630 INDEX aging stresses, ambient stress, coil/bar insulation cracks, 53 due to radiation, 54 electrical stress, form-wound coil/bar

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1 INDEX A ABB, abrasion (copper dusting), round rotor winding, abrasive particles, failure due to, general processes, 216 remedies, root cause, 216 symptoms, accelerated aging tests, 48 candidate and reference materials/systems, 55 censoring, 57 failure indicators, lognormal distribution, purpose, 54 regression analysis, SAS/STAT program, 59 specimens used, 61 statistical analysis, Weibull distribution, acceptance and pass fail criteria AC and DC hipot tests, , core insulation factory or on-site tests, core tightness, 505 El-CID test, 506 endwinding bump, 500 factory and on-site tests of rotor windings, factory and on-site tests of stator windings, IEC , 495 IEEE 43, 495 IEEE 429, 496 insulation resistance and polarization index, NEMA MG 1, 495 off-line PD test, 498 partial discharge test for conventional windings, partial discharge test for inverter fedwindings, phase resistance and/or thermal imaging, 495 power factor tip-up, 498 rated flux, round rotor synchronous machine windings, R/PI tests, , 501 salient pole synchronous machine windings, 503 semiconductive coating, 499 squirrel cage rotor windings, stator winding insulation system, strand-to-strand, 498 surge impulse, 490, 497 thermal classification, thermal cycling, voltage endurance for conventional windings, voltage endurance for form-wound inverter fed windings, 492 wedge tap, wound induction rotor windings, 504 AC hipot test, interpretation of results, NEMA MG1, IEEE/ANSI C50.12, and IEEE/ANSI C50.13, purpose, test method, theory, acrylic, 87 AEG insulation system table, aging coefficient, 147 Electrical Insulation for Rotating Machines:Design, Evaluation, Aging, Testing, and Repair, Second Edition. Greg C. Stone, Ian Culbert, Edward A. Boulter, and Hussein Dhirani John Wiley & Sons, Inc. Published 2014 by John Wiley & Sons, Inc. 629

2 630 INDEX aging stresses, ambient stress, coil/bar insulation cracks, 53 due to radiation, 54 electrical stress, form-wound coil/bar semiconductive coating deterioration, 54 mechanical stress, thermal deterioration, 54 thermal stress, thermomechanical stress, 50 airgap flux probes, 512, 518 monitoring, 516 air gap flux probe test, air pocket capacitance of, 22 in die-cast aluminum rotor windings, voltage across, 23 alkyd resins, 86 all-enamel film-based magnet wire, 102 all-epoxy Thermalastic insulation, 115 all-rigid insulation system, 118 Alstom, 114, alternators, 1 ambient stress, from chemicals, 53 humidity and, 52 from oil/moisture/dirt combinations, 52 amortisseur, 3, 5 Ampere s law, 16 Andritz, anhydride, 87 annealing, 151 aramid paper, 106, , 253, see also Nomex TM Arrhenius chemical deterioration rate equation, 88 Arrhenius model for thermal stress, 51 asbestos, 86 88, 102, 134, 235, 254, 257 asbestos cloth, 137, asbestos paper, ASEA, asphaltic mica coil insulations, asphaltic-micafolium-insulated stator coils, 85 asphaltic mica systems, 84, 93, 103 4, 186, 218, , 336 flake insulation, groundwall insulation, 86 hydrogenerator winding, 178 splittings composites, 111 windings, 178, 343, 373 asphaltic resins, 90 asphalt mica system, 94 ASTM Test Standards, 79 autoclave molding process, 135 B bake, 103 Baldor, 114 bar-to-bar copper strand connections, 105 bearing vibration monitoring, benzoyl peroxide, 87 B H curve, 144 BHEL, 119 biotite, 95 bitumen, 84, see also asphaltic mica systems bonding, 107 boron trifluoride, 93 breakdown or corrective maintenance, 510 breakdown strength, 22 broken rotor bars, 287, 293, 295, 307, 385, , 432, 524 Brown Boveri, 114, insulation system table, strip-on-edge-type salient pole winding, 608 Brush Electrical Machines Ltd, , 611 insulation system table, B-stage epoxy varnish,86 bump test, 375 burned out, 152 burr removal, 151 C calcined mica paper, 97 calcining, 96 capacitance mapping, capacitance measurements, interpretation of results, 341 purpose, 339 test methods, theory, 339 capacitance tip-up test, interpretation of results, purpose, 342 test method, theory, 342

3 INDEX 631 capacitive impedance test formotor stators, 344 capacitive model for PD, 24 censoring, 57 centrifugal force and round rotor winding failure, and salient pole rotor windings failure, Chattock coil, 452 chemical attack, failure due to, general processes, remedies, 219 root causes, 218 symptoms, 218 chemical reaction rate law, 54 clampings, 147 class A, B, and C materials, 88 coil/bar insulation cracks, 53 collector brush-rigging insulation, 136 collector insulation, 136 condition monitor, 286, 295, , 439, 515 conductive coating, see semiconductive coatings conductor coolant tube resistance, testing of, conductor shields, confidence limits, contamination, 119, 128, , 188, 205, 244, 256, 258, detection in AC maintenance hipot test, 337 and electrical tracking, , 228, 321, 518 heavy oil, 300 on slip ring insulation, 272 winding, , 320, 328, 331, 339, 347, 415, 417, 510 converter-fed random-wound stators, 182, see also inverter-fed drives (IFDs) cooling medium, machine classification by directly cooled windings, 8 9 indirect air cooling, 7 8 indirect hydrogen cooling, 8 copolymerization, 109 copolymerization reaction, 87 copper conductors, 9 replacement or reuseof, 251 copper dusting, 241 core buckling, 302 core insulation shorting, core lamination insulation failures broken bars, 293, 295 electrical degradation, ground faults, 292, 295 manufacturing defetcs, mechanical degradation, overheating issues, , 294 repairs, stator core faults, stator-to-rotor rubs due to bearing failures, 300 thermal deterioration, unbalanced magnetic pull, vibration sparking, 292, 295 core loss, factors affecting aging coefficient, 147 clamping, 147 direction of flux, 148 heat treatment, 148 impurities and alloying elements, machining, 147 pressure, 147 punching, 147 silicon/aluminum steels, 149 temperature, 148 core loss tests, core testing core loss, El-CID test, knife, rated flux, corona, 21 Crane & Co. Inc., 96 cumulative distribution function, 58 Curie point, 148 current signature analysis (CSA), data acquisition, interpretation, lower twice slip frequency sideband, 428 monitoring principles, rotor currents, squirrel-cage winding problems, 427 stator current, curve fitting, 59 cyclic mechanical stressing, cylindrical rotors, 41

4 632 INDEX D Dacron-Mylar-Dacron (DMD), 139 Dacron TM, 98, 253 Daglass TM, 254 damper winding, 3, 5 DC conductivity test interpretation of results, method, 333 purpose, reasons for resistance to increase, 332 theory, DC hipot test, 166, , 364 conventional, 328 interpretation of results, NEMA MG1 and IEC , 327 progressive stress test, purpose, ramp test, 330 step-stress, 328 test method, theory, DC magnetic field, 2 DCmotors and generators, 1 demagnetizing mmf, 146 depolarization cycle, 331 depolymerization, 62, 217 dibasic acid, 87 dip, 103 dipping general processes, remedies, root causes, symptoms, 184 direct-cooled rotor insulation, directly cooled windings, 8 9 hydrogenerators, 9 I 2 R losses, 7 8 direct water-cooled stator windings, 8 direct water cooling of turbogenerators, 9 discharge extinction voltage (DEV), 353 discharge inception voltage (DIV), 353 dissipation (or power) factor measurements, dielectric loss, interpretation of results, 347 purpose, 345 test method, theory, 345 Dongfang Electric Machinery, 122 Doosan, 115 doubly fed induction generators (DFIGs), 6, 40 doubly fed rotor concept, 6 drying oil formulations, 86 drying-oil-modified asphaltic varnish solution,84 Duritenax TM, dye penetrant, 282 rotor fluorescent, test, 479 E Eddy current losses, 146 Eglass, El-CID test, 439, core splits, 459 excitation winding, 459 factory or on-site tests, 506 interpretation of test results, PHASE current comparisons, test method, theory, electrical conncetions, failure processes and, electrical endurance tests, breakdown strength of insulation, modern epoxy-mica insulation systems, 68 proprietary tests for form-wound coils, standardized AC voltage, electrical machines, 1 electrical slot discharge, 191 electrical stress, electrical strip steel, 148 electric breakdown of insulation, 21 Electric Machinery Duraguard VPI System, electric machinery field winding, electric stress, 22 electromagnetic theory, 14 Elin, 114 EMI Sniffer, 361 enamel-film-covered copper magnet wire, enameling, end winding, 32 34

5 INDEX 633 end winding banding failures, end winding insulation and blocking, end winding vibration, effect of, general processes, remedies for, root causes, symptoms, end winding vibration monitor, data acquisition and interpretation, monitoring principles, environmental qualification by analysis, 76 by a combination of testing and analysis, 77 environmental qualification (EQ) by tsting specimens, 75 test report, 75 test sequence, epoxides (epoxy resins), epoxy enamels, 152 epoxy-glass laminate, 32 Epoxy MicaMat TM, 116 Epoxy Novolac, 560 epoxy resins, 93 Epstein acceptance tests, 148 Epstein test, 146 esterification, 87 ethylene glycol, 87 extreme value distributions, 58 F failure indicators, failure processes, due to abrasive particles, due to chemical attack, due to end winding vibration, due to poor electrical conncetions, factors affecting failure mechanism, high intensity slot discharge, inadequate end winding, inadequate resin impregnation or dipping, loose-coil-induced failure, maintenance and, 164 operating environment and, quality leading to, 163 relative failure rates of components, repair decisions and, repetitive voltage surges, semiconductive coating failure, semiconductive/grading coating overlap failure, stator coolant water leaks, thermal cycling, thermal deterioration, transient voltage surges, vibration sparking (spark erosion), winding contamination, winding design and, ferromagnetic material, 143 ferromagnetic materials, ferromagnetism, fiber-covered copper magnet wire, fiber-optic accelerometers, film coatings, finishes, 100 flux probes, , , 512, 518 monitoring, 516 test, 422, , formettes, 65, 88 form-wound coil/bar,manufacturing of asphaltic mica systems, early system, 103 global VPI systems, individual coil and bar thermoset systems, form-wound coil/bar semiconductive coating deterioration, 54 form-wound coil windings, 12 form-wound stators, 12 14, 367 coil type, contamination of, 212 environmental isssues, groundwall thermal impedance, reducing, natural materials for,84 86 recent developments, Roebel bar type, trademarked, fractional horsepower motors, 109 fretting, 33, 152, 227, 243, 248, 296, 298, , 419 Fuji Electric, 119 full-bar taping machines, 108

6 634 INDEX G gas turbine generator, 113 Gaussian distribution, 56 GEC, 114 GEC Alsthom, GE Hydro, 114 General Electric (GE), 93 94, , cooled rotor winding, insulation system table, generators, 1 generator condition monitor (GCM), generator stator cores, 155 girth cracks, 86 glass fibers, glass transition temperature, 104, 135 global vacuum pressure impregnation (GVPI), 32, 103, 105 6, 109, 116, 189 glycol maleate, 87 green insulation systems, 113 groundwall insulation, coils/bars, 19 20, electrical design, forces acting on, 20 mechanical design, partial discharge suppression, stress relief coatings for conventional stators, taping of stator, thermal design, 20 growler, H half turn coil see Roebel bars Harbin Electric Corporation (HEC), 122 harsh environment, 74 high energy line break (HELB), 74 high intensity slot discharge, general processes, 198 remedies, 199 root causes, 198 symptoms, 199 high-temperature superconductors (HTS), 140 Hi-Mold TM, hipot test, 65, 160, 166, 168, 202, 204, 216, 227, 229, 231, , 323, , , , 366, , , 478, , 501 2, 517, 520 Hi-Resin TM, Hitachi, 115, hydraulic molding process, 135 hydrogen cooling, 4,8,42,84, 392, 396 hydrogenerators, 5, 135, core fretting, relaxation, and failure, 302 direct water cooling of, 9 hysteresis loss, I IEC thermal cycling test, inadequate end winding spacing, general processes, remedies, root causes, 222 symptoms, 222 indirect air cooling, 7 8 indirect-cooled round rotor windings, 138 indirect hydrogen cooling, 8 individual coil and bar thermoset systems, induction generators, 6 induction machine wound rotors, induction motor monitoring, inductive impedance, inductive impedance, testing and monitoring of, inner conductor shield, 29 inner corona protection (ICP) coating, 29 inspection options after in-service failure, trend monitoring, 515 years of service or operating hours, insulated rotor windings, insulating material thermal aging test standards, 64 insulation relaxation, 86 Insulation Resistance and Polarization Index, absorption current, 321 capacitative current, conduction current, 321 for direct-water-cooled stator windings, 323 guidelines for DC voltages to be applied during IR/PI test, 324 interpretation of data, 324 IR/PI test, leakage surface current, 321

7 INDEX 635 recommended minimum insulation resistance values, 325 for rotor windings, 323 for stator windings, 323 test method, insulation system, 10 conductor shields, evolution of wire and strand, in form-wound stators, 13 glass fibers, groundwall, laminates, liquid synthetic resins, materials, mechanical supports, mica, plastic films, polymer-fiber-based nonwovens, present, 112 principal drivers, in random-wound stators, 12 strand, surface stress relief coatings for inverter-fed stators, taping stator groundwall insulation, transpositions, turn, wire transposition, insulation system thermal aging test standards, IEC 60034, 67 IEC , 65 IEC , 65 IEC Procedures for Thermal Evaluation, 65 IEEE 117, IEEE 1776, IEEE No. 99, 65 UL-1446, 67 internal transposition, 34 inverter-fed drives (IFDs), 113 motors, 1 stress in, 51 ionization, 22 I 2 R losses, 7 8, 192 in silicon carbide, 28 strand insulation, 16 isinglass, 95 Isotenax TM, J Jinan Power Equipment, 123 K Kaladex TM, 125 Kapton CR TM, 126 knife test, Kraftwerk Union (KWU), 114 KWU, L laminated and reinforced plastic sheet materials, laminated insulation sheet process, 101 laminates, lamination insulation, 147 ASTM A standard, 150 core, failures. see core lamination insulation failures punching, steel, 149 laminations, 9 large motor stator core, laser cutting, leakage flux test, 16, , 273, 291, 296, 299, leak location test, 378 Lewis acids, 93 Lewis bases, 93 liquid synthetic resins, lognormal distribution, loose-coil-induced failure, general processes, remedies, 190 root causes, symptoms, 189 loss of coolant accident (LOCA), 74 Louis Allis, 584 lower twice slip frequency sideband, 428 M machining operations, 147 magnetic field intensity (H), 144 magnetic fields, 143 magnetic flux leaking, 34 magnetic termite, 165 magnetic wedges, 188 magnetization saturation curve, 144

8 636 INDEX magnet wire, 101 insulation, 127 main steam line break (MSLB), 74 maintenance options breakdown or corrective maintenance, 510 condition-based (or predictive) maintenance, noncritical motors, 525 for salient pole generators and motors, for squirrel cage and wound-rotor induction motors, time-based or preventative maintenance, for turbogenerators, material property tests, mean (statistics), 56 mechanical stress, mechanical supports, in end windings, melamine-formaldehyde, 87 metallic oxides, 125 mica, 95 99, 136 backing materials, paper, specific gravity of, 95 splittings, micaceous tape insulation, Micadur Compact TM, 120, 123, 559 Micadur TM, 558 Micadur TM, 119, 123 micafolium insulation systems, 86 Micalastic TM, 115, Micapact TM, 120, 557 Micapal F insulation system, 116, Micapal II TM, 117, Micapal I TM, 93, 116 mica-paper conductor, 265 Micarex TM, 119, 556 mica splitting sheet,84 mild radiation evironment, 75 mill-applied insulation, Mitsubishi Electric Corporation, 121 modern stator winding insulation systems, 218 monitoring bearing vibration, condition monitors and tagging compounds, cooling water or gas channels, 391 current signature analysis (CSA), data acquisition and interpretation, endwinding vibration monitor, online capacitance and dissipation factor, ozone, resistance temperature detector (RTD), 392 rotor winding sensors, stator winding operations, stator winding point sensors, stator winding water leak, 435 synchronous rotor flux monitor, thermal, thermocouple (TC), 392 thermography, using online partial discharge monitor, motor and generator manufacturers consolidation of manufacturers, motorette, 89 motorettes, 88 multifactor stress testing, multilayer wire-wound, 135 multiturn coils, 173, 182, 202, 205 6, 337, , 471, muscovite, 95 Mylar TM,87, 98, 128, 134 N nanomaterials, 124, 126 natural asphalts, 85 Neccobond TM, 115 NEI Peebles Electric Products, , neodymium iron boron (NdFeB), 7 new machine winding and rewind specifications AC hipot test, 473 capacitance/dissipation factor tip-up tests, 473 completely wound and impregnated stators, test for, 473 connections test, 470 disassembly of rotor winding and associated components and assessment, endwinding blocking, 480 endwinding bracing, 469

9 INDEX 637 general item specifications, global VPI windings, test for, IEEE 1799, 470 IEEE/ANSI C50.12 and C50.13, 463 impregnated bars/coils, tests for, 471 for insulated rotor windings, insulation system capabilities, 474 IR and PI on individual phases, 473 mechanical component refurbishment, 481 mechanical inspections, 480 mica strand and/or turn insulation, 469 NEMA MG water immersion test, 473 off-line partial discharge test, 473 pass fail criteria, 465 refurbishexisting salient pole rotor windings, procedure to, sample bars or coils, tests for, 474 slot and endwinding, 469 slot wedges, 469 stator and rotor winding specifications, 464, strip-on-edge pole field windings, surge test, technical specification, up-shaft leads and radial studs, V, IR test, 473 winding process and tests, 485 windings and qualification testing, winding voltage rating, 471 wire-wound pole field windings, Nomex TM, 76, 135, 140, 253, nondestructive diagnostic test, 62 non-global VPI windings, 169 normal distribution, 57 nuclear environmental qualification tests environmental qualification (EQ) by tsting, harsh environments, high energy line break (HELB), 74 IEEE Standards, 75 loss of coolant accident (LOCA), 74 main steam line break (MSLB), 74 Nylon TM,87, 89, 134 O off-line partial discharge for inverter-fed windings, IEC Standard IEC 61934, 357 purpose, test method and interpretation, theory, off-line partial discharge test, discharge inception voltage (DIV), 353 inception and extinction voltages, interpretation of results, off-line PD detection, 352 PD pattern analysis, PD pulse currents, 351 peak magnitude of PD, purpose, test method, theory, Ohm s law, 35, 320, online capacitance and dissipation factor, monitoring, online partial discharge monitor, comparison with other machines, data acquisition, electrical interference, 404 elements, hydrogenerator PDA monitor, identifying failure processes, interpretation, monitoring principles, motor and turbine generator monitoring, PD sensors, trend over time, original equipment manufacturers (OEMs), 114, outer corona protection (OCP), 368 out-of-phase synchronization of synchronous machines, 53 oxidation, 345 ozone, 191 monitoring, P partial discharges (PDs) suppression system, in air-cooled machines, 25 slot semiconductive (semicon) coating, partial discharge suppression in inverter-fed random windings, 37 38

10 638 INDEX permanent magnet (PM) machines, 7 industrial and marine applications, 7 motor/drive configurations, advantages, 7 permanent magnet (PM) synchronous motors, 7 permeability, 145 phase and ground insulation, phase-ground voltage, 18 phase-resolved pulse magnitude analyzer, 354 phase to phase fault, , 182, 205, 219 phlogopite, 95 plastic films, polarization/depolarization current (PDC) test, interpretation of results, 331 purpose, test method, 331 theory, pollution (tracking) round rotor winding, salient pole rotor windings pollution, polycarbonate, 87 polyester resins, 90 polyethylene glycol terephthalate (PET),87 polyethylene naphthalate (PEN), 125 polyethylene terephthalate (PET)films, 94 polyhydric alcohols, 87 polymer-fiber-based nonwovens, polypropylene, 87 polystyrene, 87 polyurethane, 87 polyvinyl chloride, 87 poor connection hot spot (high current-infrared camera) test, interpretation of results, 335 purpose, test method, 335 theory, power factor tip-up test, interpretation of results, 350 purpose, 348 test method, theory, 348 power frequency AC stress, 52 power law constant, 51 preformed coil, 12 prepreg, 101 pressure decay test, probability distributions, 56 proprietary voltage endurance tests, pulse phase analyzer or phase-resolved PD (PRPD) analyzer, 354 pulse width modulation (PWM), 51 pump/storage motor generator, 5 6 punching, 97 98, 138, , 299, 304 Q qualification tests, 73 77, 470 R radiation-only harsh environment, 75 radiation stress, 54 random winding, 17 random windings partial discharge suppression in inverter-fed, stator winding insulation system features, random-wound coils, random-wound stators, 12, 109 contamination of, magnet wire insulation, 127 phase and ground insulation, varnish treatment and impregnation, 128 random-wound stator winding insulation system features, rated flux test, recurrent surge oscillography (RSO) test, regression, 56 for Weibull distributed data, 60 relative dielectric constant, 23 Reliance Electric motors, 114, push-through bar type, 621 remanence, 146 repairs, bar/coil replacement and half coil splice, core lamination insulation failures, core looseness, cutting out stator coils after failure, failure processes, false tooth, 308 high speed grinding, 308 salient pole rotor winding failures,

11 INDEX 639 split core, squirrel-cage rotorwindings failures, stator and rotor cores, of stator winding damage, through-bolt insulation, 308 wound rotor winding failures, repetitive voltage surges, ground and phase insulation, remedies, root causes, 209 and round rotor winding failure, and salient pole rotor winding failure, stress relief coatings, 209 symptoms, turn insulation deterioration, and wound rotor winding failure, residual induction, 146 resin impregnation general processes, remedies, root causes, stator failure, 182 symptoms, 184 resin-rich coils, 184 resins, 84 resin/varnishviscosity, 183 resistance-temperature detector (RTD), , 181, , 403, 447, 522 Resitherm TM, , 123 Resivac TM, resonant frequency, 365 retaining ring insulation, rewedging, , 372, 374, 514, 517 rewinding, RF probe, see stator partial discharge probe ripple springs, 31 Roebel bars, 12 14, 19 20, 34 35, 104, 167, 173, 182, 206, 221, 305, 363, 490, Roebel bar stators, 19 Roebel bar windings, 12 Roebelling, 36 Roebel transpositions, 35 36, 106 rotating machines AC motors, 2 4 on the basis of cooling, 7 9 induction generator, 6 permanent magnet (PM) machines, 7 synchronous generators, 4 6 rotor core construction, rotor fluorescent dye penetrant, testing and monitoring, rotor flux test, 244, 316, , 432 rotor growler, testing and monitoring, rotor pole drop (voltage drop), testing and monitoring, rotor rated flux, testing and monitoring, rotor single-phase rotation, testing and monitoring, 385 rotor slot and turn insulation, rotor stresses, 133 rotor winding insulation, 38 45, 133 induction machine wound rotors, rotor winding sensors, monitoring, round rotor generators, 4 round rotors, round rotor winding failure mechanisms abrasions (copper dusting), centrifugal force, operating without field current, pollution (tracking), remedies, repetitive voltage surges, thermal cycling, thermal deterioration, RSO test, 245, , RTD, 173 4, 181, 403, 447, 391, 392, 522 3, 586, 589, 590, 593 S safety margins of insulation IEC and IEEE standards, 48 SCI motor stator, 47 salient pole generator rotors, 4 5, maintenance options, salient pole rotor windings, failure mechanism of abrasions (copper dusting), centrifugal force, pollution, repairs, repetitive voltage surges, thermal cycling, thermal deterioration,

12 640 INDEX saturation curve, 144 scale parameter, 58 scarf joint, 107 Scotch Brite TM, 480 semiconductive coating contact resistance, testing of, semiconductive coating failure, deterioration, 54, 350, 400 general processes, during the GVPI process, remedies, root causes, in slot, , 202, 228 symptoms, semiconductive coatings, 15, 25 29, 31, , 189, 327, 408, 489 contact resistance, testing of, test for, 499 semiconductive/grading coating overlap failure, general processes, remedies, root causes, symptoms, 196 Shanghai Electric Machinery, short circuit ring, , 280, 283, 293, 295, 385, 427, 429, 504 shrinkage of insulation, 187 side packing, 31, 72 74, , 190, 193, 198, , 373, 472 Siemens, 114, , , strap wound field coils, 622 silicon/aluminum steels and core loss, 149 silicon carbide coating, silicone rubber, 31 skin effect, 14 Skoda, 114 slip recovery, 6 slot cell insulation, 110 slot discharge, 25, , 368 slot liner repair, 251 replacement, 251 slot semiconductive (semicon) coating, slot side clearance, testing of, 373 slot wedge, 30 solventless epoxy enamels, 152 spark erosion, see vibration sparking (spark erosion) speed-increasing gearbox, 6 speed reducing gearbox, 5 squirrel cage induction motor rotor windings, 11 maintenance options, squirrel cage induction (SCI) motor, 2, 134 squirrel cage rotor windings acceptance and pass fail criteria, squirrel-cage rotorwindings, failure of cyclic mechanical stressing, poor design/manufacture, repairs, thermal deterioration, stage I slot discharge, 186 stage 2 slot discharge, 186 standard deviation, 56 standard induction motors, 7 standardized AC voltage endurance test, IEEE 1043, IEEE 1553, static excitation system, 52 stator blackout and ultraviolet imaging, IEEE 1799, 360 interpretation of results, test method, 360 theory, 359 stator coolant water leaks, general processes, remedies, root causes, symptoms, 230 stator core construction, stator end winding bump, testing and monitoring, stator output current in generators, 9 stator partial discharge probe, interpretation of results, purpose, test method, 362 theory, stator pressure and vacuum decay, testing and monitoring, stator slot radial clearance, testing and monitoring, stator wedges, testing of, interpretation of results, purpose and theory, 370 test method,

13 INDEX 641 stator winding, 9 10 stator winding structures form-wound stators, random-wound stators, 12 stator winding water leak monitoring, 435 strand insulation, effective AC resistance, 16 electrical reasons for, 16 I 2 R loss, 16 strip-on-edge-type salient pole winding, 41, 253, , 608, 612 subconductors, 14 submicron aluminum oxide, 125 superconducting sychronous rotors, 140 Super Hi-Resin TM, super-synchronous speed, 6 surface stress relief coatings for inverter-fed stators, surge voltage test, , 382 interpretation of results, NEMA MG1 and IEC 60034, 366 purpose, test method, theory, Swiss Insulation Works, 96 switching-on of motors, 53 synchronous condenser, 1 synchronous generators, 4 6 synchronous machine monitoring, 434 synchronous machine rotor windings, 11 synchronous motor, 2 3 synchronous rotor flux monitor, data acquisition and interpretation, flux density zero crossing (FDZC), 423 round rotor windings, salient pole rotors, synthetic polymers, 87 synthetic resins, 87 T tagging compounds, tan delta see dissipation (or power) factor measurements tape separation, 86 taping of stator groundwall insulation, Teflon TM, 327 Tennessee Valley Authority (TVA) test, 361 tensile stress (kpa), 21 tenter frame, 101 terephthalic acid,87 tests AC hipot test, capacitance measurements, capacitance tip-up test, capacitive impedance test formotor stators, 344 commissioning and warranty testing, conductor coolant tube resistance, DC conductivity test, DC hipot test, to determine root cause of a failure, 313 dissipation (or power) factor, inductive impedance, Insulation Resistance and Polarization Index, for maintenance pruposes, 312 off-line partial discharge for inverter-fed windings, off-line partial discharge test, off-line vs on-line, , polarization/depolarization current (PDC), poor connection hot spot (high current-infrared camera), power (dissipation) factor tip-up, recurrent surge oscillography (RSO) test, rotor fluorescent dye penetrant, rotor growler, rotor pole drop (voltage drop), rotor rated flux, rotor single-phase rotation, 385 semiconductive coating contact resistance, slot side clearance, 373 stator blackout and ultraviolet imaging, stator end winding bump, stator partial discharge probe, stator pressure and vacuum decay, stator slot radial clearance, stator wedges, surge voltage test, using expert systems, visual inspections, winding condition, thermal aging tests, 89

14 642 INDEX Thermalastic TM, , thermal cycling, acceptance and pass fail criteria, conventional thermoset deterioration, 179 general processes, girth cracking/tape separation, global VPI windings, remedies, 181 root causes, 180 in round rotor winding, in salient pole rotor windings, symptoms, thermal cycling test, 62, IEC, IEEE 1043, 73 IEEE 1310, IEEE 1553, 73 thermal deterioration, 54, core lamination insulation failures, general processes, remedies, 176 root causes, in round rotor winding, in salient pole rotor windings, in squirrel-cage rotorwindings, symptoms, thermal endurance test, 61, 88 thermal endurance tests basic principles, future trends, 67 insulating material thermal aging test standards, 64 insulation system thermal aging test standards, thermal identification and classification, thermal identification and classification, thermal stress, Arrhenius model for, 51 thermography, thermomechanical stress, 50 thermoplastic asphaltic resins, 84 thermoset, 90 three-parameter Weibull distribution, 59 three-phase motor, 9 time-based or preventative maintenance, Toshiba Tosrich insulation system, Tostight TM, tracking resistance, 78 transformer effect, 39 transformer law, 17 transient voltage surges, general processes, remedies, 206 repetitive, 202, root causes, 204 symptoms, transposition, 35 transpositions, trickle impregnation, 37 38, 45, 103, 128, 183, 211 tube VPI, turbogenerator, 1, 5, 38 all-rigid insulation system, 118 core vibration, 302 stator core assembly and support, turbogenerators, 1, 5, 38 all-rigid insulation system, 118 core vibration, 302 direct water cooling of, 9 off-line tests, online monitoring, stator core assembly and support, visual inspections, turn insulation, 17 19, 250 in form-wound coils, 18 inductive impedance, 18 phase-ground voltage, 18 in Roebel bar winding, 19 thermal stresses on, 18 turn turn AC voltage, 18 turn-to-turn faults, 38, 128, two-pole synchronous motors, 3 U ultrasonic probe, ultraviolet imaging, under excitation, , 294 urea formaldehyde, 87 US Motors, 602 V vaccum decay test, 378 vacuum pressure impregnation (VPI), 32,85, 103, 111, 198, 408, 484 variable speed drive, see inverter-fed drives (IFDs)

15 INDEX 643 varnished cambric, 84 varnish treatment and impregnation, 128 very low frequency (VLF) test, 10, 335, 338 vibration sensorsmonitoring, vibration sparking, 292 vibration sparking (spark erosion), general processes, remedies, 202 root causes, 201 symptoms, Voith generators, 114 volatile organic chemicals (VOCs),87 volatile solvents, 87 voltage drop test, 379 voltage endurance tests, 68 IEC TS, IEEE 1043/1553, 69 70, 73, 471 for inverter-fed windings, of type II insulation systems, voltage global VPI (GVPI) motor stators, volt stator winding, 13 Von Roll Samicatherm, 114 VPI cycle for the asphaltic system, 94 VPI (vacuum pressure impregnation) process, 85 W water treeing, 328 weather-protected (WP) machines, 8 wedge map, , , 480, 517, 520 wedge tap test, 371, 374 WEG, 114 Weibull distribution, Westinghouse Electric Corporation, 91, 94, , 122, gas-cooled rotorwinding (axial flow), 625 Westinghouse Hydro, 114 windage, 4 5, 7 8, 49, 136, 238 winding capacitance test, 340 winding contamination, general processes, remedies, root causes, 214 symptoms, 214 winding of an edge-wound salient pole, 110 winding wire see magnet wire wind turbines, 40 wire transposition insulation, withstand test see hipot test wound induction motor rotors, wound rotor induction motors, 2 wound rotors, wound rotor winding, failure of due to voltage surges, end winding banding failures, ground insulation, 265 high resistance connections-bar lap and wave windings, repairs, slip ring insulation shorting and grounding, three-phase windings, 265 unbalanced stator voltages,