Preface ....................................................... xxi
Author ...................................................... xxiii
Acronyms ...................................................... xxv
Chapter 1 Plating of Electrical Equipment ..................... 1
1.1 Electroplating for Contact Applications .................... 1
1.1.1 Silver Plating ...................................... 1
1.1.2 Tin Plating ......................................... 4
Applications ............................................... 5
1.1.3 Nickel Plating ...................................... 6
1.2 Electroless Plating ........................................ 8
1.2.1 Electroless Nickel: Physical Properties ............. 9
1.2.2 Electroless Nickel: Corrosion Resistance ........... 11
1.2.3 Electroless Nickel: Electrical Resistivity ......... 11
1.3 Electroless Nickel as a Plating Alternative for
Electrical Apparatuses in Corrosive Atmosphere ............ 12
1.3.1 Testing of EN for Use in Electrical
Applications ....................................... 13
1.3.2 Field Testing of EN-Plated Electrical Equipment
in Energized Conditions ............................ 18
1.4 Zinc Electroplating and Galvanization ..................... 23
1.4.1 Zinc Electroplating ................................ 23
1.4.2 Zinc Galvanization Processes ....................... 24
1.4.3 Conversion Zn Plating: Passivation with CrIII or
CrVI ............................................... 25
1.5 Metal Whiskers on Plating (Noncorrosive Phenomenon) ....... 26
1.5.1 Whisker Phenomenon and Characteristics ............. 26
1.5.2 Tin Whisker Mitigation Techniques .................. 31
1.5.3 Tin Whiskers and the RoHS Initiative ............... 33
1.5.4 WhiskeT Mitigation Levels Classification ........... 34
1.5.5 Whiskers on Other Metal Platings ................... 35
1.6 Plating on Aluminum ....................................... 37
1.6.1 Use of Aluminum in Electrical Industry ............. 37
1.6.2 Metals Used to Plate Aluminum ...................... 39
1.6.3 Methods for Plating on Aluminum .................... 39
1.6.4 Quality of Tin Plating on Al for Different
Plating Techniques ................................. 41
1.7 Plating Standards and Glossary ............................ 45
1.7.1 National and International Standards and
Regulations on Plating ............................. 45
1.8 Plating Glossary .......................................... 47
References ................................................ 58
Chapter 2 Detrimental Processes and Aging of Plating .......... 63
2.1 Issues of Tin Plating Performance ......................... 63
2.1.1 General Precautions in Using Tin Plating ........... 63
2.1.2 Thermal Deterioration of Tin Plating on Aluminum ... 64
2.1.3 Tin Pest ........................................... 70
2.2 Use of Underplating for Plating Longevity ................. 73
2.2.1 Mitigating Role of Underplating .................... 73
2.2.2 Advantages of Nickel as Underplating ............... 74
2.2.3 Recommended Thickness of Nickel Underplating ....... 76
2.3 Applications of Ni Underplating ........................... 77
2.3.1 Use of Ni Underplating for Tin Plating on Copper ... 77
2.3.2 Nickel Underplating as a Tin Whisker Mitigation
Technique .......................................... 78
2.3.3 Ni Underplating for Tin Plating on Aluminum ........ 80
2.3.4 Ni Underplating for Gold Plating ................... 84
2.4 Galvanic Corrosion: Connections Made of Dissimilar
Metals .................................................... 85
2.4.1 Hazard: Galvanic Corrosion ......................... 85
2.4.2 Definition of Dissimilar Metals .................... 86
2.4.3 Galvanic Corrosion of Copper-to-Aluminum
Connections ........................................ 87
2.4.4 Protection of Copper-to-Aluminum Connections
from Galvanic Corrosion ............................ 88
2.4.5 Galvanic Corrosion in Steel Connections with
Aluminum and Other Metals .......................... 90
2.4.6 General Precautions to Minimize Galvanic
Corrosion in Connections ........................... 91
2.5 Other Detrimental Processes Affecting Plating
Performance ............................................... 92
2.5.1 Intermetallic Compounds ............................ 92
2.5.2 Fretting Corrosion and a Means of Protection ....... 94
Chapter 3 Electrical Equipment in a Corrosive Environment ..... 99
3.1 Corrosion Factors in the Atmosphere ....................... 99
3.1.1 Types of Corrosive Atmospheres ..................... 99
3.1.2 Factors Affecting Atmospheric Corrosion ........... 101
3.1.3 Airborne Contamination in Data Centers ............ 104
3.1.4 Zinc Whiskers ..................................... 105
3.2 Effect of Environment on Bare Metals ..................... 106
3.2.1 Iron and Steel in Enclosures, Frames, Rails,
and so Forth ...................................... 106
3.2.2 Copper and Copper Alloys: Parts of the Conductive
Path .............................................. 107
3.2.3 Nickel and Nickel Alloys: Electrical Contacts
and Plating ....................................... 108
3.2.4 Aluminum and Aluminum Alloys in Electrical
Applications ...................................... 108
3.3 Atmospheric Corrosion of Silver Plating .................. 110
3.3.1 Silver Plating Corrosion and Tarnish .............. 111
3.3.2 Red-Plaque Corrosion .............................. 113
3.3.3 Underplating Corrosion ............................ 115
3.3.4 Effect of Silver Plating Thickness and Quality
on Sulfuric Corrosion ............................. 116
3.3.5 Corrosion of a Copper Bus with Flash Silver
Plating ........................................... 116
3.4 Effect of Silver Corrosion on Contact Resistance ......... 117
3.4.1 Silver Tarnish and Contact Electrical Resistance .. 117
3.4.2 Techniques of Tarnish Cleaning .................... 120
3.5 Silver Whiskers: A Mysterious and Dangerous Phenomenon ... 121
3.5.1 History of Silver Whiskers ........................ 121
3.5.2 Factors That Affect the Growth of Silver
Whiskers .......................................... 122
3.5.3 Failures in Electrical Equipment Caused by Silver
Whiskers .......................................... 123
3.5.4 Study of the Silver Whisker Phenomenon ............ 123
3.5.5 Silver Whiskers Puzzle ............................ 127
3.6 Tin Plating Corrosion .................................... 128
3.6.1 Tin Oxidation ..................................... 129
3.6.2 Reaction of Tin with Other Gases .................. 129
3.7 Zinc Plating Corrosion and Galvanized Steel .............. 130
3.7.1 Atmospheric Corrosion of Zn ....................... 130
3.7.2 White Rust on Zinc ................................ 131
3.7.3 Galvanized Steel .................................. 132
3.7.4 Signs of Galvanized Steel Corrosion ............... 133
3.7.5 Factors Affecting Galvanized Steel Corrosion ...... 135
3.7.6 Corrosion of Galvanized Steel in Circuit Breaker .. 136
3.8 Means of Corrosion Protection of Electrical Equipment .... 137
3.8.1 Protective Coatings for Conductive Parts,
Enclosures, and Frames ............................ 137
3.8.2 Means of Protection from Silver Corrosion ......... 139
3.8.3 Conversion Treatment .............................. 140
3.8.4 Chromium-Free Varnish-Preventative Processes ...... 141
3.8.5 Means of Preventing the Corrosion of Zinc-Plated
Steel Parts in Electrical Equipment ............... 141
3.8.6 Vaporized Corrosion Inhibitors .................... 142
3.8.7 Lubrication ....................................... 142
3.9 Means of Environmental Control for Corrosion Protection .. 143
3.9.1 Assessment of Electrical and Electronic Equipment
Exposure to Corrosive Environment ................. 143
3.9.2 Air Quality Monitoring ............................ 144
3.9.3 Direct Gas Monitoring ............................. 145
3.9.4 Corrosion Control Technology ...................... 145
3.9.5 Chemical and Particulate Filtration ............... 147
3.9.6 Temperature Control ............................... 147
3.10 Corrosion Glossary ....................................... 148
References ............................................... 160
Chapter 4 Lubrication of Distribution Electrical Equipment ... 165
4.1 Lubrication Primer ....................................... 165
4.1.1 Purpose of Lubrication ............................ 165
4.1.2 Lubrication Terminology ........................... 166
4.1.3 Types of Lubricating Materials .................... 167
4.1.4 Grease Composition and Properties ................. 169
4.2 Incompatibility of Lubricants ............................ 173
4.2.1 Definition of Incompatibility ..................... 173
4.2.2 Causes of Incompatibility ......................... 174
4.3 Lubricant Working Temperature Limits and Storage ......... 176
4.3.1 Lubricant Working Temperature ..................... 176
4.3.2 Lubricant Storage Conditions and Shelf Life ....... 177
4.4 Lubrication of Electrical Contacts ....................... 178
4.4.1 Principles of Contact Lubrication ................. 179
4.4.2 Choice of Lubricants Based on Design and Contact/
Plating Materials ................................. 179
4.4.3 Lubrication as Protection from Fretting
Corrosion, Mechanical Wear, and Friction .......... 183
4.4.4 Lubrication as Protection from Corrosion .......... 184
4.4.5 Durability of Lubricants .......................... 185
4.5 Practical Lubrication .................................... 186
4.5.1 Periodic Lubrication Maintenance of Electrical
Power Equipment ................................... 186
4.5.2 General Lubrication Recommendations for
Electrical Equipment .............................. 187
4.6 Lubrication Failure Modes ................................ 189
4.6.1 Causes of Lubrication Failure ..................... 189
4.6.2 Wrong Lubricant for Application ................... 190
4.6.3 Thermal Limitations ............................... 190
4.6.4 Lubricant Composition and Wrong Amount of
Lubricant ......................................... 191
4.6.5 Contaminants or Corrosives in the Lubricant ....... 191
4.6.6 Environmental Factors Causing Grease
Deterioration ..................................... 192
4.6.7 Lubricants' Incompatibility ....................... 193
4.7 Lubrication Failures of Electrical Equipment: Case
Studies .................................................. 193
4.7.1 CB Failures Caused by Lubrication at U.S.
Commercial Nuclear Power Plants ................... 193
4.7.2 Overheating of the MV Switch ...................... 194
4.8 Informational Sources for Lubricants ..................... 198
4.9 Lubrication Glossary ..................................... 201
References ............................................... 208
Chapter 5 Insulation, Coatings, and Adhesives in
Transmission and Distribution Electrical Equipment ............ 215
5.1 Insulating Materials in Power Equipment .................. 215
5.1.1 Insulating Materials Used in the Electrical
Industry .......................................... 215
5.1.2 Thermal Limitation for Electrical Insulation ...... 219
5.1.3 Thermal Degradation of Insulators ................. 222
5.1.4 Temperature Limitations for Switchgear Assembly
Based on Insulation Class ......................... 223
5.2 Aging of Insulating Materials due to Electrical Stress ... 224
5.2.1 Electrical Breakdown in Insulation ................ 224
5.2.2 Corona ............................................ 225
5.2.3 Partial Discharge ................................. 227
5.3 Environmental Aging of Insulating Materials .............. 231
5.3.1 Insulation Deterioration under Environmental
Conditions ........................................ 231
5.3.2 Biological Contamination and Corrosion of
Insulators ........................................ 232
5.3.3 Environmental Aging of Insulators in Transmission
Lines ............................................. 232
5.3.4 Stress Corrosion Cracking in Composite
Insulators ........................................ 233
5.4 HV Bushings in Transformers and CBs ...................... 234
5.4.1 Types of Bushings ................................. 234
5.4.2 Bushings: Possible Causes of Failures ............. 235
5.5 Power Cable Insulation ................................... 236
5.5.1 Cable Insulation Types ............................ 237
5.5.2 Aging of Cable Insulating Materials ............... 238
5.6 Other Insulating Media ................................... 239
5.6.1 Insulating Oil .................................... 239
5.6.2 Sulfur Hexaflouride (SF6) as Insulating and
Cooling Media ..................................... 243
5.6.3 Air and Vacuum as Insulating Media ................ 244
5.7 Powder Coating and Paint for Electrical Enclosures ....... 245
5.7.1 Electrical Enclosures: Types and Materials ........ 245
5.7.2 Powder Coating/Paint Used for Enclosures .......... 246
5.7.3 Defects and Failures of Powder Coatings and
Paints ............................................ 249
5.7.4 HVRTV Coating ..................................... 251
5.8 Electrical Insulation Standards and Glossary ............. 253
5.8.1 National and International Standards and
Regulations on Insulation ......................... 253
5.8.2 Insulation Glossary ............................... 256
Chapter 6 Electrical Equipment Life Expectancy, Aging, and
Failures ...................................................... 269
6.1 Life Expectancy for Distribution and Transmission
Equipment ................................................ 269
6.1.1 Estimation of Electrical Equipment Lifetime ....... 269
6.1.2 Overloading and Estimated Life of Electrical
Equipment ......................................... 270
6.1.3 Temperature and Estimated Life of Electrical
Equipment ......................................... 271
6.2 Signatures of Aging of Electrical Equipment in Nuclear,
Industrial, and Residential Environments ................. 272
6.2.1 Aging Factors ..................................... 272
6.2.2 Aging Equipment in an Industrial Environment ...... 273
6.2.3 Aging Equipment in Power Generation and
Transmission and Distribution ..................... 274
6.2.4 Aging Power Equipment in a Residential
Environment ....................................... 275
6.2.5 Aging Electrical Equipment in Rural/Agricultural
Applications ...................................... 277
6.3 Rural/Agricultural Applications .......................... 277
Failure Modes and Failure Rates of Aging Electrical
Equipment ................................................ 278
6.3.1 Definitions of Failure, Failure Mode, and Failure
Rate of Electrical Equipment ...................... 278
6.3.2 The Bath Tub Curve, the Hypothetical Failure
Rate vs. Time ..................................... 279
6.3.3 Failure Causes of CBs ............................. 280
6.3.4 Failure Causes and Failure Rates of Power
Transformers ...................................... 282
6.3.5 Failure Causes of MV Switchgear ................... 283
6.3.6 Failure Causes of Other MV and LV Power
Electrical Equipment .............................. 284
6.3.7 Failure Causes of Power Connectors ................ 285
6.3.8 Inadequate Maintenance and Maintenance Quality as
a Cause of Failure ................................ 287
6.4 Failure Causes and Rates of Electrical Equipment Based
on CIGRÉ Survey .......................................... 288
6.4.1 Results of the Older CIGRЙ Surveys of HV
CB Failures ....................................... 289
6.4.2 Failure Causes of GIS ............................. 290
6.4.3 Failure Causes of SF6 CBs ......................... 293
6.4.4 Failure Causes of Disconnectors and Earthing
Switches .......................................... 294
6.5 Failure Cases of High-Voltage Electrical Equipment ....... 294
6.5.1 Failures of HV Bushings ........................... 294
6.5.2 Failures of HV Transformers ....................... 295
6.5.3 Failure Mechanisms of HV Transformers and
Bushings .......................................... 296
6.5.4 Failures of HV CBs ................................ 297
6.6 Failure Cases of Low- and Medium-Voltage Electrical
Equipment ................................................ 299
6.6.1 Bushing Failures in MV Switchgear ................. 299
6.6.2 Case Studies of MV Switchgear Failures ............ 300
6.6.3 Metal-Clad Switchgear Failures .................... 302
6.6.4 Failure of MV Power Cables ........................ 303
6.6.5 LV Switchboard Failure ............................ 303
References ............................................... 305
Chapter 7 Physical Conditions of Electrical Equipment:
Testing, Monitoring, and Diagnostics .......................... 309
7.1 Parameters Defining the Physical Conditions of
Electrical Equipment ..................................... 310
7.1.1 Transformers ...................................... 310
7.1.2 HV Bushings ....................................... 310
7.1.3 Circuit Breakers .................................. 310
7.1.4 Switchgear ........................................ 310
7.1.5 Power Cables ...................................... 311
7.2 Techniques for Testing Physical Conditions of MV Cables .. 311
7.2.1 Comparison of MV Cable Testing Techniques ......... 312
7.2.2 High Potential Withstand Test ..................... 313
7.2.3 PD Diagnostics .................................... 315
7.2.4 Choice of MV Cable Diagnostics .................... 316
7.3 Testing Techniques to Assess Insulation Conditions of
HV/MV Switchgear, CBs, and Transformers .................. 317
7.3.1 Insulation Condition: PD Testing .................. 317
7.3.2 Diagnostics of Oil Condition ...................... 319
7.4 Online Monitoring Techniques for PD of MV Substations,
Switchgear, and Cables ................................... 324
7.4.1 PD Detection in Substations, Switchgear, and
Cables ............................................ 325
7.4.2 Monitoring PDs with Fiber-Optic Technology ........ 325
7.5 Testing of HV Bushing Conditions ......................... 326
7.6 Thermal Conditions of Electrical Equipment and
Temperature Monitoring ................................... 327
7.6.1 Temperature Measurement Using Thermography ........ 328
7.6.2 Continuous Temperature Measurement ................ 328
7.6.3 Fiber-Optic Technology for Temperature
Measurement ....................................... 329
7.6.4 Winding Temperature Monitoring of HV Transformers
with the Fiber-Optic Technique .................... 331
7.6.5 Wireless Temperature Monitoring ................... 332
7.7 Physical Conditions of Transmission Electrical
Equipment: Online Monitoring Techniques .................. 336
7.7.1 Condition Monitoring Technologies in Electrical
Transmission ...................................... 336
7.7.2 Overhead Transmission Lines ....................... 336
7.7.3 Properties of Transmission Overhead Lines
to Monitor, Sensing Elements and Monitoring
Techniques ........................................ 338
Chapter 8 Electrical Equipment Maintenance and Life
Extension Techniques .......................................... 347
8.1 Maintenance Strategies ................................... 347
8.2 Maintenance as a Life Extension Technique ................ 349
8.2.1 Time-Based Maintenance ............................ 349
8.2.2 Maintenance of Power Circuit Breakers ............. 349
8.2.3 Periodic Lubrication of the Power Circuit
Breaker ........................................... 351
8.2.4 Refurbishment or Reconditioning ................... 352
8.2.5 Condition-Based Maintenance ....................... 354
8.3 CBM Methodology and Life Management ...................... 356
8.3.1 Distribution Power Transformers ................... 356
8.3.2 Power Cable Systems ............................... 358
8.4 Maintenance of Electrical Equipment Exposed to Corrosion
and Water ................................................ 360
8.4.1 Water-Damaged Electrical Equipment ................ 360
8.4.2 Electrical Equipment in Nuclear Industry .......... 361
References ............................................... 363
Index ......................................................... 367
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