Electric motor maintenance and troubleshooting : [covers
Contents
1. o ooooo o lt 201 Components of the Three Phase Motor ooooomoomomomm o o 201 Rotorand Fan oh ec Func yor Rar UP RU iei SO E aol we Re Oe aloes 203 Stator Core c oS Ls uev ine dices VS c eoe ese aT E E 203 Shell qud WCAG oos ceo op ec v oin i C dtd es ad 204 End Brackets Lu acer i qus Saco dee orco ede But cu e LR da 204 Bearings ey Ces Ue SA uA UE BEA Sa eS eS EN E EG bue d 205 Operation of the Three Phase Motor s usos Vp aW ER Led 205 The Rotating Magnetic Field in a Three Phase Motor 206 Single Phase Condition a voa E UNE EUR Rd ES I ex dx qu 209 Amperes and Rotor Bar Design cu eu ed oco Y eye dones 210 PHASE ANG uua pai E Ee ya ia 211 Small Rotor BAP Src Gee kk Sosa lee des do as dr 211 Large Rotor Bars ici told e d CAN ds 212 Gode Letra CA eee dae ata Rc e ache tn ria 213 Tordue and AAA dened wie Ri ou ae pl 213 DESTA Letten ud ln ESAS 214 Introduction to Three Phase Motor Types 0 cece cece ees 217 The Nine Lead Induction Motor Le vou GN e Re pigs 217 Nine Lead Wye Connection 0 0 ee nn 219 Nine Lead Multiple Wye Connection with T10 220 Thermal Protector for the Nine Lead Wys Connected Mott vers LR ot ia AS 222 Nine Lead Delta Connection lese ee 223 Multiple Delta Connection ices x e pex y a Rn 224 Twelve Lead Connection mcus Led NEU acer es SPOT Ra 224 M ltispeed Motors ii ie Eee if ar rca 227 Sinsle Winding Two Speed Motors sus elus a ae n2. Shunt Field Control for Starting and for Above Base Speed 44 The Differential Connection Mok icra 94 S P en pone d 45 Armature Components vss hee s ve a S n be 46 COT mutator eco he dues aene ee e WE Gales adhe ated 47 Gommutator Film ug vlvea ec oe San e CER UN UAR ERU e A 48 Armature Windings seoses eedi iea Anei DET hn 49 pouabzer SMUG oen we a re ee be Er eae Cao ea ede 50 Lamimated Ion twtr aoe e cd a UU tio 50 Ch pter REVIEW au ioo puede b ROOT S PACA aaa n od 51 CHAPTER 2 Troubleshooting and Testing the DC Machine 57 Armature Problems sinuoso RODA due sd 57 Burned Commutator Bars iria aos Su od don ES AO RO 57 Dirty Commutatots eoe eim X oa ap UC a nea eld 57 Dead Spots from an Open Armature Coil ooooooooo oo 58 Open Equ lizer cl pec AS PAROS PES Te PALS RUE A 58 Stalled A ste EL a 20 Sor pAn hte wp Wey ede A aos d ed A 58 Control and Load Problems on trm Pc eee tres um he 59 BUSH chs icici lain nie droge e VA IRAM Eas ATE SOME ea 59 Brush Problems 3 eve e E eA ee EL Oe io VET 59 ConducHom ZoNa ebore en e Ran ato Med e d deb dns 60 Spiral Groove 4 sa Late Wed Rad A eate Vers diu Mea RES 61 Multiple Brushes o4 cere rho qd vec ee ace i he AA 62 Brush Box and Commutator Spacing oooomoomom mmm 62 Distance Between Brushes isses nn 62 Brush Holder Alignment 5 45 Rege ERES 63 Spring Tension s dace wake EE Aq xu Ree enw borrado gans dig 63 Br sl Shuntsz ere ei ar e
3. Tess Buia es aa 83 Nesole Probes ari ew t Sava qus bhp tw a 83 Variations in the Shunt Field Circuitry sceau d 84 Drawing Simple Schematics of a Shunt Field o o ooooo 84 Drawing a Diagram of a Two Circuit Shunt Field 84 Drawing a Diagram of a Two Circuit Two Coils per Pole Shunt Field e pe EE 85 Ground to the Frame Symptom a ros betta 87 Shorted Turns in the Shunt Field Symptoms 89 Shunt Field with an Open Circuit souder OR a 91 Shunt Field Shorted to the Series Field Symptoms 93 Locating Problems in the Series Field e esos ban 94 Ground to Frame Symptoms oc tr aid 95 Shorted Turns in the Series Field Symptoms o o ooooo 96 Locating an Open Circuit in Series Field 98 Identifying Leads of a Compound DC Motor with an Ohmmeter 99 Chapter 2 REVIEW si E NOR Ate Ez 100 Contents ix CHAPTER 3 AC Electric Motor Theory EN mea TAE 2 105 AC Terminology S cerra cu e ALL Uh de 105 Generating Alternating Curtis Paka hae e dA 105 Cycles and Hertz v ivoire ise vati tau ebd e d okton eis ES 107 Electrical Degrees and Time til seas DECR CUR e pe iaa 108 Electrical Degrees and Mechanical Degrees 111 Debrees and LOCO Os aut a yk es meetin s 111 Two Phase POWET d ond a curse aes one nets cuite tay td 111 Two Phase Rotating Magnetic Field o ooo oooooomo o 113 Revolutions per Minu
4. etos pk sa mts 390 Chapter 8 Review er 24 tun win ci Gas Aad Ha beds Des GAS M e s 391 Index RR NAO 393
5. ADIS ERA Sees 354 Sealed Beatin ee goce rcc bac eth OE Ce RT Base eee arduis 354 Labyrinth Sed jae Gu O II ved a o M Aer 354 Bearing Removal 6 ue cef e e REOR eR e Cao Re 356 Bearing Installation oC RU Ede 358 Identifying Bearing Breakdown Causes uses 359 Specialized Bearing TOOL 224 er a tester id DEES Ea ER 361 Sleeve Bearings 2 vest QU e Gon ae rate dn eR AG it i oar 363 Chapter Z REVIEW S Es s oou frr IN Cae td Aube a sers 363 CHAPTER 8 Test Instruments and ServiceS o ooooooooo o 2 2307 Instruments for Initial Testing osc zac e phe RR enna lead RA 367 Voltmeter cb face cider d Root rid d Da CRUCE aU ET 368 Clamp on Ammeter A vadis sed isis OE ep EA um 369 ODInmieler Cs cures ya Re aeu E SRI NI iia 371 IMICTODIBIRCUOES ta etude eee bed 372 Tachometer A e Mod ET Miu EBEN UT US dd 373 Contents xv Infrared QUE pcs cee tte dey toe set ehh Dad e be Ade 376 StethosCoODG ice tale ert e er EO Poth 377 Instruments for In depth Testing and Scheduled Maintenance 377 Surge TESTET oom heey WERE De ee ee ee UAR A 378 ROOT IESUS cree eas utu e wena RUE eh A L6 OS 380 Polarization Index Test with a Megohmmeter 381 Step Voltage IBSE Civi a x wed ex ee o e t man s 383 High Potential Test cies eese ee tenes 385 Power Quality Test Instruments ori mo stk 386 alo S sping hm dhe Sd eet rd Sd vietato MR eus s 388 Laser Alignment isses eh heces 389 Particle Analysis 45 es oed via qud
6. Electric Motor Maintenance and Troubleshooting Second Edition Augie Hand ma Ne We rk Chicago San Fra e Lisbon London Madrid Mexico City M lan Es Delhi x n du an Seoul Singapore Sydney Toronto Contents Troubleshooting Single Phase Motors 0 00 0 eese xvii Troubleshooting Three Phase Motors s auaa 0 0 0 cence eee xix Troubleshooting the DC Machine eee xxi Introd cton OEC PPP xxiii CHAPTER 1 The DC Machine 4 vue rer ad Basic Electricity as It Applies to MOtOrS oooooooommm cromo 1 A a uate VAG EEA a Aeh ale O ed Rk TES 2 Resist ossis be ed aisle al eek tien wad ard eI eee ee 2 AMPETES eaa d eco ufi hee da UE E e Ea e Ee PIOS re 2 Additional Information on Copper Wire 0 cece eee 3 Ohm s Law songs ea vsus pa dU A sent dd ORE 5 Walt v ee Etpa AAA den A oda d 5 Magnets and the Magnetic Circuits 20 eese ee mnn 6 The Bar Madeira IDE EM NEA T ated eq 6 The Blectrotnagnet ei vr y te rianne CERE En ERE E qu ACERO d ud 6 The Magnetic Pale xoa ey d eb vedere ato pe d So r aun e Hwee 6 Ampere Iurns 2eDenenheci a MERO EU EA OE NA e e EROR eme 9 The Magnetic Circuit a Sein cde ese doe adea Codes Acc ront a 9 Magnetic Saturation vus oq i de MC teed an Rei Sec d eve 1 Magneto Balance 1s a 12 PATER a A 12 Neutral Position in the Stator oooooooocooocorcrancnno 13 Circuits of the DC Machine os Prrrsia a ATA Ya PENA 13 Rules for Generating Direct Current 2 0 ccc c
7. a 227 Constant Horsepower Motor 2 0 eee es 228 Constant Torque Motor iiie nn 229 VYatidble Torque Motor 640 e rd 229 xii Contents Multispeed Multiwinding Motor leere 230 Two Speed Two Winding Motor 2 scele mmn 231 Multimode Nine Lead Three Phase Motors o o oooooo ooo 231 Comparing Multimode Motors to Standard Motors 232 Triple Mode Nine Lead Three Phase Motor 0000 233 Identifying the Triple Mode Nine Lead Three Phase Motor 234 Quadruple Mode Nine Lead Three Phase Motor 235 Identifying the Quadruple Mode Nine Lead Three Phase MotoT i osos x Xa e URSI X 237 Synchronous Motor erroris exec ERN I E EET RA Qa irte orden 237 Components of the Synchronous Motor 000 e eee 239 Operation of the Synchronous Motor 0 0 cece eee 240 The Synchronous Motor Control pissy ceeded oh wu eae Cae CR 241 Power Factor Correction with a Synchronous Motor 243 The Brushless Synchronous Motor 0 sesaran eee 244 Three Phase Alternate Pek a CE OE 244 Wound Rotor Mott Qvo Da YN rere pon ace UN QC EOM Gane OE 244 Components of the Wound Rotor Motor 0 0 00 e neue 245 Operation of the Wound Rotor Motor 0 0 00 cece eens 245 Liquid Used for Speed Control vj ow ade E eee 248 Reversing the Wound Rotor Motor vs slo dades 248 Wound Rotor Motor Used as a Variable Voltage Transformer 249 Wound Rot
8. adadPole MOIDE o evi Vr ec x xe o diet bear AN 155 Multispeed Shaded Pole Motor cascades tre ER 156 Troubleshooting the Shaded Pole Motor 0 0 0 eee ee 156 SPREP HABE Motor a ihs E 157 Components of the Split Phase Motor cssc wes a ng os 157 Operation of the Split Phase Motor iss des laude ERE ted 158 Troubleshooting the Split Phase Motor 0 0 0 e eee eee 158 Capacitor Motors vicos te ae A PAA EES 158 The Capacitor Run Motors aca poke aos Y det sed rata 159 The Capacitor Start Motor 3 4 3 40 Y ere et Fate baci Pes 161 Two Value Capacitor Motor Capacitor Start Capacitor Run Motor 172 Capacitor Start Motor Connections l l 178 Thermal Protective Devices i uou aed prd du Ramer RC Ced hem Cl oe 180 Components of the Bimetal Thermal Protective Devices for Single Phase Motors ROS Sew ARE NE e LER aa EN 181 Connections and Operation of the Thermal Protective Device 182 Limitations of Thermal Protective Devices 185 Contents xi Alternative Start Winding Switches o ooooooooooommom on s 186 Potential Relay Start Switch vides thee baa G ex RR RR EE 186 Electronic Stare Switch cad Eee Le a ee ac 190 Time Delay Electronic Start Switch ooooooooo 192 Heat Activated Start SW pL arat eb Es 192 Current Relay Start Switch ors OY ROLES OU Seta sc dea 193 Chapters REVIEW cbr east Se tu pred em OA UL ESTO ERS bue 195 CHAPTER 5 The Three Phase Induction MotoT
9. dme tec E MOX es dea 65 Side WEAR seen ap sexe a ad d C PE HET DUNS Gu Apte Modo 65 Uneven Commutator Segments lee nnn 65 viii Contents Brush Dusting sitesi ERU hee Pa Gi Sar FIBRE NA A Ata 65 Low Load Cunrents lt 5 sec a OR era RO E OH ah ow aka week 65 Silicone Vapor and Adverse Ambient Conditions 66 Seating Brushes see eie Wes ce E See I nee Tus 67 Neutral Location in the Stator and Armature 0 00004 68 Setting Neutral in a Motor illis een 68 Black Band Adjustment jie epe eR DC CURAS QDLELRS Yd 69 Setting Neutral in a Generator jas es hem XC XA GO RS 69 Restoring Residual Magnetism After Setting Neutral 69 Overheated Motors iot iteua oe tae Se EP PR Ree XI 70 Field Testing the DC Machine c acacce d vas cabinet ace ROCK eet S 70 Field Testing the Armature is thud ee 70 Field Testing for Grounds in the Armature Circuit with an Ohmmeter escitas a ck os ad a EAR RO RC RR Ab BS 71 Field Testing the Shunt Pi ld o 25 cooper eoe leaden dees Ge 71 Field Testing the Series Field aa e 75 Locating Problems in the DC Machines jos cese ce e Paes a 78 Locating Problems in the Armature 0 0 0 2 eee eese 79 Locating a Grounded Interpole with AC and a Clamp on Ammeter 80 Locating a Shorted Interpole Using the AC Voltage Drop Test 82 Locating a Shorted Interpole Using the Smoke Test 83 Locating Problems in the Shunt Field oes LR exa 83 ILE Comparison
10. e Multispeed Motor 0 50005 332 Testing Motors in PICS lt a ESE P p 333 Test Instruments for Testing in Place oooooo o 333 Core and Rotor Damage ers mid A AA o 333 Troubleshooting the Nine Lead Motor Wye or Delta in Place 334 xiv Contents Visual Check of the Nine Lead Motor Wye or Delta 334 Testing from Control Wye or Delta 00 000 eee 336 Starting the Motor After the Comparison Test from Control 339 Line Lead Interchange Test for Uneven Amperes 339 Recording Motor Faults ecc desde as 339 Locating Motor Fall A eee EY do ates 340 Test Equipment for Locating Motor FaultS 340 Locating Shorted Turns in a Wye Connected Nine Lead Motor 341 Locating Voltage Spike Damage in a Wye Connected Nine Lead Motor 0 0 ccc e er e s 342 Locating Shorted Turns in a Delta Connected Nine Lead Motor 344 Megohmmeter Test for Ground ire 346 Bearing Mamtenance ro ersen d tay eda e NUR sl RE Ew 346 Motor Storage Concerns iiis ee ees 347 Bearing Failure Causes cui ok Och eA a a 348 Lubrication Schedule and Bearing Life oooooo 350 Grease IyD6S s ose arias Male HA OR OM RETA PRS 351 Changing Grease Types lessen 351 Lubrication PROCESA eet ak EET PIRE wane 352 Alternate Lubrication Methods 24 eese ara EG Ur Es 353 Gearbox Lubrication 5 usu ene PIECE INA Re aer dy Veo n 353 Shielded Bearings oos SL bacon E RIFCR
11. ece eee 14 Th Shunt Generator ii a ed ERE Orem aes 15 The Armature and Interpol cres ors uode wx e 15 The Sh nt Field 4054 2524 ech RAR hee Rua Ok pal RR seb eae 16 vi Contents Operation of the Self Excited Shunt Generator Was wA eS 17 Shunt Generator Control oer t estit li E EU d 18 The Seres Generator cix ac Gi etuer pen d ocn bbs een 19 Operation of the SelfExcited Series Generator 19 The Conipound Generator eoa ese e uS Epi e c eM M 20 The Armature and Iaterpoles sued oe et vac edle d pA CE ERAS 20 The Series Field ira zie rede Neb Xd S Leu 21 The Shunt Elda A e EV Dade dtp d es ed State 21 Operation of the Self Excited Compound Generator 21 Compound Generator Control 2 ccc es 22 The Cumulative Compound Connection Generator 23 The Differential Compound Connection Generator 23 Series Field Connections for a Motor and a Generator 24 Special Purpose Machine Connections liess 25 The DO ARE Welder Sex cs ose b dd er P XR MOOR NN shaped FOR OON ds 25 Operation of the DC Welder Generator yc asc cs exces 27 Operation of the Welders Reactor sc wk ke Bae oa 27 Triterpole a CER EVI A MD NS aS 28 Operation of Interpoles zuo sau oa dot tg Magee ale re 28 The Compensating Wifndimmp ae Aqsa Rx He let VR ed S 30 Operation ofa DE MOtOr aari boc ege PEU eb AO E De iR A pU UT 31 One Armature Conductor in a Generator as It Passes T
12. nts 0 cece ee ee ees 131 Electrolytic Capacitor and Start Winding Connections 131 Parallel Electrolytic Capacitor Connection 005 131 Series Electrolytic Capacitor Connection a se seras 002005 132 Testing the Electrolytic Capacitor 0 0 2c cece ee ee 133 x Contents Capacitor Test Formula sss ce Cue es UR 15 eer ERI a 134 Determining the Right Size Capacitor sse eso n 135 Operation of the Single Phase Capacitor Start Motor 137 Transformer THET oa etse cp Swear OE ed ua iate 138 Transformer Components evitados ER RICHES 138 Transformer Function 0 0 0 00 c ee ns 139 Transformer Rate one eave SiC ERE ES 139 Solder Gun Transformer cca La Ra ake eae OH af 140 The Sauirrel Case ROtOE 5 4 oe Seas a vates ti S e ed RID IS 141 Current Flow in Stator Coils 0 ee ne 142 Function of the Squirrel Cage Rotor iaa a a wae duce OURS 144 Rotor Hertz and Amperes eli au ake dee Rond lees 145 Slip Hertz and Motor Speed sica 1 au olan se hex E ud 145 Synchronous Speed and Zero TOrque oo ooooocoooocmocr oso 146 Rotor Bar Str dir Led e eX Re SUC ER pape 147 Broken Rotor Bares oiu duro e OO EY hae tho pce Re ar RA RI US 148 Cracked End RINES oce dae eA RECO dba d WES 148 Misaligned Rotor ITOM si 25 eee Certi od e Grew a do bag e ROS 149 Chapter 3 REVIEW men stom aa b d cuoi ed S aa 149 CHAPTER 4 The Single Phase Motor oooooooooomoooo o oooooo 155 Sh
13. or Motor Used as a Hertz Changer 249 The Brushless DC Motor soin eb ES gu eR dag un Oy eon dar 249 Components of Brushless DC MOtOTS oooooooooo oo o 250 Operation of the Brushless DC Motor 0 0 0 00 c cee eee 251 Three Phase Servo Motors 4 oa dr eae tea 251 Identifying the Three Phase Induction Motor 00 000 eee 252 Nine Lead Dual Voltage Motors 0 0 cc cece cee ene 252 Three Lead Motors o CIN E SIRE Rs 253 Sik Lead MOIS 645 duae Fada a e Ic sce eR PEE DR edt 253 Twelve Lead Single Speed MOtOTS o oooooooomo omo momo 261 Du l Voltage Multispeed Motors sence Ad eres 263 European Connections ccv rr hed TAG UR wR OS 263 Chapter s REVIEW Saad o eshte aca ns da ae 269 CHAPTER 6 Troubleshooting Three Phase Motors o o oooooo o o 275 The Dual Voltage Nine Lead Motor s Internal Connections 275 Understanding the Nine Lead Wye Connection 275 Contents xiii Understanding the Nine Lead Delta Connection 278 Smaller Wire Size with Delta and Multicircuit Winding 281 Identifying Unmarked Leads in a Nine Lead Three Phase Motor 285 Identifying Unmarked Leads in a Wye Connection 285 Identifying Unmarked Leads in a Delta Connection 288 Theory of Unmarked Lead Test nica da 292 Typical Winding Problems eos COE es 3S 293 Shorted TUER oere a gt Dep Scu ete ee A AY aod EGO Not dett 293 o c
14. os eode he KER eee OI LM QUU SM RES LU 1 Qe 294 PhagesttPhase Short co such v pao oa Sanaa APPS 295 A A Caton P6 9 dead tae a FAS es 298 Burned Windings from Operating on Single Phase 298 Submerged MOP pO es oves eae a eu 300 Assorted Rotor PRODIEM Sas Suede hing TES en O 301 When Motors Overheat cae vue faces 3 act tae Roc ou REDE ee eae 304 Line Caused Overhaadtiig ia veu uu Lex faa e eae ee 304 Operator Catised Overheating eee a 309 Control Caused Overheating iria se s oo p eI rtp aa Oe e DRE 3ll Motor Fault Overheating oud ea cea Read ERR SERT 312 Location Caused Overheatitig 2e so Y rue eed 316 Maintenance Caused Overheating oooooooomommmo roo 316 Chapter 6 A han SRE GAGA heres AQ ud seid ee d 317 CHAPTER 7 Troubleshooting Less Common Motors oooo ooo 321 Troubleshooting Logic Using Voltage Rules ooooo oo o 321 Troubleshooting Less Common Motors 0 0 0 eese 322 Troubleshooting Identified Motors 5e oid sardine endl wale ed 322 Troubleshooting the Synchronous Motor ees 323 The DC Exciter Field and Discharge Resist0T 324 The Amortisseur Winding 0 0 00 cee eee 325 Stator WIND coo acusa Fede Le hon CES Pool a Hae 326 Troubleshooting the Two Speed One Winding MOt0T o o oo ooooooo 327 Troubleshooting Multispeed Multiwinding MotoYS ooooo oo 329 Circulating Current in Multiwinding Multispeed Motors 330 Rotor Problems in th
15. te Poles and Hertz 200005 114 The Single Phase Alternator 00 0 0 0c cue cece eee eas 15 Current Ampere Power and Reactive Terms o ooo o o o 116 Inductive Reactarice A Re wick cine o PS M bh Nang wade s 116 Impedance A A EA 118 Inductive Reactance and Counter voltage o oooomooomo o 118 Power PACO ss a Met Get COR Meese ti da 118 A Spee Crh aaro GA tit 118 Magnetizing Amperes and Lagging Power Factor 119 Power Factor in Motors cese dio ERREUR SUR nhe ae 121 Low Power Factor Concerns o eve exe xe RE XE RM 121 Inductive Reactance and Hertz Change 000 esee 122 Formula for 50 Hz to 60 Hz Power Change 00040 122 Impedance in a Three Phase Winding 00 esses 122 Capacitance and Capacitive Reactance ccc eee eee 123 Capacitor FUNCION ir us e rS PN rada 123 Capacitor Valte as le o 124 Capacitors for Single Phase Motors llis ooo 125 Oi Filled o AAA A E 125 Oil Filled Capacitor in Single Phase MOtoIS o o ooooo o o 125 Oil Filled Capacitor Components 2 0 ccc eee eens 126 Oil Filled Capacitor Connection in a Two Value Capacitor Single Phase Motor 0c c cece eee sees 126 Mounting the Oil Filled Capacitor 0 0 cece eee 128 Electrolytic Capacitors i ess tx Ree e AU ea Se ba see oe Rs 128 Electrolytic Capacitor Function in the Capacitor Start Motor 128 Electrolytic Capacitor Compone
16. wo Poles 3l One Armature Conductor in a Motor as It Passes Two Poles 33 GUM ES Oa Bes Duas eere Su Ah detain b Cade aoe sets d a o M Ud Pate 34 Counter voltage Compared to Charging a Battery 34 Counter voltage in a Motor Armature llle 35 Base Peras e iot rs E ND abbr d sra sedi tance OS 36 Below BASE Speedo anong ma aed abbr y req ele de dfe poe saa 36 Aboye Base PO x cc 2040 00 sicot ea iad epar EE Md ed tes s 36 TORQUE or the DG Motor eus donas RIS aH Rd Er DE PA 37 The Shunt Motoi oue encode ER CT das abe dba dites 37 The Armature and Interpoles siria teda ded ea oda 37 The Shan Fielda Granera a Sac oY d a ub aui Nos asit add 37 Operation of the Shunt DC Motor iura RE a CEA 38 The Permanent Magnet DEMO I osi ven de EUR ee esas 39 Operation of the Permanent Magnet Motor 000005 39 Restoring Magnetism 0 0 0 ccc eee ee 39 Theseries MOLDED Dus vou ew o vibe ee EDS 40 Contents vii The Compound DC Motor acosador be ee REG es Er EROS 42 The Armature and Interpoles iaa taa Pa ES NR 42 The ene Field oo ccce d tea doe eite ioter OUR UNE ede d 42 This Series Field ccs pS Ses Ex m ets 43 Operation of the Compound Motor Connected Cumulative compounds s use mm eR ER E ed pa 43 The Stabiliged Shunt Mot e ac yes setae yee whine MR PERS UA E ER 43 Speed Control for a Compound DC Motor 2 06 05 cece ee en 44 Armature Control for Starting and for Below Base Speed 44
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