Rotating Machine Insulation Systems p. 1 Types of Rotating Machines p. 1 AC Motors p. 2 Synchronous Generators p. 4 Classification by Cooling p.

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1 Preface p. xvii Rotating Machine Insulation Systems p. 1 Types of Rotating Machines p. 1 AC Motors p. 2 Synchronous Generators p. 4 Classification by Cooling p. 6 Purpose of Windings p. 7 Stator Winding p. 7 Insulated Rotor Windings p. 9 Squirrel Cage Induction Motor Rotor Windings p. 9 Types of Stator Winding Construction p. 9 Random-Wound Stators p. 10 Form-Wound Stators--Coil Type p. 10 Form-Wound Stators--Roebel Bar Type p. 12 Stator Winding Insulation System Features p. 12 Strand Insulation p. 12 Turn Insulation p. 17 Groundwall Insulation p. 18 Groundwall partial Discharge Suppression p. 20 Groundwall Stress Relief Coatings p. 24 Mechanical Support in the Slot p. 27 Mechanical Support in the End-Winding p. 29 Transposition Insulation p. 31 Rotor Winding Insulation System Components p. 34 Salient Pole Rotor p. 35 Round Rotors p. 36 Induction Motor Wound Rotors p. 38 References p. 40 Evaluating Insulation Materials and Systems p. 43 Aging Stresses p. 44 Thermal Stress p. 45 Electric Stress p. 46 Ambient Stress (Factors) p. 47 Mechanical Stress p. 48 Multiple Stresses p. 49 Principles of Accelerated Aging Tests p. 49 Candidate and Reference Materials/Systems p. 50 Statistical Variation p. 50 Failure Indicators p. 55 Thermal Endurance Tests p. 56 Basic Principles p. 56

2 Thermal Identification and Classification p. 57 Insulating Material Thermal Aging Tests p. 58 Insulation Systems Thermal Aging Tests p. 58 Future Trends p. 60 Electrical Endurance Tests p. 60 Proprietary Tests for Form-Wound Coils p. 61 Standardized Test Methods for Form-Wound Coils p. 62 Thermal Cycling Tests p. 63 IEEE Thermal Cycling Test p. 63 IEC Thermal Cycling Test p. 64 Multifactor Stress Testing p. 65 Nuclear Environmental Qualification Tests p. 65 Environmental Qualification (EQ) by Testing p. 66 Environmental Qualification by Analysis p. 66 Environmental Qualification by a Combination of Testing and Analysis p. 67 Material Property Tests p. 67 References p. 69 Historical Development of Insulation Materials and Systems p. 73 Natural Materials p. 74 Early Synthetics p. 76 Plastic Films and Nonwovens p. 78 Liquid Synthetic Resins p. 79 Polyesters p. 79 Epoxides (Epoxy Resins) p. 81 Mica p. 83 Mica Splittings p. 83 Mica Paper p. 84 Glass Fibers p. 86 Laminates p. 87 Evolution of Wire and Strand Insulation p. 88 Manufacture of Random-Wound Stator Coils p. 89 Manufacture of Form-Wound Coils and Bars p. 89 Early Systems p. 89 Asphaltic Mica Systems p. 90 Individual Coil and Bar Thermoset Systems p. 90 Global VPI Systems p. 91 Wire Transposition Insulation p. 92 Insulating Liners, Separators and Sleeving p. 93 Random-Wound Stators p. 93 Rotors p. 93 References p. 94

3 Stator Winding Insulation Systems in Current Use p. 95 Methods of Applying Form-Wound Stator Coil Insulation p. 97 Description of Major Trademarked Form-Wound Stator Insulation Systems p. 99 Westinghouse Electric Co.: Thermalastic p. 99 General Electric Co.: Micapals I and II Epoxy Mica Mat, Micapal HT, and Hydromat p. 100 Alsthom, GEC Alsthom, Alstom Power: Isotenax, Resitherm, Resiflex, Resivac and Duritenax p. 101 Siemens AG, KWU: Micalastic p. 102 ABB Industrie AG: Micadur, Micadur Compact, Micapact, Micarex p. 102 Toshiba Corporation: Tosrich, Tostight I p. 103 Mitsubishi Electric Corporation p. 104 Hitachi Ltd.: HiResin, Hi-Mold, Super Hi-Resin p. 104 Summary of Present-Day Insulation Systems p. 104 Recent Developments for Form-Wound Insulation Systems p. 105 Random-Wound Stator Insulation Systems p. 107 Magnet Wire Insulation p. 107 Phase and Ground Insulation p. 108 Varnish Treatment and Impregnation p. 108 Revolutionary Stator Winding Insulation Systems p. 108 Superconducting Windings p. 108 PowerFormer p. 109 References p. 110 Rotor Winding Insulation Systems p. 113 Rotor Slot and Turn Insulation p. 114 Collector Insulation p. 115 End-Winding Insulation and Blocking p. 116 Retaining Ring Insulation p. 116 Direct-Cooled Rotor Insulation p. 117 Core Laminations and Their Insulation p. 119 Electromagnetic Materials p. 119 Magnetic Fields p. 119 Ferromagnetism p. 119 Magnetization Saturation Curve p. 120 Ferromagnetic Materials p. 120 Permeability p. 121 Hysteresis Loop p. 121 Eddy Current Loss p. 122 Other Factors Affecting Core Loss p. 122 Effect of Direction of the Grain p. 124 Effect of Temperature p. 124 Effect of Heat Treatment p. 124 Effect of Impurities and Alloying Elements p. 124

4 Silicon/Aluminum Steels p. 125 Mill-Applied Insulation p. 125 Lamination Punching and Laser Cutting p. 125 Annealing and Burr Removal p. 126 Enameling or Film Coatings p. 127 References p. 127 General Principles of Winding Failure, Repair and Rewinding p. 129 Failure Processes p. 129 Relative Failure Rates of Components p. 131 Factors Affecting Failure Mechanism Predominance p. 132 Factors Affecting Repair Decisions p. 133 Cutting Out Stator Coils After Failure p. 134 Rewinding p. 134 References p. 135 Stator Failure Mechanisms and Repair p. 137 Thermal Deterioration p. 137 General Process p. 137 Root Causes p. 139 Symptoms p. 140 Remedies p. 141 Thermal Cycling p. 141 General Process p. 142 Root Causes p. 144 Symptoms p. 145 Remedies p. 145 Inadequate Impregnation or Dipping p. 146 General Process p. 146 Root Causes p. 146 Symptoms p. 148 Remedies p. 148 Loose Coils in the Slot p. 148 General Process p. 148 Root Causes p. 149 Symptoms p. 151 Remedies p. 152 Semiconductive Coating Failure p. 152 General Process p. 152 Root Causes p. 153 Symptoms p. 153 Remedies p. 154 Semiconductive/Grading Coating Overlap Failure p. 155

5 General Process p. 155 Root Causes p. 156 Symptoms p. 156 Remedies p. 156 Repetitive Voltage Surges p. 157 General Process p. 158 Root Cause p. 159 Symptoms p. 160 Remedies p. 160 Contamination (Electrical Tracking) p. 161 General Process p. 161 Root Causes p. 164 Symptoms p. 164 Remedies p. 164 Abrasive Particles p. 165 General Process p. 165 Root Causes p. 165 Symptoms and Remedies p. 166 Chemical Attack p. 166 General Process p. 166 Root Causes p. 167 Symptoms p. 167 Remedies p. 167 Inadequate End-Winding Spacing p. 168 General Process p. 168 Root Causes p. 170 Symptoms p. 170 Remedies p. 171 End-Winding Vibration p. 172 General Process p. 172 Root Causes p. 173 Symptoms p. 174 Remedies p. 174 Stator Coolant Water Leaks p. 175 General Process p. 175 Root Causes p. 176 Symptoms p. 177 Remedies p. 177 Poor Electrical Connections p. 177 General Process p. 178 Root Causes p. 178

6 Symptoms p. 178 Remedies p. 179 References p. 179 Rotor Winding Failure Mechanisms and Repair p. 181 Round Rotor Windings p. 181 Thermal Deterioration p. 181 Thermal Cycling p. 183 Abrasion Due To Imbalance or Turning Gear Operation p. 186 Pollution (Tracking) p. 187 Repetitive Voltage Surges p. 188 Centrifugal Force p. 189 Remedies p. 191 Salient Pole Rotor Windings p. 192 Thermal Aging p. 192 Thermal Cycling p. 193 Pollution (Tracking and Moisture Absorption) p. 194 Abrasive Particles p. 195 Centrifugal Force p. 195 Repetitive Voltage Surges p. 196 Remedies p. 196 Wound Induction Rotor Windings p. 198 Transient Overvoltages p. 198 Unbalanced Stator Voltages p. 199 High-Resistance Connections--Bar Lap and Wave Windings p. 199 End-Winding Banding Failures p. 200 Slip Ring Insulation Shorting and Grounding p. 200 Remedies p. 201 Squirrel Cage Induction Rotor Windings p. 202 Thermal p. 202 Cyclic Mechanical Stressing p. 203 Poor Design/Manufacture p. 206 Repairs p. 208 References p. 209 Core Lamination Insulation Failure and Repair p. 211 Thermal Deterioration p. 211 General Process p. 212 Root Causes p. 212 Common Symptoms p. 213 Electrical Degradation p. 214 General Process p. 214 Root Causes p. 214

7 Common Symptoms p. 217 Mechanical Degradation p. 218 General Process p. 218 Root Causes p. 218 Symptoms p. 221 Failures Due To Manufacturing Defects p. 221 General Process p. 221 Root Causes p. 222 Symptoms p. 222 Core Repairs p. 222 Loose Cores p. 223 Core Insulation Shorting p. 223 Core Damage Due to Winding Electrical Faults p. 224 False Tooth p. 225 Cracked Through-Bolt Insulation p. 225 References p. 225 General Principles of Testing and Monitoring p. 227 Purpose of Testing and Monitoring p. 227 Assessing Winding Condition and Remaining Winding Life p. 227 Prioritizing Maintenance p. 228 Commissioning and Warranty Testing p. 228 Determining Root Cause of Failure p. 228 Off-Line Testing Versus On-Line Monitoring p. 229 Role of Visual Inspections p. 230 Expert Systems to Convert Data into Information p. 230 Off-Line Expert Systems p. 231 On-Line Expert Systems p. 231 References p. 233 Off-Line Rotor and Stator Winding Tests p. 235 Insulation Resistance and Polarization Index p. 235 Purpose and Theory p. 238 Test Method p. 240 Interpretation p. 241 DC Hipot p. 243 Purpose and Theory p. 243 Test Method p. 243 Interpretation p. 245 DC Conductivity Test p. 246 Purpose and Theory p. 246 Test Method p. 246 Interpretation p. 247

8 AC Hipot Test p. 247 Purpose and Theory p. 248 Test Method p. 249 Interpretation p. 249 Capacitance Test p. 249 Purpose and Theory p. 250 Test Method p. 250 Interpretation p. 251 Capacitance Tip-Up Test p. 252 Purpose and Theory p. 252 Test Method p. 253 Interpretation p. 253 Capacitive Impedance For Motor Stators p. 254 Dissipation (or Power) Factor Test p. 254 Purpose and Theory p. 255 Test Method p. 255 Interpretation p. 257 Power (Dissipation) Factor Tip-Up Test p. 257 Purpose and Theory p. 257 Test Method p. 258 Interpretation p. 259 Off-Line Partial Discharge Test p. 259 Purpose and Theory p. 259 Test Method p. 261 Interpretation p. 262 Partial Discharge Probe Tests p. 263 Purpose and Theory p. 263 Test Method p. 264 Interpretation p. 264 Stator Surge Comparison Test p. 265 Purpose and Theory p. 265 Test Method p. 267 Interpretation p. 267 Inductive Impedance Test p. 268 Semiconductive Coating Contact Resistance Test p. 269 Purpose and Theory p. 269 Test Method p. 269 Interpretation p. 270 Conductor Coolant Tube Resistance p. 270 Purpose and Test Method p. 270 Stator Wedge Tap Test p. 270

9 Purpose and Theory p. 271 Test Method p. 271 Interpretation p. 271 Slot Side Clearance Test p. 272 Purpose and Theory p. 272 Test Method p. 272 Interpretation p. 272 Stator Slot Radial Clearance Test p. 273 Purpose and Theory p. 273 Test Method p. 273 Interpretation p. 273 Stator End-Winding Resonance Test p. 273 Purpose and Theory p. 274 Test Method p. 274 Interpretation p. 274 Rotor Voltage Drop Test p. 274 Purpose and Theory p. 275 Test Method p. 275 Interpretation p. 275 Rotor RSO and Surge Test p. 275 Purpose and Theory p. 275 Test Method p. 276 Interpretation p. 276 Rotor Growler Test p. 277 Purpose and Theory p. 277 Test Method p. 277 Interpretation p. 278 Rotor Fluorescent Dye Penetrant p. 278 Purpose and Theory p. 278 Test Method and Interpretation p. 278 Rotor Rated Flux Test p. 278 Purpose and Theory p. 278 Test Method p. 278 Interpretation p. 279 Rotor Single-Phase Rotation Test p. 279 Purpose and Theory p. 279 Test Method p. 279 Interpretation p. 279 Stator Blackout Test p. 279 Purpose and Theory p. 280 Test Method p. 280

10 Interpretation p. 280 Stator Pressure and Vacuum Decay Test p. 281 Purpose and Theory p. 281 Test Methods and Interpretation p. 281 References p. 282 In-Service Monitoring of Stator and Rotor Windings p. 285 Thermal Monitoring p. 286 Stator Winding Point Sensors p. 286 Rotor Winding Sensors p. 288 Data Acquisition and Interpretation p. 288 Thermography p. 289 Condition Monitors and Tagging Compounds p. 290 Monitoring Principles p. 291 Interpretation p. 292 Ozone p. 293 Monitoring Principles p. 293 Interpretation p. 294 On-Line Partial Discharge Monitor p. 295 Monitoring Principles p. 295 Interpretation p. 302 End-Winding Vibration Monitor p. 307 Monitoring Principles p. 307 Data Acquisition and Interpretation p. 308 Synchronous Rotor Flux Monitor p. 308 Monitoring Principles p. 308 Data Acquisition and Interpretation p. 310 Current Signature Analysis p. 311 Monitoring Principles p. 311 Data Acquisition p. 313 Interpretation p. 314 Air Gap Monitoring for Salient Pole Machines p. 315 Monitoring Principles p. 315 Voltage Surge Monitor p. 316 Monitoring Principles p. 316 Interpretation p. 316 Bearing Vibration Monitor p. 317 Induction Motor Monitoring p. 317 Synchronous Machine Monitoring p. 318 References p. 319 Core Testing p. 321 Knife Test p. 321

11 Purpose and Theory p. 321 Test Method p. 322 Interpretation p. 322 Rated Flux Test p. 323 Purpose and Theory p. 323 Test Method p. 324 Interpretation p. 328 Core Loss Test p. 328 Purpose and Theory p. 328 Test Method p. 328 Interpretation p. 328 Low Core Flux Test (EL-CID) p. 329 Purpose and Theory p. 329 Test Method p. 330 Interpretation p. 331 References p. 332 Acceptance and Site Testing of New Windings p. 333 Stator Windings Insulation System Prequalification Tests p. 333 Power Factor Tip-Up Test p. 333 Partial Discharge Test p. 334 Impulse (Surge) Test p. 335 Voltage Endurance Test p. 335 Thermal Cycling Test p. 337 Thermal Classification Tests p. 338 Stator Winding Insulation System Factory and On-Site Tests p. 339 Insulation Resistance and Polarization Index Tests p. 339 AC and DC Hipot Tests p. 340 Impulse (Surge) Tests p. 341 Strand-to-Strand Test p. 342 Power Factor Tip-Up Test p. 342 Partial Discharge Test p. 343 Capacitance Test p. 343 Semiconductive Coating Test p. 344 Wedge Tap p. 344 Factory and On-Site Tests for Rotor Windings p. 345 Tests Applicable to All Insulated Windings p. 345 Round-Rotor Synchronous Machine Windings p. 346 Salient Pole Synchronous Machine Windings p. 347 Wound Induction Rotor Windings p. 347 Squirrel Cage Rotor Windings p. 347 Core Insulation Factory and On-Site Tests p. 348

12 Core Tightness Test p. 348 Rated Flux Test p. 348 EL-CID Test p. 349 References p. 350 Maintenance Strategies p. 351 Maintenance and Inspection Options p. 351 Breakdown or Corrective Maintenance p. 352 Time-Based or Preventative Maintenance p. 352 Condition-Based or Predictive Maintenance p. 354 Inspections p. 355 Maintenance Strategies for Various Machine Types and Applications p. 357 Turbogenerators p. 357 Salient Pole Generators and Motors p. 359 Squirrel Cage and Wound-Rotor Induction Motors p. 361 Index p. 365 About the Authors p. 371 Table of Contents provided by Blackwell's Book Services and R.R. Bowker. Used with permission.

A Perspective on On-line Partial Discharge Testing of Stator Windings. Greg Stone Iris Power Qualitrol

A Perspective on On-line Partial Discharge Testing of Stator Windings Greg Stone Iris Power Qualitrol gstone@irispower.com Outline Insulation deterioration processes accompanied by PD Early on-line PD