical con/ruction1 & ! pulley end bracket & be>+s ( all sizes are split to facilitate removal ( ! rotor & complete inspection4 ,^! ma*9es range 9 size f #ej to #bjj horse p[]1 ! rugg$ con/ruction adapt+ !m to heavy & sev]e s]vice1 su* z is met ) 9 m9+1 ! con/ruction ( dams1 canals1 aqu$ucts1 tunnels1 etc4 ,illu/ration3 ,,fig4 #a1gef4--,wagn] squirrel cage armature = polyphase induction motor1 z employ$ on motors ( f #e to #be horse p[]4 ,! features ( con/ruction z se5 9 ! illu/ration are b> inductors1 v5tilat+ passages ?r\gh ! core lam91 rivet$ connection betwe5 inductors & end r+s v5tilat+ vanes on end plate1 extra l>ge end r+s4 ,! object ( mak+ ! r+s unusually l>ge is to make ! resi/ance ( ! r+s l[] ?an is desirable = "s classes ( s]vice1 9 ord] to obta9 motors hav+ m9imum slip1 increas$ effici5cy1 & maximum ov]load capacity "u normal op]ation4 ,:5 ! torque requir$ by "s v unusual & entirely abnormal in/allation exce$s t ( ! av]age conditions1 x is an easy matt] to r$uce ! section ( ! end r+s1 by turn+ !m d[n 9 a la!1 !reby increas+ ! resi/ance & />t+ torque4 ,field ,w9d+s = ,induction ,motors4--,! field w9d+s ( induction motors are almo/ always made to produce m ?an two poles 9 ord] t ! spe$ may n be unreasonably high4 ,?is w be se5 f ! foll[+3 ,if ,p be ! numb] ( pairs ( poles p] phase1 f1 ! frequ5cy1 & ,n1 ! numb] ( revolutions ( ! rotat+ field p] m9ute1 !n #fj f ,n -------- ,p ,?us = a frequ5cy ( #ajj & "o pair ( poles1 ,n #fj #ajj #a #f1jjj4 ,by increas+ ! numb] ( pairs ( poles to #aj1 ! frequ5cy rema9+ ! same1 ,n #fj #ajj #aj #fjj4 ,h5ce1 9 design1 by increas+ ! numb] ( pairs ( poles ! spe$ ( ! motor is r$uc$4 ,illu/ration3 ,,fig4 #a1geg4--,ri*mond squirrel cage armature4 ,! copp] b>s are d\ble rivet$ at ei!r end to ! resi/ance r+s1 !n dipp$ into a sold] ba?4 ,ques4 ,/ate an objection to v high spe$ ( ! rotat+ field4 ,ans4 ,! m rapid ! rotation ( ! field1 ! great] is ! />t+ difficulty4 ,ques4 ,besides employ+ a multiplicity ( poles1 :at o!r means is us$ to r$uce ! spe$8 ,ans4 ,r$uc+ ! frequ5cy4 ,ques4 ,:at difficulty is enc\nt]$ ) l[ frequ5cy curr5ts8 ,ans4 ,if ! frequ5cy be v l[1 ! curr5t w\ld n be suitable = inc&esc5t lamp light+1 because at l[ frequ5cy ! rise & fall ( ! curr5t 9 ! lamps is p]ceptible4 ,illu/ration3 ,,fig4 #a1geh4--;,field con/ruction ( ,crock]-,:eel] induction motor ) magnetic bridge4 ,/eel bridges are ins]t$ 9 ! grooves :]e ! coils are plac$1 to protect !m f dirt & me*anical injury & at ! same "t provide a pa? = ! magnetic flux :i* has a m uni=m reluctance1 !reby insur+ a bett] di/ribution ( ! flux 9 ! air gap & at ! same "t reta9+ op5 slot con/ruction f :i* ! coils c be readily remov$4 ,ques4 ,:at is ! g5]al "* ( ! field w9d+8 ,ans4 ,! field core slots conta9 a di/ribut$ w9d+ ( sub/antially ! same "* z ! armature w9d+ ( a revolv+ field polyphase alt]nator4 ,ques4 ,are ! poles =m$ 9 ! usual way8 ,ans4 ,!y are produc$ by prop]ly connect+ ! gr\ps ( coils & n by w9d+s conc5trat$ at c]ta9 po9ts on sali5t or sep>ately project+ masses ( iron1 z 9 direct curr5t ma*9es4 ,ques4 ,h[ are ! coils gr\p$8 ,ans4 ,?ree phase w9d+s are usually ,y connect$4 ,illu/ration3 ,,fig4 #a1gei4--,we/]n ,electric squirrel cage armature4 ,! inductors consi/ ( solid copp] b>s emb$d$ 9 ! slots ( a lam9at$ core1 ) _! project+ ends securely fitt$ & sold]$ to heavy copp] r+s4 ,ques4 ,:at o!r arrangem5t is sometimes us$8 ,ans4 ,9 "s cases ,y gr\p+ is us$ = />t+ & gr\p+ = runn+4 99 99 99 99 99 ,/>t+ ( ,induction ,motors4--,x mu/ be evid5t t if ! field w9d+ ( an induction motor ^: armature is at re/1 be connect$ directly 9 ! circuit )\t us+ any />t+ device1 ! ma*9e is plac$ 9 ! same condition z a trans=m] ) ! second>y %ort circuit$ & ! prim>y connect$ to ! supply circuit4 ,ow+ to ! v l[ resi/ance ( ! armature1 ! ma*9e1 unless x be ( v small size1 w\ld probably be de/roy$ by ! heat g5]at$ be=e x c\ld come up to spe$4 ,accord+ly "s =m ( />t+ device is necess>y4 ,!re are sev]al me?ods ( />t+1 z )3 #a4 ,resi/ances 9 ! field2 #b4 ,auto-trans=m] or comp5sator2 #c4 ,resi/ance 9 armature4 ,illu/ration3 ,,fig4 #a1gfj4--;,holz] ,cabot comb9ation polyphase induction motor set1 consi/+ ( w\nd frame & ?ree rotors3 #a1 squirrel cage armature1 #b1 w\nd armature1 #c1 rotat+ field4 ,! set is int5d$ = s*ool demon/ration ( induction motor ph5om5a4 ,! motor op]at+ ) ! squirrel cage armature has an inh]5t con/ant spe$ *>act]i/ic & on brake te/s w %[ its exceptionally /rong />t+ torque & ability to take excessive ov]loads4 ,?is motor c be us$ z a g5]ator also1 9 ! s5se t if connect$ to ! l9e & driv5 above syn*ron\s spe$ by "s ext]nal means1 x w act z an asyn*ron\s g5]ator & return p[] to ! l9e4 ,= v>iable spe$ s]vice1 an armature hav+ a w9d+ ^u x simil> to t on ! frame mu/ be us$4 ,ext]nal resi/ances ins]t$ 9 ! armature circuit may be us$ to produce1 fir/1 a r$uction ( />t+ curr5t1 second1 an increase ( />t+ torque1 or ?ird1 a v>iation ( spe$4 ,?us an ext5sive li/ ( exp]im5ts c be p]=m$ ) ?is phase w\nd armature directly along ! l9e ( pres5t eng9e]+ practice4 ,! phase w\nd armature c be us$ z an alt]nator 9 ! same s5se z m5tion$ above = ! squirrel cage ma*9e4 ,= syn*ron\s motor & ?ree phase op]ation ! revolv+ field ) project+ poles & slip r+s w\ld be us$1 ! field be+ excit$ f a direct curr5t supply4 ,ques4 ,expla9 ! me?od ( ins]t+ resi/ances 9 ! field4 ,ans4 ,v>iable resi/ances are ins]t$ 9 ! circuits lead+ to ! field magnets & me*anically arrang$ s t ! resi/ances are v>i$ simultane\sly = ea* phase 9 equal am\nts4 ,^! />t+ resi/ances are enclos$ 9 a box simil> to a direct curr5t motor rheo/at4 ,ques4 ,is ?is a good me?od8 ,ans4 ,x is m economical to ins]t a v>iable inductance 9 ! circuit1 by us+ an auto-trans=m]4 ,illu/ration3 ,,fig4 #a1gfa4--,we/+h\se auto-/>t]4 ,polyphase induction motors may be />t$ by connect+ !m directly to ! circuit ) an ord9>y swit*1 & ! small] motors are />t$ 9 ?is way 9 practice4 ,9 ! l>g] motors1 h[ev]1 ! />t+ torque at normal voltage is sev]al times its full load torque2 !re=e1 !y are />t$ on a r$uc$ voltage1 & ! full pressure ( ! circuit is n appli$ until !y h practically rea*$ _! op]at+ spe$4 ,! figure %[s connections ) a two phase alt]nat+ curr5t circuit4 ,! auto-/>t] consi/s ( two auto-trans=m]s ,t & ,t'1 ea* hav+ only a s+le w9d+ = bo? prim>y & second>y1 :i* are tapp$ at c]ta9 po9ts by swit*es1 ?us divid+ ! w9d+ into a numb] ( loops1 s t "o ( sev]al voltages may be appli$ = />t+1 & ! />t+ torque ?us adju/$ to ! "w t has to be p]=m$4 ,at ! highe/ po9ts tapp$ by ! swit*es ,s1 & ,s'1 ! full pressure1 & at ! l[e/ po9ts1 ! l[e/ pressure1 is appli$ to ! motor by ! op]ation ( ! ma9 swit* ,m4 ,?is swit* has f\r blades & ?ree positions4 ,:5 ?r[n to ! left z indicat$1 x connects ! auto-trans=m]s ,t & ,t'1 across ! circuits ,a & ,b respectively1 s t ! pressure across ! trans=m] coils1 z det]m9$ by ! position ( ! swit*es ,s & ,s'1 is appli$ to ! motor circuits ,a & ,b4 ,! int]m$iate position ( ! swit* ,m int]rupts bo? circuits4 ,to />t ! motor1 ! swit* ,m is ?r[n to ! left & a r$uc$ pressure appli$2 aft] ! motor has />t$ & come up to spe$ ! swit* ,m is ?r[n to ! "r1 ?us cutt+ out ! trans=m] & connect+ ! motor directly to ! circuit4 ,! />t+ device c be locat$ at a po9t remote f ! motor1 ?us elim9at+ dang] f fire due to possible sp>ks1 9 case :]e x is necess>y to in/all ! motors 9 gra9 elevators1 wool5 mills1 or 9 any place expos$ to inflammable gases1 or float+ p>ticles ( combu/ible matt]4 ,?is feature is also valuable 9 cases :]e motors are susp5d$ f ! ceil+1 or in/all$ 9 places n easily accessible4 ,ques4 ,:at is ! auto-trans=m] or comp5sator me?od ( />t+8 ,ans4 ,x consi/s ( r$uc+ ! pressure at ! field t]m9als by int]pos+ an imp$ance coil across ! supply circuit & fe$+ ! motor f v>iable po9ts on its w9d+s4 ,illu/ration3 ,,fig4 #a1gfb4--;,auto-trans=m] or comp5sator connections = ?ree phase induction motor4 ,9 op]ation :5 ! d\ble ?r[ swit* is ?r[n ov] to />t+ position1 ! curr5t = ea* phase ( ! motor fl[s ?r\gh an auto-trans=m]1 :i* consi/s ( a *ok+ coil = ea* phase1 arrang$ s t ! curr5t may be made to pass ?r\gh any portion ( x 7z #a1 #b1 #c7 to r$uce ! voltage to ! prop] am\nt = />t+4 ,aft] ! motor has come up to spe$ on ! r$uc$ voltage1 ! swit* is ?r[n ov] to runn+ position1 ?us supply+ ! full l9e voltage to ! motor4 #g;,9 actual con/ruction fuses are usually connect$1 s t !y w be 9 circuit 9 ! runn+ position1 b n 9 ! />t+ position1 :]e !y might be bl[n by ! l>ge />t+ curr5t4 #g ,,note4--,! con/ruction ( />t+ devices = induction motors is fully expla9$ lat]1 ! accompany+ cuts s]v+ m]ely to illu/rate ! pr9ciples involv$4 ,int]nal ,resi/ance ,induction ,motors4--,! armature ( ?is type ( induction motor diff]s f ! squirrel cage v>iety 9 t ! w9d+ is n %ort circuit$ ?r\gh copp] r+s1 b1 9 />t+1 is %ort circuit$ ?r\gh a resi/ance m\nt$ directly on ! %aft 9 ! int]ior ( ! armature4 ,:5 ! motor is ?r[n 9 circuit1 a v l[ />t+ curr5t is drawn f ! l9e due to ! add$ resi/ance 9 ! armature4 ,z ! motor comes up to spe$1 ?is resi/ance is gradually cut out1 & at full spe$ ! motor op]ates z a squirrel cage motor1 ) %ort circuit$ w9d+4 _/ ,ques4 ,h[ is ! resi/ance gradually cut out 9 int]nal resi/ance motors8 ,ans4 ,by op]at+ a lev] :i* engages a coll> free to slide horizontally on ! %aft4 ,! coll> moves ov] ! int]nal resi/ance grids 7locat$ )9 ! armature spid]71 ?us gradually r$uc+ _! value until !y are cut out4 ,illu/ration3 ,,fig4 #a1gfc4--,view ( armature int]ior ( ,wagn] polyphase induction motor ) w\nd armature1 %[+ ! c5trifugal device :i* at ! prop] spe$ %ort circuits all ! coils1 trans=m+ ! motor to ! squirrel cage type4 ,! w9d+ is connect$ ) a v]tical commutator s call$4 ,inside ! armature are two gov]nor weights1 :i* are ?r[n outw>ds by ! c5trifugal =ce :5 ! ma*9e rea*es ! prop] spe$1 ?us pu%+ a solid copp] r+ 7:i* encircles ! %aft7 into contact ) ! inn] ends ( ! commutator b>s1 ?us completely %ort circuit+ ! armature w9d+4 ,ques4 ,= :at size motors is ! int]nal resi/ance me?od suit$8 ,ans4 ,small motors4 ,ques4 ,:y is x n desirable = l>ge motors8 ,ans4 ,! excessive ,i,r loss 9 ! resi/ances1 if conf9$ )9 ! armature spid]1 w\ld produce consid]able heat+1 & on ?is acc\nt x is be/ plac$ ext]nal to ! motor4 ,ques4 ,on :at class ( circuit are int]nal resi/ance motors desirable8 ,ans4 ,on circuits devot$ to light+ s]vice z well z p[] s]vice1 :]e a high degree ( voltage regulation is ess5tial4 ,! initial ru% ( curr5t :5 a squirrel cage motor is ?r[n on ! l9e is m or less objectionable & !re are c5tral /ations :i* all[ only resi/ance type ( induction motor to be us$ on _! l9es4 ,illu/ration3 ,,fig4 #a1gfd4--,we/]n ,electric w\nd armature = int]nal resi/ance induction motor4 ,9 />t+ ! inductors are %ort circuit$ ?r\gh a resi/ance :i* is gradually cut out z ! motor comes up to spe$4 ,illu/ration3 ,,figs4 #a1gfe ,,to #agfi4--,we/]n ,electric w\nd armature = ext]nal resi/ance1 or slip r+ induction motor1 %[+ bru% rigg+1 slip r+s & b> w9d+4 ,ext]nal ,resi/ance or ,slip ,r+ ,motors4--,9 l>ge ma*9es1 & ^? :i* mu/ run at v>iable spe$1 su* z is requir$ 9 ! op]ations ( cranes1 hoi/s1 dr$ges1 etc41 x is advisable t ! regulat+ resi/ances be plac$ ext]nally to ! motor4 ,motors hav+ ?is feature are comm]cially kn[n z slip r+ motors1 because connections are made betwe5 ! ext]nal resi/ances & ! armature inductors by means ( slip r+s4 ,illu/ration3 ,,fig4 #a1ggj4--,ri*mond slip r+ motor4 ,illu/ration3 ,,fig4 #a1gga4--,ri*mond slip r+ armature z us$ on motor 9 fig4 #a1ggj4 ,illu/ration3 ,,fig4 #a1ggb4--,we/]n ,electric rivet$ frame slip r+ induction motor = v>iable spe$ s]vice2 adapt$ ei!r to cont9u\s or int]mitt5t op]ation4 ,z ) ! int]nal resi/ance motor ! armature w9d+ ( a slip r+ motor is n %ort circuit$ ?r\gh copp] r+s 9 />t+1 b ?r\gh a resi/ance1 :i* 9 ?is case is locat$ ext]nally4 ,ques4 ,h[ is ! armature w9d+ connect$8 ,ans4 ,x is connect$ 9 ,y gr\p+ & ! free ends connect$ to ! slip r+s1 leads go+ f ! bru%es to ! v>iable ext]nal resi/ances1 ^! be+ illu/rat$ 9 fig4 #a1ggi4 ,illu/ration3 ,,figs4 #a1ggc to #a1ggh4--,sprague skeleton type motor frame ) v>i\s types ( armature4 ,fig4 #a1ggg1 pla9 squirrel cage armature2 fig4 #a1ggh1 int]nal resi/ance armature2 fig4 #a1ggc slip r+ armature4 ,9 ! con/ruction ( ! pla9 squirrel cage armature1 fig4 #a1ggg1 copp] b>s are ins]t$ 9 ! slots ( ! core1 & are insulat$ f ! core by enclos+ tubes :i* project ab\t "o-half in* beyond ! iron at ea* side4 ,! b>s are %ort circuit$ at _! ends by copp] r+s4 ,^! r+s are ?91 b ( consid]able radial dep? & are held ap>t by spac+ wa%]s4 ,!y h rectangul> holes pun*$ ne> _! outw>d p]iph]y1 ?r\gh :i* ! armature b>s pass1 & to :i* !y are sold]$4 ,! int]nal resi/ance armature1 fig4 #a1ggh1 is provid$ ) a phase w9d+1 />t+ 7int]nal7 resi/ance1 & swit* locat$ on ! %aft4 ,! />t+ resi/ance is design$ to give approximately full load torque ) full load curr5t at />t+4 ,a great] torque ?an full load torque c be obta9$ = />t+1 if requir$1 by cutt+ out resi/ance4 ,! resi/ance consi/s ( ca/ iron grids enclos$ 9 a triangul> cov] :i* is bolt$ to ! end plates hold+ ! armature lam9 toge!r1 & is %ort circuit$ by slid+ lam9at$ spr+ metal bru%es along ! inside surface ( ! grids4 ,! bru%es are support$ by a metal sleeve slid+ on ! %aft :i* is op]at$ by a lev] secur$ to ! be>+ bracket & locat$ j above ! be>+4 ,a rod pass+ ?r\gh ! end ( ! %aft op]ates ! %ort circuit+ arrangem5t 9 sizes up to ab\t #be horse p[]4 ,! ext]nal resi/ance or slip r+ armature1 fig4 #a1ggc1 is simil> 9 con/ruction to fig4 #a1ggh1 ) ! exception t slip r+s are provid$ because ( ! ext]nal location ( ! resi/ance4 ,^! r+s connect ! inductor ?r\gh bru%es to a controll+ & ext]nal resi/ance1 two or m c>bon bru%es be+ provid$ = ea* r+1 z 9 fig4 #a1ggf4 ,s+le ,phase ,induction ,motors4--,! g5]al utility ( s+le phase motors1 p>ticul>ly ! small] sizes1 is con/antly be+ enl>g$ by ! gr[+ practice ( c5tral /ations g5]at+ polyphase curr5t1 ( supply+ _! light+ s]vice ?r\gh s+le phase di/ribution1 & p]mitt+ ! use ( s+le phase motors ( mod]ate capacity on ! light+ circuit4 ,illu/ration3 ,,fig4 #a1ggi4--;,ext]nal resi/ance or slip r+ induction motor connections4 ,! squirrel cage armature w9d+ is n %ort circuit$ by copp] end r+s1 b connect$ 9 ,y gr\p+ & ! ?ree free ends connect$ to ?ree slip r+s1 leads go+ f ! bru%es to ?ree ext]nal resi/ances1 arrang$ z triplex rheo/at hav+ ?ree arms rigidly connect$ z %[n1 s t ! ?ree resi/ances may be v>i$ simultane\sly & 9 equal am\nts4 ,illu/ration3 ,,fig4 #a1hjj4--;,allis-,*alm]s phase w\nd ext]nal resi/ance type or slip r+ armature con/ruction4 ,! w9d+ is = ?ree phases & ! t]m9als are br\ght out to ?ree slip r+s4 ,! front bracket is slightly modifi$ to make room = ^! r+s on ! inside4 ,= />t+ duty suffici5t resi/ance is suppli$ to r$uce ! />t+ curr5t tak5 by ! motor to #a times ! normal full load curr5t4 ,9 ! runn+ position ! resi/ance is all cut out ( ! circuit4 ,= spe$ regulation suffici5t resi/ance is suppli$ to r$uce ! spe$ #ej on normal full load torque4 ,illu/ration3 ,,figs4 #a1hja to #a1hbh4--;,disassembl$ view ( ,we/]n ,electric ?ree phase ext]nal resi/ance or slip r+ mill type induction motor4 ,x is adapt$ to sev]e work+ conditions1 su* z are met ) 9 /eel mills1 crane & hoi/ s]vice1 etc4 ,design$ = #bbj or #ddj volt1 #be cycle circuits4 ,! frame is divid$ horizontally into an upp] & a l[] /eel ca/+1 bo? ( :i* are bolt$ toge!r at ! corn]s by f\r heavy bolts4 ,! l[] ca/+ is provid$ ) f\r feet = bolt+ ! motor to its f\ndation4 ,! end ( ! upp] frame :i* cov]s ! slip r+s is equipp$ ) malleable iron cov]s held 9 place by lock bolts4 ,! field & armature are ( ! usual con/ruction4 ,"o end ( ! armature w9d+ is protect$ aga9/ me*anical injury by ! slip r+s :i* are ( heavy con/ruction & ( practically ! same diamet] z ! armature1 & ! o!r end by a deta*able flange ( ! same diamet] z ! outside ( ! w9d+4 ,! slip r+s are m\nt$ on ! same spid] z ! armature1 s t ! %aft c be remov$ )\t di/urb+ any ( ! connections4 ,! bru%es are equipp$ ) rivet$ pigtails1 & held 9 brass bru% boxes ma*9$ to gauge4 ,heavy coil$ clock spr+s are us$ to ma9ta9 an ev5 pressure ( ! bru%es on ! slip r+s4 ,! armature leads are br\ght out ?r\gh holes 9 ! upp] half ( ! frame1 & ! field leads are br\ght ?r\gh a block1 :i* fits 9 an op5+ 9 ! upp] edge ( ! l[] half4 ,! simplicity ( s+le phase sy/ems 9 comp>ison ) polyphase sy/ems1 makes !m m desirable = small alt]nat+ curr5t plants4 ,! disadvantage ( s+le phase motors is t !y are n self-/>t+4 ,a s+le phase motor consi/s ess5tially ( an armature & field magnet hav+ a s+le phase w9d+ & also "s phase splitt+ arrangem5t = />t+4 ,illu/ration3 ,,fig4 #ahbi4--;,g5]al ,electric s+le phase induction motor4 ,x is suitable = con/ant spe$ s]vice :]e full load torque at />t+ does n exce$ #adj p] c5t41 & 9 g5]al is adapt$ to drive all ge>$ & belt$ ma*9]y requir+ con/ant spe$ ) light or mod]ate />t+ torque4 ,illu/ration3 ,,fig4 #a1hcj4--,simplifi$ diagram %[+ ! pr9ciple ( phase splitt+ = />t+ s+le phase induction motors4 ,by ! use ( an auxili>y set ( coils connect$ 9 p>allel ) ! ma9 coils & hav+ 9 s]ies a resi/ance or cond5s] z %[n1 ! s+le phase curr5t deliv]$ by ! alt]nator is split into two phases1 :i* are employ$ to produce a rotat+ field on :i* ! motor is />t$4 ,illu/ration3 ,,figs4 #a1hca to #a1hej4--,p>ts ( ,sprague s+le phase clut* type induction motor4 ,! armature is ( ! high resi/ance smoo? core squirrel cage type1 ! core lam9 be+ assembl$ ^u a /eel sleeve4 ,on />t+ ! armature revolves freely ar\nd ! %aft on roll] be>+s until x accel]ates to ab\t #ge ( its rat$ spe$1 :5 a c5trifugal clut* engages ) an out] %ell key$ directly on ! %aft1 ?us ?r[+ on ! load4 ,?is type ( motor is adapt$ to drive all belt$1 ge>$1 or direct connect$ ma*9]y requir+ con/ant spe$ ) mod]ate />t+ torque1 su* z g5]ators1 bl[]s1 l9e %aft+ 9 ma*9e %ops & factories1 drill presses1 laundry ma*9]y1 bak+ ma*9]y1 & ! l4 ,:5 great] torque is requir$ at ! mom5t ( />t+ type ,,ri motors %\ld be us$1 or clut* c\pl+s may be in/all$ betwe5 ! motor & ! ma*9e x is to drive4 ,! p>ts are z foll[s2 ,a1 field frame2 ,b1 field coils2 ,c1 t]m9al block2 ,d1 t]m9al block screws2 ,e1 connectors2 ,f1 be>+ head pulley end2 ,g1 be>+ head opposite pulley end2 ,h1 motor clamp+ bolts2 ,i1 oil well cov]2 ,j1 oil well plug2 ,k1 dra9 plug2 ,l1 oil filt]2 ,m1 cap bolts2 ,n1 be>+ l9+2 ,o1 oil r+2 ,p1 belt tight5] screw2 ,q1 armature core2 ,r1 lat*2 ,s1 driv+ %ell2 ,t1 driv+ %ell set screw2 ,u1 clut* r+2 ,v1 clut* r+ spr+2 ,w1 spr+ adju/+ screw2 ,x1 nut = belt tight5] screw2 ,y1 %aft2 ,z1 driv+ %ell key2 ,aa1 armature be>+2 ,ba1 pulley2 ,ca1 pulley set screw2 ,da1 pulley key2 ,ea1 slid+ base2 ,fa1 yoke4 ,ques4 ,:y is a s+le phase motor n self-/>t+8 ,ans4 ,because ! nature ( ! field produc$ by a s+le phase curr5t is oscillat+ & n rotat+4 ,ques4 ,h[ is a s+le phase motor />t$8 ,ans4 ,by splitt+ ! phase1 a field is set up normal to ! axis ( ! armature1 & ne>ly #ij displac$ 9 phase f ! field 9 t axis4 ,?is cross field produces ! useful torque4 ,illu/ration3 ,,fig4 #a1hea4--;,g5]al ,electric high resi/ance clut* type smoo? core squirrel cage armature ( s+le phase induction motor4 ,! core lam9 are slott$ ne> ! circumf]5ce to reta9 ! b> inductors1 :i* ext5d beyond ! core at ei!r end :]e !y are p]man5tly connect$ to heavy %ort circuit+ r+s4 ,illu/ration3 ,,figs4 #a1heb to #a1hee4--,p>ts ( ,g5]al ,electric c5trifugal clut* pulley z us$ on clut* type1 s+le phase induction motor4 ,a1 clut*2 ,b1 friction b&2 ,c1 adju/+ spr+2 ,d1 out] clut* %ell ) pulley sleeve2 ,e1 solid removable pulley2 ,f1 int]nal me*anism compris+ p>ts ,a1 ,b1 & ,c2 ,g1 out] %ell & pulley compris+ p>ts ,d & ,e4 ,illu/ration3 ,,figs4 #a1hef & #a1heg4--,p>tly assembl$ clut* pulley4 ,f1 int]nal me*anism compris+ p>ts ,a1 ,b1 ,c1 ( fig4 #a1heb4 ,g1 out] %ell & pulley1 compris+ p>ts ,d & ,e ( fig4 #a1heb4 ,phase ,splitt+2 ,production ( ,rotat+ ,field f ,oscillat+ ,field4--,z previ\sly /at$1 an oscillat+ field1 t is1 "o due to a s+le phase curr5t1 does n furni% any />t+ torque4 ,x is !re=e necess>y to provide a rotat+ field = a s+le phase induction motor to />t on1 :i*1 aft] ! motor has come up to spe$1 may be cut out & ! motor w !n op]ate ) ! oscillat+ field4 ,a rotat+ field may be obta9$ f s+le phase curr5t by :at is kn[n z splitt+ ! phase4 ,illu/ration3 ,,fig4 #a1heh4--,swit* end view ( ,g5]al ,electric drawn %ell type fractional horse p[] s+le phase motor4 ,ques4 ,describe "o me?od ( splitt+ ! phase4 ,ans4 ,! field ( ! motor is provid$1 9 addition to ! ma9 s+le phase w9d+1 ) an auxili>y s+le phase w9d+1 & ! two w9d+s are connect$ 9 p>allel to ! s+le phase supply ma9s ) a resi/ance or a cond5s] plac$ 9 s]ies ) ! s+le phase w9d+1 z %[n 9 diagram fig4 #a1hcj1 ! two w9d+s be+ displac$ f ea* o!r on ! armature ab\t #ij magnetic degrees1 j z 9 ! ord9>y two phase motor4 ,ques4 ,:at is ! con/ruction ( ! two w9d+s8 ,ans4 ,! ma9 coils are ( m turns ?an ! auxili>y1 be+ spread ov] m surface1 & are heavi] because !y are = con/ant use2 :]eas ! auxili>y coils are us$ only :ile />t+4 ,illu/ration3 ,,figs4 #a1hei to #a1hfb4--;,detail con/ruction ( clut* p>ts ( ,g5]al ,electric drawn %ell type fractional horse p[] s+le phase motor4 ,! />t+ swit*1 :i* is assembl$ )9 ! motor frame1 consi/s ess5tially ( ?ree p>ts3 a rotat+ memb] m\nt$ on ! armature & provid$ ) two spr+ controll$ pivot$ lev]s 9 contact ) an insulat$ collector r+4 ,ques4 ,:at are ! auxili>y coils sometimes call$8 ,ans4 ,/>t+ coils4 ,ques4 ,:at are %ad+ coils8 ,ans4 ,auxili>y coils z plac$ on fan motors 9 ! mann] %[n 9 fig4 #a1hfc4 ,ques4 ,h[ c s+le phase motors be />t$ )\t ! use ( ext]nal phase splitt+ devices8 ,ans4 ,su* app>atus may be avoid$ by hav+ ! auxili>y w9d+ ( l>g] self-inductance ?an ! ma9 w9d+4 ,ques4 ,:at is ! "* ( ! />t+ torque produc$ by splitt+ ! phase8 ,ans4 ,x does n give /rong />t+ torque4 ,illu/ration3 ,,fig4 #a1hfc4--,s+le phase fan motor ) %ad+ coils = />t+4 ,9 addition to ! ma9 field coils1 "o tip ( ea* pole piece is surr\nd$ by a %ort circuit$ coil ( wire or frame ( copp]1 z indicat$ 9 ! figure4 ,?is coil1 or copp] frame1 is call$ a %ad+ coil & x causes a phase diff]5ce betwe5 ! pulsat+ flux t emanates f ! ma9 portion ( ea* pol> projection & ! pulsat+ flux :i* emanates f ! pole tip1 ?us introduc+ a two phase action on ! armature :i* is suffici5tly pron\nc$ to />t ! motor4 ,ques4 ,h[ is ! pla9 squirrel cage armature modifi$ to enable ! motor to />t ) a heavi] load8 ,ans4 ,an automatic clut* is provid$ :i* all[s ! armature to turn free on ! %aft until x accel]ates almo/ to runn+ spe$4 ,?is type motor is kn[n z ! clut* type ( s+le phase induction motor4 ,9 op]ation :5 ! circuit is clos$1 ! armature />ts to revolve ^u ! %aft2 :5 x rea*es a prem$itat$ spe$1 a c5trifugal clut* exp&s & engages ! clut* disc1 :i* is fa/5$ to ! %aft4 ,illu/ration3 ,,fig4 #a1hfd4--;,diagram %[+ action ( %ad+ coil 9 alt]nat+ curr5t motor4 ,! extremities ( ^! pole pieces are divid$ into two bran*es1 "o ( :i* a copp] r+ call$ a %ad+ coil is plac$ z %[n1 :ile ! o!r is left un%ad$4 ,! action ( ! %ad+ coils is z foll[s3 ,consid] ! field poles to be en]giz$ by s+le phase curr5t1 & assume ! curr5t to be fl[+ 9 a direction to make a nor? pole at ! top4 ,consid] ! poles to be j at ! po9t ( =m+4 ,l9es ( =ce w t5d to pass d[nw>d ?r\gh ! %ad+ coil & ! rema9d] ( ! pole4 ,any *ange ( l9es )9 ! %ad+ coil g5]ates an e4m4f41 :i* causes to fl[ ?r\gh ! coil a curr5t ( a value dep5d+ on ! e4m4f4 & always 9 a direction to oppose ! *ange ( l9es4 ,! field flux is1 !re=e1 p>tly %ift$ to ! free portion ( ! pole1 :ile ! accumulation ( l9es ?r\gh ! %ad+ coil is ret>d$4 ,illu/ration3 ,,figs4 #a1hfe & #a1hff4--;,=t ,wayne split phase factional horse p[] induction motor ) /ation>y armature4 ,! object ( plac+ ! squirrel cage armature w9d+ on ! /ation>y "p or frame is to decrease ! radial dep? ( ! latt] m ?an w\ld be possible ) ! usual arrangem5t :]e ! armature =ms ! rotat+ "p4 ,! small radial dep? ( ! /ation>y armature makes possible a revolv+ field ( maximum diamet] giv+ 9 turn an exceptionally l>ge air gap area1 :i* r$uces ! magnetiz+ curr5t1 h5ce improves ! p[] factor ( ! motor4 ,ques4 ,expla9 9 detail ! action ( ! clut* type ( motor 9 />t+4 ,ans4 ,x c />t a load :i* requires mu* m ?an full load torque at />t+1 because ! motor be+ ne>ly up to full spe$1 has available n only its maximum ov]load capacity1 b also ! mom5tum ( ! armature to ov]come ! in]tia ( ! driv5 app>atus4 ,9 ?is x is assi/$ by a c]ta9 am\nt ( slippage 9 ! clut*1 :i* is ! case :5 ! armature spe$ is pull$ d[n to su* a po9t z to r$uce ! grip ( ! c5trifugal clut*4 ,illu/ration3 ,,figs4 #a1hfg & #a1hfh4--;,g5]al ,electric disassembl$ clut* z us$ on clut* type1 s+le phase 7,,ks7 induction motor4 ,9 />t+1 ! armature revolves freely on ! %aft until approximately #ge p] c5t4 ( normal rat$ spe$ is rea*$4 ,! load is !n pick$ up by ! automatic action ( a c5trifugal clut*1 :i* rigidly engages an out] %ell1 key$ directly to ! %aft4 ,! brass friction b& ( ! clut* is p]man5tly key$ to ! pulley end ( ! armature4 ,commutator ,motors4--,ma*9es ( ?is class are simil> 9 g5]al con/ruction to direct curr5t motors4 ,!y h a clos$ coil w9d+1 :i* is connect$ to a commutator4 ,!re are sev]al types ( commutator motor1 namely3 #a4 ,s]ies2 #b4 ,%unt2 #c4 ,comp5sat$2 #d4 ,repulsion4 ,s9ce1 z /at$1 commutator motors are simil> to direct curr5t motors1 ! "q may be ask$3 ,is x possible to run a direct curr5t motor ) alt]nat+ curr5t8 ,if ! ma9s lead+ to a direct curr5t motor be rev]s$1 ! direction or rotation rema9s ! same1 because ! curr5ts ?r\gh bo? ! field magnets & armature are rev]s$4 ,x mu/ foll[ !n t an alt]nat+ curr5t appli$ to a direct curr5t motor w\ld cause rotation ( ! armature4 ,illu/ration3 ,,fig4 #a1hfi4--,wagn] s+le phase v>iable spe$ commutator motor4 ,! commutator is ( ! regul> horizontal type & ! bru%es rema9 9 contact all ! "t4 ,z ! torque ( alt]nat+ motors v>ies directly z ! squ>e ( ! appli$ pressure1 wide spe$ v>iation may be obta9$ by v>y+ ! voltage appli$ at ! motor t]m9als4 ,action ( ,clos$ ,coil ,rotat+ 9 ,alt]nat+ ,field4--,:5 a clos$ coil rotates 9 an alt]nat+ field1 !re are sev]al diff]5t pressures set up & 9 ord] to c>efully di/+ui% betwe5 !m1 !y may be call$3 ,illu/ration3 ,,figs4 #a1hgj & #a1hga4--;,diagrams illu/rat+ con/ruction & op]ation ( ,wagn] unity p[] factor s+le phase motor4 ,9 ! field con/ruction1 fig4 #a1hgj1 two w9d+s are us$4 ,! ma9 w9d+ #a produces ! initial field magnetization z h]et(ore2 ! auxili>y w9d+ #b controls ! p[] factor or comp5sates ! motor4 ,! ma9 /ructural dep>ture is 9 ! armature1 ! con/ruction ( :i* is m cle>ly indicat$ 9 fig4 #a1hga4 ,"h aga9 two w9d+s are employ$4 ,! ma9 or pr9cipal w9d+ #d is ( ! usual well kn[n squirrel cage type & occupies ! bottom ( ! armature slots4 ,! second or auxili>y w9d+ #c is ( ! usual commut$ type1 is connect$ to a /&>d =m ( horizontal commutator & occupies ! upp] portion ( ! armature slots4 ,betwe5 ! two is plac$ a magnetic sep>ator 9 ! =m ( a roll$ /eel b>4 ,two sets ( bru%es are provid$1 z indicat$ 9 ! diagram ( connections %[n 9 fig4 #a1hgj4 ,! ma9 pair ( bru%es #e-f is plac$ 9 ! axis ( ! ma9 field w9d+ #a & is %ort circuit$4 ,! auxili>y pair ( bru%es #g-h is plac$ at "r angles to ! axis ( ! ma9 field w9d+ & is connect$ 9 s]ies ) x at />t+4 ,! auxili>y field w9d+ #b is p]man5tly connect$ to "o auxili>y bru% #g1 & is adapt$ to be connect$ to ! o!r auxili>y bru% #h by means ( ! swit* #i4 ,! purpose ( ! peculi> armature con/ruction illu/rat$ 9 fig4 #a1hga & ( ! bru% arrangem5t & connections %[n 9 fig4 #a1hgj is to acc5tuate1 at />t+1 ! effect ( ! squirrel cage along ! axis #e-f ( ! ma9 field w9d+ #a1 :ile suppress+ x z f> z possible along ! axis #g-h at "r angles to ma9 w9d+4 ,! magnetic sep>ator plac$ above ! squirrel cage w9d+ #d t5ds to suppress ! effect ( t w9d+ along all axes1 by mak+ x less responsive to outside inductive effects4 ,b ! influ5ce ( ! sep>ator is nullifi$ along ! axis ( ! ma9 field w9d+ by ! pres5ce ( ! %ort circuit$ bru%es #e-f1 :ile no means are provid$ = nullify+ its effects along ! axis at "r angles to t ( ! ma9 field w9d+4 ,?us ! ma9 field w9d+ #a w be able to induce heavy curr5ts 9 bo? armature w9d+s because ( ! %ort circuit$ bru%es 9 ! axis #e-f1 & 9 spite ( ! magnetic sep>ator2 :ile ! armature w9d+ #c1 connect$ 9 s]ies ) #a1 w n be able to produce heavy curr5ts 9 ! squirrel cage w9d+ #d along ! axis #g-h because ( ! magnetic sep>ator betwe5 #c & #d1 :i* %unts or side tracks ! induc+ magnetic flux4 ,9 op]ation1 at />t+1 swit* #i ( fig4 #a1hgj is op51 ! commut$ w9d+ #c along ! axis #g-h be+ connect$ 9 s]ies ) ! ma9 field w9d+ #a & across ! ma9s4 ,! w9d+ #a induces a l>ge curr5t 9 ! armature w9d+s #c & #d along ! axis #e-f1 & ! w9d+ #c produces a l>ge flux along ! axis #g-h4 ,! armature curr5ts 9 ! ma9 axis co-act+ ) ! flux ?read+ ! armature along ! auxili>y axis yield ! great] "p ( ! />t+ torque4 ,z ! motor spe$s up1 ! squirrel cage gradually assumes ^? functions :i* x p]=ms 9 ! ord9>y s+le phase1 squirrel cage motor1 develop+ a magnetic field ( its own along ! axis #g-h & a correspond+ly p[]ful torque1 :i* increases v rapidly z syn*ronism is approa*$1 b falls sudd5ly to z]o at or ne> actual syn*ronism4 ,x is kn[n t ! magnetiz+ curr5ts circulat+ 9 ! b>s ( ! squirrel cage ( a s+le phase motor h1 at syn*ronism1 d\ble ! frequ5cy ( ! /ator curr5ts2 ! fluxes !y produce mu/ !re=e also be ( d\ble frequ5cy4 ,n[1 ! magnetic sep>ator is made ( solid /eel1 &1 :ile ?is sep>ator =ms a suffici5tly effective %unt = ! fluxes ( l9e frequ5cy induc$ f ! field1 x is q ineffective z a %unt = ! d\ble frequ5cy fluxes produc$ by ! armature4 ,) respect to ! squirrel cage1 ! effect ( ?is magnetic sep>ator dim9i%es ) increas+ spe$1 & at syn*ronism ! ma*9e op]ates practically 9 ! same mann] z if ! magnetic sep>ator did n exi/4 #a4 ,! trans=m] pressure2 #b4 ,! g5]at$ pressure2 #c4 ,! self-induction pressure4 ,^! pressures may be def9$ z foll[s3 ,! trans=m] pressure is t pressure induc$ 9 ! armature by ! alt]nat+ flux f ! field magnets4 ,illu/ration3 ,,fig4 #a1hgb4--;,diagram ( r+ armature 9 alt]nat+ field illu/rat+ ! pr9ciples ( commutator motors4 ,= in/ance1 assum+ 9 fig4 #a1hgb ! armature to be at re/1 z ! alt]nat+ curr5t :i* en]gizes ! magnets rises & falls 9 value1 ! v>iations ( flux :i* ?reads ?r\gh ! coils ( ! r+ w9d+1 induce pressure 9 !m 9 j ! same way t pressure is induc$ 9 ! second>y ( a trans=m]4 ,a r+ w9d+ is us$ = simplicity2 ! same conditions obta9 9 a drum w9d+4 ,! g5]at$ pressure is t pressure induc$ 9 ! armature by ! cutt+ ( ! flux :5 ! armature rotates4 ,! self-induction pressure is t pressure induc$ 9 bo? ! field & armature by self-induction4 ,nature ( ! ,g5]at$ ,pressure4--,9 fig4 #a1hgb1 ! g5]at$ pressure induc$ by ! rotation ( ! armature is m9imum at ! neutral plane ,c ,d & maximum at ,a ,b4 ,x t5ds to cause curr5t to fl[ up ea* half ( ! armature f ,d to ,c1 produc+ poles at ^! po9ts4 ,illu/ration3 ,,fig4 #a1hgc4--,wagn] s+le phase repulsion induction commutator motor4 ,its work+ pr9ciple is repulsion />t & induction op]ation4 ,/>t+ ) ! ma*9e at re/1 bru%es 9 pairs cross connect$ ?r\gh a l[ resi/ance conductor1 be> ^u ! commutator1 tempor>ily %ort circuit+ ! armature w9d+ !n develop+ a /rong />t+ torque on ! repulsion pr9ciple4 ,on atta9+ full load spe$ ! individual segm5ts ( ! commutator are all positively connect$ toge!r by ! op]ation ( an automatic c5trifugal gov]nor1 !reby trans=m+ ! armature w9d+ to ! squirrel cage =m1 ! motor !n cont9u+ z an induction motor4 ,! gov]nor at ! same "t removes ! bru%es f contact ) ! commutator to save we>4 ,if ! p[] s]vice %\ld fail = any reason1 ! motor returns to ! />t+ condition1 & picks up its load :5 ! p[] comes on aga9 )\t att5tion ( ! op]ator4 ,nature ( ! ,trans=m] ,pressure4--,?is is caus$ by v>iations ( ! flux pass+ ?r\gh ea* coil ( ! armature w9d+4 ,evid5tly ?is v>iation is lea/ at ! plane ,a ,b because at ?is po9t ! coils are incl9$ v acutely to ! flux1 & greate/ at ! plane ,c ,d :]e ! coils are p]p5dicul> to ! flux4 ,accord+ly1 ! trans=m] pressure induc$ 9 ! armature w9d+ is lea/ at ,a ,b & greate/ at ,c ,d4 ,! trans=m] pressure acts 9 ! same direction z ! g5]at$ pressure z indicat$ by ! long arr[s & gives rise to :at may be call$ local armature curr5ts4 ,illu/ration3 ,,figs4 #a1hgd & #a1hge4--;,armature ( ,wagn] s+le phase repulsion-induction commutator motor z se5 f ! commutator & re> ends1 %[+ ! v]tical commutator & type ( gov]nor employ$ on ! small] sizes4 ,! op]ation is expla9$ 9 fig4 #a1hgc4 ,nature ( ! ,self-induction ,pressure4--,! self-induction pressure1 be+ opposite 9 direction to ! impress$ pressure1 x mu/ be evid5t t 9 ! op]ation ( an alt]nat+ curr5t commutator motor1 ! impress$ pressure mu/ ov]come n only ! g5]at$ ,illu/ration3 ,,fig4 #a1hgf4--;,g5]al ,electric s+le phase comp5sat$ repulsion motor4 ,! frame is ( ! rivet$ =m & ! field w9d+ consi/s ( di/ribut$ conc5tric coils1 ea* be+ sep>ately insulat$ & tap$ up to ea* core slot4 ,! comp5sat+ w9d+ 7dep5d+ usually on ! size ( frame71 =ms ei!r ! c5t] portion ( ! ma9 w9d+ or a sep>ate w9d+ conc5tric !re)4 ,! pol> gr\p+s are arrang$ = a frequ5cy ( #be & #fj4 ,!re are f\r t]m9al leads p]mitt+ int]*angeability ( op]ation on #aaj or #bbj volt circuits4 ,by connect+ adjac5t pairs ( ^! t]m9als 9 multiple1 motors ( ?is type are made adaptable = #aaj volt s]vice2 = d\ble ?is pressure ! f\r lead+ 9 wires are connect$ 9 s]ies4 ,! motor w op]ate satisfactorily :]e ! ari?metical sum ( voltage & frequ5cy v>iation does n exce$ #aj p] c5t42 t is1 ! voltage may be #aj p] c5t4 high if ! frequ5cy rema9 at normal1 or ! frequ5cy may be #aj p] c5t4 high assum+ no v>iation 9 voltage4 ,a decrease ( #e p] c5t4 9 frequ5cy accompani$ by a simil> increase 9 voltage is p]missible or1 z above /at$1 any simil> comb9ation ^: ari?metical sum is )9 #aj p] c5t4 ( normal4 ,! armature w9d+ is ( ! s]ies drum type connect$ to a commutator c>ry+ two sets ( bru%es1 ea* set be+ displac$ electrically f ! o!r by #ij degrees4 ,! fir/ set1 kn[n z ! en]gy bru%es1 is p]man5tly %ort circuit$ & dispos$ at an angle to ! l9es ( field or prim>y magnetization1 z 9 an ord9>y repulsion motor4 ,! second set1 or comp5sat+ bru%es1 is connect$ to a small portion ( ! prim>y w9d+ includ$ 9 ! field circuit1 s z to impress ^u ! armature an electromotive =ce1 :i* s]ves bo? to raise ! p[] factor & at ! same "t ma9ta9 approximately syn*ron\s spe$ at all loads4 ,! armature lam9ations are built up on a ca/ iron sleeve hav+ ! same inside bore z ! commutator4 ,9 case ! %aft become damag$ or worn1 x c be readily press$ out & replac$ )\t di/urb+ ! commutator or w9d+s4 ,! motor is connect$ to run c\nt] clockwise4 ,clockwise rotation is obta9$ by int]*ang+ ! leads to ! comp5sat+ bru%es & slightly %ift+ ! bru% hold] yoke4 ,?is type motor may be ?r[n on ! l9e )\t ! use ( a rheo/at1 & is suitable = op]at+ refrig]at+ ma*9es1 air compressors1 h\se pumps or simil> app>atus :]e a float swit* or pressure regulator is us$ to close or op5 ! supply circuit4 _/ pressure b also ! self-induction pressure4 ,h5ce1 z comp>$ to an equival5t direct curr5t motor1 ! appli$ voltage mu/ be great] ?an 9 ! direct curr5t ma*9e1 to produce an equal curr5t4 ,illu/ration3 ,,fig4 #a1hgg4--;,armature ( ,g5]al ,electric s+le phase comp5sat$ repulsion motor1 assembl$ ready = dip & b&+4 ,illu/ration3 ,,fig4 #a1hgh4--;,ca/ bru% rigg+ ( ,g5]al ,electric s+le phase comp5sat$ repulsion motor z us$ = ! #c & #e horse p[] motors4 ,! ,local ,armature ,curr5ts4--,^! curr5ts produc$ by ! trans=m] pressure occur 9 ^? coils und]go+ commutation4 ,!y are l>ge1 because ! maximum trans=m] action occurs 9 !m1 t is1 9 ! coils %ort circuit$ by ! bru%es4 ,ques4 ,:y d ! local armature curr5ts cause sp>k+8 ,ans4 ,because ( ! sudd5 int]ruption ( ! l>ge volume ( curr5t1 & also because ! flux set up by ! local curr5ts be+ 9 opposition to ! field flux1 t5ds to weak5 ! field j :5 & :]e its greate/ /r5g? is requir$ = commutation4 ,illu/ration3 ,,fig4 #a1hgi4--;,field ( ,sprague s+le phase comp5sat$ repulsion motor4 ,! frame is ( ! skeleton =m :i* exposes ! core1 giv+ effective heat radiation4 ,! s+le phase field w9d+ is ( ! di/ribut$ conc5tric type4 ,to facilitate connection to circuits ( ei!r #aaj or #bbj volts1 f\r pla9ly tagg$ leads are br\ght out to ! back ( ! removable t]m9al bo>d4 ,ques4 ,:at is ! /r5g? ( ! local curr5t8 ,ans4 ,!y may be f #e to #ae times ! /r5g? ( ! normal armature curr5t4 ,ques4 ,^u :at does ! local armature curr5t dep5d8 ,ans4 ,^u ! numb] ( turns ( ! %ort circuit$ coils1 _! resi/ance1 & ! frequ5cy4 ,ques4 ,h[ c ! local curr5ts be r$uc$ to avoid heavy sp>k+8 ,ans4 #a4 ,by r$uc+ ! numb] ( turns ( ! %ort circuit$ coils1 t is1 provid+ a great] numb] ( commutator b>s2 #b1 r$uc+ ! frequ5cy2 & #c1 increas+ ! resi/ance ( ! %ort circuit$ coil circuit3 a1 by means ( high resi/ance connectors2 or b1 by us+ bru%es ( high] resi/ance4 ,illu/ration3 ,figs4 #a1hhj to #a1hhd4--;,assembly & disassembl$ view ( %ort circuit+ device z us$ on ,bell s+le phase repulsion induction motor4 ,! armature1 :i* is w\nd 9 a simil> mann] to ^? us$ 9 direct curr5t motors1 has a commutator1 & bru%es1 :i* be+ %ort circuit$ on !mselves1 all[ great />t+ torque1 ) small />t+ curr5t4 ,! motor />ts by ! repulsion pr9ciple1 & on rea*+ ne>ly full spe$1 a c5trifugal gov]nor pu%es ! copp] r+ aga9/ ! commutator segm5ts1 !reby %ort circuit+ !m1 & ! motor !n op]ates on ! induction pr9ciple4 ,ques4 ,:at are high resi/ance connectors8 ,ans4 ,! connectors betwe5 ! armature w9d+ & ! commutator b>s1 z %[n 9 fig4 #a1hhe4 ,ques4 ,does ! add$ resi/ance ( prev5tive leads1 or high resi/ance bru%es1 mat]ially r$uce ! effici5cy ( ! ma*9e8 ,ans4 ,n to any great ext5t1 because x is v small 9 comp>ison ) ! resi/ance ( ! :ole armature w9d+4 ,illu/ration3 ,,fig4 #a1hhe4--,section ( r+ armature ( commutator motor %[+ local curr5t set up by trans=m] action ( ! alt]nat+ flux4 ,ques4 ,:at is ! objection to r$uc+ ! numb] ( turns ( ! %ort circuit$ coils to dim9i% ! t5d5cy to sp>k+8 ,ans4 ,! co/ ( ! additional numb] ( commutator b>s & connectors z well z ! add$ me*anism4 ,ques4 ,:at effect has ! inductance ( ! field & armature on ! p[] factor8 ,ans4 ,x produces phase diff]5ce betwe5 ! curr5t & impress$ pressure result+ 9 a l[ p[] factor4 ,ques4 ,:at is ! effect ( ?is l[ p[] factor8 ,ans4 ,! regulation & effici5cy ( ! sy/em is impair$4 ,! frequ5cy1 ! field flux & ! numb] ( turns 9 ! w9d+ h influ5ce on ! p[] factor4 ,ques4 ,h[ does ! frequ5cy affect ! p[] factor8 ,ans4 ,l[]+ ! frequ5cy t5ds to improve ! p[] factor4 ,! use ( v l[ frequ5cies has ! disadvantage ( dep>t+ f /&>d frequ5cies1 & ! probability t ! great] co/ ( trans=m]s & alt]nators w\ld (fset ! ga94 ,illu/ration3 ,,fig4 #a1hhf4--;,g5]al ,electric #e ,h4,p41 #f pole adju/able spe$ s+le phase comp5sat$ repulsion motor4 ,?is type is suitable = s]vice requirem5ts dem&+ ! use ( a motor ^: spe$ c be adju/$ ov] a consid]able range1 ?is spe$ at a fix$ controll] sett+ rema9+ practically unaffect$ by any load )9 ! motor's rat$ capacity4 ,) ! controll] on ! high spe$ po9ts1 ! motor possesses an inh]5t spe$ regulation betwe5 no load & full load ( approximately #f p] c5t4 ,at ! l[ spe$ po9ts1 "u simil> load conditions1 ! spe$ v>iation w be approximately #bj p] c5t4 ,to secure adju/able spe$ control1 ! armature circuits employ trans=m]s1 ^: prim>ies are excit$ by ! l9e circuit4 ,! second>ies ( ^! trans=m]s are divid$ into two sections2 ! fir/ or regulat+ circuit is plac$ across ! en]gy bru%es2 ! o!r section1 s9ce x is connect$ 9 s]ies ) ! comp5sat+ w9d+1 ma9ta9s ! high p[] factor & spe$ regulation obta9$ 9 ! con/ant spe$ type4 ,! spe$ range is #b3a1 approximately "o-half ( ?is range be+ bel[ & "o-half above syn*ron\s spe$4 ,s]ies ,motors4--,?is class ( commutator motor is ab\t ! simple/ ( ! sev]al types belong+ to ?is division4 ,9 g5]al design ! s]ies motor is id5tical ) ! s]ies direct curr5t motor1 b all ! iron ( ! magnetic circuit mu/ be lam9at$ & a neutraliz+ w9d+ is (t5 employ$4 ,x w be readily und]/ood t ! torque is produc$ 9 ! same way z 9 ! direct curr5t ma*9e1 :5 x is rememb]$ t ! direction ( rotation ( ! direct curr5t s]ies motor is indep5d5t ( ! direction ( ! voltage appli$4 ,at any mom5t ! torque w be proportional to ! product ( ! curr5t & ! flux :i* x is at t mom5t produc+ 9 ! magnetic sy/em1 & ! av]age torque w be ! product ( ! av]age curr5t & ! av]age flux x produces1 s t if ! iron p>ts be unsaturat$1 z !y mu/ be if ! iron losses are n to be too high1 ! torque w be proportional simply to ! squ>e ( ! curr5t1 !re be+ no "q ( p[] factor ent]+ into ! consid]ation4 ,illu/ration3 ,,fig4 #a1hhg4--;,diagram ( s+le phase s]ies commutator motor4 ,x is practically ! same z ! s]ies direct curr5t motor1 ) ! exception t all ! metal ( ! magnetic circuit mu/ be lam9at$4 ,ques4 ,:at are ! *>act]i/ics ( ! s]ies motor8 ,ans4 ,!y are simil> to ! direct curr5t s]ies motor1 ! torque be+ a maximum at />t+ & decreas+ z ! spe$ increases4 ,ques4 ,= :at s]vice is ! s]ies motor especially suit$8 ,ans4 ,on acc\nt ( its p[]ful />t+ torque x is p>ticul>ly desirable = traction s]vice4 ,neutraliz$ ,s]ies ,motor4--,a *ief defect ( ! s]ies motor is ! excessive self-induction ( ! armature1 h5ce 9 almo/ e mod]n s+le phase s]ies motor a neutraliz+ coil is employ$ to dim9i% ! armature self-induction4 ,! neutraliz+ coil is w\nd ^u ! frame #ij magnetic degrees or half a pole pit* f ! field w9d+ & arrang$ to c>ry a curr5t equal 9 magnetic pressure & opposite 9 phase to ! curr5t 9 ! armature4 ,illu/ration3 ,,fig4 #a1hhh4--;,diagram ( neutraliz$ s]ies motor2 conductive me?od4 ,9 ! simple s]ies motor1 !re w be a di/ortion ( ! flux z 9 ! direct curr5t motor4 ,z ! di/ort+ magnetic pressure is 9 phase ) t ( ! magnets1 ! di/ortion ( ! flux w be a fix$ effect4 ,if ! poles be def9ite z 9 direct curr5t ma*9es1 ?is di/ortion may n s]i\sly affect ! runn+ ( ! motor1 b ) a magnetiz+ sy/em l t univ]sally adopt$ 9 induction motors ! flux w be %ift$ z a :ole 9 ! direction ( ! di/ortion1 :i* w produce ! same effect z if 9 ! =m] case ! bru%es _h be5 %ift$ =w>d1 :]eas = good commutation !y %\ld h be5 %ift$ backw>d4 ,z 9 direct curr5t ma*9es1 ?is di/ortion is undesirable s9ce x is n conducive to sp>kless work+1 & also r$uces to a m or less ext5t ! torque ex]t$ by ! motor4 ,! simple/ rem$y is to provide neutraliz+ coils displac$ #ij magnetic degrees to ! ma9 field coils z %[n4 ,! neutraliz+ curr5t is obta9$ by ! me?od ( connect+ ! neutraliz+ coils 9 s]ies 9 ! ma9 circuit4 ,! curr5t ?r\gh ! neutraliz+ w9d+ may be obta9$1 ei!r #a4 ,conductively2 or #b4 ,inductively4 ,9 ! conductive me?od1 fig4 #a1hhh1 ! w9d+ is connect$ 9 s]ies z %[n4 ,9 ! inductive me?od1 fig4 #a1hhi1 ! w9d+ is %ort circuit$ ^u itself & ! curr5t obta9$ inductively1 ! neutraliz+ w9d+ be+ virtually ! second>y ( a trans=m]1 ( :i* ! armature is ! prim>y4 ,ques4 ,:5 is ! conductive me?od to be pref]r$8 ,ans4 ,:5 ! motor is to be us$ on mix$ circuits4 ,illu/ration3 ,,fig4 #a1hhi4--;,diagram ( neutraliz$ s]ies motor2 inductive me?od4 ,al?\gh ! conductive me?od ( neutralization is employ$ 9 ne>ly all ma*9es1 x is possible m]ely to %ort circuit ! neutraliz+ w9d+ ^u itself1 in/ead ( connect+ x 9 s]ies ) ! armature circuit4 ,9 ?is case ! flux due to ! armature circuit _c be elim9at$ altoge!r1 z suffici5t flux mu/ always rema9 to produce en\gh pressure to balance t due to ! residual imp$ance ( ! neutraliz+ coil4 ,x w\ld be a mi/ake to inf]1 h[ev]1 t on ?is acc\nt ?is me?od ( neutralization is less effective ?an ! conductive "o1 s9ce ! residual flux simply s]ves to transf] to ! armature circuit a drop 9 pressure precisely equival5t to t due to ! resi/ance & local self-induction ( ! neutraliz+ coil 9 ! conductive me?od4 ,%unt ,motors4--,! simple %unt motor has inh]5tly _m prop]ties :i* r5d] x unsuitable = practical use1 & accord+ly is ( little importance4 ,ow+ to ! _m turns ( ! field w9d+ !re is l>ge inductance 9 ! %unt field circuit4 ,illu/ration3 ,,fig4 #a1hij4--;,diagram ( simple %unt commutator motor4 ,ow+ to its _m inh]5t defects x is ( little importance4 ,illu/ration3 ,,fig4 #a1hia4--;,comp5sat$ %unt induction s+le phase motor4 ,! trans=m] %[n 9 ! arrangem5t is capable ( be+ replac$ by a coil plac$ on ! frame hav+ ! same axis z ! field w9d+1 s t ! flux produc$ by ! field w9d+ induces 9 ! coil a pressure 9 phase ) ! supply pressure4 ,su* a coil w n[ be at "r angles to ! circuit to :i* x is connect$4 ,9 a simil> mann] a coil at "r angles to ! armature circuit1 t is1 ! circuit p>allel to ! /ator axis1 if connect$ 9 s]ies ) t circuit1 w also s]ve to comp5sate ! motor4 ,! inductance ( ! armature is small z comp>$ ) t ( ! field2 accord+ly1 ! two curr5ts diff] consid]ably 9 phase4 ,! phase diff]5ce betwe5 ! field & armature curr5ts & ! correspond+ relation betwe5 ! respective fluxes results 9 a weak torque4 ,illu/ration3 ,,fig4 #a1hib4--;,fynn's %unt conductive s+le phase motor4 ,9 ord] to supply along ! /ator axis a con/ant field1 suitable = produc+ ! cross flux to :i* ! torque is due by its action on ! circuit p]p5dicul> to ! /ator axis1 ! armature circuit1 z x may be call$1 has a neutraliz+ coil 9 s]ies ) x1 s t ! armature circuit & neutraliz+ coil toge!r produce no flux4 ,9 addition to ?is1 !re is a magnetiz+ coil along ! same axis1 :i* is connect$ across ! ma9s & s produces ! same flux z ! prim>y coil 9 a %unt induction ma*9e4 ,fynn has propos$ a numb] ( me?ods ( v>y+ ! spe$ & comp5sat+ ?is ma*9e4 ,x is1 h[ev]1 complicat$ 9 itself1 & is only suit$ = v l[ voltages1 s t on ord9>y circuits x w\ld ne$ a sep>ate trans=m]4 ,x is necess>y to use lam9at$ con/ruction 9 ! field circuit to avoid eddy curr5ts1 :i* o!rwise w\ld be excessive4 ,fig4 #a1hij is a diagram ( a simple %unt commutator motor4 ,repulsion ,motors4--,9 ! c\rse ( 8 obs]vations on ! effects ( alt]nat+ curr5ts1 9 #ahhf-g1 ,elihu ,?omson obs]v$ t a copp] r+ plac$ 9 an alt]nat+ magnetic field t5ds ei!r to move out ( ! field1 t is1 x is repell$ by ! field 7h5ce ! "n repulsion motor71 or to return s z to set itself edgeways to ! magnetic l9es4 ,! explanation ( ! repulsion ph5om5on is z foll[s3 ,:5 a clos$ coil is susp5d$ 9 an alt]nat+ field s t l9es ( =ce pass ?r\gh x1 z 9 fig4 #a1hic1 an alt]nat+ pressure w be induc$ 9 ! coil :i* w be #ij lat] 9 phase ?an ! induc+ flux1 & s9ce e coil conta9s "s inductance ! result+ curr5t w lag m or less ) respect to ! pressure induc$ 9 ! coil4 ,illu/ration3 ,,fig4 #a1hic4--;,effect ( alt]nat+ field on copp] r+4 ,if a copp] r+ be susp5d$ 9 an alt]nat+ field s t ! plane ( ! r+ is oblique to ! l9es ( =ce1 x w turn until its plane is p>allel to ! l9es ( =ce1 t is1 to ! position 9 :i* x does n encircle any l9es ( =ce4 ,! turn+ mom5t act+ ^u ! r+ is proportional to ! curr5t 9 x1 to ! /r5g? ( ! field1 & to ! cos9e ( ! angle 4 ,h5ce x is proportional to ! product s9 cos 4 ,! t5d5cy to turn is z]o bo? at #j & at #ij2 9 ! =m] case because !re is no curr5t1 9 ! latt] because ! curr5t has no lev]age4 ,x is a maximum :5 #de4 ,ev5 9 ?is position !re w\ld be no torque if !re 7 no lag ( ! curr5ts 9 ! r+1 = ! phase ( ! induc$ pressure is 9 quadrature ) ! phase /ate ( ! field4 ,:5 ! field is ( maximum /r5g? !re is no pressure1 & :5 ! pressure rea*es its maximum !re is no field4 ,if !re be self-induction 9 ! r+ caus+ ! curr5t to lag1 !re w be a net turn+ mom5t t5d+ to dim9i% 4 ,! l>ge/ torque w be obta9$ :5 ! lag ( ! curr5t 9 ! r+ is #de4 ,! cos9e ( ?is phase relation becomes a negative quantity :i* means t ! coil is repell$ by ! field4 ,x is only :5 ! r+ is 9 an oblique position t x t5ds to turn4 ,if x be plac$ ) its plane directly at "r angles to ! direction ( ! magnetic l9es1 x w n turn2 if ev] s little displac$ to ! "r or left1 x w turn until its plane is p>allel to ! l9es4 ,illu/ration3 ,,figs4 #a1hid to #a1ijh4--,p>ts ( ,g5]al ,electric s+le phase comp5sat$ repulsion motor4 ,! field frame employs ! rivet$ =m ( con/ruction1 s t ! ends ( ! lam9ations are expos$ directly to ! air1 insur+ l[ op]at+ temp]atures & high ov]load capacity4 ,! field w9d+ consi/s ( a ma9 w9d+ ( ! di/ribut$ conc5tric type & a comp5sat+ w9d+4 ,! s]ies type ( w9d+ is employ$1 & ! complet$ rotor is treat$ ) a special insulat+ comp\nd1 :i* r5d]s ! coils moi/ure pro( "u ord9>y conditions4 ,on motors ( m ?an #b horse p[] capacity a v5tilat+ fan is atta*$ to ! rotor :i* provides a cont9u\s supply ( cool air :ile ! motor is 9 op]ation4 ,two types ( bru% hold] yoke are us$4 ,! small] motors use a m\ld$ yoke ( insult+ comp\nd1 re9=c$ by a ca/ iron ,l section r+ emb$d$ 9 ! m\ld$ /ructure4 ,ca/ iron yokes are us$ on l>g] motors4 ,! bru%es are ( c>bon ) copp] pigtails1 :i* c>ry all ! curr5t4 ,! bru%es 9 ?is ma*9e rema9 p]man5tly 9 contact ) ! commutator4 ,! p>ts are3 ,a1 field2 ,b1 field w9d+2 ,c1 l9e t]m9al2 ,d1 tube t]m9al2 ,e1 comp5sat+ t]m9al2 ,f1 t]m9al bo>d2 ,g1 bru% yoke2 ,h1 bru% hold]2 ,i1 c>bon bru%2 ,j1 bru% /ud2 ,k1 %ort circuit connection2 ,l1 armature2 ,m1 commutator1 ,n1 %aft2 ,o1 fan2 ,p1 commutator end %ield2 ,q1 pulley end %ield2 ,r1 oil well cov]2 ,s1 oil plugs2 ,t1 oil gauge2 ,u1 be>+ l9+2 ,v1 oil r+2 ,w1 pulley2 ,x1 pulley set screw2 ,y1 commutator end %ield hold+ bolts2 ,z1 pulley end %ield hold+ bolts2 ,,aa1 base2 ,,bb1 float bolts2 ,,cc1 belt tight5] screw4 ,! production ( torque may be expla9$ by say+ t ! curr5t induc$ 9 ! r+ produces a cross field :i* be+ out ( phase )1 & incl9$ to ! field impress$ by ! prim>y alt]nat+ curr5t1 causes a rot>y field1 & ?is 9 turn1 react+ on ! conductor1 a turn+ mom5t results4 ,illu/ration3 ,,fig4 #a1iji4--;,fynn's comp5sat$ %unt induction motor4 ,?is is a comb9ation ( ! comp5sat$ %unt induction motor ) ! ord9>y squirrel cage =m4 ,9 "o =m1 9 addition to ! ord9>y drum w9d+ on ! armature1 !re is ano!r ?ree phase w9d+ into ! />1 ( :i* ! drum w9d+ is connect$4 ,?is second w9d+ is connect$ to ?ree slip r+s :i* are %ort circuit$ :5 ! ma*9e is up to spe$4 ,^u ! commutator are plac$ a pair ( bru%es connect$ to an auxili>y w9d+ plac$ on ! frame 9 su* a position t ! flux f ! prim>y coil induces 9 x a pressure ( suitable phase to produce comp5sation4 ,! same pair ( bru%es is also us$ = />t+4 ,elihu ,?ompson took an ord9>y direct curr5t armature1 plac$ x 9 an alt]nat+ field1 & hav+ %ort circuit$ ! bru%es1 plac$ !m 9 an oblique position ) respect to ! direction ( ! field4 ,! effect 0 to cause ! armature to rotate ) a consid]able torque4 ,! inductors ( ! armature act$ j z an obliquely plac$ r+1 b ) ?is diff]5ce1 t ! obliquity 0 cont9u\sly pres]v$ by ! bru%es & commutator1 not)/&+ t ! armature turn$1 & ?us ! rotation 0 cont9u\s4 ,?is t5d5cy ( a conductor to turn f an oblique position 0 ?us utiliz$ by him to get ov] ! difficulty ( />t+ a s+le phase motor4 ,) ?is object 9 view he !n con/ruct$ motors 9 :i* ! use ( commutator & bru%es 0 re/rict$ to ! "w ( m]ely />t+ ! armature1 :i* :5 s />t$ 0 !n entirely %ort circuit$ on itself1 ?\gh disconnect$ f ! re/ ( ! circuit1 ! op]ation !n be+ solely on ! induction pr9ciple4 ,illu/ration3 ,fig4 #a1iaj4--;,diagram ( connection ( ,sprague s+le phase comp5sat$ repulsion motor4 ,to rev]se direction ( rotation int]*ange leads ,c & ,c & slightly %ift ! bru% hold] yoke4 ,bru%es ,e & ,e are p]man5tly %ort circuit$4 ,?is diagram ( connections applies also to fig4 #a1iaa4 ,ques4 ,:at difficulty 0 exp]i5c$ ) ,?omson's motor8 ,ans4 ,s9ce an op5 coil armature 0 us$1 ! torque develop$ 0 due to only "o coil at a "t1 :i* involv$ a necess>ily high curr5t 9 ! %ort circuit$ coil result+ 9 heavy sp>k+4 ,ques4 ,h[ 0 ?is rem$i$8 ,ans4 ,by ! use ( clos$ coil armatures 9 lat] con/ruction4 ,ques4 ,did ?is effectually /op sp>k+8 ,ans4 ,no4 ,ques4 ,:at o!r means is employ$ 9 mod]n designs to r$uce sp>k+8 ,ans4 ,comp5sation & ! use ( a di/ribut$ field w9d+1 high resi/ance connectors1 high resi/ance bru%es1 etc4 ,ques4 ,:at are ! names ( ! two classes ( repulsion motor8 ,ans4 ,! simple & ! comp5sat$ types4 ,ques4 ,describe a simple repulsion motor4 ,ans4 ,x consi/s ess5tially ( an armature1 commutator & field magnets4 ,! armature is w\nd exactly l a direct curr5t armature1 & ! w9d+s are connect$ to a commutator4 ,! c>bon bru%es :i* re/ on ?is commutator are n connect$ to ! outside l9e1 h[ev]1 b are all connect$ toge!r ?r\gh heavy %ort circuit+ connectors4 ,! bru%es are plac$ ab\t #fj or #gj f ! neutral axis4 ,! field is w\nd exactly l t ( ! usual induction motor4 ,ques4 ,:at is ! action ( ?is type ( motor8 ,ans4 ,if no?+ be done to prev5t1 ! motor w increase 9 spe$ at no load until ! armature bur/s1 j z x w 9 a s]ies direct curr5t motor4 ,ques4 ,:at provision is made to avoid ?is dang]8 ,ans4 ,a gov]nor is usually m\nt$ on ! armature :i* %ort circuits ! w9d+s1 aft] ! motor has be5 />t$4 ,! motor !n runs z a squirrel cage induction motor4 ,z a rule ! bru%es are lift$ (f ! commutator :5 ! armature is %ort circuit$1 s z to prolong _! life4 ,?is is a v successful motor1 b x is ( c\rse m co/ly ?an ! simple squirrel cage motor us$ on two & ?ree-phase circuits4 ,illu/ration3 ,,fig4 #a1iaa4--;,diagram ( connections ( ,sprague v>iable spe$ s+le phase comp5sat$ repulsion motor & controll]4 ,! controll] is design$ to give spe$ r$uction & spe$ increase z resi/ance or reactance is ins]t$ 9 ! en]gy & comp5sat+ circuits4 ,) ! exception ( ! leads br\ght out f ^! circuits1 ! con/ant spe$ & v>iable spe$ motors are id5tical4 ,! /&>d controll] gives approximately #b3a spe$ v>iation4 ,ques4 ,:at "n may appropriately be appli$ to ! motor8 ,ans4 ,x may be call$ ! repulsion induction motor1 because x is con/ruct$ = repulsion />t & induction runn+4 ,ques4 ,describe a comp5sat$ repulsion motor4 ,ans4 ,9 its simple/ =m x consi/s ( a simple repulsion motor 9 :i* !re are two indep5d5t sets ( bru%es1 "o set be+ %ort circuit$1 :ile ! o!r set is 9 s]ies ) ! field magnet w9d+1 z 9 ! s]ies alt]nat+ curr5t motor4 ,ques4 ,:at names are giv5 to ! two sets ( bru%es on a comp5sat$ repulsion motor8 ,ans4 ,! en]gy or ma9 %ort circuit+ bru%es1 & ! comp5sat+ bru%es4 ,illu/ration3 ,fig4 #a1iab4--;,diagram ( connections ( ,sprague rev]s+ type ( s+le phase comp5sat$ repulsion motor4 ,z %[n1 !re is a special rev]se field w9d+ hav+ t]m9als = connection to a f\r pole d\ble ?r[ swit*4 ,ques4 ,:at is ! behavior ( ! armature ( a comp5sat$ repulsion motor at />t+8 ,ans4 ,x possesses at />t+ mo/ ( ! app>5t reactance ( ! motor1 & ! effect ( spe$ is to decrease su* app>5t reactance1 ! latt] becom+ z]o at ei!r positive or negative syn*ronism1 & negative at high] spe$s 9 ei!r direction4 ,ques4 ,:at is ! nature ( ! field circuit ( ! comp5sat$ repulsion motor at />t+8 ,ans4 ,at />t+ x is practically non-inductive1 ! effect ( spe$ be+ to introduce a spuri\s resi/ance :i* increases directly ) ! spe$1 & becomes negative :5 ! spe$ is rev]s$4 ,ques4 ,= :at use is ! comp5sat$ repulsion motor especially adapt$8 ,ans4 ,= light railroad s]vice4 ,ques4 ,:5 employ$ ?us :at is ! me?od ( control8 ,ans4 ,a s]ies trans=m] is us$ 9 ! field circuit4 ,ques4 ,:at frequ5cies are employ$ ) ?is motor8 ,ans4 #be to #fj1 ! pref]r$ frequ5cy be+ #dj4 ,ques4 ,to :at important use is ! repulsion pr9ciple put8 ,ans4 ,x is sometimes employ$ = />t+ on s+le phase induction motors4 ,9 ?is me?od1 aft] br++ ! motor up to spe$1 ! w9d+ is !n %ort circuit$ ^u itself1 & ! motor !n op]ates on ! induction pr9ciple4 ,ques4 ,:at "n is giv5 to ?is type ( motor8 ,ans4 ,x is call$ ! repulsion induction motor4 ,p[] ,factor ( ,induction ,motors4--,9 ! case ( a direct curr5t motor1 ! en]gy suppli$ is f\nd by multiply+ ! curr5t /r5g? by ! voltage1 b 9 all induction motors ! effect ( self-induction causes ! curr5t to lag beh9d ! pressure1 !reby increas+ ! am\nt ( curr5t tak5 by ! motor4 ,accord+ly1 z ! increas$ curr5t is n utiliz$ by ! motor 9 develop+ p[]1 ! value obta9$ by multiply+ ! curr5t by ! voltage repres5ts an app>5t en]gy :i* is great] ?an ! real en]gy suppli$ to ! motor4 ,illu/ration3 ,fig4 #a1iac4--;,fairbanks-,morse squirrel cage armature1 %[+ ball be>+s4 ,x is evid5t1 t if x 7 possible to elim9ate ! lag entirely1 ! real & app>5t watts w\ld be equal1 & ! p[] factor w\ld be unity4 ,! importance ( p[] factor & its effect ^u bo? alt]nator capacity & voltage regulation is des]v+ ( ! mo/ c>eful consid]ation ) all electrical app>atus1 9 :i* an inh]5t phase diff]5ce exi/s betwe5 ! pressure & ! curr5t1 z = in/ance 9 /atic trans=m]s & induction motors4 ,:ile ! belief is curr5t t any decrease 9 p[] factor f unity value does n dem& any increase ( me*anical output1 ?is is n true1 s9ce all int]nal alt]nator & l9e losses manife/ !mselves z heat1 ! wa/$ en]gy to produce ?is heat be+ suppli$ by ! prime mov]4 ,ap>t f ! poor voltage regulation ( alt]nat+ curr5t g5]ators requir+ abnormal field excitation to comp5sate = l[ p[] factor1 "s ( ! /ation's rat$ output is r5d]$ unavailable & consequ5tly produces no rev5ue4 ,! poor /eam economy ( und]load$ eng9es is also a s]i\s s\rce ( fuel wa/age4 ,illu/ration3 ,fig4 #a1iad4--;,fairbanks-,morse #bj horse p[] squirrel cage induction motor connect$ to a #bj in* self-fe$ rip & *amf]+ saw4 ,! abs5ce ( commutator & bru%es on ! squirrel cage armature elim9ates sp>k+ & !re=e r5d]s ?is type ( motor p>ticul>ly adapt$ = use 9 places :]e sp>k+ w\ld be dang]\s1 su* z 9 wood work+ plants1 textile mills1 etc4 ,c>eful inve/igations h %[n t ! p[] factor ( indu/rial plants us+ induction motor drive ) units ( v>i\s sizes w av]age betwe5 #fj & #hj p] c5t4 ,) plants supply+ curr5t to und]load$ motors hav+ inh]5tly high lagg+ curr5t values1 a comb9$ factor z l[ z #ej p] c5t4 may be expect$4 ,s9ce /&>d alt]nators are seldom design$ to c>ry _! rat$ kil[att load at less ?an #hj p] c5t4 p[] factor1 ! net available output is1 !re=e1 consid]ably increas$4 ,illu/ration3 ,fig4 #a1iae4--,me?od ( ca/+ end r+s on squirrel cage armatures ( ,fairbanks-,morse induction motors4 ,! metal be+ fus$ to ! b>s at a temp]ature 9 excess ( #a1hcb degrees ,fahr41 x is readily se5 t ! de/ructive effect ( any subsequ5t heat+ is elim9at$4 ,:ile giv+ ! mo/ intimate contact at ! jo9ts1 a multiplicity ( jo9ts is avoid$ z well z sold]4 ,spe$ & ,torque ( ,motors4--,! spe$ ( an induction motor dep5ds *iefly on ! frequ5cy ( ! circuit & runs )9 #e p] c5t4 ( its rat$ spe$2 x w produce full torque if ! l9e voltage d n v>y m ?an #e to #aj p] c5t4 ,at l[ voltage ! spe$ w n be greatly r$uc$ z 9 a direct curr5t motor1 b z ! torque is l[ ! motor is easily /opp$ :5 a light load is ?r[n on4 ,! curr5t tak5 by an induction motor f a con/ant pressure l9e v>ies ) ! spe$ z 9 a direct curr5t motor4 ,:5 a load is ?r[n on1 ! spe$ is r$uc$ correspond+ly & z ! self-induction or reactance is dim9i%$1 m curr5t circulates 9 ! squirrel cage w9d+1 :i* 9 turn reacts on ! field coils 9 a simil> mann] & m curr5t fl[s 9 !m f ! l9e4 ,9 ?is mann] ! motor automatically takes curr5t f ! l9e proportional to ! load & ma9ta9s a ne>ly con/ant spe$4 ,! s-call$ con/ant spe$ motors require slight v>iations 9 spe$ to automatically take curr5t f ! l9e :5 ! load v>ies4 ,induction motors v>y 9 spe$ f #e to #aj p] c5t41 :ile syn*ron\s motors v>y b a fraction ( "o p] c5t4 ,s+le phase motors to r5d] effici5t s]vice mu/ be able1 :]e requisite1 to develop suffici5t turn+ mom5t or torque to accel]ate1 f /&/ill1 loads possess+ l>ge in]tia or excessive /atic friction2 = example1 meat *opp]s & gr9d]s1 sug> or laundry c5trifugals2 heavy pun* presses2 gr\p driv5 ma*9es runn+ f c\nt]%afts ) possibly ov] taut belt+1 poor alignm5t1 lubrication1 etc4 ,,*apt] ,,lii ,,trans=m]s ,! developm5ts 9 ! field ( electrical eng9e]+ :i* h r5d]$ feasible ! transmission ( high pressure curr5ts ov] long di/ances1 toge!r ) ! reliability & effici5cy ( mod]n g5]at+ units1 h result$ 9 notable economies 9 ! g5]ation & di/ribution ( electric curr5t4 ,?is has be5 accompli%$ l>gely by ! use ( di/ant wat] p[] or ! c5tralization ( ! g5]at+ plants ( a l>ge t]ritory 9 a s+le p[] /ation4 ,! trans=m] is "o ( ! ess5tial factors 9 effect+ ! economical di/ribution ( electric en]gy1 & may be def9$ z an app>atus us$ = *ang+ ! voltage & curr5t ( an alt]nat+ circuit4 ,a trans=m] consi/s ess5tially (3 #a4 ,a prim>y w9d+2 #b4 ,a second>y w9d+2 #c4 ,an iron core4 ,basic ,pr9ciples4--,if a curr5t be pass$ ?r\gh a coil ( wire encircl+ a b> ( s(t iron ! iron w become a magnet2 :5 ! curr5t is discont9u$ ! b> loses its magnetization4 ,conv]sely3 ,if a b> ( iron c>ry+ a coil ( wire be magnetiz$ 9 a direction at "r angles to ! plane ( ! coil a mom5t>y electric pressure w be induc$ 9 ! wire2 if ! curr5t be rev]s$1 ano!r mom5t>y pressure w be induc$ 9 ! opposite direction 9 ! coil4 ,^! actions are fully expla9$ 9 *aps4 ,x & ,,xi1 & z !y are p]fectly famili> ph5om5a1 a detail$ explanation ( ! pr9ciples ^u :i* !y dep5d is n necess>y "h4 ,f ! fir/ two /atem5ts giv5 above x is evid5t t if a b> ( iron be provid$ ) two coils ( wire1 "o ( :i* is suppli$ f a s\rce ( alt]nat+ curr5t1 z %[n diagrammatically by fig4 #a1iaf1 at ea* impulse ( ! excit+ curr5t a pressure w be induc$ 9 ! second>y coil1 ! direction ( ^! impulses alt]nat+ l t ( ! excit+ curr5t4 ,ques4 ,:at "n is giv5 to ! coil ?r\gh :i* curr5t f ! s\rce fl[s8 ,ans4 ,! prim>y w9d+4 ,illu/ration3 ,fig4 #a1iaf4--;,diagram ( elem5t>y trans=m] ) non-cont9u\s core & connection ) s+le phase alt]nator4 ,! ?ree ess5tial p>ts are3 prim>y w9d+1 second>y w9d+1 & an iron core4 ,ques4 ,:at "n is giv5 to ! coil 9 :i* a curr5t is induc$8 ,ans4 ,! second>y w9d+4 ,simil>ly1 ! curr5t f ! s\rce 7alt]nator7 is call$ ! prim>y curr5t & ! induc$ curr5t1 ! second>y curr5t4 ,ques4 ,:at is ! objection to ! elem5t>y trans=m] %[n 9 fig4 #a1iaf8 ,ans4 ,! non-cont9u\s core4 ,) ?is type core1 ! flux emanat+ f ! nor? pole ( ! b> has to return to ! s\? pole ?r\gh ! surr\nd+ air2 & z ! reluctance ( air is mu* great] ?an t ( iron1 ! magnetism w be weak4 ,ques4 ,h[ is ?is ov]come8 ,ans4 ,by ! use ( a cont9u\s core z %[n 9 fig4 #a1iag4 ,ques4 ,is ?is ! be/ arrangem5t1 & :y8 ,ans4 ,no4 ,if ! w9d+s 7 put on z 9 fig4 #a1iag1 ! leakage ( magnetic l9es ( =ce w\ld be excessive1 z indicat$ by ! dott$ l9es4 ,9 su* a case ! l9es :i* leak ?r\gh air h no effect ^u ! second>y w9d+1 & are !re=e wa/$4 ,illu/ration3 ,fig4 #a1iag4--;,diagram ( elem5t>y trans=m] ) cont9u\s core & connections ) alt]nator4 ,! dott$ l9es %[ ! leakage ( magnetic l9es4 ,to rem$y ?is ! arrangem5t %[n 9 fig4 #a1iah is us$4 ,ques4 ,h[ is ! magnetic leakage r$uc$ to a m9imum 9 comm]cial trans=m]s8 ,ans4 ,9 ^!1 & ev5 9 ord9>y induction coils 7! op]at+ pr9ciple ( :i* is ! same z t ( trans=m]s7 ! magnetic leakage is r$uc$ to ! l[e/ possible am\nt by arrang+ ! coils "o )9 ! o!r1 z %[n 9 cross section 9 fig4 #a1iah4 ,! ,induc$ ,voltage4--,! pressure induc$ 9 ! second>y w9d+ w dep5d on ! ratio betwe5 ! numb] ( turns 9 ! two w9d+s4 ,= example1 a trans=m] ) #ejj turns ( wire 9 its prim>y w9d+ & #ej turns 9 its second>y w9d+ w\ld h a trans=mation ratio ( #aj to #a1 & if x 7 suppli$ ) prim>y curr5t at #a1jjj volts1 ! second>y pressure at no load w\ld be #ajj volts4 ,illu/ration3 ,fig4 #a1iah4--;,cross section %[+ comm]cial arrangem5t ( prim>y & second>y w9d+s on core4 ,"o is sup]pos$ on ! o!r4 ,?is arrangem5t compels practically all ( ! magnetic l9es creat$ by ! prim>y w9d+ to pass ?r\gh ! second>y w9d+4 ,,example4--,if t5 amp]es fl[ 9 ! prim>y w9d+ & ! trans=mation ratio be #aj1 !n #aj #aj #ajj amp]es w fl[ ?r\gh ! second>y w9d+4 ,?us1 a direct proportion exi/s betwe5 ! pressures & turns 9 ! two w9d+s & an inv]se proportion betwe5 ! amp]es & turns1 t is3 prim>y voltage3 second>y voltage prim>y turns3 second>y turns prim>y curr5t3 second>y curr5t second>y turns3 prim>y turns ,f ! above equations x is se5 t ! watts ( ! prim>y circuit equal ! watts ( ! second>y circuit4 ,ques4 ,are ! above relations /rictly true1 & :y8 ,ans4 ,no1 !y are only approximate1 because ( trans=m] losses4 ,9 ! above example1 ! total wattage 9 ! prim>y circuit is #a1jjj #aj #aj kw41 & t 9 ! second>y circuit is #ajj #ajj #aj kw4 ,h5ce1 :ile bo? volts & amp]es are widely diff]5t 9 ! two circuits1 ! watts = ea* are ! same 9 ! ideal case1 t is1 assum+ p]fect trans=m] action or #ajj effici5cy4 ,n[1 ! usual loss 9 comm]cial trans=m]s is ab\t #aj1 s t ! actual watts deliv]$ 9 ! second>y circuit is 7#ajj #ajj7 #ij #i kw4 ,illu/ration3 ,,fig4 #a1iai4--,wagn] trans=m] coil =m$1 ready = tap+4 ,^! are kn[n z pan cake coils4 ,!y are w\nd ) flat cotton cov]$ copp] /rip4 ,9 heavy coils1 sev]al /rips 9 p>allel are us$ p] turn 9 ord] to facilitate ! w9d+ & produce a m compact coil4 ,! ,no ,load ,curr5t4--,:5 ! second>y w9d+ ( a trans=m] is op5 or disconnect$ f ! second>y circuit no curr5t w fl[ 9 ! w9d+1 b a v small curr5t call$ ! no load curr5t w fl[ 9 ! prim>y circuit4 ,! reason = ?is is z foll[s3 ,! curr5t fl[+ 9 ! prim>y w9d+ causes repeat$ rev]sals ( magnetic flux ?r\gh ! iron core4 ,^! v>iations ( flux induce pressures 9 bo? coils2 t induc$ 9 ! prim>y call$ ! rev]se pressure is opposite 9 direction & v ne>ly equal to ! impress$ pressure1 t is1 to ! pressure appli$ to ! prim>y w9d+4 ,accord+ly ! only =ce available to cause curr5t to fl[ ?r\gh ! prim>y w9d+ is ! diff]5ce betwe5 ! impress$ pressure & rev]se pressure1 ! effective pressure4 ,illu/ration3 ,,fig4 #a1ibj4--,wagn] coils ) insulation ready = core assembly4 ,! flat coils1 sometimes call$ pancake coils are w\nd ( flat1 cotton cov]$1 copp] /rip ) ample insulation betwe5 lay]s4 ,9 heavy coils sev]al flat /rips 9 multiple are us$ p] turn 9 ord] to facilitate ! w9d+ & produce a m compact coil4 ,9 _m cases normal curr5t fl[ p] high t5sion coil is v l[ & c\ld be c>ri$ ) a v small cross sectional area ( copp]2 h[ev]1 flat /rip is almo/ always us$ on acc\nt ( ! increas$ me*anical /ability ?us obta9$4 ,! ,magnetiz+ ,curr5t4--,! magnetiz+ curr5t ( a trans=m] is sometimes spok5 ( z t curr5t :i* ! prim>y w9d+ takes f ! ma9s :5 work+ at normal pressure4 ,! true magnetiz+ curr5t is only t compon5t ( ?is total no load curr5t :i* is 9 quadrature ) ! supply pressure4 ,! rema9+ compon5t has to ov]come ! v>i\s iron losses1 & is !re=e an 9 phase compon5t4 ,! relation betwe5 ^! two compon5ts det]m9es ! p[] factor ( ! s call$ magnetiz+ curr5t4 ,illu/ration3 ,,figs4 #a1iba & #a1ibb4--;,assembl$ coils ( ,we/+h\se #aj & #ae kva4 trans=m]s2 views %[+ v5tilat+ ducts4 ,! true magnetiz+ compon5t is small if ! trans=m] be well design$1 & be work$ at l[ flux d5sity4 ,action ( ,trans=m] ) ,load4--,if ! second>y w9d+ ( a trans=m] be connect$ to ! second>y circuit by clos+ a swit* s t curr5t fl[s ?r\gh ! second>y w9d+1 ! trans=m] is said to be load$4 ,! action ( ?is second>y curr5t is to oppose ! magnetiz+ action ( ! slight curr5t already fl[+ 9 ! prim>y w9d+1 ?us decreas+ ! maximum value rea*$ by ! alt]nat+ magnetic flux 9 ! core1 !reby decreas+ ! induc$ pressure 9 ea* w9d+4 ,! am\nt ( ?is decrease1 h[ev]1 is v small1 inasmu* z a v small decrease ( ! induc$ pressure 9 ! prim>y coil greatly increases ! diff]5ce betwe5 ! pressure appli$ to ! prim>y coil & ! oppos+ pressure induc$ 9 ! prim>y coil1 s t ! prim>y curr5t is greatly increas$4 ,9 fact1 ! increase ( prim>y curr5t due to ! load+ ( ! trans=m] is j great en\gh 7or v ne>ly7 to exactly balance ! magnetiz+ action ( ! curr5t 9 ! second>y coil2 t is1 ! flux 9 ! core mu/ be ma9ta9$ approximately con/ant by ! prim>y curr5t :atev] value ! second>y curr5t may h4 ,:5 ! load on a trans=m] is increas$1 ! prim>y ( ! trans=m] automatically takes additional curr5t & p[] f ! supply ma9s 9 direct proportion to ! load on ! second>y4 ,:5 ! load on ! second>y is r$uc$1 = example by turn+ (f lamps1 ! p[] tak5 f ! supply ma9s by ! prim>y coil is automatically r$uc$ 9 proportion to ! decrease 9 ! load4 ,?is automatic action ( ! trans=m] is due to ! balanc$ magnetiz+ action ( ! prim>y & second>y curr5ts4 ,illu/ration3 ,,fig4 #a1ibc4--,re> view ( ,=t ,wayne di/ribut+ trans=m]1 %[+ hang] irons = atta*+ to pole cross arm4 ,classification ( ,trans=m]s4--,z 9 ! case ( motors1 ! great v>iety ( trans=m] makes x necess>y t a classification1 to be compreh5sive1 mu/ be made f sev]al po9ts ( view1 z3 #a4 ,) respect to ! trans=mation1 z a4 ,/ep up trans=m]s2 b4 ,/ep d[n trans=m]s4 #b4 ,) respect to ! arrangem5t ( ! coils & magnetic circuit1 z a4 ,core trans=m]s2 b4 ,%ell trans=m]s2 c4 ,comb9$ core & %ell trans=m]s4 #c4 ,) respect to ! k9d ( circuit !y are to be us$ on1 z a4 ,s+le phase trans=m]s2 b4 ,polyphase trans=m]s4 #d4 ,) respect to ! me?od employ$ 9 cool+1 z a4 ,dry trans=m]s2 b4 ,air cool$ trans=m]s natural draught2 =c$ draught1 or air bla/2 c4 ,oil cool$ trans=m]s2 d4 ,wat] cool$ trans=m]s4 #e4 ,) respect to ! nature ( _! output1 z a4 ,con/ant pressure trans=m]s2 b4 ,con/ant curr5t trans=m]s2 c4 ,curr5t trans=m]s2 d4 ,auto-trans=m]s4 #f4 ,) respect to ! k9d ( s]vice1 z a4 ,di/ribut+2 b4 ,p[]4 #g4 ,) respect to ! circuit connection t ! trans=m] is con/ruct$ =1 z a4 ,s]ies trans=m]s2 b4 ,%unt trans=m]s4 ,/ep ,up ,trans=m]s4--,?is =m ( trans=m] is us$ to trans=m a l[ voltage curr5t into a high voltage curr5t4 ,su* trans=m]s are employ$ at ! g5]at+ end ( a transmission l9e to raise ! voltage ( ! alt]nators to su* value z w enable ! electric p[] to be economically transmitt$ to a di/ant po9t4 ,illu/ration3 ,,fig4 #a1ibd4--;,diagram ( elem5t>y /ep up trans=m]4 ,z %[n ! prim>y w9d+ has two turns & second>y #aj turns1 giv+ a ratio ( voltage trans=mation ( #aj #b #e4 ,s9ce only z mu* curr5t fl[s 9 ! second>y w9d+ z 9 ! prim>y1 ! latt] requires heavi] wire ?an ! =m]4 ,copp] ,economy ) ,/ep ,up ,trans=m]s4--,to compreh5d fully ! be>+ ( ! matt]1 x mu/ be rememb]$ t ! en]gy suppli$ p] second is ! product ( two factors1 ! curr5t & ! pressure at :i* t curr5t is suppli$2 ! magnitudes ( ! two factors may v>y1 b ! value ( ! p[] suppli$ dep5ds only on ! product ( ! two2 = example1 ! en]gy furni%$ p] second by a curr5t ( #aj amp]es suppli$ at a pressure ( #b1jjj volts is exactly ! same 9 am\nt z t furni%$ p] second by a curr5t ( #djj amp]es suppli$ at a pressure ( #ej volts2 9 ea* case1 ! product is #bj1jjj watts4 ,n[ ! loss ( en]gy t occurs 9 transmission ?r\gh a well insulat$ wire dep5ds also on two factors1 ! curr5t & ! resi/ance ( ! wire1 & 9 a giv5 wire is proportional to ! squ>e ( ! curr5t4 ,9 ! above example ! curr5t ( #djj amp]es1 if transmitt$ ?r\gh ! same wire z ! #aj amp]es curr5t1 w\ld1 because x is =ty times z great1 wa/e sixte5 hundr$ times z mu* en]gy 9 heat+ ! wire4 ,x foll[s t1 = ! same loss ( en]gy1 ! #aj amp]e curr5t at #b1jjj volts may be c>ri$ by a wire hav+ only _/? ( ! sectional area ( ! wire us$ = ! #djj amp]e curr5t at #ej volts4 ,! co/ ( copp] conductors = ! di/ribut+ l9es is !re=e v greatly economiz$ by employ+ high pressures = di/ribution ( small curr5ts4 ,illu/ration3 ,,fig4 #a1ibe4--;,diagram ( elem5t>y /ep d[n trans=m]4 ,z %[n ! prim>y w9d+ has #aj turns & ! second>y #b1 giv+ a ratio ( voltage trans=mation ( #b #aj 4#b4 ,! curr5t 9 ! second>y be+ #e times great] ?an 9 ! prim>y w require a proportionately heavi] wire4 ,/ep ,d[n ,trans=m]s4--,:5 curr5t is suppli$ to consum]s = light+ purposes1 & = ! op]ation ( motors1 etc41 consid]ations ( safety z well z ^? ( suitability1 require ! deliv]y ( ! curr5t at comp>atively l[ pressures rang+ f #ajj to #bej volts = lamps1 & f #ajj to #fjj volts = motors4 ,?is involves t ! high pressure curr5t 9 ! transmission l9es mu/ be trans=m$ to l[ pressure curr5t at ! receiv+ or di/ribut+ po9ts by /ep d[n trans=m]s1 an elem5t>y trans=m] be+ %[n 9 fig4 #a1ibe4 ,illu/ration3 ,,figs4 #a1ibf & #a1ibg4--;,core type trans=m]4 ,x consi/s ( a c5tral core ( lam9at$ iron1 ar\nd :i* ! coils are w\nd4 ,a usual =m ( core type trans=m] consi/s ( a rectangul> core1 ar\nd ! two long limbs ( :i* ! prim>y & second>y coils are w\nd1 ! l[ t5sion coil be+ plac$ next ! core4 ,trans=m]s ( ?is type h a l>ge numb] ( turns 9 ! prim>y w9d+ & a small numb] 9 ! second>y1 9 ratio dep5d+ on ! am\nt ( pressure r$uction requir$4 ,core ,trans=m]s4--,?is type ( trans=m] may be def9$ z "o hav+ an iron core1 ^u :i* ! wire is w\nd 9 su* a mann] t ! iron is envelop$ )9 ! coils1 ! out] surface ( ! coils be+ expos$ to ! air z %[n 9 figs4 #a1ibf & #a1ibg4 ,%ell ,trans=m]s4--,9 ! %ell type ( trans=m]1 z %[n 9 fig4 #a1ibh1 ! core is 9 ! =m ( a %ell1 be+ built ar\nd & ?r\gh ! coils4 ,a %ell trans=m] has1 z a rule1 few] turns & a high] voltage p] turn ?an ! core type4 ,ques4 ,:at is ! comp>ison betwe5 core & %ell trans=m]s8 ,ans4 ,! relative advantages ( ! two types has be5 ! subject ( consid]able discussion among manufactur]s2 ! companies :o =m]ly built only %ell type trans=m]s1 n[ build core types1 :ile ) o!r build]s ! opposite practice obta9s4 ,illu/ration3 ,,fig4 #a1ibh4--,%ell type trans=m]4 ,9 con/ruction ! lam9at$ core is built ar\nd & ?r\gh ! coils z %[n4 ,= l>ge rat+s ?is type has "s advantages ) respect to insulation1 :ile = small rat+s ! core type is to be pref]r$ 9 ?is respect4 ,! %ell arrangem5t ( ! core gives bett] cool+2 ) ?is arrangem5t m9imum magnetic leakage is easily obta9$4 ,ques4 ,^u :at does ! *oice betwe5 ! two types *iefly dep5d8 ,ans4 ,^u manufactur+ conv5i5ce r ?an op]at+ *>act]i/ics4 ,! major insulation 9 a core type trans=m] consi/s ( sev]al l>ge pieces ( great me*anical /r5g?1 :ile 9 ! %ell type1 !re are requir$ an extremely l>ge numb] ( relatively small pieces ( insulat+ mat]ial1 :i* necessitates c>eful workman%ip to prev5t defects 9 ! f9i%$ trans=m]1 :5 ?9 or fragile mat]ial is us$4 ,bo? core & %ell trans=m]s are built = all rat+s2 = small rat+s ! core type possesses c]ta9 advantages ) ref]5ce to insulation1 :ile = l>ge rat+s1 ! %ell type possesses bett] cool+ prop]ties1 & has less magnetic leakage ?an ! core type4 ,illu/ration3 ,,fig4 #a1ibi4--,view illu/rat+ ! con/ruction ( cores & coils ( ,maloney trans=m]s4 ,illu/ration3 ,,fig4 #a1icj4--,maloney mica %ield betwe5 prim>y & second>y coils1 %[+ lapp+ feature :i* prev5ts ! wr9kl+ & crack+ ( ! mica4 ,comb9$ ,core & ,%ell ,trans=m]s4--,an improv$ type ( trans=m] has be5 introduc$ :i* c be consid]$ ei!r z two sup]pos$ %ell trans=m]s ) coils 9 common1 or z a s+le core type trans=m] ) divid$ magnetic circuit & hav+ coils on only "o leg4 ,x is be/ consid]$ h[ev]1 z a comb9$ core & %ell trans=m]1 & = small sizes x possesses mo/ ( ! advantages ( bo? types4 ,x c be con/ruct$ at less co/ ?an c ei!r a core or a %ell trans=m] hav+ ! same op]at+ *>act]i/ics & temp]ature limits4 ,illu/ration3 ,,figs4 #a1ica & #a1icb4--,! ,b]ry comb9$ core & %ell trans=m]4 ,x consi/s ( a numb] ( inn] & out] v]tical & radial lam9at$ iron blocks built up ( ! usual ?9 %eet iron1 ) ! coils betwe54 ,! magnetic circuit is complet$ at ! top & bottom by o!r lam9at$ blocks plac$ horizontally1 & ! :ole is held toge!r betwe5 top & bottom ca/ iron frame plates by a bolt pass+ "r d[n ! c5t]4 ,fig4 #a1ica gives a g5]al view1 ,w be+ ! w9d+1 & ,b1 ,b1 ,b1 etc41 ! out] lam9at$ blocks4 ,! con/ruction w be bett] und]/ood f fig4 #a1icb1 :]e x may be suppos$ t ! top cap & lam9at$ cross pieces h be5 remov$4 ,"h ,i1 ,i1 ,i & ,o1 ,o1 ,o are respectively ! inn] & out] radial v]tical blocks1 ,p ! prim>y1 & ,s1 ,s ! second>y2 ! latt] be+ 9 two sections ) ! prim>y s&wi*$ betwe51 z an extra precaution aga9/ %ock4 ,x w be evid5t t ?is =m ( trans=m] possesses excell5t v5tilation2 & ?is is /ill fur!r enhanc$ by op5+ out ! w9d+ at int]vals to leave v5tilat+ ap]tures1 z at ,a1 ,a1 ,a4 ,fig4 #a1icb %[s only #f sets ( radial blocks1 b ! usual plan is to provide #bd or #cf1 accord+ to ! size ( ! trans=m]4 ,fig4 #a1icb %[s a cross section ( ! fir/ trans=m] ( ?is type to be develop$ comm]cially1 & kn[n z an iron clad trans=m]2 ?is con/ruction has be5 us$ 9 ,engl& = "s "t4 ,fig4 #a1icc %[s ! ,am]ican practice4 ,illu/ration3 ,,fig4 #a1icc4--,plan ( core ( ,g5]al ,electric comb9$ core & %ell trans=m]4 ,! core us$ conta9s f\r magnetic circuits ( equal reluctance1 9 multiple2 ea* circuit consi/+ ( a sep>ate core4 ,9 ?is con/ruction "o leg ( ea* circuit is built up ( two diff]5t wid?s ( pun*+s =m+ su* a cross section t :5 ! f\r circuits are assembl$ toge!r !y int]lock to =m a c5tral leg1 ^u :i* ! w9d+ is plac$4 ,! f\r rema9+ legs consi/ ( pun*+s ( equal wid?4 ,^! occupy a position surr\nd+ ! coil at equal di/ances f ! c5t]1 on ! f\r sides2 =m+ a *annel betwe5 ea* leg & coil1 !reby pres5t+ l>ge surfaces to ! oil & all[+ its free access to all p>ts ( ! w9d+4 ,! pun*+s ( ea* size trans=m] are all ( ! same l5g?1 assembl$ alt]nately1 & =m+ two lap jo9ts equally di/ribut$ 9 ! f\r corn]s ( ! core1 !reby giv+ a magnetic circuit ( l[ reluctance4 ,ques4 ,h[ is economy ( con/ruction obta9$ 9 design+ comb9$ core & %ell trans=m]s8 ,ans4 ,! cross section ( iron 9 ! c5tral leg ( ! core is made some:at less ?an t ext]nal to ! coils1 9 ord] to r$uce ! am\nt ( copp] us$ 9 ! coils4 ,s+le & ,polyphase ,trans=m]s4--,a s+le phase trans=m] may be def9$ z "o hav+ only "o set ( prim>y & second>y t]m9als1 & 9 :i* ! fluxes 9 ! "o or m magnetic circuits are all 9 phase1 z di/+ui%$ f a polyphase trans=m]1 or comb9ation 9 "o unit ( sev]al "o phase trans=m]s ) sep>ate electric circuits b hav+ c]ta9 magnetic circuits 9 common4 ,9 polyphase trans=m]s !re are two or m magnetic circuits ?r\gh ! core1 & ! fluxes 9 ! v>i\s circuits are displac$ 9 phase4 ,ques4 ,is x necess>y to use a polyphase trans=m] to trans=m a polyphase curr5t8 ,ans4 ,no1 a sep>ate s+le phase trans=m] may be us$ = ea* phase4 ,illu/ration3 ,,figs4 #a1icd & #a1ice4--,top view %[+ core & coils 9 place1 & view ( coils ( ,we/+h\se di/ribut+ trans=m]4 ,! coils are w\nd f r\nd wire 9 ! small] sizes ( trans=m]s & f /rap copp] 9 ! l>g] sizes4 ,/rap w\nd coils all[ a great] curr5t c>ry+ conductor section ?an coils w\nd f l>ge r\nd wire1 z !re is little wa/e space betwe5 ! diff]5t turns ( ! conductor4 ,! coils are arrang$ conc5trically ) ! high t5sion w9d+ betwe5 ! two l[ t5sion coils1 ?is arrangem5t giv+ ! f9e regulation f\nd 9 ^! trans=m]s4 ,! l[ t5sion coils are w\nd 9 lay]s :i* ext5d across ! :ole l5g? ( ! coil op5+ 9 ! iron1 :ile ! high t5sion coils are w\nd 9 two p>ts & plac$ end to end4 ,?is con/ruction r$uces ! normal voltage /ra9s to a value :i* w n give tr\ble "u any condition ( s]vice4 ,! magnetic circuit is built up ( lam9at$1 alloy /eel pun*+s1 ea* lay] ( lam9 be+ rev]s$ ) ref]5ce to ! prec$+ lay] & all jo9ts butt$4 ,?is gives a cont9u\s magnetic circuit ( l[ reluctance1 l[ iron loss & l[ excit+ curr5t4 ,:5 assembl$1 ! magnetic circuit consi/s ( f\r sep>ate p>allel circuits encircl+ ! coils & protect+ ! w9d+s f me*anical injury4 ,sep>ate high & l[ t5sion t]m9al blocks ( glaz$ porcela9 are m\nt$ ^u ext5sions ( ! upp] end frames4 ,all dang] ( confus+ ! leads or inadv]t5tly mak+ an electrical connection betwe5 ! high & l[ t5sion sides ( ! trans=m] is ?us av]t$4 ,! high t5sion w9d+ has f\r leads br\ght to ! /uds 9 ! t]m9al block4 ,adju/able brass connectors or l9ks betwe5 ! /uds provide = s]ies or multiple connections betwe5 two po9ts ( ! high t5sion w9d+4 ,! position ( ! /uds & ! l5g? ( ! l9ks are s proportion$ t wrong connections on ! block are impossible4 ,b>ri]s on ! porcela9 block sep>ate ! /uds & prev5t dang] ( arc+4 ,leads ) means ( prev5t+ creep+ ( oil by capill>y action are atta*$ to ^! /uds & br\ght out ( ! core ?r\gh porcela9 bu%+s4 ,ques4 ,is !re any *oice betwe5 a polyphase trans=m] & sep>ate s+le phase trans=m]s = trans=m+ a polyphase curr5t8 ,ans4 ,yes1 ! polyphase trans=m] is pref]able1 because less iron is requir$ ?an w\ld be ) ! sev]al s+le phase trans=m]s4 ,! polyphase trans=m] !re=e is some:at light] & also m effici5t4 ,illu/ration3 ,,figs4 #a1icf & #a1icg4--;,core & %ell types ( ?ree phase trans=m]4 ,9 ! core type1 fig4 #a1icf1 !re are ?ree cores ,a1 ,b1 & ,c1 jo9$ by ! yokes ,d & ,d'4 ,?is =ms a ?ree phase magnetic circuit1 s9ce ! in/antane\s sum ( ! fluxes is z]o4 ,ea* core is w\nd ) a prim>y coil ,p1 & a second>y coil ,s4 ,z %[n1 ! prim>y w9d+ ( ea* phase is divid$ into ?ree coils to ensure bett] insulation4 ,! prim>ies & second>ies may be connect$ /> or me%4 ,! core ,b has a %ort] return pa? ?an ,a & ,c1 :i* causes ! magnetiz+ curr5t 9 t phase to be less ?an 9 ! ,a & ,c phases4 ,?is has sometimes be5 obviat$ by plac+ ! ?ree cores at ! corn]s ( an equilat]al triangle 7z 9 figs4 #a1ici & #a1idj71 b ! extra tr\ble involv$ is n ju/ifi$1 z ! unbalanc+ is a no load condition1 & practically disappe>s :5 ! trans=m] is load$4 ,! %ell type1 fig4 #a1icg1 consi/s practically ( ?ree sep>ate trans=m]s 9 "o unit4 ,! flux pa?s are "h sep>ate1 ea* pair ( coils be+ ?read$ by its own flux1 :i* does n1 z 9 ! core type1 return ?r\gh ! o!r coils4 ,?is gives ! %ell type an advantage ov] ! core type1 = %\ld "o phase burn out1 ! o!r two may /ill be us$1 especially if ! faulty coils be %ort circuit$4 ,! effect ( su* %ort circuit+ is to prev5t all b a v small flux f ?read+ ! faulty coil4 ,ques4 ,"n two v>ieties ( polyphase trans=m]8 ,ans4 ,! core1 & ! %ell types z %[n 9 figs4 #a1icf & #a1icg4 ,ques4 ,h[ %\ld a ?ree phase trans=m] be op]at$ ) "o phase damag$8 ,ans4 ,! damag$ w9d+s %\ld be sep>at$ electrically f ! o!r coils4 ,! pressure w9d+ ( ! damag$ phase %\ld be %ort circuit$ ^u itself & ! correspond+ l[ pressure w9d+ %\ld also be %ort circuit$ ^u itself4 ,! w9d+ ?us %ort circuit$ w *oke d[n ! flux pass+ ?r\gh ! portion ( ! core surr\nd$ by !m )\t produc+ 9 any portion ( ! w9d+ a curr5t great] ?an a small fraction ( ! curr5t :i* w\ld normally exi/ 9 su* portion at full load4 ,trans=m] ,losses4--,z previ\sly m5tion$1 ! ratio betwe5 ! appli$ prim>y voltage & ! second>y t]m9al voltage ( a trans=m] is n always equal to ! ratio ( prim>y to second>y turns ( wire ar\nd ! core4 ,! comm]cial trans=m] is n a p]fect conv]t] ( en]gy1 t is1 ! input1 or watts appli$ to ! prim>y circuit is always m ?an ! output or watts deliv]$ f ! second>y w9d+4 ,illu/ration3 ,,fig4 #a1ich4--;,int]ior ( ,g5]al ,electric oil cool$ #ejj kva4 #cc1jjj volt outdoor trans=m] %[+ lift+ arrangem5t4 ,?is is due to ! v>i\s losses :i* take place1 & ! diff]5ce betwe5 ! input & ! output is equal to ! sum ( ^! losses4 ,!y are divid$ into two classes3 #a4 ,! iron or core losses2 #b4 ,! copp] losses4 ,! iron or core losses are due to #a4 ,hy/]esis2 #b4 ,eddy curr5ts2 #c4 ,magnetic leakage 7negligibly small74 ,illu/ration3 ,,figs4 #a1ici & #a1idj4--,triangul> arrangem5ts ( cores ( ?ree phase trans=m]4 ,fig4 #a1ici1 =m ) ?ree corn]$ yokes at bottom & top ( cores2 fig4 #a1idj1 =m ) circul> yokes4 ,:ile ^! designs give p]fect symmetry = ! ?ree phases1 !re is "s tr\ble 9 ! me*anical arrangem5t ( ! yokes4 ,if ^! be /amp$ out triangul>ly & ins]t$ horizontally betwe5 ! ?ree cores1 x is necess>y to int]pose a lay] ( insulation1 o!rwise !re w\ld be objectionable eddy curr5ts =m$ 9 ! /amp+s4 ,^? :i* are class$ z copp] losses are due to #a4 ,heat+ ! conductors 7! ,i,r loss72 #b4 ,eddy curr5ts 9 conductors4 ,hy/]esis4--,9 ! op]ation ( a trans=m] ! alt]nat+ curr5t causes ! core to und]go rapid rev]sals ( magnetism4 ,?is requires an exp5diture ( en]gy :i* is conv]t$ into heat4 ,illu/ration3 ,,fig4 #a1ida4--,view %[+ me*anical con/ruction ( coil & core ( ,moloney pole type to #ej kw4 trans=m]4 ,moloney /&>d trans=m]s ( ^! sizes are regul>ly w\nd = #a1ajj to #b1bjj prim>y volts4 ,= #a1ajj volts ! prim>y coils are connect$ 9 p>allel by means ( connect+ l9ks2 = #b1bjj volts1 !y are connect$ 9 s]ies4 ,! porcela9 prim>y t]m9al bo>d is provid$ ) two connect+ l9ks s t connections c be made = ei!r #a1ajj or #b1bjj volts4 ,?is loss ( en]gy z be=e expla9$ is due to ! "w requir$ to *ange ! position ( ! molecules ( ! iron1 9 rev]s+ ! magnetization4 ,extra p[] !n mu/ be tak5 f ! l9e to make up = ?is loss1 ?us r$uc+ ! effici5cy ( ! trans=m]4 ,ques4 ,^u :at does ! hy/]esis loss dep5d8 ,ans4 ,^u ! quality ( ! iron 9 ! core1 ! magnetic d5sity at :i* x is work$ & ! frequ5cy4 ,ques4 ,) a giv5 quality ( iron h[ does ! hy/]esis loss v>y8 ,ans4 ,x v>ies z ! #a4f p[] ( ! voltage ) con/ant frequ5cy4 ,ques4 ,9 con/ruction1 :at is done to obta9 m9imum hy/]esis loss8 ,ans4 ,! s(te/ iron obta9able is us$ = ! core1 & a l[ degree ( magnetization is employ$4 ,illu/ration3 ,,fig4 #a1idb4--;,=t ,wayne trans=m] coils & core complete4 ,illu/ration3 ,,fig4 #a1idc4--,top view ( ,=t ,wayne 7type ,a7 trans=m] cov] remov$1 %[+ assembly ( coils & core & disposition ( leads4 ,eddy ,curr5ts4--,! iron core ( a trans=m] acts z a clos$ conductor 9 :i* small pressures ( diff]5t values are induc$ 9 diff]5t p>ts by ! alt]nat+ field1 giv+ rise to eddy curr5ts4 ,en]gy is ?us consum$ by ^! curr5ts :i* is wa/$ 9 heat+ ! iron1 ?us r$uc+ ! effici5cy ( ! trans=m]4 ,ques4 ,h[ is ! loss r$uc$ to a m9imum8 ,ans4 ,by ! usual me?od ( lam9at+ ! core4 ,! iron core is built up ( v ?9 %eet iron or /eel /amp+s1 & ^! are insulat$ f ea* o!r by v>ni% & are laid face to face at "r angles to ! pa? t ! eddy curr5ts t5d to foll[1 s t ! curr5ts w\ld h to pass f %eet to %eet1 ?r\gh ! insulation4 ,ques4 ,9 practice1 ^u :at does ! ?ickness ( ! lam9 or /amp+s dep5d8 ,ans4 ,^u ! frequ5cy4 ,! lam9 v>y 9 ?ickness f ab\t 4#jad to 4#jbe in*1 accord+ z ! frequ5cy is respectively high or l[4 ,illu/ration3 ,,fig4 #a1idd4--;,g5]al ,electric #aj kva41 7type ,h7 trans=m] remov$ f tank4 ,t "p ( ! /eel core compos+ ! magnetic circuit outside ( ! w9d+ is divid$ into f\r equal sections4 ,ea* section is locat$ a suffici5t di/ance f ! w9d+ s t all portions ( ! w9d+ & core are equally expos$ to ! cool+ action ( ! oil4 ,on all except ! v smalle/ sizes ! w9d+ is divid$ by *annels & ducts ?r\gh :i* a cont9ual circulation ( oil is ma9ta9$4 ,! result is uni=m temp]ature ?r\gh\t ! trans=m]1 ?us elim9at+ ! detrim5tal effects ( unequal expansion 9 ! coils ) consequ5t rubb+ & abrasion ( ! insulation4 ,ques4 ,does a trans=m] take any curr5t :5 ! second>y circuit is op58 ,ans4 ,yes1 a no load curr5t passes ?r\gh ! prim>y4 ,ques4 ,:y8 ,ans4 ,! en]gy ?us suppli$ balances ! core losses4 ,illu/ration3 ,,fig4 #a1ide4--;,cov] con/ruction ( ,wagn] #cej kva41 oil fill$ #a1ajj-b1bjj volt trans=m]4 ,9 trans=m]s ) corrugat$ cases1 ! base & top r+ are ca/ to ! corrugat$ iron %eets4 ,ques4 ,are ! iron or copp] losses ! m important1 & :y8 ,ans4 ,! iron losses1 because ^! are go+ on z long z ! prim>y pressure is ma9ta9$1 & ! copp] losses take place only :ile en]gy is be+ deliv]$ f ! second>y4 ,/rictly speak+1 on no load 7t is :5 ! second>y circuit is op57 a slight copp] loss takes place 9 ! prim>y coil b because ( its smallness is n m5tion$4 ,x is1 to be exact1 includ$ 9 ! expression iron losses1 z ! precise mean+ ( ?is t]m signifies n only ! hy/]esis & eddy curr5t losses b ! copp] loss 9 ! prim>y coil :5 ! second>y is op54 ,! importance ( ! iron losses is app>5t 9 not+ t 9 electric light+ ! lights are 9 use only a small fraction ( ! #bd h\rs1 b ! iron losses cont9ue all ! "t1 ?us ! great] "p ( ea* day en]gy mu/ be suppli$ to ea* trans=m] by ! p[] company to meet ! losses1 dur+ :i* "t no money is receiv$ f ! cu/om]s4 ,"s companies make a m9imum *>ge p] mon? :e!r any curr5t is us$ or n to (fset ! no load trans=m] losses & r5t ( met]4 ,illu/ration3 ,,figs4 #a1idf to #a1idh4--,me?ods ( connect+ ! l[ t5sion sides ( ,we/+h\se trans=m]s us+ ! connectors illu/rat$ 9 figs4 #a1idi to #a1iec4 ,ques4 ,h[ may ! iron losses be r$uc$ to a m9imum8 ,ans4 ,by hav+ %ort magnetic pa?s ( l>ge area & us+ iron or /eel ( high p]meability4 ,! design & con/ruction mu/ keep ! eddy curr5ts z l[ z possible4 ,z be=e /at$ ! iron losses take place cont9ually1 & s9ce mo/ trans=m]s are load$ only a small fraction ( a day x is v important t ! iron losses %\ld be r$uc$ to a m9imum4 ,) a l>ge numb] ( trans=m]s on a l9e1 ! magnetiz+ curr5t t is wa/$1 is consid]able4 ,dur+ ,may1 #aiaj1 ! ,u4 ,s4 ,bureau ( ,/&>ds issu$ a circul> %[+ t ea* watt sav+ 9 core losses 0 a sav+ ( #hh c5ts1 :i* is evid5t economy 9 ! use ( high grade trans=m]s4 ,copp] ,losses4--,s9ce ! prim>y & second>y w9d+s ( a trans=m] h resi/ance1 "s ( ! en]gy suppli$ w be lo/ by heat+ ! copp]4 ,! am\nt ( ?is loss is proportional to squ>e ( ! curr5t1 & is usually spok5 ( z ! ,i,r loss4 ,illu/ration3 ,,figs4 #a1idi to #a1iec4--,we/+h\se l[ t5sion trans=m] connectors = connect+ ! l[ t5sion leads to ! fe$] wires4 ,! trans=m]s ( ! small] capacities h knuckle jo9t connectors & ^? ( ! l>g] sizes h int]leav$ connectors4 ,^! connectors =m a me*anically /rong jo9t ( high curr5t c>ry+ capacity4 ,s9ce ! high t5sion leads are connect$ directly to ! cut out or fuse blocks1 connectors are n requir$ on ^! leads4 ,! use ( ^! connectors all[s a trans=m] to be remov$ & ano!r ( ! same or a diff]5t capacity sub/itut$ usually )\t sold]+ or unsold]+ a jo9t4 ,! connectors also facilitate *anges 9 ! l[ t5sion connections4 ,ques4 ,def9e ! copp] losses4 ,ans4 ,! copp] losses are ! sum ( ! ,i,r losses ( bo? ! prim>y & second>y w9d+s1 & ! eddy curr5t loss 9 ! conductors4 ,ques4 ,is ! eddy curr5t loss 9 ! conductors l>ge8 ,ans4 ,no1 x is v small & may be disreg>d$1 s t ! sum ( ! ,i,r losses ( prim>y & second>y c be tak5 z ! total copp] loss = practical purposes4 ,ques4 ,:at effect has ! p[] factor on ! copp] losses8 ,ans4 ,s9ce ! copp] loss dep5ds ^u ! curr5t 9 ! prim>y & second>y w9d+s1 x requires a l>g] curr5t :5 ! p[] factor is l[ ?an :5 high1 h5ce ! copp] losses increase ) a l[]+ ( ! p[] factor4 ,illu/ration3 ,,fig4 #a1ied4--,me?od ( br++ out ! second>y leads 9 ,wagn] c5tral /ation trans=m]s4 ,ea* prim>y lead is br\ght into ! case ?r\gh a simil> bu%+4 ,obs]ve ! elim9ation ( all possibility ( gr\nd+ ! cable on ! case or core4 ,ques4 ,:at effect o!r ?an heat+ has resi/ance 9 ! w9d+s8 ,ans4 ,x causes poor regulation4 ,?is is objectionable1 especially :5 inc&esc5t lights are 9 use1 because ! voltage fluctuates inv]sely ) load *anges1 t is1 x drops z lamps are turn$ on & rises z !y are turn$ (f1 produc+ disagreeable *anges 9 ! brilliancy ( ! lamps4 ,cool+ ( ,trans=m]s4--,ow+ to ! fact t a trans=m] is a /ation>y piece ( app>atus1 n receiv+ v5tilation f mov+ p>ts1 its effici5t cool+ becomes a v /rong feature ( ! design1 especially 9 ! case ( l>ge high pressure trans=m]s4 ,! effective cool+ is r5d]$ m difficult because trans=m]s are inv>iably enclos$ 9 m or less air tight cases1 except 9 v dry situations1 :]e a p]=at$ metal cov]+ may be p]mitt$4 ,illu/ration3 ,,figs4 #a1iee & #a1ief4--,we/+h\se trans=m] t]m9al blocks = high & l[ t5sion conductors4 ,! f9al degree to :i* ! temp]ature rises aft] cont9u\s work+ = "s h\rs1 dep5ds on ! total losses 9 iron & copp]1 on ! total radiat+ surface1 & on ! facilities af=d$ = cool+4 ,!re are v>i\s me?ods ( cool+ trans=m]s1 ! cool+ m$iums employ$ be+ #a4 ,air2 #b4 ,oil2 #c4 ,wat]4 ,! means adopt$ = gett+ rid ( ! heat :i* is inevitably develop$ 9 a trans=m] by ! wa/e en]gy is "o ( ! important consid]ations ) respect to its design4 ,ques4 ,:at is ! behavi\r ( a trans=m] ) respect to heat+ :5 op]at$ cont9u\sly at full load8 ,ans4 ,! temp]ature gradually rises until at ! end ( "s h\rs x becomes con/ant4 ,! diff]5ce betwe5 ! con/ant temp]ature & t ( ! second>y atmosph]e is call$ ! temp]ature rise at full load4 ,its am\nt con/itutes a mo/ important feature 9 ! comm]cial value ( ! trans=m]4 ,illu/ration3 ,,figs4 #a1ieg to #a1ifj4--,porcela9 bu%+ = ,we/+h\se trans=m]s4 ,ques4 ,:y is a high rise ( temp]ature objectionable8 ,ans4 ,x causes rapid det]ioration ( ! insulation1 increas$ hy/]esis losses1 & great] fire risk4 ,dry ,trans=m]s4--,?is classification is us$ to di/+ui% trans=m]s us+ air z a cool+ m$ium f ^? :i* employ a liquid su* z wat] or oil to effect ! cool+4 ,air ,cool$ ,trans=m]s4--,?is "n is giv5 to all trans=m]s :i* are cool$ by curr5ts ( air )\t reg>d to ! mann] 9 :i* ! air is circulat$4 ,!re are two me?ods ( circulat+ ! air1 z by #a4 ,natural draught2 #b4 ,=c$ draught1 or bla/4 ,ques4 ,describe a natural draught air cool$ trans=m]4 ,ans4 ,9 ?is type1 ! case conta9+ ! w9d+s is op5 at ! top & bottom4 ,! column ( air 9 ! case exp&s z its temp]ature rises1 becom+ light] ?an ! cold air on ! outside & is consequ5tly displac$ by ! latt]1 result+ 9 a circulation ( air ?r\gh ! case4 ,! process is id5tical ) furnace draught4 ,illu/ration3 ,,figs4 #a1ifa to #a1ifc4--;,fuse blocks = ,we/+h\se trans=m]s4 ,! fuses furni%$ ) ! trans=m]s are m\nt$ 9 a wea!r pro( porcela9 fuse box ( special design4 ,! /ation>y contacts are deeply recess$ 9 ! porcela9 & are well sep>at$ f ea* o!r4 ,! contacts are s con/ruct$ t ! plug is held securely 9 place by giv+ x a p>tial turn aft] ins]t+ x4 ,:5 ! plug is 9 position1 ! fuse is 9 sight & its condition c be not$ :i* elim9ates all dang] ( pull+ ! fuse :ile same is /ill intact & ! trans=m] is "u load4 ,ques4 ,describe a =c$ draught or air bla/ trans=m]4 ,ans4 ,! case is clos$ at ! bottom & op5 at ! top4 ,a curr5t ( air is =c$ ?r\gh f bottom to top z %[n 9 fig4 #a1ifd by a fan4 ,ques4 ,h[ are ! coils be/ adapt$ to air cool+8 ,ans4 ,!y are built up high & ?91 & assembl$ ) spaces betwe5 !m1 = ! circulation ( ! air4 ,ques4 ,:at are ! requirem5ts ) respect to ! air supply 9 =c$ draught trans=m]s8 ,ans4 ,air bla/ trans=m]s require a l>ge volume ( air at a comp>atively l[ pressure4 ,?is v>ies f "o-half to "o ounce p] squ>e in*4 ,! l>g] trans=m]s require great] pressure to ov]come ! resi/ance ( long] air ducts4 ,illu/ration3 ,,fig4 #a1ifd4--;,=c$ draught or air bla/ trans=m]4 ,z is indicat$ by ! classification1 ?is type ( trans=m] is cool$ by =c+ a curr5t ( air ?r\gh ducts1 provid$ betwe5 ! coils & betwe5 sectionaliz$ portions ( ! core4 ,! cold air is =c$ ?r\gh ! int]ior ( ! core conta9+ ! coils by a bl[]1 ! air pass+ v]tically ?r\gh ! coils & out ?r\gh ! top4 ,"p ( ! air is sometimes div]t$ horizontally ?r\gh ! v5tilat+ ducts provid$ 9 ! core1 pass+ (f at "o side ( ! trans=m]4 ,! am\nt ( air go+ ?r\gh ! coils1 or ?r\gh ! core1 may be controll$ indep5d5tly by provid+ damp]s 9 ! passages4 ,ques4 ,h[ mu* air is us$ ord9>ily = cool+ p] kw4 ( load8 ,ans4 ,ab\t #aej cu4 ft4 ( air p] m9ute4 ,9 =c$ draught trans=m]s1 ! air pressure ma9ta9$ by ! bl[] v>ies f to #a oz4 p] squ>e in*4 ,=c$ draught or air bla/ trans=m]s are seldom built 9 small sizes or = voltages high] ?an ab\t #ce1jjj volts4 ,oil ,cool$ ,trans=m]s4--,9 ?is type ( trans=m] ! coils & core are imm]s$ 9 oil & provid$ ) ducts to all[ ! oil to circulate by convection & ?us s]ve z a m$ium to transmit ! heat to ! case1 f :i* x passes by radiation4 ,illu/ration3 ,,fig4 #aife4--,look+ d[n into a ,wagn] c5tral /ation trans=m]1 %[+ ! connection bo>d1 :i* provides facility = v>y+ ! ratio ( trans=mation & also = int]*ang+ ! prim>ies4 ,ques4 ,expla9 9 detail ! circulation ( ! oil4 ,ans4 ,! oil1 heat$ by contact ) ! expos$ surfaces ( ! core & coils1 rises to ! surface1 fl[s outw>d & desc5ds along ! sides ( ! trans=m] case1 f ! out] surface ( :i* ! heat is radiat$ into ! air4 ,ques4 ,h[ may ! effici5cy ( ?is me?od ( cool+ be increas$8 ,ans4 ,by provid+ ! case ) ext]nal ribs or f9s1 or by flut+ s z to increase ! ext]nal cool+ surface4 ,illu/ration3 ,,fig4 #aiff4--,section ?r\gh ,we/+h\se kilovolt amp]e type ,s trans=m]4 ,,fig4 #aifg4--,section ?r\gh ,we/+h\se #ej kilovolt amp]e type ,s trans=m] %[+ l>ge oil ducts4 ,ques4 ,9 :at types ( trans=m] is ?is mode ( oil cool+ us$8 ,ans4 ,light+ trans=m]s4 ,9 su* trans=m]s1 ! l>ge volume ( oil absorbs consid]able heat1 s t ! rise ( temp]ature is ret>d$4 ,h5ce1 = mod]ate p]iods ( op]ation1 say #c or #d h\rs1 ! av]age light+ p]iod1 ! maximum temp]ature w\ld n be rea*$4 ,ques4 ,9 :at o!r capacities except t ( cool+ ag5t1 does ! oil act8 ,ans4 ,x is a good insulator1 pres]ves ! insulation f oxidation1 increas+ ! breakd[n resi/ance ( ! insulation1 & g5]ally re/ores ! insulation 9 case ( puncture4 ,illu/ration3 ,,fig4 #a1ifh4--,wagn] #cjj kva1 #d1djj volt ?ree phase oil cool$ trans=m]4 ,9 ?is type ( trans=m] ! case is fill$ ) oil & flut$ s z to increase ! cool+ surface1 an oil dra9 valve is screw$ to a wr\ght iron nipple ca/ into ! base1 ! duct to :i* is 9 su* a position z to make x possible n only to dra9 all ( ! oil f ! trans=m]1 b :5 desirable1 to draw (f a small quantity f ! bottom4 ,%\ld any moi/ure be 9 ! oil x is !re=e drawn (f fir/4 ,ques4 ,:at is ! special objection to oil8 ,ans4 ,dang] ( fire4 ,ques4 ,:at k9d ( oil is us$ 9 trans=m]s8 ,ans4 ,m9]al oil4 ,ques4 ,:at are ! requirem5ts ( a good grade ( trans=m] oil8 ,ans4 ,x %\ld %[ v little evaporation at #bab ,fahr41 & %\ld n give (f gases at su* a rate z to produce an explosive mixture ) ! air at a temp]ate bel[ #cef4 ,x %\ld n conta9 moi/ure1 acid1 alkali or sulphur comp\nds4 ,illu/ration3 ,,fig4 #a1ifi4--,section ?r\gh ,=t ,wayne 7type ,a7 trans=m] %[+ int]ior ( case1 core conductors1 & insulation1 also division ( lam94 ,! pres5ce ( moi/ure c be detect$ by ?ru/+ a r$ hot nail 9 ! oil2 if ! oil crackle1 wat] is pres5t4 ,moi/ure may be remov$ by rais+ ! temp]ature slightly above ! boil+ po9t1 #bab ,fahr41 b ! "t consum$ 7sev]al days7 is excessive4 ,wat] ,cool$ ,trans=m]s4--,a wat] cool$ trans=m] is "o 9 :i* wat] is ! cool+ ag5t1 &1 9 mo/ cases1 oil is ! m$ium by :i* heat is transf]r$ f ! coils to ! wat]4 ,9 con/ruction1 pipes or a jacket$ cas+ is provid$ ?r\gh :i* ! cool+ wat] is pass$ by =c$ circulation1 z %[n 9 figs4 #a1igj & #a1iga4 ,illu/ration3 ,,fig4 #a1igj4--,wat] cool$ trans=m] ) int]nal cool+ coil1 t is1 ) cool+ coil )9 ! trans=m] case4 ,9 ?is type1 ! cool+ coil1 ?r\gh :i* ! circulat+ wat] passes1 is plac$ 9 ! top ( ! case or tank1 ! latt] is fill$ ) oil s t ! coil is subm]g$4 ,! oil acts simply z a m$ium to transf] ! heat g5]at$ by ! trans=m] to ! wat] circulat+ ?r\gh ! cool+ coil4 ,9 op]ation a cont9ual circulation ( ! oil takes place1 z indicat$ by ! arr[s1 due to ! alt]nate heat+ & cool+ x receives z x fl[s pa/ ! trans=m] coils & cool+ coil respectively4 ,9 "s cases tubul> conductors are provid$ = ! circulation ( ! wat]4 ,wat] cool$ trans=m]s may be divid$ into two classes1 z ^? hav+3 #a4 ,int]nal cool+ coils2 #b4 ,ext]nal cool+ coils4 ,ques4 ,describe ! fir/ nam$ type4 ,ans4 ,inside ! trans=m] case ne> ! top is plac$ a coil ( wr\ght iron pipe1 ?r\gh :i* ! cool+ wat] is pump$4 ,! case is fill$ ) oil1 :i* by !rmo-circulation fl[s upw>d ?r\gh ! coils1 transf]r+ ! heat absorb$ f ! coils to ! wat]2 on cool+ x becomes m d5se 7heavi]7 & desc5ds along ! inside surface ( ! cas+4 ,illu/ration3 ,,fig4 #a1iga4--,wat] cool$ trans=m] ) ext]nal cool+ coil4 ,9 ?is arrangem5t ! cool+ coil is plac$ 9 a sep>ate tank z %[n4 ,"h =c$ circulation is employ$ = bo? ! heat transf] m$ium 7oil7 & ! cool+ ag5t 7wat]71 two pumps be+ necess>y4 ,! cool oil ent]s ! trans=m] case at ! l[e/ po9t & absorb+ heat f ! trans=m] coils x passes (f ?r\gh ! top connection lead+ to ! cool+ coil & expansion tank4 ,s9ce ! trans=m] tank is clos$1 an expansion tank is provid$ to all[ = expansion ( ! oil due to heat+4 ,! wat] circulation is arrang$ z illu/rat$4 ,ques4 ,h[ mu* circulat+ wat] is requir$8 ,ans4 ,x dep5ds ^u ! diff]5ce betwe5 ! initial & dis*>ge temp]atures ( ! circulat+ wat]4 ,illu/ration3 ,,fig4 #a1igb4--;,int]ior ( ,g5]al ,electric wat] cool$ #adj1jjj volt trans=m] %[+ cool+ coil4 ,ques4 ,9 wat] cool$ trans=m]s h[ mu* cool+ surface is requir$ = an int]nal cool+ coil8 ,ans4 ,! surface ( ! cool+ coil %\ld be f 4#e to #a4c sq4 94 p] watt ( total trans=m] loss1 dep5d+ ^u ! am\nt ( heat :i* ! ext]nal surface ( ! trans=m] case w dissipate4 ,= a wat] temp]ature rise ( #dc ,fahr41 #a4cb lbs4 ( wat] p] m9ute is requir$ p] kw4 ( load4 ,trans=m] ,insulation4--,?is subject has n1 until ! la/ few ye>s1 be5 giv5 ! same special att5tion t _m o!r electrical problems h receiv$1 al?\gh ! developm5t ( ! trans=m] f its orig9al =m1 consi/+ ( an iron core enclos$ by coils ( wire1 to its pres5t degree ( ref9em5t & economy ( mat]ial1 has be5 comp>atively rapid4 ,9 trans=m] con/ruction x is obvi\sly v important t ! insulation be ( ! be/ quality to prev5t burn outs & int]ruptions ( s]vice4 ,ques4 ,:at is ! major insulation8 ,ans4 ,! insulation plac$ betwe5 ! core & second>y 7l[ pressure7 coils1 & betwe5 ! prim>y & second>y coils4 ,illu/ration3 ,,fig4 #a1igc4--;,assembl$ coils ( ,g5]al ,electric wat] cool$ #ejj kva41 #ff1jjj volt trans=m]4 ,x consi/s usually ( mica tubes1 sometimes appli$ z %eets held 9 place by ! w9d+s1 :5 no v5tilat+ ducts are provid$1 or m\ld$ to correct =m & held betwe5 %eets ( t\gh insulat+ mat]ial :]e ducts are provid$ = air or oil circulation4 ,ques4 ,describe ! m9or insulation4 ,ans4 ,x is ! insulation plac$ betwe5 adjac5t turns ( ! coils4 ,s9ce ! diff]5ce ( pressure is small betwe5 ! adjac5t turns ! insulation ne$ n be v ?ick4 ,x usually consi/s ( a d\ble ?ickness ( cotton wrapp$ ar\nd ea* conductor4 ,= r\nd conductors1 ! ord9>y d\ble cov]$ magnet wire is satisfactory4 ,ques4 ,:at is ! mo/ effici5t insulat+ mat]ial = trans=m]s8 ,ans4 ,mica4 ,x has a high dielective /r5g?1 is firepro(1 & is ! mo/ desirable insulator :]e !re are no %>p corn]s4 ,illu/ration3 ,,fig4 #a1igd4--,?ree ,we/+h\se #bj kva1 outdoor trans=m]s1 = irrigation s]vice4 ,^! are m\nt$ on a drag s t !y may be readily transport$ f place to place4 #cc1jjj volts high t5sion2 #b1bjj & #ddj volts l[ t5sion1 #ej cycles4 ,^! outdoor trans=m]s are ( ! oil imm]s$1 self-cool+ type & h be5 develop$ to meet ! requirem5ts = trans=m]s ( capacities great] or ( voltages high] ?an are usually f\nd 9 di/ribution "w4 ,!y are 9 reality di/ribut+ trans=m]s = high voltage1 outdoor in/allations1 s+le or ?ree phase s]vice1 = voltages up to #aaj1jjj4 ,:]e ! magnitude ( ! load does n w>rant an exp5sive in/allation1 trans=m]s ( ! outdoor type are p>ticul>ly applicable4 ,! co/ ( a build+ & outlet bu%+s :i* is (t5 ! item ( greate/ exp5se is elim9at$ :]e outdoor type trans=m]s are in/all$4 ,oil ,insulat$ ,trans=m]s4--,high voltage trans=m]s are insulat$ ) oil1 z x is v important to ma9ta9 c>eful insulation n only betwe5 ! coils1 b also betwe5 ! coils & ! core4 ,9 ! case ( high voltage trans=m]s1 any accid5tal /atic dis*>ge1 su* z t due to lightn+1 :i* might de/roy "o ( ! air insulat$ type1 might be successfully )/ood by "o insulat$ ) oil1 = if ! oil insulation be damag$ x w m5d itself at once4 ,by provid+ good circulation = ! oil1 ! trans=m] c get rid ( ! heat produc$ 9 x readily & op]ate at a l[ temp]ature1 :i* n only increases its life b cuts d[n ! electric resi/ance ( ! copp] conductors & !re=e ! ,i,r loss4 ,effici5cy ( ,trans=m]s4--,! effici5cy ( trans=m]s is ! ratio ( ! electric p[] deliv]$ at ! second>y t]m9als to ! electric p[] absorb$ at ! prim>y t]m9als4 ,accord+ly1 ! output mu/ equal ! input m9us ! losses4 ,if ! iron & copp] losses at a giv5 load be kn[n1 _! values & consequ5tly ! effici5cy at o!r loads may be readily calculat$4 ,,example4--,if a #aj kil[att con/ant pressure trans=m] at full load & temp]ature h a copp] loss ( 4#af kil[att1 or #a4f p] c5t41 & ! iron loss be ! same1 !n its output #aj effici5cy ------ -------------- #ajj #if4i p] c5t4 input #aj 4#af 4#af ,at ?ree-qu>t]s load ! output w be #g4e kil[atts2 & z ! iron loss is practically con/ant at all loads & ! copp] loss is proportional to ! squ>e ( ! load1 ! output #g4e effici5cy ------ --------------- #ajj #if4h p] c5t4 input #g4e 4#af 4#ji ,! matt] ( effici5cy is important1 especially 9 ! case ( l>ge trans=m]s1 z a l[ effici5cy n only means a l>ge wa/e ( p[] 9 ! =m ( heat1 b also a great increase 9 ! difficulties enc\nt]$ 9 keep+ ! app>atus cool4 ,! effici5cy curve %[n 9 fig4 #a1ige1 s]ves to indicate1 h[ev]1 h[ slight a m>g9 actually rema9s = improvem5t 9 ?is p>ticul> 9 ! design & con/ruction ( l>ge trans=m]s4 ,illu/ration3 ,,fig4 #a1ige4--;,effici5cy curve ( ,we/+h\se #cge kw41 trans=m]4 ,pressure #ejj to #ae1jjj volts2 frequ5cy #fj4 ,effici5cies at diff]5t loads3 full load effici5cy1 #ih2 full load effici5cy1 #ih2 full load effici5cy1 #ig4f2 full load effici5cy1 #if4a2 regulation non-inductive load1 #a4d2 load hav+ 4#i p[] factor1 #c4c4 ,! effici5cy ( trans=m]s is1 9 g5]al1 high] ?an t ( o!r electrical ma*9es2 ev5 9 q small sizes x rea*es ov] #ij p] c5t41 & 9 ! l>ge/1 is frequ5tly z high z #ih4e p] c5t4 ,to measure ! effici5cy ( a trans=m] directly1 by measur+ input & output1 does n con/itute a satisfactory me?od :5 ! effici5cy is s high4 ,a v accurate result c be obta9$1 h[ev]1 by measur+ sep>ately1 by wattmet]1 ! core & copp] losses4 ,! core loss is measur$ by plac+ a wattmet] 9 circuit :5 ! trans=m] is on circuit at no load & normal frequ5cy4 ,! copp] loss is measur$ by plac+ a wattmet] 9 circuit ) ! prim>y :5 ! second>y is %ort circuit$1 & :5 en\gh pressure is appli$ to cause full load curr5t to fl[4 ,if x be desir$ to sep>ate ! load losses f ! true ,i,r loss1 ! resi/ances c be measur$1 & ! ,i,r loss calculat$ & subtract$ f ! wattmet] read+4 ,! losses be+ kn[n1 ! effici5cy at any load is readily f\nd by tak+ ! core loss z con/ant & ! copp] loss z v>y+ proportionally to ! squ>e ( ! load4 ,?us1 output effici5cy --------------- #ajj output losses ,all ,day ,effici5cy ( ,trans=m]s4--,?is d5otes ! ratio ( ! total watt h\r output ( a trans=m] to ! total watt h\r input tak5 ov] a work+ day4 ,to compute ?is effici5cy x is necess>y to "k ! load curve ( ! trans=m] ov] a day4 ,suppose t ?is is equival5t to #e h\rs at full load1 & #ai h\rs at no load4 ,!n1 if ,w be ! core loss 9 watts1 ,w ! copp] loss at rat$ load1 & ,w ! rat$ output1 output #e ,w1 losses #e 7,w ,w7 #ai ,w1 input #e 7,w ,w ,w7 #ai ,w1 & ! all day effici5cy is equal to #e,w #ajj --------------------- p] c5t4 #e7,w ,w ,w7 #ai,w ,comm]cial or all day effici5cy is a mo/ important po9t 9 a good trans=m]4 ,! pr9cipal factor 9 secur+ a high all day effici5cy is to keep ! core loss z l[ z possible4 ,! core loss is con/ant--x cont9ues :ile curr5t is suppli$ to ! prim>y1 :ile copp] loss takes place only :5 ! second>y is deliv]+ en]gy4 ,9 g5]al1 if a trans=m] is to be op]at$ at light loads ! great] "p ( ! day1 x is mu* m economical to use "o design$ = a small iron loss ?an = a small full load copp] loss4 ,illu/ration3 ,,figs4 #a1igf & #a1igg4--,we/+h\se d\ble pole fuse box2 views %[+ box op5 ) tubes 9 place1 & ) tubes remov$4 ,trans=m] ,fuse ,blocks4--,^! may be ( ei!r ! s+le pole or d\ble pole type4 ,fig4 #a1igf %[s a d\ble pole fuse box op5$1 & fig4 #a1igg1 ! fuse box op5$ & ! tubes remov$4 ,( ! f\r wires1 ,w1 ,w1 ,w1 ,w1 ent]+ ! box f b5ea?1 two are f ! prim>y ma9s1 & two lead to ! prim>y coil ( ! trans=m]4 ,^! wires t]m9ate 9 metallic receptacles ,r1 ,r1 ,r1 ,r1 9 ! porcela9 plate ,p1 fig4 #a1igg1 :i* are bridg$ ov] 9 pairs by fuse wires plac$ inside porcela9 tubes ,t1 ,t1 z %[n 9 fig4 #a1igf4 ,^! tubes are air tight except = a small outlet ,o 9 ea*1 :i* fit into ! receptacles ,b1 ,b1 9 ! porcela9 plate & op5 out at ! back ( ! block1 z %[n 9 fig4 #a1igg4 ,! fuse wires are connect$ betwe5 metallic spr+ tubes ,s1 ,s1 ,s1 ,s1 :i* fit into ! receptacles ,r1 ,r1 ,r1 ,r4 ,if a sudd5 load or a %ort circuit occur 9 ! trans=m]1 ! int5se heat1 accompany+ ! melt+ or bl[+ ( ! fuse1 causes a rapid expansion ( ! air inside ! tube1 s t a /rong bla/ ( air ru%es ?r\gh ! outlet ,o ( ! tube & imm$iately ext+ui%es ! arc4 ,by ?is arrangem5t1 su/a9$ arc+ is prev5t$1 z ! action ( ! tube causes ! arc to ext+ui% itself automatically :5 ! curr5t is int]rupt$4 ,! porcela9 tubes are held 9 position by ! spr+ ,k1 & ! prim>y ( ! trans=m] becomes entirely disconnect$ f ! circuit :5 ! tubes are lift$ out4 ,?is =m ( con/ruction enables ! l9eman to deta* ! tubes f ! fuse box1 & ins]t ! fuse at 8 conv5i5ce4 ,fur!rmore1 :5 ins]t+ a fuse 9 a %ort circuit$ l9e1 he does n run ! risk ( be+ hurt1 z ! heat$ vapor ( ! explod+ fuse c escape ?r\gh ! outlet provid$ = t purpose1 & 9 a pr$et]m9$ direction4 ,! me?od ( atta*+ ! lid n only p]mits ( quick access to ! int]ior ( ! box1 b enables ! l9eman to tight5 ! jo9ts by means ( ! ?umb screws ,l1 ,l1 s z to keep ! box wat]pro(4 ,illu/ration3 ,,fig4 #a1igh4--;,diagram illu/rat+ connections & pr9ciples ( auto-trans=m]s z expla9$ 9 ! accompany+ text4 ,auto-trans=m]s4--,9 ?is class ( trans=m]1 !re is only "o w9d+ :i* s]ves = bo? prim>y & second>y4 ,on acc\nt ( its simplicity x is made *eaply4 ,auto-trans=m]s are us$ :]e ! ratio ( trans=mation is small1 z a consid]able sav+ 9 copp] & iron c be effect$1 & ! :ole trans=m] r$uc$ 9 size z comp>$ ) "o hav+ sep>ate w9d+s4 ,fig4 #a1igh illu/rates ! electrical connections & ! relations betwe5 ! volts & numb] ( turns4 ,by us+ ! end wire & tapp+ 9 on turn ,no4 #bj a curr5t at #bj volts pressure is readily obta9$ :i* may be us$ = />t+ up motors requir+ a l>ge />t+ curr5t & yet n draw heavily on ! l9e4 ,s9ce ! prim>y is connect$ directly to ! second>y x w\ld be dang]\s to use an auto-trans=m] on high pressure circuits4 ,?is type ( trans=m] has only a limit$ use1 usually z comp5sator = motor />t+ boxes4 ,illu/ration3 ,,figs4 #a1igi & #a1ihj4--,two w9d+ trans=m] & s+le w9d+ or auto-trans=m]4 ,fig4 #a1igi %[s a #bjj3ajj volt trans=m] hav+ a #aj amp4 prim>y & a #bj amp4 second>y1 ! curr5ts be+ 9 opposite directions4 ,if ^! curr5ts be sup]pos$ by us+ "o w9d+ only1 ! auto-trans=m] %[n 9 fig4 #a1ihj is obta9$ :]e ! w9d+ c>ries #aj amp4 only & requires only "o-half ! copp] 7assum+ ! same mean l5g? ( turn74 ,if ,r be ! ratio ( an auto-trans=m]1 ! relative size ( x comp>$ ) a trans=m] ( ! same ratio & output is 77,r - #a7 _/ ,r73#a4 ,= example1 a #aj kw4 trans=m] ( #djj volts prim>y & #cjj volts second>y c\ld be replac$ by an auto-trans=m] ( #aj 7#a4cc - #a7 _/ #a4cc #b4e kw42 or1 9 o!r words1 ! am\nt ( mat]ial us$ 9 a #b kw4 trans=m] c\ld be us$ to w9d an auto-trans=m] ( #djj3cjj ratio & #aj kw4 output4 ,con/ant ,curr5t ,trans=m]s = ,s]ies ,arc ,light+4--,! pr9ciple ( ! con/ant curr5t trans=m] z us$ = s]ies arc light+ is readily und]/ood by ref]5ce to ! elem5t>y diagram %[n 9 fig4 #a1iha4 ,a con/ant alt]nat+ curr5t is suppli$ to ! /ation>y prim>y coil :i* induces a curr5t 9 ! movable second>y coil4 ,! pressure induc$ 9 ! coil w dep5d on ! numb] ( l9es ( flux :i* pass ?r\gh x & by *ang+ its position 9 ! magnetic field ov] ! prim>y a v>iable e4m4f4 c be produc$ & a con/ant curr5t ma9ta9$ 9 ! light+ circuit :5 ! lamps are turn$ on or (f1 or if ! resi/ance ( ! circuit be l[]$ by ! consumption ( ! c>bons4 ,illu/ration3 ,,fig4 #a1iha4--;,elem5t>y diagram illu/rat+ ! pr9ciples ( con/ant curr5t trans=m] z us$ = s]ies arc light+4 ,s9ce ! induc$ curr5ts 9 ! second>y are repell$ by ! prim>y !re is a t5d5cy = ! second>y coil to jump out ( ! prim>y field1 & 9 case ( a v l>ge curr5t due to a %ort circuit 9 ! lamp circuit1 ! second>y curr5t is quickly r$uc$ to normal by ! rapid movem5t ( ! coil upw>d4 ,by adju/+ ! c\nt]weight = a giv5 numb] ( amp]es requir$ by ! arc1 ! curr5t w be ma9ta9$ con/ant by ! movem5t ( ! second>y coil4 ,! magnetic field produc$ by ! prim>y mu/ be kept ! same by a con/ant curr5t f ! alt]nator1 !re=e1 :5 ! lamp load is increas$ ! prim>y voltage increases simil> to t ( an ord9>y s]ies w\nd direct curr5t dynamo4 ,9 o!r words ! alt]nator & regulat+ trans=m] supply a con/ant curr5t & v>iable voltage4 ,illu/ration3 ,,fig4 #a1ihb4--,me*anism ( ,g5]al ,electric air cool$ con/ant curr5t trans=m]4 ,x op]ates on ! pr9ciple expla9$ 9 ! accompany+ text & is built to supply #be to #ajj arc lamps at #f4f to #g4e amp]es4 ,! trans=m]s are int]*angeable & w op]ate on #fj or #abe cycles4 ,! relative positions ( ! two coils may be *ang$ 9 ord] to regulate ! /r5g? ( ! curr5t m closely1 by %ift+ ! position ( ! arc c>ry+ ! c\nt]balance by means ( ! adju/+ screw on x4 ,a da% pot fill$ ) special oil prev5ts sudd5 movem5ts ( ! second>y coil & keeps ! curr5t ?r\gh ! lamps ne>ly con/ant1 :5 !y are be+ cut 9 or out ( ! circuit4 ,9 />t+ up a con/ant curr5t trans=m]1 x is necess>y to sep>ate ! two coils z f> z possible & !n close ! prim>y circuit swit* & all[ ! two coils to come toge!r4 ,if ! prim>y circuit be ?r[n directly on ! g5]ator ! heavy ru% ( curr5t :i* w foll[ due to ! two coils be+ too close toge!r might injure ! lamps4 ,con/ant curr5t inc&esc5t light+ sy/ems = use 9 small t[ns also use ?is me?od = automatically regulat+ ! curr5t4 ,regulation4--,?is t]m applies to ! means adopt$ ei!r to obta9 con/ancy ( pressure or curr5t4 ,9 ! trans=m]1 regulation is inh]5t1 t is1 ! app>atus automatically effects its own regulation4 ,! regulation ( a trans=m] means1 ! *ange ( voltage due to *ange ( load on ! second>y2 x may be def9$ m precisely z3 ! p]c5tage increase 9 ! second>y voltage z ! load is decreas$ f its normal value to z]o4 ,?us1 obs]vation %\ld be made ( ! second>y voltage1 at full load & at no load1 ! prim>y pressure be+ held con/ant at ! normal value4 ,illu/ration3 ,,fig4 #a1ihc4--;,g5]al ,electric air cool$ con/ant curr5t trans=m]4 ,view %[+ ext]nal appe>ance ) case on4 ,! regulation is said to be good or close1 :5 ?is *ange is small4 ,9 ! design ( a trans=m]1 good regulation & l[ iron losses are 9 opposition to "o ano!r :5 ! be/ results are desir$ 9 bo?4 ,a well design$ trans=m]1 h[ev]1 %\ld give good results1 bo? z to regulation & iron losses1 ! relative value dep5d+ ^u ! class ( "w x has to d1 & size4 ,trans=m] ,connections4--,! alt]nat+ curr5t has ! advantage ov] direct curr5t1 9 ! ease ) :i* ! pressure & curr5t c be *ang$ by diff]5t connections ( trans=m]s4 ,on s+le phase circuits ! trans=m] connections c be v>i$ to *ange curr5t & pressure1 & 9 addition on polyphase circuits ! phases c also be *ang$ to almo/ any =m4 ,s+le ,phase ,connections4--,! me?od ( connect+ ord9>y di/ribut+ trans=m]s to con/ant pressure ma9s is %[n by ! elem5t>y diagram1 fig4 #a1ihd1 :]e a trans=m] ( #aj to #a ratio is indicat$ ) its prim>y w9d+ connect$ to a #a1jjj volt ma91 & a second>y w9d+ to deliv] #ajj volts4 ,illu/ration3 ,,fig4 #a1ihd4--,s+le phase trans=m] connection ) con/ant pressure ma94 ,illu/ration3 ,,fig4 #a1ihe4--,usual me?od ( s+le phase trans=m] connections = resid5ce light+ ) ?ree wire second>ies4 ,a balanc+ trans=m] is connect$ to ! ?ree wire circuit ne> ! c5t] ( di/ribution z %[n4 ,fig4 #a1ihf %[s a trans=m] ) ea* w9d+ divid$ into two sections4 ,ea* prim>y section is w\nd = #a1jjj volts1 & ea* second>y section = #ej volts4 ,by connect+ ! entire prim>y w9d+ 9 s]ies1 ! trans=m] may be suppli$ f a #b1jjj volt ma91 z indicat$1 & if ! second>y w9d+ be also connect$ all 9 s]ies1 z %[n1 ! no load voltage w be #ajj betwe5 ! second>y t]m9als4 ,illu/ration3 ,,fig4 #a1ihf4--;,diagram ( s+le phase trans=m] hav+ prim>y & second>y w9d+s 9 two sections1 %[+ voltages p] section ) s]ies connections4 ,! sections ( ! prim>y w9d+ may be connect$ 9 p>allel to a #a1jjj volt ma91 & #ajj volts obta9$ f ! second>y1 or ! prim>y & second>y w9d+s may be connect$ ea* ) its two sections 9 p>allel1 & trans=mations made f #a1jjj to #ej volts z repres5t$ 9 fig4 #a1ihg4 ,?is is a v common me?od ( con/ruction = small trans=m]s1 :i* are provid$ ) conv5i5t t]m9al blocks = comb9+ ! sections ( ea* w9d+ to suit ! requirem5ts ( ! case4 ,:5 ! two sections ( ei!r w9d+ are connect$ 9 p>allel z %[n 9 fig4 #a1ihg1 c>e mu/ be tak5 to connect correspond+ ends ( ! two sections toge!r4 ,comb9+ ,trans=m]s4--,two or m trans=m]s built to op]ate at ! same pressure & frequ5cy may be connect$ toge!r 9 a v>iety ( ways2 9 fact1 ! prim>y & second>y t]m9als may ea* be consid]$ exactly z ! t]m9als ( direct curr5t dynamos1 ) c]ta9 re/rictions4 ,illu/ration3 ,,fig4 #a1ihg4--;,diagram ( s+le phase trans=m] ) prim>y & second>y w9d+s ( two sections ea*1 %[+ voltages p] section ) p>allel connection4 ,ques4 ,:at are ! two pr9cipal precautions :i* mu/ be obs]v$ 9 comb9+ trans=m] t]m9als8 ,ans4 ,! t]m9als mu/ h ! same pol>ity at a giv5 in/ant1 & ! trans=m]s %\ld h practically id5tical *>act]i/ics4 ,! latt] condition is n absolutely ess5tial1 b x is emphatically pref]able4 ,= example1 if a trans=m]1 :i* has #b p] c5t4 regulation1 be connect$ 9 p>allel1 z indicat$ 9 fig4 #a1ihh1 ) "o :i* has #c p] c5t4 regulation1 at no load ! trans=m]s w give exactly ! same voltage at ! second>y t]m9als1 b at full load "o w h a second>y pressure (1 say1 #ih volts1 :ile ! o!r has #ig volts4 ,! result is t ! trans=m] giv+ only #ig volts w be subject to a rev]se pressure ( "o volt f its mate4 ,?is w n cause excessive curr5t to fl[ backw>d ?r\gh ! second>y w9d+ ( ! l[ voltage trans=m]1 b x w di/urb ! phase relations & l[] ! p[] factor & effici5cy ( ! comb9ation4 ,9 su* a case x is mu* bett] to "w ! second>y circuits ( ! two trans=m]s sep>ately4 ,9 case ! trans=m]s h practically ! same *>act]i/ics x is necess>y1 z /at$ above1 to make sure t ! second>y t]m9als connect$ toge!r h ! same pol>ity at a giv5 in/ant2 x is n necess>y to f9d out def9itely :at ! pol>ity is1 m]ely t x is ! same = bo? t]m9als4 ,?is c be easily done z %[n 9 fig4 #a1ihi4 ,illu/ration3 ,,fig4 #a1ihh4--;,diagram %[+ unlike s+le phase trans=m]s 9 p>allel4 ,ques4 ,:at may be said ) respect to op]at+ trans=m] second>ies 9 p>allel8 ,ans4 ,x is seldom advantage\s4 ,occasionally x may be necess>y z a tempor>y exp$i5t1 b :]e ! load is su* z to require a great] capacity ?an t ( a trans=m] already in/all$1 x is mu* bett] to replace x by a l>ge trans=m] ?an to supplem5t x by an additional trans=m] ( its own size4 ,ques4 ,h[ are ! second>ies arrang$ 9 mod]n trans=m]s & :y8 ,ans4 ,! second>y w9d+s are divid$ into at lea/ two sections s t !y may be connect$ ei!r 9 s]ies or p>allel4 ,ques4 ,expla9 h[ second>y connections are made = diff]5t voltages4 ,ans4 ,if1 = in/ance1 ! second>y pressure ( a trans=m] hav+ two sections be #ajj volts ) ! t]m9als 9 p>allel1 z 9 fig4 #a1iij1 !n connect+ !m 9 s]ies w give #bjj volts at ! free second>y t]m9als1 z indicat$ 9 fig4 #a1iia4 ,ques4 ,:at precaution %\ld be tak5 9 connect+ second>y sections 9 p>allel 9 core type if ! two sections be w\nd on diff]5t limbs ( ! cores8 ,illu/ration3 ,,fig4 #a1ihi4--,me?od ( comp>+ in/antane\s pol>ity4 ,two ( ! t]m9als are connect$ z %[n by a small /rip ( fuse wire1 & !n t\*+ ! o!r two t]m9als toge!r4 ,if ! fuse bl[s1 !n ! connections mu/ be rev]s$2 if x does n1 !n !y may be made p]man5t4 ,ans4 ,x w be advisable to make ! connections ample & p]man5t1 s t !re w n be any liability to a diff]5ce betwe5 ! curr5t fl[+ 9 "o second>y w9d+ & t fl[+ ?r\gh ! o!r4 ,two ,phase ,connections4--,9 ! case ( two phase di/ribution ea* circuit may be treat$ z entirely indep5d5t ( ! o!r s f> z ! trans=m]s are conc]n$4 ,two trans=m]s are us$1 "o be+ connect$ to "o prim>y phase & supply+ "o second>y phase1 ! o!r be+ connect$ to ! o!r prim>y phase & supply+ ! o!r second>y phase z indicat$ 9 fig4 #a1iif1 exactly z ?\gh ea* prim>y & second>y phase 7 an ord9>y s+le phase sy/em1 indep5d5t ( ! o!r phase4 ,illu/ration3 ,,figs4 #a1iij & #a1iia4--,me?ods ( alt]+ ! second>y connections ( a trans=m] hav+ two sections 9 ! second>y to obta9 a diff]5t voltage4 ,fig4 #a1iij %[s ! two sections 9 p>allel giv+ say #ajj volts2 fig4 #a1iia %[s ! two sections 9 s]ies giv+ #bjj volts4 ,ques4 ,is ! above me?od usually employ$8 ,ans4 ,no1 ! me?od %[n 9 fig4 #a1iig is g5]ally us$4 ,?ree ,phase ,connections4--,!re is n s mu* fre$om 9 mak+ ?ree phase trans=m] connections1 z ) s+le or two phase1 because ! ?ree phases are insep>ably int]l9k$4 ,h[ev]1 ! sy/em gives rise to sev]al me?ods ( trans=m] connection1 :i* are kn[n z3 #a4 ,/>2 #b4 ,delta2 #c4 ,/>-delta2 #d4 ,delta-/>4 ,illu/ration3 ,,figs4 #a1iib to #a1iie4--,?ree phase trans=m] connections4 ,fig4 #a1iib delta connection2 fig4 #a1iic /> connection2 fig4 #a1iid delta /> connection2 fig4 #a1iie />-delta connection4 _/ ,delta ,connection4--,9 ! delta connection bo? prim>ies & second>ies are connect$ 9 delta gr\p+1 z 9 fig4 #a1iib4 ,/> ,connection4--,?is me?od consi/s 9 connect+ bo? ! prim>ies & second>ies 9 /> gr\p+1 z 9 fig4 #a1iic4 ,delta-/> ,connection4--,9 ?is me?od ! prim>ies are connect$ 9 delta gr\p+ & ! second>ies 9 /> gr\p+1 z 9 fig4 #a1iid4 ,/>-delta ,connection4--,?is consi/s 9 connect+ ! prim>ies 9 /> gr\p+1 & ! second>ies 9 delta gr\p+1 z 9 fig4 #a1iie4 ,illu/ration3 ,,fig4 #a1iif4--,two phase trans=m] connections4 ,two s+le phase trans=m]s are us$ & connections made j z ?\gh ea* phase 7 an ord9>y s+le phase sy/em4 ,ques4 ,:at advantage has ! /> connection ov] ! delta connection8 ,ans4 ,ea* /> trans=m] is w\nd = only #eh ( ! l9e voltage4 ,9 high voltage transmission1 ?is admits ( mu* small] trans=m]s be+ built = high pressure ?an possible ) ! delta connection4 ,ques4 ,:at advantages are obta9$ ) ! delta connection8 ,ans4 ,:5 ?ree trans=m]s are delta connect$1 "o may be remov$ )\t int]rupt+ ! p]=mance ( ! circuit1 ! two rema9+ trans=m]s 9 a mann] act+ 9 s]ies to c>ry ! load ( ! miss+ trans=m]4 ,illu/ration3 ,,fig4 #a1iig4--,two phase trans=m] connections1 ) second>ies arrang$ = ?ree wire di/ribution1 ! prim>ies be+ indep5d5tly connect$ to ! two phases4 ,9 ! ?ree wire circuit1 ! middle or neutral wire is made ab\t "o-half l>g] ?an ea* ( ! two out] wires4 ,9 fig4 #a1iif x makes no diff]5ce :i* second>y t]m9al ( a trans=m] is connect$ to a giv5 second>y wire1 s long z no trans=m]s are us$ 9 p>allel4 ,= example1 ref]r+ to ! diagram1 ! left h& second>y t]m9al ( trans=m]1 ,a1 c\ld j z well be connect$ to ! l[] wire ( ! second>y phase1 ,a1 & its "r h& t]m9al connect$ to ! upp] wire1 ! only requirem5t be+ t ! two pairs ( ma9s %all n be mix$2 t is1 trans=m]1 ,a1 mu/ n be connect$ ) "o second>y t]m9al to phase1 ,a & ! o!r to phase1 ,b4 ,9 ! case %[n by fig4 #a1iig1 !re is n q s mu* fre$om 9 mak+ connections4 ,"o second>y t]m9al ( ea* trans=m] mu/ be connect$ to "o ( ! out] wires & ! o!r two t]m9als mu/ be bo? connect$ to ! l>g] middle wire ( ! second>y sy/em4 ,x makes no diff]5ce1 h[ev]1 :i* two second>y t]m9als are jo9$ & connect$ to ! middle wire s long z ! o!r t]m9al ( ea* trans=m] is connect$ to an out] wire ( ! second>y sy/em4 ,! desire to gu>d aga9/ a %ut d[n due to ! disabl+ ( "o trans=m] has l$ to ! ext5sive use ( ! delta connection1 especially = ! second>ies or l[ pressure side4 ,x %\ld be not$ t if "o trans=m] be disabl$1 ! effici5cy ( ! o!r two w be greatly r$uc$4 ,to op]ate a damag$ ?ree phase trans=m]1 ! damag$ w9d+s mu/ be sep>at$ electrically f ! o!r coils1 ! damag$ prim>y & second>y be+ respectively %ort circuit$ ^u !mselves4 ,ques4 ,:at k9ds ( trans=m]s are us$ = ?ree phase curr5t8 ,ans4 ,ei!r a ?ree phase trans=m]1 or a sep>ate s+le phase trans=m] = ea* phase4 ,illu/ration3 ,,fig4 #a1iih4--,?ree wire connections = trans=m] hav+ two second>y sections on diff]5t legs ( ! core4 ,if ! second>y t]m9als be connect$ up to a ?ree wire di/ribution1 z "h %[n diagrammatically1 x is advisable to make ! fuse1 #b1 9 ! middle wire1 consid]ably small] ?an necess>y to pass ! normal load 9 ei!r side ( ! circuit1 because1 %\ld ! fuse1 #a1 be bl[n1 ! second>y circuit ?r\gh ! section1 ,sa1 w be op51 & ! correspond+ half ( ! prim>y w9d+1 ,pa1 w h a mu* high] imp$ance ?an ! half ( ! prim>y w9d+1 ,pb1 ! inductance ( :i* is s ne>ly neutraliz$ by ! load on ! second>y w9d+1 ,sb4 ,! result w be t ! voltage ( ! prim>y section1 ,pa1 w be v mu* great] ?an t ( ! section1 ,pb1 & z ! sections are 9 s]ies ! curr5t mu/ be ! same ?r\gh bo? halves ( ! w9d+2 ! drop or diff]5ce ( pressure1 !re=e1 betwe5 ! t]m9als ( ,pa w be mu* high] ?an t betwe5 ! t]m9als ( ,pb1 consequ5tly1 ! second>y voltage ( ,sb w be greatly l[]$ & ! s]vice impair$4 ,z ! prim>y w9d+1 ,pa1 is design$ to take only "o-half ( ! total voltage1 ! unbalanc+ ref]r$ to w subject x to a consid]ably high] pressure ?an ! normal value2 consequ5tly1 ! magnetic d5sity 9 t leg ( ! trans=m] core w be mu* high] ?an normal1 & ! trans=m] w heat disa/r\sly4 ,if ! fuse1 #b1 9 ! middle wire be made1 say1 "o-half ! capacity ( ea* ( ! o!r fuses1 ?is condition w be reliev$ by ! bl[+ ( ?is fuse1 & z ! lamps 9 ! live circuit w\ld n be any:]e ne> c&le p[] if ! circuit rema9$ intact1 ! bl[+ ( ! middle fuse w n be any disadvantage to ! us] ( ! lamps4 ,"s mak]s avoid ! cont+5cy j describ$ by divid+ ea* second>y coil into two sections & connect+ a section on "o leg 9 s]ies ) a section on ! o!r leg ( ! core1 s t curr5t appli$ to ei!r pair ( ! second>y t]m9als w circulate ab\t bo? legs ( ! core4 ,illu/ration3 ,,figs4 #a1iii to #b1jjb4--,?ree phase delta1 & /> connections us+ ?ree trans=m]s4 ,!re are two ways ( connect+ up ! prim>ies & second>ies1 "o kn[n z ! delta connection1 & illu/rat$ diagrammatically by fig4 #a1iii1 & ! o!r kn[n z ! /> connection1 & illu/rat$ by fig4 #b1jja4 ,9 bo? diagrams ! l9e wires are lett]$1 ,a1 ,b & ,c4 ,fig4 #b1jjj %[s ! prim>ies & second>ies connect$ up delta fa%ion1 correspond+ to fig4 #a1iii1 & fig4 #b1jjb %[s !m connect$ up /> fa%ion1 correspond+ to fig4 #b1jja4 ,9 bo? ( ! latt] sket*es ! second>y wires are lett]$ to correspond ) ! respective prim>y wires4 ,:5 ! prim>ies are connect$ up delta fa%ion1 ! voltage betwe5 ! t]m9als ( ea* prim>y w9d+ is ! same z ! voltage betwe5 ! correspond+ two wires ( ! prim>y circuit1 & ! same is true ( ! second>y trans=m] t]m9als & circuit wires4 ,! curr5t1 h[ev]1 fl[+ ?r\gh ! trans=m] w9d+ is less ?an ! curr5t 9 ! l9e wire1 = ! reason t ! curr5t f any "o l9e wire divides betwe5 ! w9d+s ( two trans=m]s4 ,= example1 9 figs4 #a1iii & #b1jjj1 "p ( ! curr5t f ! l9e wire1 ,a1 w fl[ f ,a to ,b ?r\gh ! left h& trans=m]1 & "p f ,a to ,c ?r\gh ! "r h& trans=m]2 if ! curr5t 9 ! l9e wire1 ,a1 be #ajj amp]es1 ! curr5t 9 ea* trans=m] w9d+ w be #eg4gce amp]es4 ,:5 trans=m]s are connect$ up /> fa%ion1 z 9 figs4 #b1jja & #b1jjb1 ! curr5t 9 ea* trans=m] w9d+ is ! same z t 9 ! l9e wire to :i* x is connect$1 b ! voltage betwe5 ! t]m9als ( ea* trans=m] w9d+ is #eg4gce p] c5t4 ( ! voltage f wire to wire on ! circuit4 ,= example1 if ! prim>y voltage f ,a to ,b is #a1jjj volts1 ! voltage at ! t]m9als ( ! left h& trans=m] 7f ,a to ,j7 w be only #egg4ce volts1 & ! same is true ( ea* ( ! o!r trans=m]s if ! sy/em is balanc$4 ,^! /atem5ts apply1 ( c\rse1 to bo? prim>y & second>y w9d+s1 f :i* x w become evid5t t if ! ?ree trans=m]s ( a ?ree phase circuit be connect$ up /> fa%ion at ! prim>ies1 & delta fa%ion at ! second>ies1 ! second>y voltage w be l[] ?an if bo? sides are connect$ up /> fa%ion4 ,= example1 if ! trans=m]s be w\nd = a ratio ( #aj to #a1 & are connect$ up ) bo? prim>ies & second>ies alike1 no matt] :e!r x be delta fa%ion or /> fa%ion1 ! second>y voltage w be "o-t5? ( ! prim>y voltage2 b if ! prim>ies be connect$ up /> fa%ion on a #a1jjj volt circuit1 & ! second>ies be connect$ up delta fa%ion1 ! second>y voltage w be only #eg4gce volts1 in/ead ( #ajj volts4 ,! explanation ( ! diff]5ce betwe5 ! voltage p] coil 9 a delta sy/em & t 9 a /> sy/em is t 9 ! =m] ea* w9d+ is connect$ directly across f wire to wire2 :]eas 9 ! /> sy/em1 two w9d+s are 9 s]ies betwe5 ea* pair ( l9e wires4 ,! voltage ( ea* w9d+ is n r$uc$ to "o-half1 h[ev]1 because ! pressures are out ( phase ) ea* o!r1 be+ #abj1 or "o-?ird ( a cycle1 ap>t2 consequ5tly1 in/ead ( hav+ #ejj volts at ! t]m9als ( ea* coil 9 fig4 #b1jja ! voltage is #egg4ce4 ,! same explanation applies to ! curr5t values 9 a delta sy/em4 ,! curr5t phase betwe5 ,a & ,b1 9 fig4 #a1iii1 is #abj remov$ f t 9 ! w9d+ betwe5 ,a & ,c2 consequ5tly ! sum ( ! two curr5ts1 9 ! wire1 ,a1 is #a4gcb times ! curr5t 9 ea* wire2 or1 to /ate x ! opposite way1 ! curr5t 9 ea* w9d+ is #eg4gce ( ! curr5t 9 ! wire1 ,a4 ,x w be well = ! read] to rememb] t 9 all cases pressures diff]+ 9 phase :5 connect$ 9 s]ies1 comb9e accord+ to ! well-kn[n law ( ! p>allelogram ( =ces2 curr5ts diff]+ 9 phase1 & connect$ 9 p>allel1 comb9e accord+ to ! same law4 ,ques4 ,:at po9ts are to be consid]$ 9 *oos+ betwe5 ?ree phase & s+le phase trans=m]s = ! ?ree phase curr5t trans=mation8 ,ans4 ,no specific rule c be giv5 reg>d+ ! selection ( s+le phase or ?ree phase trans=m]s s9ce bo? designs are equally reliable2 local conditions w g5]ally det]m9e :i* type is pref]able4 ,! foll[+ g5]al rem>ks may1 h[ev]1 be helpful3 ,s+le phase trans=m]s are pref]able :]e only "o trans=m] gr\p is in/all$ & :]e ! exp5se ( a sp>e trans=m] w\ld n be w>rant$4 ,9 su* in/allations ! burn out ( "o phase ( a ?ree phase unit w\ld cause consid]able inconv5i5ce = ! reason t ! :ole trans=m] w\ld h to be disconnect$ f ! circuit be=e repairs c\ld be made4 ,if s+le phase trans=m]s be us$ & connect$ 9 delta on bo? prim>y & second>y1 ! damag$ trans=m] c be cut out ) a m9imum am\nt ( tr\ble & ! o!r two trans=m]s c be op]at$ at normal temp]ature op5 delta at #eh p] c5t4 ( ! normal capacity ( ! gr\p ( ?ree trans=m]s1 until ! ?ird unit c be replac$4 ,) a ?ree phase %ell type trans=m]1 if bo? ! prim>y & second>y be delta connect$1 tr\ble 9 "o phase w n prev5t ! use ( ! o!r two phases 9 op5 delta4 ,by %ort circuit+ bo? prim>y & second>y ( ! defective phase1 & cutt+ x out ( circuit ! magnetic flux 9 t section is entirely neutraliz$4 ,?is _c be done1 h[ev]1 ) any b delta connect$ %ell type trans=m]s4 ,illu/ration3 ,,fig4 #b1jjc4--;,diagram %[+ ?ree wire second>y connections ,g5]al ,electric 7type ,h7 trans=m]4 ,z w be se51 ! me?od adopt$ consi/s ( di/ribut+ equally1 on ea* side ( ! prim>y coil1 bo? halves ( ! second>y w9d+1 s t ea* second>y ?r\gh\t its l5g? is closely adjac5t to ! entire prim>y w9d+4 ,9 ord] to insure ! exact equality ( resi/ance & reactance 9 ! two second>y w9d+s necess>y to obta9 p]fect regulation ( ! two halves1 ! inside portion ( ! second>y w9d+ on "o side ( ! prim>y coil is connect$ 9 s]ies ) ! outside portion ( t on ! o!r side4 ,z a result1 ! drop ( voltage 9 ei!r side ( ! second>y "u any ord9>y conditions ( unbalanc$ load1 does n exce$ ! li/$ regulation drop4 ,?is p>ticul> arrangem5t is us$ because x is ! simple/ & be/ me?od = ?is con/ruction4 ,:]e a l>ge numb] ( ?ree phase trans=m]s c be us$1 x is g5]ally advisable to in/all ?ree phase units1 ! foll[+ advantages be+ 9 _! favor z comp>$ ) s+le phase units3 #a4 ,require less floor space ?an ?ree s+le phase units2 #b4 ,weigh less ?an ! s+le phase units2 #c4 ,simpl] connections1 z only ?ree prim>y & ?ree second>y leads are g5]ally br\ght out2 #d4 ,trans=m] pres5ts a symmetrical & compact appe>ance4 ,ques4 ,:at is ! "* ( ! con/ruction ( ?ree phase trans=m]s8 ,ans4 ,! ?ree phase trans=m] is practically simil> to t ( ! s+le phase1 except t some:at heavi] & l>g] p>ts are requir$ = ! core /ructure4 ,,comp>ison ,,( ,,air ,,bla/1 ,,wat] ,,cool$1 ,,& ,,oil ,,cool$ ,,trans=m]s ,air bla/ type ,wat] cool$ type ,oil cool$ type ---------------------------------------- ---------------------------- #a4 ,,co/ ---------------------------------------- ---------------------------- ,a4 ,fir/ co/ ,necess>ily m ,lea/ exp5sive ( all ,necess>ily m exp5sive ?an ! types4 exp5sive ?an ! air wat] cool$ type ( bla/ & wat] cool$ simil> rat+4 type ( simil> rat+4 ,b4 ,! in/allation is ,be+ heavi] ?an ! ,be+ heavi] ?an ! extremely simple4 air bla/ type1 ^! air bla/ & wat] trans=m]s1 z a cool$ type1 ^! ,moi/ure t may rule1 require heavi] trans=m]s require h collect$ on ! app>atus = heavi] app>atus = surfaces dur+ in/all+4 ,bo? in/all+4 ,bo? transportation trans=m] & tank trans=m] & tank or /orage %\ld be %\ld be ?or\ghly %\ld be ?or\ghly ?or\ghly dri$ out4 dri$ out be=e be+ dri$ out be=e be+ fill$ ) oil4 fill$ ) oil4 ,! oil is usually suppli$ 9 #ej gal4 h]metically seal$ /eel b>rels to m9imize possibility ( moi/ure dur+ transportation4 ---------------------------------------- ---------------------------- ,c4 ,auxili>y app>atus ,a duct1 or *amb]1 ,9 mo/ cases1 cool+ ,d n require cool+ ( consid]able size wat] may be obta9$ wat] or bl[]4 is requir$ "u ! ) suffici5t natural trans=m]s 9 ord] head4 ,h[ev]1 !re to conduct ! cool+are frequ5t cases 9 air to !m4 :i* x c be obta9$ only by ! ,a bl[] outfit = use ( pumps4 supply+ air is requir$4 ,a sy/em ( pip+ = ! cool+ wat] & oil dra9age is requir$1 ! co/ ( :i* dep5ds1 ( c\rse1 on ! /ation lay\t4 ,d4 ,ma9t5ance ,an occasional ,a wat] pump+ outfit ,no air or wat] clean+1 = :i* a w\ld possibly require circulation to dem& supply ( compress$ a trifle m att5tionatt5tion4 air at ab\t #bj lb4 ?an a bl[] outfit 9 pressure is :i* !re are no recomm5d$4 valves or pip+4 ,! bl[] outfit requires no m c>e ?an any o!r simil> app>atus4 #b4 ,,floor ,,space ---------------------------------------- ---------------------------- ,always requires space ,extra space only ,only require space = = cool+ app>atus4requir$ :5 auxili>y! trans=m] z no pump+ app>atus is extra app>atus is necess>y4 necess>y #c4 ,,location ---------------------------------------- ---------------------------- ,z ! trans=m]s ,trans=m]s are ,trans=m]s are are op5 at ! top completely enclos$ bcompletely enclos$ b !y %\ld n be location %\ld be su*location %\ld be su* locat$ :]e !re ist no wat] w fallt no wat] w fall mu* du/ or dirt nor on leads or bu%+s4 on leads or bu%+s4 :]e wat] f any s\rce is liable to ,! build+ %\ld be fall on !m4 well v5tilat$4 ,!re is no auxili>y app>atus4 ,! bl[] %\ld be ,location ( auxili>y s situat$ z to app>atus w dep5d obta9 clean dry air on ! /ation lay\t4 ( a temp]ature n great] ?an #gg ,fahr4 #d4 ,,g5]al ,,appe>ance ---------------------------------------- ---------------------------- ,t]m9al leads may ,leads are br\ght out ,leads are br\ght out be locat$ 9 ! ( ! top ( ! ( ! top ( ! base & ! air trans=m]s4 trans=m]s4 *amb] may be us$ = conduct+ & ,wat] cool+ pipes di/ribut+ ! are connect$ at ! connect+ wir+4 top 9 mo/ cases4 ,! abs5ce ( ov]head wir+ aids 9 simplify+ ! appe>ance ( ! /ation4 #e4 ,,op]ation ---------------------------------------- ------------------------------ ,equal reliability 9 all ?ree types4 ,:ile full load effici5cies are practically equal 9 ! ?ree designs1 x is necess>y to *ange ! proportion ( iron & copp] losses some:at z ! copp] loss ( ! air bla/ trans=m] is a small] "p ( its total loss ?an ( ! wat] cool$ & oil cool$ types4 ,z a result1 ! regulation ( ! air bla/ trans=m] is a trifle bett]4 #f4 ,,g5]al ---------------------------------------- ------------------------------ ,! above in=mation reg>d+ selection ( type is n applicable to air bla/ trans=m]s = circuits mat]ially 9 excess ( #cc1jjj volts4 ,on acc\nt ( ! great ?ickness ( ! solid insulation ne$$ & ! consequ5t difficulty 9 radiat+ heat f ! copp]1 x is impracticable to design ! air bla/ type = m ?an ?is voltage4 ,! oil imm]s$ designs are !re=e recomm5d$ = trans=m]s above #cc1jjj volts4 ,bo? oil cool$ & wat] cool$ types are available = all voltages1 be+ re/rict$ 9 ?is respect only by ! limitations ( transmission facilities4#h #h ,,note4--,no special f\ndations are necess>y = any type ( trans=m] o!r ?an a good1 ev5 floor1 hav+ suffici5t /r5g? to support ! weight4 ,illu/ration3 ,,figs4 #b1jjd to #b1jaa4--;,connections ( /&>d trans=m]s4 ,all /ock trans=m]s are w\nd = "s /&>d trans=mation ratio1 su* z #aj to #a1 b v>i\s leads are br\ght out by means ( :i* ratios ( #e1 #aj & #bj to #a may be obta9$ = "o trans=m]4 ,! figures %[ ! voltage comb9ations possible ) a /&>d trans=m]4 ,ques4 ,h[ are trans=m]s connect$ = f\r wire ?ree phase di/ribution8 ,ans4 ,:5 ! second>ies ( ?ree trans=m]s are /> connect$1 a f\r? wire may be run f ! neutral po9t1 ?us obta9+ ! f\r wire sy/em4 ,illu/ration3 ,,fig4 #b1jab4--,me?od ( det]m9+ core loss4 ,connect voltmet] & wattmet] z %[n 9 ! illu/ration to ! l[ t5sion side ( ! trans=m]4 ,by means ( a v>iable voltage trans=m] br+ ! appli$ voltage to ! po9t = :i* ! trans=m] is design$4 ,! wattmet] indicates directly ! core loss1 :i* includes a v small loss due to ! curr5t 9 ! copp]4 ,cautions4--#a4 ,make sure ( ! voltage & frequ5cy4 ,! manufactur]s' tabulat$ /atem5ts ref] to a def9ite voltage & frequ5cy & ^! h a decid$ influ5ce ^u ! core loss4 #b4 ,! high t5sion circuit mu/ rema9 op5 dur+ ! te/4 ,! voltage betwe5 any ma9 wire & ! neutral w be #eg p] c5t4 ( ! voltage betwe5 any two ma9 wires4 ,= g5]al di/ribution ?is sy/em is desirable1 requir+ less copp] & great] flexibility ?an o!r sy/ems4 ,?ree phase #bjj volt motors may be suppli$ f ! ma9 wires & #aae volt lamps connect$ betwe5 ea* ( ! ?ree ma9 wires & ! neutral2 if ! lamp load be v ne>ly balanc$ ! curr5t fl[+ 9 ! neutral wire w be v small1 z 9 ! case ( ! ord9>y ?ree wire direct curr5t sy/em4 ,h[ to ,te/ ,trans=m]s4--,! tr\bles incid5t to gas or wat] s]vice h _! p>allels 9 electric p[] di/ribution4 ,illu/ration3 ,,fig4 #b1jac4--,me?od ( det]m9+ copp] loss4 ,connect ammet] & wattmet] to high t5sion side ( trans=m] %ort circuit second>y leads1 z %[n 9 ! illu/ration1 & by means ( a v>iable voltage1 adju/ curr5t to ! full load value = :i* ! trans=m] is int5d$4 ,! wattmet] read+ %[s ! copp] loss at full load4 ,! full load prim>y curr5t ( any trans=m] is f\nd f ! foll[+ equation4 full load curr5t full load watts prim>y volts ,,example3 ,to f9d prop] full load curr5t on a five kw4 #b1bjj volt trans=m]1 divide #e1jjj watts by #b1bjj volts1 ! full load curr5t w !n be #b4bg amp]es4 ,a slight v>iation 9 prim>y curr5t greatly increases or decreases ! copp] loss4 ,rem>ks4--,copp] loss increases ) temp]ature because ! resi/ance ( ! metal rises4 ,d n ov]load ! curr5t coil ( ! wattmet]4 ,= great] accuracy ! ,i,r drop ( pot5tial me?od %\ld be us$4 ,companies engag$ 9 ! =m]1 cr$it a l>ge p]c5tage ( _! losses to leaky valves & defective ma9s4 ,! rem$y may involve heavy exp5se & ! loss is (t5 tol]at$ z ! less] ( two evils4 ,9 electric p[] di/ribution ! trans=m] takes 9 "p ! place ( ! valve & pipe sy/em4 ,an inf]ior or defective trans=m] usually treats bo? ! c5tral /ation & its cu/om]s badly1 be+ 9 ?is respect m imp>tial ?an ! gas or wat] pipe :i* may annoy b "o ( ! int]e/$ p>ties at a "t4 ,l a neglect$ or defective gas fixture a trans=m] c m5ace life1 fail+1 h[ev]1 to give ! w>n+ ! =m] gives1 & ) a m hidd5 ?reat on acc\nt ( its location4 ,illu/ration3 ,,fig4 #b1jad4--;,diagram ( connections = regulation te/4 ,connect trans=m] "u te/ to high t5sion supply circuit4 ,a second trans=m] ) same or o!r kn[n *ange ratio is also to be connect$ up1 z illu/rat$4 ,by means ( a d\ble pole d\ble ?r[ swit*1 ! voltmet] c be made to read ! pressure on ! second>y ( ei!r trans=m]4 ,suppos+ ! same *ange ratio x is evid5t t if bo? rema9 unload$ ! voltmet] w indicate ! same pressure4 ,a gradually increas+ lamp load up to ! limit ( ! trans=m] capacity1 w be att5d$ by a drop 9 pressure at ! t]m9als4 ,?is drop c be read z ! diff]5ce ( ! voltmet] indications1 & :5 express$ 9 p] c5t4 ( second>y voltage /&s = regulation4 ,rem>ks3 ,! auxili>y trans=m] is necess>y 9 ord] to make sure ( ! high t5sion l9e voltage4 ,a l>ge trans=m] "u te/ may cause prim>y drop 9 tak+ p[]4 ,?is mu/ be set d[n aga9/ x 9 te/+ regulation4 ,! second trans=m] gives notice ( su* drop1 :atev] be ! cause4 ,figs4 #b1jab to #b1jad us$ by c\rtesy ( ! ,moloney ,electric ,co4 ,ap>t f ?is1 correspond+ to an exasp]at$ cu/om] :o compla9s at home & to 8 fri5ds ( dim lamps1 black5$ lamps1 y w f9d 9 ! p[] /ation ! manag]1 :o1 also worri$ & 9 no bett] humor1 contemplates ! diff]5ce 9 met] read+s at ! end ( ! l9e4 ,8 bus9ess does n increase & w\ld n increase ev5 if he c\ld l[] ! rates1 :i* he _c d because ( ^! met] read+s4 ,he may be confid5t ( 8 eng9es & g5]ators1 & t 8 l9e is up & all "r1 b he v seldom kn[s :at ! trans=m]s are do+ on top ( ! poles4 ,p]haps he feels t ?is wa/e is s slight t x makes no mat]ial diff]5ce4 ,?is c be readily asc]ta9$ by means ( a set ( te/+ in/rum5ts4 ,p]haps ! trans=m]s 7 pur*as$ because ( _! attractive prices & nev] te/$4 ,wat]1 plumb+1 gas & /eam fitt+s are subject$ to te/4 ,:y n trans=m]s8 ,ev5 m s because trans=m]s take con/ant toll f ! company in/all+ !m1 :ile gas & wat] fitt+s1 once pass$1 are (f ! contractor's h&s4 ,! busy manag] has little "t = complicat$ treatises & monographs on electrical measurem5ts & ev5 h&books confront him ) =bidd+ =mul4 ,accord+ly ! me?ods ( trans=m] te/+1 :i* are v simple1 are illu/rat$ 9 ! accompany+ cuts4 ,manag]s ( electric p[] & light+ companies %\ld /udy !m c>efully4 ,illu/ration3 ,,fig4 #b1jae4--,wagn] c5tral /ation core type trans=m] repair unit consi/+ ( "o half set ( prim>y & second>y w9d+s toge!r ) ! section ( ! iron core ^u :i* ! coils are w\nd4 ,an ammet]1 voltmet] & wattmet] are requir$ to make ! te/s4 ,losses are small 9 good trans=m]s & h5ce ! in/rum5ts %\ld be accurate4 ,= ! same reason in/rum5ts %\ld be *os5 ( ! prop] capacity to give _! be/ read+s4 ,if !re be any d\bt ab\t ! te/+ in/rum5ts be+ correct1 !y %\ld be calibrat$ be=e be+ us$4 ,! te/+ circuits %\ld be prop]ly fus$ = ! protection ( ! in/rum5ts4 ,x is h>dly logical1 b a v common practice is to mi/ru/ met]s & to wat* !m closely1 :ile ! trans=m]s are guilty ( !ft un*all5g$1 & keep busily at x on a l>ge scale4 ,illu/ration3 ,,fig4 #b1jaf4--,moloney tubul> air draft oil fill$ trans=m]4 ,! case is made ( ca/ iron1 ) l>ge /eel tubes pass+ f ! bottom ?r\gh ! top4 ,9 op]ation ! air 9 ! tubes becomes hot & exp&s2 a draft is ?us produc$ :i* c>ries away consid]able heat4 ,trans=m] ,op]ation ) ,gr\nd$ ,second>y4--,! op]ation ( a trans=m] ) a gr\nd$ second>y has be5 approv$ by ! ,am]ican ,in/itute ( ,electrical ,eng9e]s1 & by ! ,national ,bo>d ( ,fire ,und]writ]s4 ,?is me?od ( op]ation effectually prev5ts a high voltage occurr+ ^u ! l[ t5sion wires 9 case ( a breakd[n or o!r electrical connections occurr+ betwe5 ! prim>y & second>y w9d+s4 ,illu/ration3 ,,fig4 #b1jag4--,moloney pressure trans=m] adapt$ = swit*bo>d "w 9 connection ) voltmet]s1 wattmet]s !1 etc41 9 sizes f #be to #ejj watts4 ,9 case ( a breakd[n )\t ! second>y gr\nd$1 any "o t\*+ a "p ( ! l[ t5sion sy/em1 su* z a lamp socket1 might receive ! full high pressure voltage4 ,) ! l[ t5sion gr\nd$1 ! fuse 9 ! high t5sion circuit w bl[ & ! fault be discov]$ ^u replac+ x4 ,trans=m] ,capacity = ,motors4--,! voltage regulation ( a well design$ trans=m] is )9 #c p] c5t4 ( its rat$ voltage on a non-inductive load su* z inc&esc5t lamps1 b :5 motors are connect$ to ! circuit _! self-induction causes a loss ( #e p] c5t4 or m1 & if ! load be fluctuat+1 x is bett] to use indep5d5t trans=m]s = ! motor1 :i* w prev5t consid]able fluctuations 9 ! inc&esc5t lamps4 ,arc lamps d n %[ slight voltage *anges z mu* z inc&esc5t lamps4 ,! prop] rat+ ( trans=m]s = two phase & ?ree phase induction motors is giv5 9 table on ! next page4 ,illu/ration3 ,,fig4 #b1jah4--,moloney curr5t trans=m] swit*bo>d or indoor type4 ,x is us$ ord9>ily = insulat+ an ammet]1 a curr5t relay1 ! curr5t coil ( a watt met] or watt h\r met] f a high t5sion circuit1 = r$uc+ ! l9e curr5t to a value suitable = ^! in/rum5ts4 ,a ?ree phase induction motor may be op]at$ f ?ree s+le phase trans=m]s or "o ?ree phase trans=m]4 ,:ile ! "o ?ree phase trans=m] greatly r$uces ! space & simplifies ! wir+1 ! use ( ?ree s+le phase trans=m]s is m flexible &1 9 case "o trans=m] burns out1 ! connection c be readily *ang$ s t two trans=m]s w op]ate ! motor at r$uc$ load until ! burn$ out trans=m] is replac$ or repair$4 ,illu/ration3 ,,fig4 #b1jai4--;,diagram %[+ a me?od ( op]at+ a ?ree phase motor on a two phase circuit1 us+ a trans=m] hav+ a tap made 9 ! middle ( ! second>y w9d+1 s z to get ! necess>y additional phase4 ,:ile ?is does n give a true balanc$ ?ree phase second>y1 x is close en\gh = motor "w4 ,9 ! above arrangem5t1 ! ma9 trans=m] supplies #ed p] c5t4 ( ! curr5t & ! o!r ) ! split w9d+ #df p] c5t4 ,x is well to all[ "o kil[att p] horse p[] ( ! motor 9 select+ ! size = ! trans=m]s1 except+ 9 ! small sizes :5 a little l>g] kil[att rat+ is f\nd to be ! mo/ desirable4 ,trans=m]s = ,two & ,?ree ,phase ,motors ---------------------------------------- -------------------- ,s+le phase trans=m] voltages ,deliv]$ ---------------------------------------- -------- voltage ( #aaj volt motor #bbj volt motor circuit ---------------------------------------- ------ ,prim>y ,second>y ,prim>y ,second>y ---------------------------------------- ----------------- #a1ajj #a1ajj #abb #a1ajj #bdd #b1bjj #b1bjj #abb #b1bjj #bdd ---------------------------------------- ----------------- ,v small trans=m]s %\ld n be us$1 ev5 :5 ! motor is l>ge comp>$ to ! "w x has to d1 z ! heavy />t+ curr5t may burn !m out4 ,! foll[+ tables give ! prop] sizes ( trans=m] = ?ree types ( induction motor & ! approximate curr5t tak5 by ?ree phase induction motors at #bbj volts4 ---------------------------------------- ------------------- ,capacities ( ,trans=m]s = ,induction ,motors ---------------------------------------- ------------------ ,kil[atts p] trans=m] ,size ( motor ---------------------------------------- - horse p[] ,two s+le ,?ree s+le ,"o ?ree phase phase phase trans=m]s trans=m]s trans=m] ---------------------------------------- ---------------- #a #j4f #j4f #b #a4e #a4j #b4j #c #b4j #a4e #c4j #e #c4j #b4j #e4j #g #d4j #c4j #g4e #aj #e4j #d4j #aj4j #ae #g4e #e4j #ae4j #bj #aj4j #g4e #bj4j #cj #ae4j #aj4j #cj4j #ej #be4j #ae4j #ej4j #ge #dj4j #be4j #ge4j #ajj #ej4j #cj4j #ajj4j ---------------------------------------- ---------------- ,curr5t tak5 by ,?ree ,phase ,induction ,motors at #bbj ,volts ---------------------------------------- ------------------ ,horse p[] ,approximate full ,horse p[] ,approximate full ( motor load curr5t ( motor load curr5t ---------------------------------------- ------------------ #a #c4b #bj #ej4 #b #f4j #cj #ge4 #c #i4j #ej #abe4 #e #ad4j #ge #ahe4 #aj #bg4j #ajj #bej4 #ae #dj4j #aej #cgj4 ---------------------------------------- ------------------ ,trans=m] ,connections = ,motors4--,fig4 #b1jbj %[s ! connection ( a ?ree phase s call$ delta connect$ trans=m] ) ! ?ree prim>ies connect$ to ! l9es lead+ f ! alt]nator & ! ?ree second>ies lead+ to ! motor4 ,! connections = a ?ree phase motor us+ two trans=m]s is %[n 9 fig4 #b1jba & is id5tical ) ! previ\s arrangem5t1 except t "o trans=m] is left out & ! o!r two made correspond+ly l>g]4 ,! copp] requir$ 9 any ?ree wire ?ree phase circuit = a giv5 p[] & loss is #ge p] c5t4 t necess>y ) ! two wire s+le phase or f\r wire two phase sy/em hav+ ! same voltage betwe5 l9es4 ,illu/ration3 ,,fig4 #b1jbj4--,?ree phase motor trans=m] connections2 ! s-call$ ,delta connect$ trans=m]s4 ,! connections ( ?ree trans=m]s = a l[ t5sion sy/em ( di/ribution by ! f\r wire ?ree phase sy/em are %[n 9 fig4 #b1jbb4 ,! ?ree trans=m]s h _! prim>ies jo9$ 9 delta connection & ! second>ies 9 ,y connection4 ,! ?ree upp] l9es ( ! second>y are ! ?ree ma9 ?ree phase l9es1 & ! l[e/ l9e is ! common neutral4 ,illu/ration3 ,,fig4 #b1jba4--,?ree phase motor connections us+ two trans=m]s4 ,! voltage across ! ma9 conductors is #bjj volts1 :ile t betwe5 ei!r ( !m & ! neutral is #aae volts2 #bjj volt motors %\ld be jo9$ to ! ma9s :ile #aae volt lamps are connect$ betwe5 ! ma9s & neutral4 ,! arrangem5t is simil> to ! ,edison ?ree wire sy/em & ! neutral c>ries curr5t only :5 ! lamp load is unbalanc$4 ,! voltage betwe5 ! ma9s %\ld be us$ 9 calculat+ ! size ( wires1 & ! size ( ! neutral wire %\ld be made 9 proportion to ea* ( ! ma9 conductors t ! light+ load is to ! total load4 ,illu/ration3 ,,fig4 #b1jbb4--;,delta-/> connection ( ?ree trans=m]s = l[ pressure1 ?ree phase1 f\r wire sy/em4 ,:5 lights only are us$ ! neutral %\ld be ! same z ! ma9 conductors4 ,! copp] requir$ 9 su* a sy/em = a giv5 p[] & loss is ab\t #cc4c p] c5t4 z comp>$ ) a two wire s+le phase sy/em or a f\r wire two phase sy/em us+ ! same voltage4 ,illu/ration3 ,,fig4 #b1jbc4--;,diagram ( trans=m] connections = motors on ! monocyclic sy/em4 ,monocyclic ,motor ,sy/em4--,motors on ! monocyclic sy/em are op]at$ f two trans=m]s connect$ z %[n 9 fig4 #b1jbc4 ,9 ! monocyclic sy/em ! s+le phase curr5t is us$ to supply ! light+ load & two wires only are necess>y1 b if a self-/>t+ induction motor be requir$1 a ?ird or teas] wire is br\ght to ! motor & two trans=m]s us$4 ,! teas] wire supplies ! qu>t] phase curr5t requir$ to />t ! motor1 :i* aft]w>ds runs z a s+le phase syn*ron\s motor & little or no curr5t fl[s ?r\gh ! teas] circuit z long z ! motor keeps 9 syn*ronism2 9 case x fall beh9d1 ! teas] curr5t t5ds to br+ x up to spe$ in/ead ( ! motor /opp+1 z w\ld be ! case ( a s+le phase motor4 ,illu/ration3 ,,fig4 #b1jbd4--,moloney flam+ auto type arc lamp trans=m] = #aaj volts prim>y to #ee volts second>y4 ,a hook 9 bottom ( case provides means = susp5sion ( lamp4 ,! trans=m] may be op]at$ on circuits f #ajj to #abj volts prim>y1 #ej to #fj volts second>y4 ,! second>y capacity is #h to #ab amp]es4 ,! voltage ( ! trans=m]s %\ld be te/$ by means ( a voltmet] or two inc&esc5t lamps jo9$ 9 s]ies1 be=e />t+ up ! motor1 to see if ! prop] trans=m] connections h be5 made & prev5t an excessive fl[ ( curr5t4 ,if "o ( ! trans=m]s be rev]s$ ! voltage w be almo/ d\bl$2 9 fact1 x is a good plan to *eck up all ! trans=m] connections ) ! voltmet] or lamps :i* w (t5 save a burn out4 ---------------------------------------- ----------------------- ,ratio ( trans=mation at no load ---------------------- ,arrangem5t ( ,prim>y ,= ) ) l9ks on ! coils circuit second>y second>y connect+ bo>d w be voltage coils 9 coils 9 connect$ normal at multiple s]ies4 9 ---------------------------------------- ---------------------- ,,illu/ration ,multiple #a1ajj #aj3a #e3a ---------------------------------------- ---------------------- ,,illu/ration ,multiple #a1ajj #i4je3a #d4eb3a ---------------------------------------- ---------------------- ,,illu/ration ,s]ies #b1bjj #bj3a #aj3a ---------------------------------------- ---------------------- ,,illu/ration ,s]ies #b1bjj #ai4je3a #i4e3a ---------------------------------------- ---------------------- ,,illu/ration ,s]ies #b1bjj #ah4a3a #i4je3a ---------------------------------------- ---------------------- ,,figs4 #b1jbe to #b1jbi4--;,diagrams ( ,wagn] trans=m] connection bo>d1 & table %[+ v>i\s arrangem5ts ( ! t]m9al l9ks1 correspond+ trans=mation ratios1 & suitable prim>y voltages4 99_/ ,illu/ration3 ,,fig4 #b1jcj4--;,in/allation ( a trans=m] on pole2 view %[+ me?od ( atta*m5t & disposition ( ! prim>y & second>y leads1 cut\ts1 etc4 ,illu/ration3 ,,fig4 #b1jca4--;,diagram ( /atic boo/] or regulat+ trans=m]4 ,x is us$ = regulat+ ! pressure on fe$]s4 ,9 ! figure1 ,b are ! /ation bus b>s1 ,r ! regulable trans=m]1 ,f ! two wire fe$]s1 & ,t a di/ant trans=m] fe$+ into ! l[ pressure ?ree wire di/ribut+ network ,n4 ,! two ends ( ! prim>y1 & "o end ( ! second>y ( ,r1 are connect$ to ! bus b>s z %[n4 ,! o!r end ( ! second>y1 z well z a numb] ( int]m$iate po9ts1 are jo9$ up to a multiple way swit* ,s1 to :i* "o ( ! fe$] conductors is atta*$1 ! o!r fe$] ma9 be+ connect$ to ! opposite bus b>4 ,z w be evid5t f ! figure1 by manipulat+ ,s extra volts may be add$ to ! bus b> pressure at w1 & ! drop along ,f comp5sat$ =4 ,r is a /ep trans=m]1 ! total second>y diff]5ce ( pressure be+ comp>atively small4 ,! above device possesses r s]i\s drawbacks1 9 t ! swit* ,s has to c>ry ! ma9 curr5t1 & t ! supply w\ld be /opp$ if ! swit* got out ( ord]4 ,kapp improv$ on ! arrangem5t by putt+ ! swit* 9 ! prim>y circuit4 ,,*apt] ,,liii ,,conv]t]s ,! alt]nat+ curr5t mu/ *ange to a direct curr5t 9 _m cases z 9 railroad "w because ! induction motor is n s satisfactory z ! direct curr5t s]ies motor & ! alt]nat+ curr5t s]ies motor is sl[ 9 com+ into g5]al use4 ,9 all k9ds ( electrolytic "w1 trans=mation mu/ be made1 & 9 _m cities :]e ! direct curr5t sy/em 0 />t$1 x is /ill cont9u$ = local di/ribution1 b ! l>ge ma9 /ations g5]at+ alt]nat+ curr5ts & frequ5tly locat$ "s di/ance away f ! c5t] ( di/ribution h replac$ a numb] ( small c5tral /ations4 ,trans=mation may be made by any ( ! foll[+ me?ods3 #a4 ,rot>y conv]t]s2 #b4 ,motor g5]ator sets2 #c4 ,a,m]cury vapor rectifi]s2 #d4 #i;,electrolytic rectifi]s4 #i ,,note4--,rectifi]s are expla9$ 9 detail 9 ,*apt] ,,liv4 ,/rictly speak+1 a conv]t] is a revolv+ app>atus = conv]t+ alt]nat+ curr5t into direct curr5t or vice v]sa2 x is usually call$ a rot>y conv]t] & is to be di/+ui%$ f ! o!r me?ods m5tion$ above4 ,broadly1 h[ev]1 a conv]t] may be consid]$ z any species ( app>atus = *ang+ electrical en]gy f "o =m into ano!r4 ,accord+ to ! /&>dization rules ( ! ,a4 ,i4 ,e4 ,e4 conv]t]s may be classifi$ z3 #a4 ,direct curr5t conv]t]s2 #b4 ,syn*ron\s conv]t]s2 #c4 ,motor conv]t]s2 #d4 ,frequ5cy conv]t]s2 #e4 ,rot>y phase conv]t]s4 ,illu/ration3 ,,figs4 #b1jcb & #b1jcc4--;,gramme r+ dynamo & alt]nator armatures illu/rat+ conv]t] op]ation4 ,! curr5t g5]at$ by ! dynamo is assum$ to be #ajj amp]es4 ,n[1 suppose1 an armature simil> to fig4 #b1jcb to be revolv+ 9 a simil> field1 b let its w9d+s be connect$ at two diametrically opposite po9ts to two slip r+s on ! axis1 z 9 fig4 #b1jcb4 ,if driv5 by p[]1 x w g5]ate an alt]nat+ curr5t4 ,z ! maximum voltage betwe5 ! po9ts t are connect$ to ! slip r+s w be #ajj volts1 & ! virtual volts 7z measur$ by a voltmet]7 betwe5 ! r+s w be #gj4g 7 #ajj #b71 if ! p[] appli$ 9 turn+ ?is armature is to be #aj kil[atts1 & if ! circuit be non-inductive1 ! output 9 virtual amp]es w be #aj1jjj #gj4g #ada4d4 ,if ! resi/ances ( ea* ( ! armatures be negligibly small1 & if !re be no frictional or o!r losses1 ! p[] giv5 out by ! armature :i* s]ves z motor w j suffice to drive ! armature :i* s]ves z g5]ator4 ,if bo? armatures be m\nt$ on ! same %aft & plac$ 9 equal fields1 ! comb9ation is a motor dynamo4 ,9 actual ma*9es ! v>i\s losses are met by an increase ( curr5t to ! motor4 ,s9ce ! armatures are id5tical1 & z ! simil>ly plac$ w9d+s are pass$ ?r\gh id5tical magnetic fields1 "o w9d+ ) prop] connections to ! slip r+s & commutator w d = bo?4 ,9 ?is case only "o field is ne$$2 su* a ma*9e is call$ a conv]t]4 ,a direct curr5t conv]t] conv]ts f a direct curr5t to a direct curr5t4 ,a syn*ron\s conv]t] 7commonly call$ a rot>y conv]t]7 conv]ts f an alt]nat+ curr5t to a direct curr5t4 ,a motor conv]t] is a comb9ation ( an induction motor ) a syn*ron\s conv]t]1 ! second>y ( ! =m] fe$+ ! armature ( ! latt] ) curr5t at "s frequ5cy o!r ?an ! impress$ frequ5cy2 t is1 x is a syn*ron\s conv]t] 9 comb9ation ) an induction motor4 ,a ,frequ5cy ,conv]t] 7pref]ably call$ a frequ5cy *ang]7 conv]ts alt]nat+ curr5t at "o frequ5cy into alt]nat+ curr5t ( ano!r frequ5cy ) or )\t a *ange 9 ! numb] ( phases or voltages4 ,a ,rot>y ,phase ,conv]t] *anges alt]nat+ curr5t ( "o or m phases into alt]nat+ curr5t ( a diff]5t numb] ( phases1 b ( ! same frequ5cy4 ,illu/ration3 ,,fig4 #b1jcd4--;,diagram ( r+ w\nd s+le phase rot>y conv]t]4 ,x is a comb9ation ( a syn*ron\s motor & a dynamo4 ,! w9d+ is connect$ to ! commutators 9 ! usual way1 & divid$ into two halves by leads connect+ segm5ts #ahj ap>t to collector r+s4 ,a bipol> field is %[n = simplicity2 9 practice ! field is multipol> & en]giz$ by direct curr5t4 ,rot>y ,conv]t]s4--,! syn*ron\s or rot>y conv]t] consi/s ( a syn*ron\s motor & a direct curr5t g5]ator comb9$ 9 "o ma*9e4 ,x resembles a direct curr5t g5]ator ) an unusually l>ge commutator & an auxili>y set ( collector r+s4 ,ques4 ,9 g5]al1 h[ does a rot>y conv]t] op]ate8 ,ans4 ,on ! collector r+ side x op]ates z a syn*ron\s motor1 :ile on ! commutator side1 z a dynamo4 ,its design 9 c]ta9 respects is a compromise betwe5 alt]nat+ curr5t & direct curr5t practice mo/ noticeably ) respect to ! numb] ( poles & spe$4 ,ques4 ,^u :at does ! spe$ dep5d8 ,ans4 ,s9ce ! input side consi/s ( a syn*ron\s motor1 ! spe$ is gov]n$ by ! frequ5cy ( ! alt]nat+ curr5t suppli$1 & ! numb] ( poles4 ,illu/ration3 ,,fig4 #b1jce4--;,diagram ( two phase rot>y conv]t]4 ,?is is id5tical ) ! s+le phase ma*9e ) ! exception t ano!r pair ( collector r+s are add$1 & connect$ to po9ts on ! w9d+ at "r angles to ! fir/1 giv+ f\r bru%es on ! alt]nat+ side = ! two phase curr5t4 ,! pressure w be ! same = ea* phase z 9 ! s+le phase rot>y4 ,neglect+ losses ! curr5t = ea* phase w be equal to ! direct curr5t #a _/ #b direct curr5t 4#gjg4 ,fig4 #b1jcd is a diagram ( a r+ w\nd rot>y conv]t]4 ,?is /yle w9d+ is %[n to simplify ! explanation4 ,9 practice drum w\nd armatures are us$1 ! op]ation1 h[ev]1 is ! same4 ,) ?is simple ma*9e ! foll[+ pr9ciples c be demon/rat$3 #a4 ,if ! coil be rotat$1 alt]nat+ curr5ts c be tak5 f ! collector r+s & x is call$ an alt]nator4 #b4 ,by connect+ up ! wires f ! commutator segm5ts1 a direct curr5t w fl[ 9 ! ext]nal circuit mak+ a dynamo4 #c4 ,two sep>ate curr5ts c be tak5 f ! armature1 "o supply+ alt]nat+ curr5t & ! o!r direct curr5t2 su* a ma*9e is call$ a d\ble curr5t g5]ator4 #d4 ,if a direct curr5t be s5t 9 ! armature coil ?r\gh ! commutator1 ! coil w beg9 to rotate z 9 a motor & an alt]nat+ curr5t c be tak5 out ( ! collector r+s4 ,su* an arrangem5t is call$ an inv]t$ rot>y conv]t]4 #e4 ,if ! ma*9e be br\ght up to syn*ron\s spe$ by ext]nal means & !n suppli$ ) alt]nat+ curr5t at ! collector r+s1 !n if ! direction ( ! curr5t ?r\gh ! armature coil & ! pole piece h ! prop] magnetic relation1 ! coil w cont9ue to rotate 9 syn*ronism ) ! curr5t4 ,a direct curr5t c be tak5 f ! commutator1 & :5 us$ ?us1 ! ma*9e is call$ simply a rot>y conv]t]4 ,illu/ration3 ,,fig4 #b1jcf4--;,diagram ( ?ree phase rot>y conv]t]4 ,9 ?is type1 ! w9d+ is tapp$ at ?ree po9ts #abj di/ant f ea* o!r1 & leads connect$ ) ! correspond+ commutator segm5ts4 ,illu/ration3 ,,figs4 #b1jcg to #b1jda4--,v>i\s rot>y conv]t] & trans=m] connections4 ,fig4 #b1jcg two phase connections2 fig4 #b1jch ?ree phase delta connections2 fig4 #b1jci ?ree phase ,y or /> connections2 fig4 #b1jdj six phase delta connections2 fig4 #b1jda six phase ,y connections4 ,ques4 ,:at is ! relation betwe5 ! impress$ alt]nat+ pressure & ! direct pressure at ! commutator8 ,ans4 ,! ratio betwe5 ! impress$ alt]nat+ pressure & ! direct curr5t pressure giv5 out is !oretically con/ant1 !re=e1 ! direct pressure w always be z #a to 4#gjg = s+le phase conv]t]s or if ! pressure ( ! ma*9e us$ above indicate #ajj volts at ! direct curr5t end1 x w indicate #gj4g volts at ! alt]nat+ curr5t side ( ! circuit4 ,ques4 ,"n two diff]5t classes ( conv]t]4 ,ans4 ,s+le phase & polyphase4 ,ques4 ,:at is ! advantage ( polyphase conv]t]s8 ,ans4 ,9 ! majority ( cases two or ?ree phase conv]t]s are us$ on acc\nt ( economy ( copp] 9 ! transmission l9e4 ,ques4 ,h[ is ! armature ( a polyphase conv]t] connect$8 ,ans4 ,simil> to t ( an alt]nator ) ei!r delta or ,y connections4 ,figs4 #b1jcg to #b1jda %[ v>i\s conv]t] connections betwe5 ! collector r+s & commutator4 ,fig4 #b1jcg indicates h[ ! armature is tapp$ = two phase connections4 ,fig4 #b1jch %[s ?ree phase delta connections1 & fig4 #b1jci ! ?ree phase ,y or /> connections4 ,six phase delta & ,y connections are frequ5tly us$ z %[n 9 fig4 #b1jdj & fig4 #b1jda1 bo? ( :i* require two second>y coils 9 ! trans=m]1 "o set ( :i* is rev]s$1 s z to supply ! curr5t 9 ! prop] direction4 ,ques4 ,) respect to ! wave1 :at is ! relation betwe5 ! direct & alt]nat+ pressures8 ,ans4 ,! direct curr5t voltage w be equal to ! cre/ ( ! pressure wave :ile ! alt]nat+ voltage w dep5d on ! virtual value ( ! maximum voltage ( ! wave accord+ to ! connections employ$4 ,table ( ,alt]nat+ ,curr5t & ,voltage 9 ,t]ms ( ,direct ,curr5t 7,accord+ to ,/e9metz7 ---------------------------------------- -------------------------------- ,,direct ,,s+le ,,two ,,?ree ,,curr5t ,,phase ,,phase ,,phase ---------------------------------------- -------------------------- ,,volts ,,betwe5 ,,collector ,,r+ #a ,,& ,,neutral ,,po9t #a_/7bb74ceda_/7bb74ced #a_/7bb74ced ---------------------------------------- -------------------------- ,,volts ,,betwe5 ,,adjac5t #a #a_/b4gjg 4#e #c_/7bb74fab ,,collector ,,r+s ---------------------------------------- -------------------------- ,,amp]es #a #ba4dad #a_/b4gjg 7#bb7_/c4idc ,,p] ,,l9e ---------------------------------------- -------------------------- ,,amp]es ,,betwe5 #a #ba4dad 4#e 7#bb7_/7cc74ede ,,adjac5t ,,l9es ---------------------------------------- -------------------------------- ---------------------------------------- --------------------- ,,six ,,twelve n ,,phase ,,phase ,,phase ---------------------------------------- ---------------- ,,volts ,,betwe5 ,,collector ,,r+ ,,& ,,neutral ,,po9t#a_/7bb74ceda_/7bb74ceda_/7bb74ced ---------------------------------------- ---------------- ,,volts ,,betwe5 ,,adjac5t #a_/7bb74ced 4#ahc 7,,s97_/n77_/#b ,,collector ,,r+s ---------------------------------------- ---------------- ,,amp]es #b_/c4dgb 4#bcf 7#bb7_/n ,,p] ,,l9e ---------------------------------------- ---------------- ,,amp]es ,,betwe5 #b_/c4dgb 4#dee 7#b,,s97_/n77_/n ,,adjac5t ,,l9es ---------------------------------------- --------------------- ,9 a s+le phase rot>y1 ! value ( ! direct pressure is #a to 4#gjg1 !re=e a rot>y :i* mu/ supply #fjj volts direct curr5t mu/ be suppli$ by #fjj 4#gjg #dbd volts alt]nat+ curr5t4 ,= ?ree phase rot>ies ! ratio is #a to 4#fab1 or 9 ord] to produce #fjj volts direct curr5t1 #fjj 4#fab #cfg volts on ! alt]nat+ curr5t side ( ! rot>y is requir$4 ,illu/ration3 ,,fig4 #b1jdb4--,we/+h\se rot>y conv]t] armature coils4 ,^! are w\nd f b> copp] & are int]*angeable4 ,! armature coils are heavily insulat$ to )/& ! te/s specifi$ 9 ! /&>dization rules ( ! ,am]ican ,in/itute ( ,electrical ,eng9e]s4 ,fig4 #b1jcd %[s a complete diagram ( ! electrical connections4 ,a s+le phase rot>y is illu/rat$ s z to simplify ! wir+4 ,! table ( ,/e9metz on page #a1dfd gives ! values ( ! alt]nat+ volts & amp]es 9 units ( direct curr5t4 ,ques4 ,h[ is ! voltage ( a rot>y v>i$ on ! direct curr5t side8 ,ans4 ,pressure or pot5tial regulators are put 9 ! high t5sion alt]nat+ curr5t circuit & may be regulat$ by small motors op]at$ f ! ma9 swit*bo>d or op]at$ by h&4 ,ques4 ,:at is ! advantage ( unity p[] factor = rot>y conv]t]s8 ,ans4 ,x prev5ts ov]heat+ :5 ! rot>y is deliv]+ its full load 9 watts4 ,ques4 ,:at greatly influ5ces ! p[] factor ( ! high t5sion l9e8 ,ans4 ,! /r5g? ( ! magnetic field4 ,illu/ration3 ,,fig4 #b1jdc4--,we/+h\se rot>y conv]t] armature spid]4 ,x is made ( ca/ iron or ca/ /eel4 ,! dovetail grooves are ma*9$ 9 ! feet or ends ( ! arms & 9 ^! slots ! lam9ations =m+ ! armature coil engage4 ,ques4 ,does v>iation ( ! field /r5g? mat]ially affect ! voltage8 ,ans4 ,no4 ,s9ce v>iation ( ! field /r5g? does n mat]ially affect ! voltage1 by adju/+ ! resi/ance 9 s]ies ) ! magnetic circuit1 ! /r5g? ( ! field c be *ang$ & ! p[] factor kept #a or ne>ly #a z diff]5t loads are ?r[n on & (f ! rot>y4 ,ques4 ,:at is ! effect ( a field too /rong or too weak8 ,ans4 ,if too /rong1 a lead+ curr5t is produc$1 & if too weak1 ! curr5t lags1 bo? ( :i* r$uce ! p[] factor & are objectionable4 ,usually !re is a p[] factor met] connect$ up 9 ! ma9 g5]at+ /ation & "o also 9 ! rot>y sub/ation1 & x is ! duty ( ! att5dant at ! sub/ation to ma9ta9 ! prop] p[] factor4 ,ques4 ,:at is ! ord9>y range ( sizes ( rot>ies8 ,ans4 ,f #c kw4 to #c1jjj kw4 ,illu/ration3 ,,fig4 #b1jdd4--;,equaliz] connections ( ,we/+h\se rot>y conv]t]4 ,! armature coils are cross connect$ at po9ts ( equal voltage & taps are l$ out f ! w9d+ at suitable po9ts to ! slip r+s4 ,?is con/ruction insures a uni=m armature saturation bel[ ea* pole piece & elim9ates "o cause ( sp>k+ at ! commutator4 ,ques4 ,:at is ! g5]al con/ruction ( a rot>y conv]t]8 ,ans4 ,x is built simil> to a dynamo ) ! addition ( suitable collector r+s connect$ to ! armature w9d+s at po9ts hav+ ! prop] phase relations4 ,/&>d rot>y conv]t]s h be5 develop$ = #be & #fj cycles4 ,! /&>d railway ma*9es are comp\nd w\nd1 ! s]ies field be+ design$ = a comp\nd+ ( #fjj volts at no load & full load :5 suppli$ f a s\rce ( con/ant pressure ) n m ?an #aj p] c5t4 resi/ance drop & ) #bj to #cj p] c5t4 reactance 9 ! circuit4 ,! l>ge size ma*9es are usually w\nd = six phase op]ation4 ,illu/ration3 ,,figs4 #b1jde & #b1jdf4--,we/+h\se pole con/ruction = conv]t]s4 ,fig4 #b1jde1 pole )\t w9d+s2 fig #b1jdf1 pole ) w9d+s4 ,poles are built up ( /eel lam9ations held toge!r ) rivets4 ,projections on ! inn] ends ( ! poles =m seats = ! field coils & hold !m 9 position4 ,copp] damp]s set 9 slots 9 ! pole faces insure /able op]ation4 ,rot>y conv]t]s = railway s]vice are almo/ inv>iably comp\nd w\nd4 ,! s]ies w9d+s are =m$ ( b>e copp] /rap4 ,! %unt w9d+s are ( insulat$ copp] /rap or wire4 ,spaces betwe5 coil turns & sections are provid$ = v5tilation4 ,comp\nd+ ( ,rot>y ,conv]t]s4--,comp\nd+ is desirable :]e ! load is v>iable1 su* z is ! case ) int]urban railway sy/ems4 ,! purpose ( ! comp\nd+ is to comp5sate automatically = ! drop due to l9e1 trans=m]1 & conv]t] imp$ance4 ,on acc\nt ( ! l[ p[] factor caus$ by ov] comp\nd+1 & ! fact t sub/ations are cu/om>ily connect$ to ! trolley at its ne>e/ po9t )\t fe$] resi/ance1 ov] comp\nd+ is n recomm5d$4 ,an adju/able %unt to ! s]ies field is provid$ ) ea* ma*9e4 ,%unt w\nd conv]t]s are satisfactory = sub/ations 9 l>ge cities & simil> in/allations :]e due to ! l>g] numb] ( c> units dem&+ p[]1 ! load is m ne>ly con/ant4 ,ratio ( ,conv]sion4--,! relation betwe5 ! alt]nat+ & direct curr5t voltages v>ies slightly 9 diff]5t ma*9es1 due to diff]5ces 9 design4 ,! be/ op]at+ conditions exi/ :5 ! desir$ direct curr5t voltage is obta9$ ) unity p[] factor at ! conv]t] t]m9als :5 load$4 ,illu/ration3 ,,fig4 #b1jdg4--,we/+h\se rot>y conv]t] bru% rigg+ %[+ me?od ( brac+ ! bru%es4 ,! bru%es are support$ by a rigid ca/ iron rock] r+ :i* fits accurately 9 ! frame4 ,a h&:eel worm & screw arrangem5t = %ift+ ! bru%es is provid$4 ,ca/ iron arms bolt$ to1 b insulat$ f ! r+s1 c>ry ! rods on :i* ! bru% hold]s are m\nt$4 ,bru% hold]s are ( brass ca/ 9 "o piece1 ( ! slid+ type & h braid$ copp] %unts4 ,bru% t5sion is adju/able4 ,illu/ration3 ,,fig4 #b1jdh4--,we/+h\se commutat+ pole rot>y conv]t]4 ,! con/ruction details are sub/antially ! same z = ! railway conv]t]1 ) exception ( ! commutat+ poles4 ,! application ( commutat+ pole conv]t]s is p>ticul>ly desirable :]e special requirem5ts su* z great ov]load capacity or l>ge capacity & l[ voltage enable !m to %[ to ! greate/ advantage4 ,commutat+ poles z appli$ to rot>y conv]t]s fulfill ! same functions z 9 ! m famili> applications to dynamos & motors4 ,t is1 ! commutat+ pole insures sp>kless commutation f no load to heavy ov]loads ) a fix$ bru% position4 ,bru% %ift+ devices are n furni%$ on commutat+ pole conv]t]s4 ,commutat+ pole rot>y conv]t]s = railway s]vice are normally arrang$ = automatic comp\nd+ :i* is effect$ by ! prop] comb9ation ( s]ies excitation & inductance betwe5 ! g5]ator & ! rot>y conv]t]4 ,?is inductance is normally includ$ 9 ! trans=m] b 9 special cases may be p>tly 9 a trans=m] & p>tly 9 a sep>ate reactance4 ,x is possible to produce by ?is means a slight increase 9 ! direct curr5t voltage provid$ ! voltage drop 9 ! alt]nat+ curr5t l9e be n excessive4 ,usually x is s arrang$ t ! comp\nd+ t c be obta9$ is j suffici5t to ov]come ! alt]nat+ curr5t l9e voltage drop4 ,! /&>d ,we/+h\se me?od ( />t+ is alt]nat+ curr5t self-/>t+4 ,) ?is me?od ( self-/>t+1 ! bru%es ( a commutat+ pole rot>y conv]t] mu/ be lift$ f ! commutator dur+ ! />t+ op]ation to prev5t sp>k+4 ,a me*anical device1 z %[n 9 fig4 #b1jej1 is provid$ :i* accompli%es ?is4 ,) direct curr5t or motor />t+ a bru% lift+ device is n necess>y4 ,ques4 ,^u :at does ! ratio ( conv]sion dep5d8 ,ans4 ,^u ! numb] ( phases & me?od ( connect+ ! w9d+s4 ,= s+le phase or two phase ma*9es x is #a to 4#g2 = ?ree phase1 #a to 4#fab1 or six phase1 #a to 4#g or #a to 4#fac dep5d+ ^u ! k9d ( connection us$ = ! trans=m]4 ,= example1 a two phase rot>y receiv+ alt]nat+ curr5t at #dbf volts w deliv] direct curr5t at #fjj volts1 :ile a ?ree phase rot>y receiv+ alt]nat+ curr5t at #cfg volts w deliv] direct curr5t at #fjj volts4 ,illu/ration3 ,,fig4 #b1jdi4--;,commutat+ pole ( ,we/+h\se commutat+ pole rot>y conv]t]4 ,! commutat+ poles are simil> 9 g5]al con/ruction to ! ma9 poles4 ,! coils are ( b>e copp] /rap w\nd on edge4 ,v5tilat+ spaces are provid$ betwe5 ! pole & coil & betwe5 turns4 ,! copp] w9d+ is b>e except = a few turns at ea* end4 ,insulat+ bolts reta9 ! turns 9 _! prop] position4 ,ques4 ,:at difficulty w\ld be enc\nt]$ if o!r ratios ( conv]sion ?an ^? giv5 above 7 requir$8 ,ans4 ,an armature ) a s+le w9d+ c\ld n be us$4 ,x w\ld be necess>y to use a ma*9e ) two di/9ct armature w9d+s or else a motor g5]ator set4 ,ques4 ,:at *ange 9 voltage is necess>y betwe5 a conv]t] & ! alt]nator :i* furni%es ! curr5t8 ,ans4 ,! voltage mu/ be r$uc$ to ! prop] value by a /ep d[n trans=m]4 ,voltage ,regulation4--,z ! ratio ( ! alt]nat+ to ! direct curr5t voltage ( a conv]t] is practically con/ant1 means mu/ be provid$ to comp5sate = voltage v>iation due to *anges ( load 9 ord] to ma9ta9 ! direct curr5t pressure con/ant4 ,illu/ration3 ,,fig4 #b1jej4--,we/+h\se bru% lift+ device = commutat+ pole rot>y conv]t]4 ,a rack is atta*$ to ea* bru% z %[n4 ,into ?is rack ! spr+ h+$ lift+ hook ( ! rais+ device engages only :5 ! lift+ lev] is %ift$ t[>d ! rais$ position4 ,! lift+ arrangem5t is indep5d5t ( ! bru%es dur+ normal runn+1 s x c 9 no way affect ! op]ation ( ! ma*9e4 ,ea* bru% is m]ely rais$ & l[]$ )9 its own hold] s ! bru% position or commutation is n alt]$4 ,!re are sev]al me?ods ( do+ ?is1 z by3 #a4 ,%ift+ ! bru%es 7objectionable72 #b4 ,split pole me?od2 #c4 ,regulat+ pole me?od2 #d4 ,reactance me?od2 #e4 ,multi-tap trans=m] me?od2 #f4 ,syn*ron\s regulator4 ,%ift+ ! ,bru%es4--,7 x n = ! difficulties enc\nt]$1 ?is w\ld be a mo/ conv5i5t me?od ( voltage regulation1 s9ce by ?is proc$ure ! direct curr5t voltage may be v>i$ f maximum to z]o4 ,x is1 h[ev]1 n practical because ( ! excessive sp>k+ produc$ :5 ! bru%es are %ift$ out ( ! neutral plane4 ,illu/ration3 ,,figs4 #b1jea to #b1jec4--,woodbridge split pole rot>y conv]t]4 ,ea* pole is split into ?ree sections & provid$ ) w9d+s z indicat$ 9 fig4 #b1jea4 ,:5 excit$ z 9 fig4 #b1jeb1 ! commutator voltage is at its highe/ value2 :5 excit$ z 9 fig4 #b1jec1 ! commutator voltage is l[4 ,! *ange 9 commutator voltage = con/ant collector r+ voltage is 9 virtue ( ! prop]ty ( rot>y conv]t]s t ! ratio ( ^! two voltages is a function ( ! wid? ( ! pole arc4 ,split ,pole ,me?od4--,9 ord] to ov]come ! difficulty enc\nt]$ 9 %ift+ ! bru%es ! split pole me?od 0 devis$ by ,woodbridge 9 :i* ea* field pole is split into two or ?ree p>ts4 ,! effect ( ?is is ! same z %ift+ ! bru%es except t no sp>k+ results4 ,! o!r "p is arrang$ s t its excitation may be v>i$1 ?us %ift+ ! resultant plane ( ! field ) respect to ! direct curr5t bru%es4 ,"o ( ^! p>ts is p]man5tly excit$ & x produces ne> its edge ! fr+e ( field necess>y = sp>kless commutation4 ,regulat+ ,pole ,me?od4--,z appli$ to ! rot>y conv]t] regulat+ poles fulfill ! same functions z commutat+ or int]poles 7see page #che7 on motors & dynamos1 t is1 !y insure sp>kless commutation f no load to heavy ov]loads ) a fix$ bru% position4 ,illu/ration3 ,,fig4 #b1jed4--;,g5]al ,electric regulat+ pole rot>y conv]t]4 ,! field /ructure is divid$ into two p>ts1 a ma9 pole & a regulat+ pole4 ,! ratio betwe5 ! voltages on ! direct curr5t & alt]nat+ curr5t sides may be readily v>i$ by v>y+ ! excitation ( ! regulat+ poles1 ! only auxili>y app>atus requir$ be+ a field rheo/at = controll+ ! excit+ curr5t4 ,:]e automatic regulation is requir$1 ma*9es may be provid$ ) comp\nd w9d+s1 or automatic field regulators may be us$ responsive to ei!r voltage or curr5t4 ,^! conv]t]s are adapt$ = a v>iety ( purposes :]e a v>iable conv]sion ratio is requir$1 ei!r to ma9ta9 con/ant ,d4 ,c4 voltage ) v>y+ ,a4 ,c4 voltage or to v>y ! ,d4 ,c4 voltage z requir$4 ,conv]t]s may be op]at$ inv]t$ :]e x is requir$ to furni% con/ant or v>iable ,a4 ,c4 voltage f a ,d4 ,c4 s\rce4 ,:]e conv]t] & inv]t$ conv]t] op]ation are desir$1 an opposite direction ( rotation is requir$ = ! inv]t$ op]ation4 ,conv]t]s ( ?is type are built 9 capacities f #cjj kw4 up to #c1jjj kw41 & con/ruct$ to give a voltage range betwe5 #bdj & #cjj volts1 to cov] ! usual light+ circuit requirem5ts4 ,9 design1 !y are simil> to /&>d rot>y conv]t]s1 ) ! exception t ! regulat+ poles are locat$ next to ! ma9 pole pieces & a slightly diff]5t =m ( pole piece bridge is us$ = ! ma9 poles1 9 ord] to all[ ! auxili>y poles to be readily remov$ or assembl$4 ,! regulat+ poles are us$ 9 ord] to v>y ! ratio betwe5 ! alt]nat+ curr5t collector r+s & ! direct curr5t side )\t ! use ( auxili>y app>atus su* z induction regulators or dial swit*es :i* involve complicat$ connections & _m additional wires4 ,! regulat+ poles are arrang$ ) suitable connection s t ! curr5t ?r\gh !m c be rais$1 l[]$ or rev]s$4 ,illu/ration3 ,,fig4 #b1jee4--;,detail ( ,we/+h\se commutat+ pole rot>y conv]t] bru%1 %[+ rack4 ,! bru% lift+ me*anism & its op]ation is expla9$ 9 fig4 #b1jej4 ,! *>act]i/ics ( ! regulat+ pole conv]t] be+ novel1 a detail$ explanation ( ! pr9ciples involv$ is giv5 to facilitate a cle> und]/&+ ( its op]ation4 ,consid] a ma*9e ) a field /ructure z %[n 9 fig4 #b1jef resembl+ 9 appe>ance a ma*9e ) commutat+ poles1 b ) ! bru%es s set t "o ( ! regulat+ poles adds its flux to t ( "o ma9 pole1 cutt+ ! inductors betwe5 two direct curr5t bru%es4 ,! regulat+ pole is %[n ) a wid? equal to #bj p] c5t4 ( t ( ! ma9 pole4 ,to obta9 def9ite figures1 x w be assum$ t ! ma*9e at normal spe$1 ) ! ma9 poles excit$ to normal d5sity1 b ) no excitation on ! regulat+ poles1 gives #bej volts direct curr5t pressure4 ,!n ) ea* regulat+ pole excit$ to ! same d5sity z ! ma9 poles1 & ) a pol>ity correspond+ to t ( ! ma9 pole 9 ! same section betwe5 bru%es1 ! direct curr5t pressure w rise to #cjj volts at ! same spe$1 s9ce ! total flux cutt+ ! inductors 9 "o direction betwe5 bru%es has be5 increas$ #bj p] c5t4 ,if1 on ! o!r h&1 ! excitation ( ! regulat+ poles be rev]s$ & increas$ to ! same d5sity z t ( ! ma9 poles1 ! direct curr5t pressure w fall to #bjj volts1 s9ce 9 ?is case ! regulat+ poles give a rev]se pressure1 t is1 a pressure oppos+ t g5]at$ by ! ma9 poles4 ,illu/ration3 ,,fig4 #b1jef4--;,diagram ( field ( regulat+ pole conv]t] illu/rat+ pr9ciples expla9$ 9 ! accompany+ text4 ,n[1 if ! ma*9e be equipp$ ) collector r+s1 t is1 if x be a conv]t]1 ?is me?od ( v>y+ ! direct curr5t voltage f #bjj to #cjj volts does n give ne>ly z great a v>iation ( ! alt]nat+ curr5t voltage2 9 fact1 ! latt] voltage w be ! same :5 deliv]+ #bjj volts z :5 deliv]+ #cjj volts direct curr5t pressure1 if ! field excitation be ! same4 ,?is may be se5 by ref]5ce to fig4 #b1jeg1 :i* is a diagram ( ! alt]nat+ curr5t voltage develop$ 9 ! armature w9d+s by ! two sets ( poles4#aj #aj ,,note4--,9 ! ,burnham split pole rot>y conv]t]1 ea* pole is divid$ into only two sections1 "o l>g] ?an ! o!r4 ,a ma9 %unt w9d+ is arrang$ on ! l>ge sections1 & a w9d+ = provid+ ! voltage regulation is plac$ on ! o!r section4 ,:5 ! curr5t is s5t ?r\gh ?is latt] w9d+ 9 "o direction ! voltage is rais$1 :5 9 ! o!r direction ! voltage is l[]$4 ,! horizontal l9e ,,oa repres5ts ! alt]nat+ curr5t voltage g5]at$ by ! ma9 poles1 alone1 ) ! regulat+ poles unexcit$1 t is1 :5 deliv]+ #bej volts direct curr5t pressure4 ,= a six phase conv]t] ,,oa measures ab\t #ahj volts diametrically1 t is1 betwe5 electrically opposite collector r+s4 ,if n[ ! regulat+ poles be excit$ to full /r5g?1 to br+ ! direct curr5t pressure up to #cjj volts1 ! alt]nat+ curr5t voltage g5]at$ by ! regulat+ poles w be #ij degrees out ( phase ) t g5]at$ by ! ma9 poles 7s9ce !y are plac$ midway betwe5 ! ma9 poles71 & w be ab\t #dj volts z %[n by ! l9e ,,ab4 ,! resultant alt]nat+ curr5t volts across ! collector r+s w be repres5t$ by ! l9e ,,ob ) a value equal to #ahd4 ,illu/ration3 ,,fig4 #b1jeg4--,voltage diagram = regulat+ pole conv]t] illu/rat+ pr9ciples expla9$ 9 ! accompany+ text4 ,aga91 if ! regulat+ poles be rev]s$ at full /r5g?1 to cut ! direct curr5t pressure d[n to #bjj volts1 ! alt]nat+ curr5t voltage ( ! ma9 & regulat+ poles w be ,,oa & ,,ac respectively1 giv+ ! resultant ,,oc equal to ,,ob ) a value ( #ahd volts4 ,accord+ly1 ! direct curr5t pressure may be ei!r #bjj or #cjj volts ) ! same alt]nat+ curr5t pressure1 & if ! ma9 field be kept con/ant1 ! direct curr5t pressure may range betwe5 #bjj or #cjj volts1 :ile ! alt]nat+ curr5t pressure v>ies only betwe5 #ahj & #ahd volts4 ,! alt]nat+ curr5t pressure c be kept con/ant ?r\gh ! full range ( direct curr5t voltage by *ang+ ! ma9 field s z always to give an equal & opposite flux *ange to t ( ! regulat+ field4 ,a con/ant total flux may ?us be obta9$ equal to ! radius ( ! arc ,,bc1 fig4 #b1jeg4 ,9 ?is case ! l9e ,,oa1 repres5t+ ! ma9 field /r5g?1 w equal ,,ob :5 ! regulat+ field is n excit$1 & #bej volts c only be obta9$ at ?is adju/m5t4 ,?is me?od ( op]ation gives unity p[] factor ) a con/ant impress$ pressure ( #ahd volts alt]nat+ curr5t ) a range ( direct curr5t voltage f #bjj to #cjj volts4 ,illu/ration3 ,,figs4 #b1jeh & #b1jei4--;,diagrams illu/rat+ ! effect on ! alt]nat+ curr5t voltage due to v>y+ ! regulat+ field /r5g? 7( a ma*9e proportion$ accord+ to fig4 #b1jfj71 f a d5sity equal to t 9 ! ma9 poles to ! same d5sity rev]s$1 ! ma9 field /r5g? rema9+ con/ant4 ,! ,d4 ,c4 voltage 9 ?is case v>ies f #cj p] c5t4 above t produc$ by ! ma9 field alone to #cj p] c5t4 bel[1 or f #cbe to #age volts1 :ile ! ,a4 ,c4 voltage v>ies only f #bjj to #age volts4 ,to keep ! ,a4 ,c4 voltage con/ant ) su* a ma*9e ! ma9 field mu/ be /r5g!n$ z ! regulat+ field is weak5$ or rev]s$ to r$uce ! ,d4 ,c4 voltage4 ,?is /r5g!n+ increases ! core loss p>ticul>ly on l[ direct curr5t voltages1 :i* h[ev]1 are r>ely requir$1 h5ce a ma*9e proportion$ z 9 fig4 #b1jfj1 w\ld n be op]at$ ?r\gh s wide a range z #age to #cbe volts4 ,assume t ! range is #bdj to #cjj volts1 & t at ! highe/ voltage1 bo? ma9 & regulat+ fields h ! same d5sity1 pres5t+ to ! armature practically "o cont9u\s pole face ( uni=m flux int5sity4 ,! diagram ( ,a4 ,c4 compon5t voltages to give con/ant ,a4 ,c4 resultant voltage across ! r+s = ! case1 is %[n 9 fig4 #b1jei4 ,at #cjj volts ,d4 ,c41 ! ma9 field produces an ,a4 ,c4 voltage ,,oa1 & ! regulat+ field1 a voltage ,,ab1 ) a resultant ,,ob1 equal to ab\t #bjj volts ,a4 ,c4 ,at #bgj volts ,d4 ,c41 ! ma9 field produces an ,a4 ,c4 voltage ,,oa1 & a regulat+ field voltage ,,ab1 giv+ a resultant ,a4 ,c4 voltage ,,ob1 equal to #bjj volts4 ,simil>ly1 at #bdj volts ,d4 ,c41 ! ma9 field produces an ,a4 ,c4 voltage ,,oa1 & ! regulat+ field 7n[ rev]s$7 produces ! rev]se voltage ,,ab1 giv+ ! resultant ,,ob aga9 equal to #bjj volts4 ,x w be not$ t1 !oretically ! ma9 field /r5g? mu/ be increas$ ab\t #ae p] c5t4 above its value at #cjj volts ,d4 ,c4 9 ord] to keep ! ,d4 ,c4 voltage at #bej volts4 ,ques4 ,:]e %\ld ! regulat+ poles be locat$ = be/ results8 ,ans4 ,a bett] con/ruction is obta9$ by plac+ !m clos] to ! correspond+ ma9 pole1 z 9 fig4 #b1jfj1 ?an :5 spac$ midway betwe5 ! ma9 poles z 9 fig4 #b1jef4 ,ques4 ,:5 ! regulat+ poles are spac$ z 9 fig4 #b1jfj1 :at is ! effect on ! direct curr5t voltage8 ,ans4 ,! effect is ! same z = ! midway position 7fig4 #b1jef7 except = magnetic leakage f ! ma9 poles to ! regulat+ poles :5 ! latt] is oppos$ to ! =m]1 t is1 :5 ! direct curr5t voltage is be+ depress$4 ,illu/ration3 ,,fig4 #b1jfj4--;,diagram illu/rat+ placem5t ( regulat+ poles4 ,9 practice ma*9es are n built z indicat$ diagrammatically 9 fig4 #b1jef1 t is1 ) regulat+ poles spac$ midway betwe5 ! ma9 poles1 because a bett] con/ruction is obta9$ by plac+ ! regulat+ pole clos] to ! correspond+ ma9 pole1 z %[n above4 ,ques4 ,:at is ! effect on ! alt]nat+ curr5t voltage8 ,ans4 ,x is some:at alt]$ z expla9$ 9 figs4 #b1jeh & #b1jei4 ,reactance ,me?od4--,?is consi/s 9 ins]t+ inductance 9 ! supply circuit & runn+ ! load curr5t ?r\gh a few turns ar\nd ! field cores4 ,?is me?od is sometimes call$ comp\nd+1 & z x is automatic x is g5]ally us$ :]e !re is a rapidly fluctuat+ load4 ,illu/ration3 ,,fig4 #b1jfa4--,we/+h\se #cjj kw41 #a1ejj volt1 ?ree phase1 #be cycle1 commutat+ pole rot>y conv]t]4 ,! illu/ration %[s cle>ly ! commutat+1 & ma9 poles & ! relative sizes1 also arrangem5t ( ! t]m9al connections4 ,if a lagg+ curr5t be pass$ ?r\gh an inductance1 ! collector r+ voltage w be l[]$1 b w be rais$ 9 case ( a lead+ curr5t4 ,! degree ( excitation gov]ns ! *ange 9 ! phase ( ! curr5t to ! conv]t]1 ! excitation1 9 turn1 be+ regulat$ by ! load curr5t4 ,accord+ly ) s]ies inductance1 ! effect ( ! s]ies coils on ! field ( ! conv]t] is q simil> to t ( ! comp\nd+ ( ! ord9>y railway dynamo4 ,multi-tap ,trans=m] ,me?od4--,! employm5t ( a v>iable ratio /ep d[n trans=m] = voltage regulation is a non-automatic me?od ( control &1 accord+ly1 is n desirable except 9 cases :]e ! load is fairly con/ant ov] consid]able p]iods ( "t4 ,x requires no special explanation4 ,illu/ration3 ,,fig4 #b1jfb4--,me*anical oscillator & spe$ limit device ( ,we/+h\se commutat+ pole rot>y conv]t]4 ,x automatically prev5ts ! armature ( ! conv]t] rema9+ 9 "o position & ?us n all[+ bru%es to we> grooves 9 bo? commutator & collector r+s4 ,! oscillator is a self-conta9$ device c>ri$ at "o end ( ! %aft4 ,! op]at+ p>ts consi/ ( a h>d5$ /eel ball & a /eel plate ) a circul> ball race1 back$ by a spr+4 ,! ma*9e is s in/all$ ) a slight incl9ation t[>d ! end c>ry+ ! oscillator4 ,z ! armature revolves ! ball is c>ri$ upw>d & ow+ to ! conv]g5ce ( ! /eel race & %aft face1 ! spr+ is compress$4 ,! reaction ( ! spr+ =ces ! armature away f its natural position & all[s ! ball to drop back to ! l[e/ po9t ( ! race4 ,syn*ron\s ,boo/] ,me?od4--,?is consi/s ( comb9+ ) ! conv]t] a revolv+ armature alt]nator hav+ ! same numb] ( poles4 ,ques4 ,h[ is ! w9d+ ( ! boo/] alt]nator armature connect$8 ,ans4 ,x is connect$ 9 s]ies ) ! input circuits on ! conv]t]4 ,illu/ration3 ,,fig4 #b1jfc4--,we/+h\se #b1jjj kw41 #bgj volt1 direct curr5t1 #f phase1 #afg ,r4,p4,m41 syn*ron\s boo/] rot>y conv]t]1 hav+ a voltage range f #bcj to #caj volts4 ,x consi/s ( a /&>d rot>y conv]t] 9 comb9ation ) a revolv+ armature alt]nator m\nt$ on ! same %aft ) ! rot>y conv]t] & hav+ ! same numb] ( poles4 ,by v>y+ ! field excitation ( ! alt]nator1 ! alt]nat+ curr5t voltage impress$ on ! rot>y conv]t] c be increas$ or decreas$ z desir$4 ,! direct curr5t voltage deliv]$ by ! conv]t] is !reby v>i$ accord+ly4 ,! pr9ciple ( op]ation ( ! boo/] conv]t] is !re=e v simple & easily und]/ood4 ,x is simply a comb9ation ( two /&>d pieces ( electrical app>atus1 accord+ly !re are incorporat$ 9 x no details ( con/ruction ess5tially diff]5t f ^? enc\nt]$ 9 /&>d rot>y conv]t]s & alt]nators4 ,! only novelty is 9 _! comb9ation4 ,! frames may be support$ ei!r f ! rot>y conv]t] frame1 z 9 ! small units1 or f ! b$ plate1 z 9 ! l>g] ones4 ,a syn*ron\s boo/] conv]t] c be built1 if necess>y1 ) a v]tical %aft to satisfy special floor space & head room requirem5ts4 ,ques4 ,h[ are ! field w9d+s connect$8 ,ans4 ,!y are ei!r f$ ) curr5t regulat$ by means ( a motor op]at$ field circuit rheo/at1 or jo9$ 9 s]ies ) ! commutator leads ( ! conv]t]4 ,illu/ration3 ,,fig4 #b1jfd4--;,armature ( ,we/+h\se syn*ron\s boo/] conv]t]4 ,heavy ca/ yokes =m ! frames4 ,!y are proportion$ to rigidly support ! lam9at$ /eel field poles4 ,! poles are fa/5$ to ! frame ) ?r\gh bolts4 ,a lift+ hook is provid$ on all frames4 ,! b$ plates are 9 "o piece = ! small] ma*9es b two piece b$ plates are us$ = ! l>g] ones4 ,! be>+s are r+ oil+ & h babbitt we>+ surfaces t are r5ewable4 ,illu/ration3 ,,fig4 #b1jfe4--,we/+h\se field frames & be>+s = syn*ron\s boo/] rot>y conv]t]4 ,! frames consi/ ( heavy ca/ yokes4 ,! poles are fa/5$ to ! frames ) ?r\gh bolts4 ,! b$ plate is 9 "o piece = ! small ma*9es & 9 two pieces = ! l>ge ones4 ,ques4 ,= :at s]vice is ! syn*ron\s boo/] me?od desirable8 ,ans4 ,= any application :]e a relatively wide v>iation 9 direct curr5t voltage is necess>y4 ,x is p>ticul>ly desirable = 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 ,illu/ration3 ,,fig4 #b1jff4--;,g5]al ,electric motor g5]ator set consi/+ ( #b1cjj volt syn*ron\s motor & #eej volt dynamo4 ,motor ,g5]ator ,sets4--,! ord9>y rot>y conv]t] is ! mo/ economical ma*9e = conv]t+ alt]nat+ curr5ts into direct curr5ts1 & :]e slight v>iations 9 ! direct curr5t voltage is necess>y1 !y are mo/ly us$ on acc\nt ( _! high effici5cy1 & because !y are compact4 ,illu/ration3 ,,fig4 #b1jfg4--;,g5]al ,electric motor g5]ator set consi/+ ( #bcj volt induction motor & #abe volt dynamo4 ,9 _m c5tral /ations :]e !y supply a great v>iety ( app>atus1 ! motor g5]ator sets are employ$ z ! g5]ator is indep5d5t ( ! alt]nat+ curr5t l9e voltage & any degree ( voltage regulation c be p]=m$4 ,motor ,g5]ator ,comb9ations4--,! foll[+ comb9ations ( motor g5]ators are made & us$ to suit local conditions3 ,syn*ron\s motor dynamo ,induction motor dynamo ,direct curr5t motor dynamo ,direct curr5t motor alt]nator ,syn*ron\s motor alt]nator ,induction motor alt]nator ,illu/ration3 ,,fig4 #b1jfh4--;,g5]al ,electric g5]ator set1 z in/all$ = ! ,clevel& ,electric ,illum9at+ ,company1 ,clevel&1 ,ohio4 ,x consi/s ( #aa1dca volt motor & #bge volt g5]ator4 ,spe$1 #cfj revolutions p] m9ute4 ,/&>d practice has adopt$ high t5sion alt]nat+ curr5t = transmission sy/ems1 b direct curr5t di/ribution is v frequ5tly us$4 ,?is is p>ticul>ly true :]e alt]nat+ curr5t app>atus has be5 introduc$ 9 old direct curr5t light+ sy/ems4 ,! syn*ron\s motor or ! induction motor connect$ to a g5]ator /&s next 9 importance to ! rot>y conv]t] because x is easy to op]ate & ! pressure may be *ang$ by a rheo/at plac$ 9 ! field circuit ( ! g5]ator4 ,! l9e wires c>ry+ full voltage c usually be connect$ direct to ! motor & ?us d away ) ! necess>y /ep-d[n trans=m] requir$ by ! rot>y4 ,ques4 ,:at is ! behavior ( a rot>y conv]t] :5 hunt+8 ,ans4 ,x is liable to fla% ov] at ! direct curr5t bru%es1 :i* is common 9 high frequ5cy conv]t]s :]e !re are a great numb] ( poles & ! bru%es are necess>ily spac$ close toge!r ar\nd ! commutator4 ,ques4 ,is ?is fault s pron\nc$ ) motor g5]ator sets8 ,ans4 ,! motor g5]ator op]at+ on a high frequ5cy circuit1 ! g5]ator c be design$ ) a few poles & ! bru%es set f> ap>t :i* w greatly r$uce ! *ance ( fla%+ ov]4 ,a syn*ron\s motor w drive a g5]ator at a con/ant spe$ dur+ *anges 9 load on x1 & by hav+ a field regulat+ resi/ance x c be us$ to improve ! p[] factor ( ! sy/em4 ,:5 an induction motor is us$ its spe$ drops (f sl[ly z ! load comes on ! g5]ator1 & x is necess>y to regulate ! voltage ( ! g5]ator by means ( a field rheo/at1 or comp\nd w\nd ma*9es may be us$4 ,:ile an induction motor requires no sep>ate excitation ( ! field magnets l ! syn*ron\s motor1 its effect on ! p[] factor ( ! sy/em is undesirable4 ,al?\gh x is seldom necess>y to conv]t direct curr5t to alt]nat+1 su* an arrangem5t ( a direct curr5t motor driv+ an alt]nator is (t5 ju/ifi$ 9 place ( an inv]t$ rot>y conv]t]1 z 9 ?is case ! alt]nat+ curr5t voltage c be *ang$ indep5d5t ( ! direct curr5t voltage4 ,! rac+ ( an inv]t$ rot>y "u a heavy inductive load or %ort circuit does n take place 9 motor g5]ator set m5tion$ above4 ,illu/ration3 ,,fig4 #b1jfi4--;,g5]al ,electric frequ5cy *ang] set1 consi/+ ( a #aa1jjj volt syn*ron\s motor ) direct connect$ excit] & a #b1cjj volt alt]nator4 ,frequ5cy ,*ang+ ,sets4--,a frequ5cy ( #be cycles is g5]ally us$ on railway "w & 9 l>ge cities us+ ! ,edison ?ree wire sy/em1 & z a #be cycle curr5t is n desirable = electric light+ x is necess>y to *ange x to #fj cycles by means ( a frequ5cy *ang] %[n 9 fig4 #b1jfi = di/ribution 9 ! outly+ di/ricts4 ,! two ma*9es 9 ?is comb9ation are ( ! same con/ruction1 only ! syn*ron\s motor w\ld h eight poles & h ! #be cycle curr5t pass+ ?r\gh x1 :ile ! g5]ator w\ld h #bj poles & produce #fb cycles p] second at #cjj revolutions p] m9ute4 ,by supply+ ! motor ) #bd cycles1 ! g5]ator w\ld produce #fj cycles4 ,illu/ration3 ,,fig4 #b1jgj4--;,g5]al ,electric f\r unit frequ5cy *ang] set consi/+ ( a #aa1jjj volt syn*ron\s motor1 #ac1bjj volt alt]nator1 #bej volt excit]1 & #ddj volt />t+ induction motor4 ,:]e p>allel op]ation is requir$ betwe5 syn*ron\s motor driv5 frequ5cy *ang]s1 a me*anical adju/m5t is necess>y betwe5 ! fields or armatures ( ! alt]nator & motor to obta9 equal division ( ! load4 ,! adju/m5t c be obta9$ by %ift+ ! keyway1 or by special cradle con/ruction4 ,9 ! latt] me?od1 "o ma*9e is bolt$ to a cradle fa/5$ to ! base4 ,by tak+ out ! bolts1 ! frame c be turn$ ar\nd ?r\gh a small angle relative to ! cradle & !re=e to ! armature frame ( ! o!r ma*9e1 :5 ! bolts c be replac$4 ,x w be se5 f ! figure t ! sep>ate excit] is fa/5$ on ! base plate & has its armature directly connect$ to ! %aft4 ,p>allel ,op]ation ( ,frequ5cy ,*ang]s4--,x is v difficult to con/ruct two or m frequ5cy *ang]s & jo9 !m to syn*ron\s motors s t ! curr5t wave ( "o ma*9e w be 9 phase ) ! o!r1 s9ce ! spe$ ( ! motor w dep5d on ! frequ5cy ( ! l9e & be indep5d5t ( ! load ?r[n on x4 ,:5 alt]nators are run 9 p>allel1 if "o ma*9e lag beh9d1 ! o!r c>ries ! load ) ! result t ! lightly load$ ma*9e w spe$ up & get 9 /ep ) ! o!r1 or 9 o!r words a syn*roniz+ curr5t w fl[ betwe5 ! two alt]nators & t5d to keep !m 9 prop] relation ) respect to phase & load4 ,illu/ration3 ,,fig4 #b1jga4--;,diagram ( ,cascade motor g5]ator set or motor conv]t]1 z x is call$ 9 ,engl& :]e x is us$ ext5sively = electric railway "w4 ,9 ! diagram ( motor armature w9d+1 "s ( ! connections are omitt$ = simplicity4 ,! w9d+s are ,y connect$1 & z !y are f$ by wires jo9$ to ! slip r+s at ! "r & c5t]1 ! re/ ( ! p[] passes to ! conv]t] w9d+s back to rotor w9d+ & out to ! slip r+s s t "p ( ! p[] ent]s ! rotor & "p ?r\gh ! conv]t]4 ,cascade ,conv]t]4--,?is piece ( app>atus 0 introduc$ by ,arnold & ,la ,c\r4 ,briefly1 x consi/s ( a comb9ation ( an induction motor hav+ a w\nd armature & a dynamo1 ! armatures be+ plac$ on ! same %aft4 ,! w9d+s are jo9$ 9 cascade1 t is1 9 s]ies ) ^? ( ! armature ( ! induction motor4 ,! l9e supplies ?ree phase curr5ts at high voltage direct to ! field ( ! induction motor & drives x1 g5]at+ 9 x curr5ts at a l[] voltage dep5d+ on ! ratio ( ! w9d+s4 ,illu/ration3 ,,fig4 #b1jgb4--;,g5]al ,electric %unt w\nd boo/] set4 ,sets ( ?is class are us$ 9 railway /ations to raise ! pressure ( ! fe$]s ext5d+ to di/ant po9ts ( ! sy/em1 = /orage batt]y *>g+ & regulation1 & 9 connection ) ! ,edison ?ree wire light+ sy/em4 ,! design ( ! v>i\s sets is closely dep5d5t ^u _! application4 ,boo/] sets are con/ruct$ 9 ei!r s]ies or %unt w\nd types & !y may be arrang$ = ei!r automatic or h& regulation1 dep5d+ on ! nature ( ! s]vice requir$4 ,:]e !re are a numb] ( light+ fe$]s connect$ & run at full load = only a %ort "t ea* day x w g5]ally be economical to in/all boo/]s r ?an to inve/ 9 additional fe$] copp]4 ,x is important1 h[ev]1 to consid] ea* case :]e ! "q ( in/all+ a boo/] arises1 z a sep>ate problem1 & to det]m9e if ! value ( ! p[] lo/ repres5ts an am\nt l[] ?an ! int]e/ *>ge on ! extra copp] necess>y to deliv] ! same voltage )\t ! use ( a boo/]4 ,"p ( ! curr5t ?us g5]at$ 9 ! armature passes into ! armature ( ! dynamo & is conv]t$ by ! commutator into direct curr5t z 9 a rot>y conv]t]1 b is also increas$ by ! curr5t induc$ 9 ! w9d+ ( ! dynamo armature4 ,illu/ration3 ,,fig4 #b1jgc4--;,g5]al ,electric #i4e kw4 #a1jjj ,r4,p4,m4 balanc] set4 ,?is is a =m ( direct curr5t comp5sator1 ! units ( :i* x is compos$ may be alt]nately motor or g5]ator1 & ! second>y circuit is int]connect$ ) ! prim>y4 ,balanc] sets are widely us$ to provide ! neutral ( ,edison ?ree wire light+ sy/ems4 ,!y are also in/all$ = p[] s]vice 9 connection ) ! use ( #bej volt motors on a #ejj volt s]vice or #abe volt motors on a #bej volt s]vice4 ,al?\gh ! balanc] set may be manufactur$ = m ?an "o int]m$iate voltage1 ! ,g5]al ,electric ,company recomm5ds ! ?ree wire sy/em z x is simpl]4 ,! motors may be m equally divid$ & ! res]ve m>g9 ( ! motor is m cons]vative = t class ( "w requir+ increase 9 torque ) decrease 9 spe$4 ,! voltage ( ! sy/em be+ giv51 ! capacity ( a ?ree wire balanc] set is fix$ by ! maximum curr5t ! neutral wire is requir$ to c>ry4 ,?is figure is a m def9ite specification ( capacity ?an a /atem5t 9 p] c5t4 ( unbalanc$ load4 ,z design$ = p[] "w & g5]ally = light+ s]vice1 ! bru%es ( ea* ma*9e are set at ! neutral po9t 9 ord] to get ! be/ results = op]at+ alt]nately ei!r z a g5]ator or motor4 ,:]e ! *anges ( balance are s gradual z to p]mit ( h& adju/m5t if desir$1 a consid]able increase 9 output is obta9able4 ,ques4 ,at :at spe$ does ! ma*9e run8 ,ans4 ,assum+ equal numb]s ( pole1 ! armatures rotate at a spe$ correspond+ to "o half ! circuit frequ5cy4 ,illu/ration3 ,,figs4 #b1jgd & #b1jge4--;,g5]al ,electric *>g+ sets4 ,fig4 #b1jgd set consi/s ( dynamo & direct curr5t motor2 fig4 #b1jge set consi/s ( a dynamo & alt]nat+ curr5t motor4 ,fig4 #b1jgd set is equipp$ ) #abe volt1 %unt w\nd dynamo & #bcj or #eej volt motor & range 9 capacity f 4#abe kw4 to #ac kw41 ! spe$ v>y+ f #b1bej ,r4,p4,m4 9 ! 4#abe kw4 set to #ibe ,r4,p4,m4 9 ! #ac kw4 set ) #bcj volt motor4 ,bo? motor & dynamo h ! same type & size ( frame2 ^! are bolt$ toge!r & =m a compact & symmetrical outfit1 no base be+ necess>y4 ,sets ( ! type %[n 9 fig4 #b1jge range 9 capacity f 4#b kw4 to #aj kw4 & are equipp$ ) #abe volt %unt w\nd dynamo & #aaj1 #bbj1 #ddj or #eej volt two or ?ree phase motors4 ,if desir$ !y c be furni%$ ) s+le phase motors w\nd = #aaj or #bbj volts4 ,! spe$ ( ?is type is #a1hjj ,r4,p4,m4 ,:5 a motor g5]ator set is us$ to *>ge only "o batt]y1 ! ins]tion ( a resi/ance betwe5 ! *>g+ dynamo & ! batt]y is n necess>y1 inasmu* z all adju/m5ts ( voltage c be made by v>y+ ! field /r5g? ( ! dynamo1 &1 !re=e1 !re are no l>ge losses due to resi/ance s9ce ! loss 9 ! dynamo field rheo/at is v small4 ,:5 a motor g5]ator set is us$ to *>ge two or m batt]ies ( diff]5t capacities1 or voltages1 or :i* are 9 diff]5t conditions ( *>ge1 x is necess>y to ins]t a resi/ance 9 s]ies ) ea* batt]y1 9 ord] t ! curr5t may be prop]ly adju/$ = ea* p>ticul> batt]y4 ,?us if ! motor h six poles & ! frequ5cy be #ej1 ! rot>y field revolves at #ej #fj #c #a1jjj ,r4,p4,m4 & ! motor w revolve at "o-half t spe$ or #a1jjj #b #ejj ,r4,p4,m4 ,s9ce ! connections are s arrang$ t ^! curr5ts t5d to set up 9 ! armature a revolv+ field1 rotat+ at half spe$ 9 a s5se opposite to t 9 :i* ! %aft is rotat+ at half spe$1 x foll[s t by ! sup]-position ( ?is revolv+ field ^u ! revolutions ( ! ma*9e1 ! magnetic effect is equival5t to a rotation ( ! armature at :ole spe$1 s t x op]ates 9 syn*ronism1 z does ! armature ( a rot>y conv]t]4 ,half ! electric input into ! motor "p is1 !re=e1 turn$ into me*anical en]gy to drive ! %aft1 ! o!r half acts inductively on ! armature w9d+1 g5]at+ curr5ts !re94 ,z to ! dynamo "p x is half g5]ator1 receiv+ me*anical p[] by transmission along ! %aft to furni% half its output1 & x is half conv]t]1 turn+ ! curr5ts receiv$ f ! armature into direct curr5t deliv]$ at ! bru%es4 ,ques4 ,:at action takes place 9 ! motor armature w9d+8 ,ans4 ,s9ce x runs at "o-half syn*ron\s spe$1 x g5]ates alt]nat+ curr5t ( half ! supply curr5t frequ5cy1 deliv]+ ^! to ! armature ( ! dynamo4 ,ques4 ,:at claim is made = ?is type ( app>atus8 ,ans4 ,! co/ is said to be less ?an a motor g5]ator set1 & x is claim$ to be self-syn*roniz+ & to require no special />t+ ge>1 also to be #b4e p] c5t4 m effici5t ?an a motor g5]ator4 ,ques4 ,h[ is ! ma*9e />t$ f ! high pressure side8 ,ans4 ,! field w9d+ is connect$ directly to ! high pressure leads4 ,! ?ree slip r+ bru%es are connect$ ) ext]nal resi/ances :i* are us$ :ile />t+1 ! ext]nal resi/ances be+ gradually cut out ( ! circuit z ! ma*9e comes up to spe$ 7! same z ) an ord9>y slip r+ motor74 ,ques4 ,h[ does a cascade conv]t] comp>e ) a syn*ron\s conv]t]8 ,ans4 ,x is ab\t equally exp5sive z ! syn*ron\s conv]t] ) its necess>y bank ( trans=m]s1 b is ab\t "o p] c5t4 less effici5t4 ,x is claim$ to be m desirable = frequ5cies above #dj on acc\nt ( ! improv$ commutation at ! l[ frequ5cy us$ 9 ! dynamo memb]4 ,= l[] frequ5cies ! syn*ron\s conv]t] is pref]able4 ,,*apt] ,,liv ,,rectifi]s ,! purpose ( a rectifi] is to *ange alt]nat+ curr5t into a uni-directional or pulsat+ curr5t4 ,!re are sev]al classes ( app>atus to :i* ! t]m rectifi] may be appli$1 z #a4 ,me*anical rectifi]s2 #b4 ,electrolytic rectifi]s2 #c4 ,m]cury vapor rectifi]s1 or1 m]cury arc rectifi]s2 #d4 ,electro-magnetic rectifi]s4 ,me*anical ,rectifi]s4--,by def9ition1 a me*anical rectifi] is a =m ( commutator op]at+ 9 syn*ronism ) ! g5]ator & commutat+ or rectify+ ! negative waves ( ! alt]nat+ curr5t z %[n graphically 9 figs4 #b1jgf & #b1jgh4 ,! ess5tial features ( con/ruction are %[n 9 fig4 #b1jgi4 ,ques4 ,m5tion "s application ( a me*anical rectifi]4 ,ans4 ,x is us$ on a compositely excit$ alt]nator z illu/rat$ on page #a1aib4 ,electrolytic ,rectifi]s4--,if two metals be plac$ 9 an electrolyte & !n subject$ to a def9ite diff]5ce ( pressure1 !y w 7"u c]ta9 conditions7 (f] great] resi/ance to ! passage ( a curr5t 9 "o direction1 ?an 9 ! o!r direction4 ,on acc\nt ( ?is s call$ valve effect1 electrolytic rectifi]s are sometimes call$ valves4 ,ques4 ,:at metal is g5]ally us$ = ! ca?ode8 ,ans4 ,alum9um4 ,illu/ration3 ,,figs4 #b1jgf to #b1jgh4--;,diagrams %[+ alt]nat+ curr5ts1 & p>tial & complete rectification4 ,ques4 ,:at is g5]ally us$ = ! o!r electrode8 ,ans4 ,lead or poli%$ /eel4 ,metals ( l[ atomic weight exhibit ! valve effect at high diff]5ces ( pressure1 & heavi] metals at l[ diff]5ces ( pressure4 ,ques4 ,describe ! ,nodon valve4 ,ans4 ,! ca?ode is ( alum9um or alum9um alloy1 & ! o!r electrode1 :i* has consid]ably m surface1 is ! conta9+ vessel4 ,! electrolyte is a neutral solution ( ammonia phosphate4 ,ques4 ,describe its action4 ,ans4 ,x is due to ! =mation ( a film ( normal hydroxide ( alum9um1 ov] ! surface ( ! alum9um electrode4 ,?is film pres5ts a v high resi/ance to ! curr5t :5 fl[+ 9 "o direction b v little resi/ance1 :5 fl[+ 9 ! rev]se direction4 ,illu/ration3 ,,fig4 #b1jgi4--,me*anical rectifi]4 ,! rectifi] consi/s ( two ca/+s ,m & ,s ) tee? :i* fit toge!r z %[n1 be+ insulat$ s !y d n come 9 contact ) ea* o!r4 ,e alt]nate too?1 be+ ( ! same ca/+1 is connect$ toge!r1 ! same z ?\gh jo9$ by a conduct+ wire4 ,!re are z _m tee? z !re are poles4 ,! "p ,m ( ! rectifi] is connect$ to "o ( ! collector r+s by ,f1 & ! "p ,s to ! o!r r+ by ,g4 ,ques4 ,:at is ! effect :5 a ,nodon cell is suppli$ ) alt]nat+ curr5t8 ,ans4 ,half ( ! wave w be suppress$ & an int]mitt5tly pulsat+ curr5t w result z %[n 9 fig4 #b1jgg4 ,illu/ration3 ,,figs4 #b1jhj & #b1jha4--,two views ( ,nodon valve4 ,?is is an electrolytic rectifi] 9 :i* ! ca?ode is a rod ( alum9um alloy held c5trally 9 a lead5 vessel :i* =ms ! anode & conta9s ! electrolyte1 a conc5trat$ solution ( ammonium phosphate4 ,only a %ort portion at ! l[] end ( ! ca?ode is utiliz$1 ! re/1 :i* is r small] 9 diamet]1 be+ protect$ f action by an enclos+ glass sleeve4 ,! curr5t d5sity at ! ca?ode ranges f #e to #aj amp4 p] sq4 dm4 ,9 ! l>g] sizes1 ! cells are made d\ble1 & a curr5t ( air is kept circulat+ betwe5 ! walls by means ( a motor driv5 fan4 ,9 ord] to utilize bo? halves ( ! supply wave1 ! ,gratz me?od ( connection is adopt$4 ,! maximum effici5cy is obta9$ at ab\t #adj volts1 & ! effici5cy lies betwe5 #fe & #ge p] c5t41 & is practically indep5d5t ( ! frequ5cy betwe5 ! limits ( #be & #bjj 4 ,above a pressure ( #adj volts1 ! effici5cy falls (f v rapidly1 ow+ to breakd[n ( ! film4 ,! pressure diff]5ce is high1 be+ ov] #ij p] c5t4 at full load4 ,temp]ature l>gely influ5ces ! action ( ! valve1 & %\ld nev] exce$ #abb ,fahr4 ,illu/ration3 ,,fig4 #b1jhb4--,oscillograph record f ,nodon valve %[+ orig9al supply voltage & ! correspond+ pulsat+ curr5t at ! t]m9als ( su* a valve4 ,ques4 ,h[ may bo? halves ( ! alt]nat+ waves be utiliz$8 ,ans4 ,by c\pl+ a s]ies ( cells 9 oppos$ pairs z 9 fig4 #b1jhj4 ,illu/ration3 ,,fig4 #b1jhc4--,p]=mance curves ( five amp]e ,nodon valve4 ,con/ant second>y voltage te/4 ,load$ on non-inductive resi/ances4 ,frequ5cy #ej4 ,maximum p[] factor on valve 4#g4 ,ques4 ,^u :at does ! effici5cy ( ! film dep5d8 ,ans4 ,^u ! temp]ature4 ,x %\ld n = maximum effici5cy exce$ #hf degrees ,fahr4 ,!re is also a c]ta9 critical voltage above :i* ! film breaks d[n locally1 giv+ rise to a lum9\s & some:at disruptive dis*>ge accompani$ by a rapid rise ( temp]ature & fall 9 effici5cy4 ,illu/ration3 ,,fig4 #b1jhd4--,mohawk electrolytic rectifi] & swit*bo>d2 diagram %[+ connections = *>g+ /orage batt]y4 ,op]at+ in/ructions3 ,aft] assembl+ batt]y z 9 fig4 #b1jhe1 ! film mu/ be =m$ on ! alum9um alloy electrodes s t ! rectifi] w pass curr5t only 9 ! "r direction4 ,op5 swit* ,b1 close swit* ,t to ! "r2 dis*>ge lev] c be 9 any position2 *>g+ regulator lev] mu/ be to ! extreme left1 ! z]o position2 n[ close ma9 swit* ,m4 ,mov+ regulator lev] ,r f ! z]o position to ! fir/ button or contact1 let x rema9 !re = a "t1 n less ?an five m9utes2 ?is is important1 z ! prop] rectification ( ! curr5t dep5ds on ! film =m$ on ! alum9um rods4 ,! ammet] aft] ! fir/ ru% ( curr5t may n %[ any curr5t z pass+1 or x may %[ a rev]se curr5t4 ,9 ! latt] case1 leave ! contact f+] on ! fir/ button until ! ne$le comes back to z]o4 ,?is may take "s "t1 b ! ne$le w ev5tually come back2 x also indicates t ! film is prop]ly =m$ :5 ! ne$le returns to z]o4 ,move regulator ,r to ! extreme "r /ep by /ep & note t ! ammet] cont9ues to return to z]o1 :i* indicates t ! film on rectifi] electrodes is =m$ prop]ly4 ,move regulator ,r to z]o1 close swit* ,t to ! left 9 normal *>g+ position4 ,close *>g+ swit* ,b4 ,to regulate ! fl[ ( curr5t ?r\gh ! batt]y move *>g+ lev] ,r to ! "r sl[ly until ammet] indicates ! correct *>g+ curr5t4 ,aft] ! batt]ies are *>g$ & ready = use1 dis*>ge lev] c be mov$ to connect ei!r set ( /orage batt]ies to ! load t]m9al4 ,! voltage ( ! batt]ies c be read at any "t1 by press+ ! /rap key4 ,! dis*>ge lev] connects ! batt]ies to ! volt met] & x is possible by mov+ x to measure ! voltage ( ei!r set ( batt]y1 *>g+ or dis*>g+4 ,tr\ble 9 ! rectifi] demon/rates itself by ! solution becom+ heat$4 ,! condition ( ! rectifi] c be te/$ any "t 9 a few seconds by op5+ swit* ,b & clos+ swit* ,t to ! "r4 ,if ! rectifi] be 9 prop] condition ! ammet] w read z]o4 ,& if x be n rectify+ & p]mitt+ ,a4 ,c4 curr5t to fl[ ?r\gh ! rectifi]1 ! ammet] w read negative or to ! left ( ! z]o4 ,an old solution t is heat+ & n rectify+ prop]ly w turn a r$di% br[n color4 ,ques4 ,:5 an electrolytic rectifi] is n 9 use = "s "t :at happ5s8 ,ans4 ,! electrodes w loose ! film4 ,illu/ration3 ,,figs4 #b1jhe & #b1jhf4--,mohawk electrolytic rectifi]4 ,to put 9 commission1 clean out ! j>4 ,fill ) di/ill$ or ra9 wat]4 ,add six p\nds ( electro salts1 /ir & aft] all salts are dissolv$ place ! cov] 9 position4 ,! specific gravity ( ! solution %\ld be #a4abe4 ,! middle iron electrode mu/ hang /raight d[n 9 ! solution & n t\* ei!r ( ! o!r alum9um alloy electrodes4 ,! alum9um alloy electrodes are m\nt$ on an insulat$ bracket t slides up & d[n on a rod4 ,?is rod screws 9 ! hole tap$ 9 ! middle ( ! cov]4 ,! electrodes give ! be/ results only :5 p]fectly smoo?4 ,%\ld !y get r\gh1 cov]$ ) a deposit or a :ite coat+ remove f ! solution1 & clean ) f9e s& pap]4 ,f9i% ) f9e s& pap]4 ,=m ! film aga9 & ! electrodes w be z good z new4 ,clean iron electrode occasionally4 ,ques4 ,:at mu/ be done 9 su* case8 ,ans4 ,! electrodes mu/ be re=m$4 ,ques4 ,h[ is ! loss ( film prev5t$8 ,ans4 ,by ,remov+ ! electrodes f ! electrolyte & dry+ !m4 ,illu/ration3 ,,fig4 #b1jhg4--,! ,flem+ oscillation valve4 ,x dep5ds = its action on ! well-kn[n ,edison effect 9 gl[ lamps4 ,! valve consi/s ( a c>bon filam5t gl[ lamp ) a simple c5tral horse%oe filam5t4 ,ar\nd ?is filam5t inside ! exhau/$ bulb is fix$ a small cyl9d] ( nickel1 :i* is connect$ by means ( a plat9um wire seal$ ?r\gh ! bulb to a ?ird t]m9al4 ,! valve is us$ z foll[s3 ,! c>bon loop is made inc&esc5t by a suitable batt]y4 ,! circuits 9 :i* ! oscillations are to be detect$ is jo9$ 9 s]ies ) a s5sitive mirror galvanomet]1 ! nickel cyl9d] t]m9al & ! negative t]m9al ( ! filam5t ( ! valve be+ us$4 ,! galvanomet] w !n be trav]s$ by a s]ies ( rapid dis*>ges all 9 ! same direction1 ^? 9 ! opposite direction be+ entirely suppress$4 ,ques4 ,:at att5tion mu/ be giv5 to ! electrolyte8 ,ans4 ,wat] mu/ be add$ f "t to "t to make up = evaporation4 ,?is is necess>y to keep ! solution at ! prop] d5sity4 ,ques4 ,:at is ! indication t ! rectifi] ne$s re*>g+8 ,ans4 ,excessive heat+ ( ! solution ) normal load4 ,ques4 ,:at is ! indication t a rectifi] is pass+ alt]nat+ curr5t8 ,ans4 ,x w heat1 & if ! solution be v weak1 x w cause a buzz+ s\nd4 ,illu/ration3 ,,fig4 #b1jhh4--,! ,*ur*] valve4 ,?is is ( ! modifi$ ,nodon type4 ,x diff]s f ! latt] 9 t x has two ca?odes ( alum9um & an anode ( lead or plat9um1 susp5d$ 9 ! "o cell4 ,?is p]mits ! complete utilization ( bo? halves ( ! supply wave ) "o cell in/ead ( ! f\r requir$ 9 ! ,gratz me?od4 ,! connections ( su* a cell are %[n 9 ! figure4 ,! second>y ( ! trans=m] c>ries a c5tral tapp+1 & is connect$ ?r\gh ! direct curr5t load to ! c5tral anode1 :ile ea* ( ! ca?odes is connect$ to ! ord9>y t]m9als ( ! trans=m] itself4 ,! practical limits ( ! cell are #ej volts direct curr5t1 or #acj volts at ! trans=m] t]m9als ,,ab4 ,f1 is ! anode2 ,c1 ca?ode ,i2 ,d1 ca?ode ,,ii4 ,ques4 ,:at h>m is caus$ by op]at+ a rectifi] ) a weak electrolyte8 ,ans4 ,! electrodes w eat away4 ,a few ( ! s call$ electrolytic valves are "h briefly describ$3 ,! ,audion ,valve4--,?is valve 0 inv5t$ by ,de ,=e/ 9 #aijj & is practically id5tical ) ! ,flem+ oscillation valve1 ! latt] be+ illu/rat$ 9 fig4 #b1jhf4 ,grisson ,valve4--,9 ?is valve ! ca?ode is a %eet ( alum9um1 & ! anode1 a %eet ( lead1 support$1 9 ! orig9al =m1 horizontally 9 a vessel conta9+ ! electrolyte1 consi/+ ( a solution ( sodium c>bonate4 ,cool+ is effect$ by circulat+ wat] ?r\gh metal tubes 9 ! electrolyte itself4 ,illu/ration3 ,,figs4 #b1jhi & #b1jij4--,! ,de ,f>ia valve4 ,?is is an alum9um lead rectifi]4 ,! ca?ode is a holl[ cyl9d] ( alum9um plac$ conc5trically 9 a l>g] cyl9d] ( lead1 & ! :ole imm]s$ 9 electrolyte ( sodium phosphate 9 an ebonite conta9+ vessel4 ,cool+ is effect$ by promot+ automatic circulation ( ! electrolyte by provid+ ! lead cyl9d] ) holes ne> its extremities2 ! heat$ electrolyte !n rises 9 ! lead cyl9d]1 passes out at ! upp] holes1 is cool$ by contact ) ! walls ( ! conta9+ vessel1 & desc5ds outside ! lead cyl9d]4 ,x is claim$ t ?is cool+ action is suffici5t to all[ ( a curr5t d5sity ( #h amp4 p] sq4 dm4 ( alum9um4 ,pawl[ski ,valve4--,?is is an electrolytic valve employ+ a solid electrolyte4 ,x consi/s ( a copp] plate :i* has be5 coat$ ) a cry/all9e lay] ( c>efully prep>$ copp] hemisulphide1 prep>$ by melt+ sulphur & copp] toge!r out ( contact ) air4 ,! prep>$ plate is plac$ 9 contact ) an alum9um %eet & ! comb9ation is !n =m$ by submitt+ x to an alt]nat+ pressure until sp>k+1 :i* at fir/ occurs1 ceases4 ,giles ,electric ,valve4--,?is consi/s ( a comb9ation ( sp>k gaps & capacity us$ to protect electrical app>atus aga9/ damage due to atmosph]ic dis*>ges & resonance surges4 ,! sp>k gaps are =m$ betwe5 ! edges ( %>p rimm$ discs ( non-arc+ metal4 ,^! discs are insulat$ f ea* o!r1 & f ! c5tral tube1 :i* provides a support = ! app>atus & also an e>?4 ,! cond5s] effect is obta9$ by means ( ! annul> discs & ! tube2 an adju/able sp>k gap1 a high resi/ance1 & a fuse all connect$ 9 s]ies1 complete ! valve4 ,illu/ration3 ,,fig4 #b1jia4--ge light ,we/+h\se-,coop] ,hewitt m]cury vapor rectifi] con/ant curr5t regulat+ trans=m]4 ,view %[+ assembly 9 case4 ,buttn] ,valve4--,x is ( ! ,nodon type employ+ a ca?ode ( magnesium-alum9um alloy1 & probably iron or lead z anode1 ) an electrolyte ( ammonium borate4 ,buttn] claims t ! borate is sup]ior to ! phosphate 9 t x does n attack iron1 & w keep 9 good work+ condition = long] p]iods4 ,illu/ration3 ,,fig4 #b1jib4--ge light ,we/+h\se-,coop] ,hewitt m]cury vapor rectifi] con/ant curr5t regulat+ trans=m] ) case remov$4 ,! trans=m] is ( ! repulsion coil type1 oil cool$ & oil insulat$4 ,x is s arrang$ z to give a con/ant second>y curr5t & to insulate ! arc l9es f ! prim>y circuit4 ,! regulat+ trans=m] conta9s two /ation>y second>y coils & two mov+ prim>y coils balanc$ aga9/ ea* o!r4 ,ea* second>y coil ( ! #ge light regulator is w\nd 9 two p>ts1 ow+ to ! use ( two rectifi] bulbs 9 s]ies 9 outfits ( ?is capacity4 ,! repulsion betwe5 ! prim>y & second>y coils *anges ! di/ance betwe5 !m accord+ to ! v>iation ( load1 & ! induc$ curr5t 9 ! second>y is ?us kept con/ant4 ,an increase 9 curr5t causes ! prim>y & second>y coils to sep>ate1 & a decrease 9 curr5t p]mits !m to approa* ea* o!r1 until ! normal balance is re/or$4 ,! mov+ coils are hung f %eave :eels hav+ roll] be>+s & are balanc$ s t !y are s5sitive to ! slighte/ impulse t5d+ to sep>ate !m or draw !m clos] toge!r4 7,see figs4 #a1iha-b1 & #b1aaa47 ,! w9d+s are insulat$ = a voltage consid]ably 9 excess ( t exi/+ 9 normal s]vice4 ,sev]al taps are provid$ to take c>e ( diff]5t voltages & wave =ms4 ,a comb9ation ( taps w be f\nd :i* w be suitable = any wave =m com+ )9 ! ,am]ican ,in/itute ( ,electrical ,eng9e]'s limits = a s9e wave4 ,! second>y coils are also provid$ ) taps = #he p] c5t4 ( normal load1 s t less ?an normal load c be tak5 c>e ( at a good p[] factor4 ,any "p ( ! full load c be c>ri$ tempor>ily ) ! full load connections ( ! trans=m]1 b at p]man5t light loads ! p[] factor & effici5cy w be improv$ by us+ ! #he p] c5t4 connections4 ,/&>d regulat+ trans=m]s are w\nd = #f4f & #d amp]es1 & = prim>y circuits ( #bbj1 #ddj1 #a1ajj #b1bjj1 #f1fjj & #ac1bjj volts4 ,regulators c be specially w\nd = #e4e amp]es4 ,= ?ree phase circuits ?ree regulators c be us$1 "o on ea* phase1 or !y c be furni%$ 9 pairs ) an auxili>y auto-trans=m] to give a balanc$ load4 ,! regulators c be connect$1 9 cases :]e ! unbalanc+ is n objectionable1 to sep>ate phases4 ,m]cury ,vapor ,rectifi]s4--,! ,coop] ,hewitt m]cury vapor rectifi]1 z %[n 9 fig4 #b1jic consi/s ess5tially ( a h]metically seal$ glass bulb fill$ ) m]cury vapor & provid$ ) f\r electrodes4 ,! two upp] electrodes are ( solid mat]ial & ! two l[] ( m]cury4 ,! solid electrodes are ! positive electrodes2 ! m]cury electrodes are ! negative electrodes4 ,! m]cury pools ( ! two l[] electrodes are n 9 contact :5 ! bulb is v]tical1 b ! bulb is s m\nt$ t x c be tilt$ to br+ ^! two pools tempor>ily 9 contact = />t+4 ,illu/ration3 ,,fig4 #b1jic4--;,diagram ( connections ( ,we/+h\se-,coop] ,hewitt m]cury vapor rectifi] arc light circuit4 ,! bulb conta9s highly att5uat$ vapor ( m]cury1 :i*1 l o!r metal vapors1 is an electrical conductor "u "s conditions4 ,! positive electrodes are surr\nd$ by ?is vapor4 ,curr5t c readily pass f ei!r ( ! solid electrodes to ! m]cury vapor & f x to ! m]cury electrode1 b :5 ! direction ( fl[ t5ds to rev]se1 s t curr5t w\ld pass f ! vapor to ! solid electrode1 !re is a resi/ance at ! surface ( ! electrode1 :i* entirely prev5ts ! fl[ ( curr5t4 ,illu/ration3 ,,fig4 #b1jid4--;,coop] ,hewitt m]cury vapor rectifi]4 ,! m]cury vapor rectifi] z develop$ by ,pet] ,coop] ,hewitt = *ang+ alt]nat+ curr5t into direct curr5t is ! result ( a s]ies ( c>eful exp]im5ts & inve/igations ( ! action go+ on 9 8 m]cury vapor lamp = electric light+ us$ on direct curr5t circuits only4 ,:ile _m attempts h be5 made to produce an alt]nat+ curr5t lamp1 up to ! pres5t "t1 !y h be5 unsuccessful4 ,! difficulty ( op]at+ a lamp on ! alt]nat+ curr5t circuit lies 9 ! fact t :ile a curr5t w fl[ freely ?r\gh x 9 "o direction1 :5 ! curr5t rev]ses ! negative electrode or ca?ode acts z an electric valve & /ops ! curr5t1 ?us break+ ! circuit & putt+ out ! light4 ,by foll[+ up ?is new electrical action1 ,hewitt appli$ ! pr9ciple 9 ! con/ruction ( a vacuum tube ) suitable electrodes1 & by us+ two electrodes ( iron or graphite = ! positive or incom+ curr5t & "o ( m]cury = ! negative or :]e ! curr5t leaves ! tube1 ! circuits c\ld be arrang$ s t a direct curr5t w\ld fl[ f ! m]cury electrode & be us$ = *>g+ /orage batt]ies1 electro-*emical "w or op]at+ direct curr5t flame arc lamps4 ,z %[n 9 ! figure1 ! rectifi] consi/s ess5tially ( a glass bulb into :i* are seal$ two iron or graphite anodes & "o m]cury ca?ode1 & a small />t+ electrode4 ,! bulb is fill$ ) m]cury vapor "u l[ pressure4 ,! action ( ?is device dep5ds on ! prop]ty ( ioniz$ m]cury vapor ( conduct+ electricity 9 "o direction only4 ,9 op]ation no curr5t w fl[ until ! />t+ or negative electrode resi/ance has be5 ov]come by ! ionization ( ! vapor 9 its neighborhood4 ,to accompli% ?is1 ! voltage is rais$ suffici5tly to cause ! curr5t to jump ! gap betwe5 ! m]cury ca?ode & ! />t+ ca?ode1 or by br++ ! ca?ode & />t+ electrode toge!r 9 ! vapor by tilt+ & !n sep>at+ !m1 ?us draw+ out ! arc4 ,:5 ?is has be5 done1 curr5t w only fl[ f ! anode to ! m]cury ca?ode1 & n 9 ! rev]se direction4 ,9 ord] to ma9ta9 ! action1 a lag is produc$ 9 ea* half wave by ! use ( a reactive or su/a9+ coil2 h5ce ! curr5t nev] rea*es its z]o value1 o!rwise ! arc w\ld h to be re/>t$4 ,!re are two k9ds ( losses 9 ! tube3 #a1 arc+1 or leakage f "o anode to ! o!r1 & #b1 ! m]cury arc voltage drop4 ,?is drop does n dep5d on ! load1 ! en]gy repres5t$ by ! drop be+ conv]t$ into heat1 :i* is dissipat$ at ! surface ( ! conta9+ vessel4 ,accord+ to ,/e9metz1 ! limit ( voltage mu/ be v high1 z #cf1jjj volts has be5 rectifi$4 ,! curr5t output is limit$ pr9cipally by ! lead+-9 wires to ! electrodes1 x be+ a difficult problem to seal into ! glass conta9] ! l>ge masses ( metal requir$ = ! conduction ( l>ge curr5ts4 ,frequ5cy has b little influ5ce4 ,! direct curr5t voltage ranges f #bj to #ej p] c5t4 t ( ! arc supply4 ,! life ( ! valve dep5ds some:at ^u its size1 be+ long] 9 ! small sizes & nev]1 ) fair usage1 less ?an #a1jjj h\rs4 ,illu/ration3 ,,fig4 #b1jie4--,?ree phase m]cury arc rectifi]4 ,! rectifi] bulb is provid$ ) ?ree positive electrodes or anodes1 a negative electrode or ca?ode1 & a />t+ anode1 z %[n4 ,! ?ree phase leads are connect$ to ! anodes at ! top ( ! bulb1 a bran* f "o phase be+ br\ght d[n to ! />t+ anode1 a resi/ance be+ plac$ 9 ! circuit to prev5t excessive curr5t on acc\nt ( ! proximity ( ! two l[] electrodes4 ,s9ce !re is always a pressure on "o ( ! ?ree anodes 9 ! "r direction1 a reactance coil is n necess>y4 ,! app>atus is />t$ 9 ! usual way by tilt+4 ,! alt]nat+ curr5t supply circuit is connect$ to ! two positive electrodes z %[n 9 ! diagram1 & z ! electrodes w all[ curr5t to fl[ 9 only "o direction & oppose any curr5t fl[ 9 ! opposite direction1 ! pulsations ( ! curr5t pass alt]nately f "o or ! o!r ( ! positive electrodes into ! m]cury4 ,z ^! curr5ts _c pass f ! vapor into ei!r positive electrode1 !y are con/ra9$ to pass out all 9 "o direction ?r\gh ! m]cury electrode1 f :i* !y em]ge z a uni-directional curr5t4 ,! positive electrodes ( ! rectifi] ?us act z *eck valves1 p]mitt+ curr5t to pass into ! m]cury vapor b n all[+ x to pass f ! vapor to ! solid electrodes4 ,illu/ration3 ,,figs4 #b1jif to #b1jih4--,we/+h\se diagrams %[+ comp>ative effici5cies ( diff]5t sy/ems ( s]ies arc light+4 ,ques4 ,:at condition prevails be=e ! bulb />ts to rectify8 ,ans4 ,!re appe>s to be a high resi/ance at ! surface ,illu/ration3 ,,fig4 #b1jii4--,we/+h\se-,coop] ,hewitt m]cury vapor rectifi] bulb4 ,x consi/s ess5tially ( a h]metically seal$ glass bulb fill$ ) highly att5uat$ vapor ( m]cury1 & provid$ ) electrodes4 ,its op]ation is fully expla9$ 9 ! accompany+ text4 ,illu/ration3 ,,fig4 #b1ajj4--,we/+h\se-,coop] ,hewitt m]cury vapor rectifi] bulb & box4 ,! life ( ! bulb is mat]ially increas$ by op]at+ x at c]ta9 temp]atures & = ?is reason ! bulbs 9 ! arc light rectifi] outfits are imm]s$ 9 oil & m\nt$ 9 ! same tank ) ! regulat+ trans=m]4 ,two bulbs 9 s]ies are us$ ) ! #ge light outfit4 ,! bulb is m\nt$ on tilt+ trunnions 9 a box :i* c be lift$ out ?r\gh a door 9 ! top ( ! tank )\t disconnect+ any leads4 ,! conta9+ box has contacts on ! bottom s arrang$ t :5 x is l[]$ into place1 ! bulb is automatically connect$ 9 circuit4 ,to replace a defective bulb x is only necess>y to lift out ! conta9+ box by its h&le ?r\gh ! door 9 ! top ( ! case & m\nt a new bulb 9 x1 aft] :i* ! box c be l[]$ into place4 ,x is desirable to h at ea* in/allation1 a sp>e bulb box 9 :i* a bulb c be kept1 connect$ ready = use4 ,if ?is be done1 x is only necess>y1 9 case ( tr\ble ) ! bulb1 to )draw ! old bulb & box & replace !m ) ! sp>e set4 ,?is avoids hav+ ! lamps out ( s]vice4 ( ! m]cury1 :i* mu/ be brok5 d[n s t ! curr5t c pass4 ,ques4 ,:at is ?is app>5t surface resi/ance call$8 ,ans4 ,! negative electrode resi/ance4 ,ques4 ,:at mu/ be done be=e any curr5t c pass8 ,ans4 ,! negative electrode resi/ance mu/ be ov]come4 ,:5 once />t$ ! curr5t w cont9ue to fl[1 meet+ ) practically no resi/ance z long z ! curr5t is un9t]rupt$4 ,ques4 ,:at w happ5 if ! curr5t be int]rupt$ ev5 = ! smalle/ in/ant ( "t8 ,ans4 ,! negative electrode resi/ance w re-e/abli% itself1 & /op ! op]ation ( ! bulb4 ,ques4 ,h[ is ! negative electrode resi/ance ov]come8 ,ans4 ,! bulb is tilt$ or %ak5 s t ! space betwe5 ! m]cury electrodes is bridg$ by ! m]cury4 ,ques4 ,:at happ5s :5 ! bulb is tilt$8 ,ans4 ,curr5t !n passes betwe5 ! two m]cury electrodes f ! />t+ trans=m] & ! little /ream ( m]cury :i* bridges ! space betwe5 ! electrodes breaks ) a sp>k z ! bulb is return$ to its v]tical position4 ,ques4 ,:at duty is p]=m$ by ! sp>k8 ,ans4 ,x breaks d[n ! negative electrode resi/ance4 ,ques4 ,:at conditions are n[ necess>y = cont9u\s op]ation ( ! rectifi]8 ,ans4 ,! rectifi] w n[ op]ate indef9itely z long z ! curr5t supply is un9t]rupt$ & ! direct curr5t load does n fall bel[ ! m9imum requir$ = ! arc4 ,ques4 ,is ! rectifi] self-/>t+8 ,ans4 ,aft] ! bulb has be5 />t$ a few times1 z describ$ above1 x becomes self-/>t+1 s t "u all ord9>y op]at+ conditions x w comm5ce to op]ate :5 ! swit*es connect+ x ) ! load & ! alt]nat+ curr5t supply are clos$4 ,ques4 ,:at provision is made 9 ! ,we/+h\se-,coop] ,hewitt rectifi] to r5d] x self-/>t+8 ,ans4 ,x is r5d]$ self-/>t+ by means ( a cond5s]4 ,illu/ration3 ,,fig4 #b1aja4--;,g5]al ,electric #ej light d\ble tube comb9$ unit s]ies m]cury arc rectifi] outfit2 front view4 ,?is unit consi/s ( a con/ant curr5t trans=m]1 reactance1 tube tank & excit+ trans=m] m\nt$ on a common base2 also a /atic dis*>g] & pilot lamp m\nt$ on top ( ! trans=m]4 ,?is arrangem5t makes ! rectifi] outfit1 ) ! exception ( ! swit*bo>d panel1 complete 9 itself4 ,ques4 ,describe ! arrangem5t & op]ation ( ! cond5s]4 ,ans4 ,! cond5s] is connect$ betwe5 "o ( ! positive electrodes & a coat+ ( t9foil outside ,illu/ration3 ,,fig4 #b1ajb4--;,g5]al ,electric #b1bjj volts1 #fj cycle1 prim>y1 #f4f amp]e1 second>y1 #ge light1 d\ble tube m]cury arc rectifi] outfit ) automatic %ak+ device1 ! case be+ remov$ to %[ p>ts4 ,! con/ant curr5t trans=m] is air cool$4 ,! w9d+ :i* supplies en]gy = ! excit] trans=m] is locat$ at ! top (1 & ar\nd ! core ( ! con/ant curr5t trans=m]4 ,! excit+ trans=m] is m\nt$ on ! base ( ! con/ant curr5t trans=m] inside ( ! cas+4 ,x supplies l[ pressure curr5ts to ! />t+ anodes ( ! rectifi] tube4 ,?is curr5t e/abli%es an auxili>y arc :5 ! tube is %ak51 :i* is necess>y 9 ord] to />t ! rectifi]4 ,! excit+ trans=m] is w\nd = #aaj volts & x consumes ab\t #bjj volt-amp]es4 ,! direct curr5t reactance is m\nt$ on ! base ( ! trans=m] & enclos$ 9 ! same cas+4 ,x is connect$ 9 s]ies ) ! lamp load & its function is to r$uce ! pulsations ( ! circuit to a value mo/ satisfactory = op]ation4 ,! tube tank = hold+ ! oil is m\nt$ on ! same base z ! trans=m]4 ,x is provid$ ) a cool+ coil2 a tube c>ri] is provid$ = rais+ or l[]+ ! tube 9 ! tank4 ,a !rmomet] is provid$ to gauge ! temp]ature ( ! oil 9 ! tank4 ,! /atic dis*>g]s consi/+ ( horn gaps 9 s]ies ) resi/ance1 are connect$ betwe5 ! anodes & ! ca?ode 9 ord] to protect ! tubes & o!r app>atus f excessive electrical /ra9s4 ,! horn gaps op5 ! circuit aft] dis*>ge1 & 9 case ! resi/ance becomes damag$ ! dis*>ge passes across ! sp>k gap provid$1 !reby %unt+ ! resi/ance4 ! "p ( ! bulb conta9+ ! m]cury1 & induces /atic sp>ks on ! surface ( ! m]cury :i* break d[n ! negative electrode resi/ance4 ,! action ( ! rectifi] w be bett] und]/ood by ref]5ce to ! diagram ( curr5t waves & impress$ pressure z %[n 9 figs4 #b1ajc to #b1ajf4 ,illu/ration3 ,,figs4 #b1ajc to #b1ajf4--;,diagram ( curr5t waves & impress$ pressure ( ,we/+h\se-,coop] ,hewitt m]cury vapor rectifi]4 ,! :ole ( ! alt]nat+ curr5t wave on bo? sides ( ! z]o l9e is us$4 ,! two upp] curves 9 ! diagram %[ ! curr5t waves 9 ea* ( ! two positive electrodes1 & ! resultant curve ,,iii repres5ts ! rectifi$ curr5t fl[+ f ! negative electrode4 ,curve ,,iv %[s ! impress$ alt]nat+ curr5t pressure4 ,x is evid5t t if ! "p ( ! wave bel[ ! z]o l9e 7 rev]s$1 ! result+ curr5t w\ld be a pulsat+ direct curr5t ) ea* pulsation v>y+ f z]o to a positive maximum4 ,su* a curr5t c\ld n be ma9ta9$ by ! rectifi]1 because z soon z ! z]o value 0 rea*$ ! negative electrode resi/ance ( ! rectifi] w\ld be re-e/abli%$ & ! circuit w\ld be brok54 ,to avoid ?is condition1 reactance is introduc$ into ! circuit1 :i* causes an elongation ( curr5t waves s t !y ov]lap be=e rea*+ ! z]o value4 ,! ov]lapp+ ( ! rectifi] curr5t waves r$uces ! amplitude ( ! pulsations & produces a comp>atively smoo? direct curr5t z %[n 9 curve ,,iii4 ,9 ?is way ! :ole ( ! alt]nat+ curr5t is trans=m$ to direct curr5t because ea* ( ! alt]nations 9 bo? directions is alt]nately rectifi$4 ,ques4 ,describe a m]cury vapor rectifi] outfit = s]ies arc light+4 ,ans4 ,x consi/s ( a con/ant curr5t regulat+ trans=m]1 a rectifi] bulb1 & a control panel conta9+ ! necess>y swit*es1 met]s1 etc4 ,! trans=m] & rectifi] bulb are m\nt$ 9 ! same tank4 ,illu/ration3 ,,fig4 #b1ajg4--;,g5]al ,electrical rectifi] tube z us$ on s]ies m]cury arc rectifi]4 ,! tube rectifies ! alt]nat+ curr5t into direct curr5t4 ,x consi/s ( an exhau/$ glass vessel conta9+ "o anode or positive t]m9al 9 ea* ( ! two upp] arms1 two m]cury />t+ anodes & a ca?ode or negative t]m9al ( m]cury at ! bottom ( ! tube4 ,x is subm]g$ 9 oil & support$ 9 a removable c>ri]4 ,! tube is put into op]ation by slightly %ak+ x4 ,9 ! comb9$ unit set1 ?is %ak+ is accompli%$ by an electromagnet m\nt$ above ! tube tank & op]at$ f a pull button swit* on ! panel4 ,an automatic %ak] is sometimes in/all$ :i* w automatically />t ! tube :5 ! set is />t$1 or if its op]ation %\ld become int]rupt$ :ile 9 s]vice4 ,! en]gy = ! op]ation ( ?is magnet 7#aaj volts alt]nat+ curr5t7 is obta9$ f ! small auxili>y w9d+ on ! ma9 trans=m] :i* also supplies en]gy to ! excit+ trans=m]4 ,! oil 9 :i* ! tube is plac$ is cool$ by a circulation ( wat] ?r\gh ! cool+ coils on ! inside ( ! tube tank4 ,! am\nt ( wat] necess>y = cool+ ! rectifi] tubes v>ies accord+ to local conditions1 dep5d+ ^u ! temp]ature ( ! wat] & t ( ! air 9 ! /ation b "u ! mo/ favorable conditions no wat] is requir$4 ,z rectifi]s are commonly in/all$ 9 /eam driv5 /ations1 ! drip f ! tube tanks is usually pip$ to ! boil] supply !reby elim9at+ any loss = cool+ wat]4 ,illu/ration3 ,,fig4 #b1ajh4--;,elem5t>y diagram ( m]cury arc rectifi] connections4 ,a4,a41 graphite anodes2 ,b1 m]cury ca?ode2 ,c1 small />t+ electrode2 ,d1 batt]y connection2 ,e & ,f1 reactance coils2 ,g & ,h1 trans=m] t]m9als2 ,j1 batt]y4 ,ques4 ,describe ! con/ruction & op]ation ( ! m]cury arc#aa rectifi] %[n 9 fig4 #b1ajh4 #aa ,,note4--,! t]ms vapor & arc z appli$ to rectifi]s1 d n indicate a diff]5t pr9ciple2 ! ,we/+h\se ,co4 employ ! =m]1 & ! ,g5]al ,electric ,co41 ! latt]4 ,ans4 ,fig4 #b1ajh is an elem5t>y diagram ( connections4 ,! rectifi] tube is an exhau/$ glass vessel 9 :i* are two graphite anodes ,a1 ,a'1 & "o m]cury ca?ode ,b4 ,! small />t+ electrode ,c is connect$ to "o side ( ! alt]nat+ circuit1 ?r\gh resi/ance2 & by rock+ ! tube a slight arc is =m$1 :i* />ts ! op]ation ( ! rectifi] tube4 ,at ! in/ant ! t]m9al ,h ( ! supply trans=m] is positive1 ! anode ,a is !n positive1 & ! arc is free to fl[ betwe5 ,a & ,b4 ,foll[+ ! direction ( ! arr[ /ill fur!r1 ! curr5t passes ?r\gh ! batt]y ,j1 ?r\gh "o-half ( ! ma9 reactance coil ,e1 & back to ! negative t]m9al ,g ( ! trans=m]4 ,:5 ! impress$ voltage falls bel[ a value suffici5t to ma9ta9 ! arc aga9/ ! rev]se pressure ( ! arc & load1 ! reactance ,e1 :i* h]et(ore has be5 *>g+1 n[ dis*>ges1 ! dis*>ge curr5t be+ 9 ! same direction z =m]ly4 ,?is s]ves to ma9ta9 ! arc 9 ! rectifi] tube until ! pressure ( ! supply has pass$ ?r\gh z]o1 rev]s$1 & built up su* a value z to cause ! anode ,a to h a suffici5tly positive value to />t ! arc betwe5 x & ! ca?ode ,b4 ,! dis*>ge circuit ( ! reactance coil ,e is n[ ?r\gh ! arc ,a',b in/ead ( ?r\gh its =m] circuit4 ,consequ5tly ! arc ,a',b is n[ suppli$ ) curr5t1 p>tly f ! trans=m]1 & p>tly f ! reactance coil ,e4 ,! new circuit f ! trans=m] is indicat$ by ! arr[s enclos$ 9 circles4 ,illu/ration3 ,,fig4 #b1aji4--;,diagram %[+ connections ( ,g5]al ,electric comb9$ unit m]cury arc s+le tube rectifi] outfit ) remote controll$ non-automatic %ak+ device4 ,illu/ration3 ,,fig4 #b1aaj4--;,diagram %[+ connections ( ,g5]al ,electric comb9$ unit m]cury arc d\ble tube rectifi] outfit ) remote controll$ non-automatic %ak+ device4 ,illu/ration3 ,,fig4 #b1aaa4--;,diagram %[+ connections ( ,g5]al ,electric s]ies m]cury arc rectifi]4 ,illu/ration3 ,,figs4 #b1aab & #b1aac4--;,diagram ( curr5t waves %[+ effect ( reactance coil4 ,if ! alt]nat+ curr5t wave c\ld be rectifi$ )\t ! use ( ! reactance coil1 ! direct curr5t produc$ w\ld consi/ ( a s]ies ( impulses :i* w\ld rise & fall f ! z]o l9e z illu/rat$ 9 fig4 #b1aab4 ,! action ( ! reactance coil n only ma9ta9s ! curr5t ?r\gh ! tube :ile ! supply curr5t is pass+ ?r\gh z]o1 b helps to smoo? out ! pulsations ( ! direct curr5t :i* is pass+ out ( ! ca?ode t]m9al ( ! tube to ! batt]ies1 or o!r direct curr5t app>atus put 9 its circuit4 ,! smoo?+ out effect ( ! reactance is %[n 9 fig4 #b1aac4 ,x w be se5 f ! diagram t ! curr5t does n drop d[n to z]o & ! pulsations ( ! direct curr5t are greatly r$uc$4 ,! waves ,a1 ,a1 etc41 are f ! positive waves ( ! alt]nat+ curr5t supply1 :ile ,b1 ,b1 are f ! negative waves1 & toge!r !y =m ! rectifi$ curr5t1 fl[+ 9 ! same direction to ! ext]nal direct curr5t circuit %[n at ,b 9 ! diagram1 fig4 #b1ajh4 ,ques4 ,h[ is a m]cury arc rectifi] />t$8 ,ans4 ,a rectifi] outfit ) its />t+ devices1 etc41 is %[n 9 figs4 #b1aad to #b1aaf4 ,to />t ! rectifi]1 close 9 ord] nam$ l9e swit* & circuit break]2 hold ! />t+ swit* 9 opposite position f normal2 rock ! tube g5tly by rectifi] %ak]4 ,:5 ! tube />ts1 z %[n by gre5i% blue light1 release />t+ swit* & see t x goes back to normal position4 ,adju/ ! *>g+ curr5t by means ( f9e regulation swit* on ! left2 or1 if n suffici5t1 by "o button ( co>se regulation swit* on ! "r4 ,! regulat+ swit* may h to be adju/$ occasionally dur+ *>ge1 if x be desir$ to ma9ta9 *>g+ amp]es approximately con/ant4 ,illu/ration3 ,,figs4 #b1aad to #b1aaf4--;,g5]al ,electric m]cury arc rectifi] outfit1 or *>g+ set4 ,! cut %[s front1 re>1 & side views ( ! rectifi]1 illu/rat+ ! arrangem5t on a panel1 ( ! rectifi] tube ) its connection & op]at+ devices4 ,illu/ration3 ,,figs4 #b1aag & #b1aah4--;,g5]al ,electric m]cury arc bulbs or tubes = #bjj & #aj1jjj volt circuits4 ,ques4 ,9 ! manufacture ( rectifi]s1 c\ld o!r metals be us$ = ! ca?ode 9 place ( m]cury8 ,ans4 ,yes4 ,ques4 ,:y are !y n us$8 ,ans4 ,because1 on acc\nt ( ! arc produc$1 !y w\ld gradually we> away & c\ld n be replac$ conv5i5tly4 ,9 ! case ( m]cury1 ! excess vapor is cond5s$ to liquid =m 9 ! l>ge glass bulb or cond5s+ *amb] ( ! tube & gravitates back to ! ca?ode1 :]e x is us$ ov] & ov] aga94 ,illu/ration3 ,,fig4 #b1aai4--;,g5]al ,electric s]ies m]cury arc rectifi] outfit2 view %[+ me?od ( replac+ a tube4 ,! illu/ration also %[s tube c>ri] & drip tray4 ,ques4 ,9 ! op]ation ( rectifi]s1 h[ is ! heat g5]at$ 9 ! bulb dissipat$8 ,ans4 ,9 small rectifi] sets ! heat g5]at$ is dissipat$ ?r\gh ! tube to ! air1 & 9 l>ge tubes su* z us$ 9 supply+ #dj to #fj kw4 = con/ant curr5t flam+ arc lights op]at+ at #d or #f4f amp]es1 ! tubes are imm]s$ 9 a tank ( oil1 & cool$ simil> to ! arrangem5t us$ = oil insulat$ wat] cool$ trans=m]s4 ,ques4 ,:at results are obta9$ ) oil cool$ tubes8 ,ans4 ,9 practice x is f\nd t ! life ( oil cool$ tubes is greatly increas$ & temp]ature *anges d n affect ! ability to />t up z 9 ! air cool$ tubes4 ,illu/ration3 ,,fig4 #b1abj4--;,g5]al ,electric #ajj volt m]cury arc rectifi] tube4 ,a1,a1 anodes2 ,b1 ca?ode2 ,c1 />t+ anode2 ,d1 tube or bulb4 ,ques4 ,9 ! op]ation ( a rectifi]1 "n an inh]5t feature ( ! m]cury arc4 ,ans4 ,a rev]se pressure ( approximately #ad volts is produc$1 :i* rema9s ne>ly con/ant ?r\gh *anges ( load1 frequ5cy1 & voltage4 ,its effect is to decrease ! comm]cial effici5cy slightly on light loads4 ,ques4 ,:at is ! advantage ( a rectifi] set ov] a motor g5]ator set8 ,ans4 ,high] effici5cy & l[] fir/ co/4 ,ques4 ,:at is ! capacity ( a rectifi] tube8 ,ans4 #dj to #ej amp]es4 ,ques4 ,h[ is great] capacity obta9$8 ,ans4 ,:5 a great] amp]e capacity is requir$1 two or m rectifi] sets c be jo9$ to "o circuit4 ,! rectifi] may be jo9$ 9 s]ies = produc+ an increas$ voltage or two tubes c be connect$ 9 s]ies 9 a s+le set4 ,ques4 ,= :at s]vice is a rot>y conv]t] bett] adapt$ ?an a rectifi]8 ,ans4 ,= p[] di/ribution & o!r cases :]e a great am\nt ( alt]nat+ curr5t is to be conv]t$ into direct curr5t1 ! rot>y conv]t] or l>ge motor g5]ator sets are m practical4 ,ques4 ,= :at s]vice is a rectifi] especially adapt$8 ,ans4 ,x is v desirable = *>g+ /orage batt]ies = automobiles f ! local alt]nat+ curr5t light+ circuit4 ,:5 ! consum] in/alls & op]ates ! app>atus = 8 own use & we>1 !re is consid]able sav+ ov] motor g5]ator sets because a small "o to two horse p[] motor g5]ator outfit has an effici5cy ( only #dj to #ej p] c5t4 :ile m]cury vapor rectifi]s w h f #ge to #hj p] c5t4 ,ques4 ,:at precautions %\ld be tak5 9 in/all+ a rectifi]8 ,ans4 ,x %\ld be in/all$ 9 a dry place & c>e %\ld be tak5 to avoid dangl+ wires ne> ! tube to prev5t punctur+4 ,if ! app>atus be in/all$ 9 a room ( uni=m mod]ate temp]ature v little tr\ble w be exp]i5c$ 9 />t+1 :ile extreme cold w make />t+ m difficult4 #ab;,electro-magnetic ,rectifi]s4--,devices ( ?is class consi/ ess5tially ( a d\ble contact rock] :i* rocks on pivot 7midway betwe5 ! contacts71 9 syn*ronism ) ! frequ5cy ( ! alt]nat+ curr5t1 s *ang+ ! connections at ! in/ants ( rev]sals ( ! alt]nat+ curr5t t a direct curr5t is obta9$4 #ab ,,note4--,! ,edison electromagnetic rectifi] is describ$ 9 detail 9 ,,guide ,no4 #d1 pages #idb to #ide4 ,fig4 #b1aba is a comb9$ sket* & diagram ( connections ( a type ( electromagnetic rectifi] t has be5 introduc$ = *ang+ alt]nat+ into direct curr5t4 ,! actual app>atus consi/s ( a box1 ) p]=at$ metal sides1 ab\t t5 in*es squ>e & six in*es deep4 ,?is box conta9s ! /ep d[n trans=m] ,p1,s1,s'1 & ! cond5s]s ,k & ,k'1 ! magnets & contact mak+ device ab\t to be describ$ be+ fix$ on ! poli%$ slate top ( ! box1 exactly z %[n 9 ! figure4 ,! trans=m] prim>y w9d+ ,p may be connect$ ?r\gh a swit* s ) a pair ( ways on ! ne>e/ di/ribution box1 or to a plug connection or lamp-hold]1 & ! app>atus w give a rectifi$ curr5t ( #f or #ab amp]es at #bj volts1 accord+ to ! size4 ,s & ,s' is ! second>y w9d+ ( ! trans=m]1 ) a tapp+ t midway1 jo9+ x to a s]ies circuit conta9+ two alt]nat+ curr5t electromagnets ,e & ,e'1 ^: cores are connect$ by ! long s(t iron yoke ,y4 ,pivot$ at ,p' is a /eel b> ,,sb1 :i* is pol>iz$ by ! two coils ,c & ,c' ! curr5t be+ suppli$ by a cell ,a4 ,fix$ rigidly to ,,sb1 & mov+ ) x1 is a d\ble contact piece ,,cp ) plat9um contacts opposite simil> ones on ! fix$ /uds ,,cs1 ,,cs'4 ,,cp is flexibly connect$ ?r\gh ,f to "o ( ! direct curr5t t]m9als ,t1 to :i* also are jo9$ up "o coat+ ( ea* cond5s] ,k & ,k'4 ,illu/ration3 ,,fig4 #b1aba4--;,diagram %[+ ess5tial features ( ,premi] ,amp]o electromagnetic rectifi]4 ,details ( con/ruction & pr9ciples ( op]ation are giv5 9 ! accompany+ text4 ,! o!r direct curr5t t]m9al ,t' is connect$ to ! c5t] ( ! trans=m] second>y at t2 & ,,cs & ,,cs' are respectively jo9$ up to ei!r end ( ! second>y w9d+ & to ! o!r coat+s ( ! cond5s]s4 ,illu/ration3 ,,fig4 #b1abb4--;,diagram ( ,g5]al ,electric 7,batt57 electromagnetic rectifi]4 ,x is desirable = light & occasional s]vice1 :]e direct curr5t is requir$ b only an alt]nat+ supply is available1 be+ us$ = *>g+ /orage batt]ies1 excit+ sp>k coils1 p]=m+ electrolytic "w1 etc4 ,! rectifi] consi/s ( a /ep d[n /atic trans=m] ,t1 by means ( :i* ! circuit pressure is r$uc$ to ab\t #ej volts2 also1 a pol>iz$ relay ,r1 ! contact tongue ,c ( :i* moves to "o side or ! o!r 9 sympa?y ) ! alt]nations ( ! curr5t 9 ! prim>y w9d+ ,p1 ! second>y curr5t induc$ 9 ! w9d+ ,s be+ !reby r5d]$ direct 9 ! out] circuit4 ,t'1 ,t' are ! ma9 t]m9als :i* are connect$ to ! alt]nat+ curr5t supply ?r\gh ! wires ,w4 ,lamps ins]t$ at ,l are us$ z resi/ances 9 ! prim>y circuit1 ! r$uction ( ! voltage already allud$ to be+ effect$ by ?is means4 ,9 *>g+ /orage batt]ies :]e a l[ pressure is requir$1 a lamp 7or lamps7 %\ld be connect$ 9 ! second>y circuit z %[n1 ,s ,b be+ ! /orage batt]y1 & ,l' ,l' ! lamp resi/ances 9 s]ies !re)1 ! batt]y has "o end ( ! second>y ,s connect$ to its middle4 ,?us ! alt]nat+ curr5t leav+ ! trans=m] by ! wire #a1 passes by flexible connection #b1 to ! vibrat+ contact tongue ,c ( ! relay1 ! latt] caus+ ! curr5ts 9 ei!r direction to fl[ ?r\gh ! two halves ,h1 ,h' ( ! batt]y1 :5ce ! curr5t re-ent]s ! second>y ( ! trans=m] by ! wire #c4 ,! s(t iron core ( ! relay is 9 two halves ,s' ,s' & ! armature ,a1 c>ry+ ,c1 vibrates betwe5 _! pol> extremities4 ,m1 ,m' are two p]man5t magnets ) _! l poles toge!r at ! c5t] ,c' :]e ,a is pivot$4 ,suppos+ ^! poles are nor? z indicat$1 ! extremities ( ,a w be s\?4 ,! s\? ends ( ,m1 ,m be+ 9 juxtaposition ) ! c5t]s ( ! s(t iron cores ,s'1 ,s' w r5d] _! extremities fac+ ! ends ( ,a ( nor? pol>ity4 ,! w9d+s on ,s'1 ,s' are connect$ 9 s]ies ) ea* o!r1 & 9 %unt ) ,p across ! ma9 t]m9als ,t'1 ,t'4 ,!n because ( ! pol>ization ( ,a & ,s'1 ,s'1 ! =m] w vibrate rapidly 9 sympa?y ) ! alt]nations ( ! curr5t4 ,k is a cond5s] %unt$ by a lamp resi/ance ,l1 ?is be+ f\nd to improve ! work+ ( ,r4 ,:5 ! alt]nat+ curr5t circuit is brok51 ! spr+s ,,sp1 ,,sp1 c>ri$ by ,,sb & be>+ aga9/ ! adju/able /uds1 keep ,,sb1 ,,cs & ,,cs'4 ,! app>atus ?us acts also z a no voltage circuit break]1 = %\ld ! supply fail1 ! /orage batt]y ,a' "u *>ge w be left on op5 circuit4 ,! action ( ! device is briefly z foll[s3 ,ow+ to ! direct curr5t 9 ! magnetiz+ coils ,c & ,c' "o end ( ,,sb w be p]man5tly ( nor? & ! o!r ( s\? pol>ity2 & s9ce ! pol>ities ( ! poles ,e & ,e' w alt]nate ) ! alt]nations ( ! trans=m] second>y curr5t1 ,,sb w rock rapidly on its pivot1 & contact w be made by turns ) ,,cs & ,,cs'4 ,! purpose ( ! cond5s]s ,k & ,k' is to r$uce ! sp>k+ at ^! po9ts4 ,:5 contact is made at ,,cs1 ! direct curr5t t]m9als ,t & ,t' are connect$ to ! ,s half ( ! second>y w9d+2 & :5 contact is made at ,,cs'1 !y are connect$ to ! ,s' half4 ,?us a rectifi$ uni-directional curr5t w fl[ f ,t & ,t'1 & x may be us$ to *>ge ! batt]y ,a'1 "w a small motor or = v>i\s o!r purposes requir+ direct curr5t4 ,:5 ! rectifi] is us$ = *>g+ /orage batt]ies1 ! sep>ate cell ,a may sometimes be disp5s$ )1 ! w9d+ ,c1,c' be+ connect$ to "o ( ! cells "u *>ge4 ,! rectifi] is adju/$ to suit ! frequ5cy ( ! supply circuit by alt]+ ! di/ance ( ! poles ( ,e & ,e' f ! ends ( ! pol>iz$ armature ,,sb2 & also by *ang+ ! t5sion ( ,,sp1 ,,sp by means ( ! screw /uds aga9/ :i* !y be>4 ,,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