A comprehensive graduate-level textbook on high voltage insulation engineering, updated to reflect emerging trends and techniques in the field
High Voltage and Electrical Insulation Engineering presents systematic coverage of the behavior of dielectric materials. This classic textbook opens with clear explanations of fundamental terminology, electric-field classification, and field estimation techniques. Subsequent chapters describe the field dependent performance of gaseous, vacuum, liquid, and solid dielectrics under different classified field conditions, and illustrate the monitoring of electrical insulation conditions by both single and continuous online methods. Throughout the text, numerous tables, figures, diagrams, and images are provided to strengthen understanding of all material.
Fully revised to incorporate the most current technological application techniques, the second edition offers an entirely new section on condition monitoring of electrical insulation. Updated chapters discuss recent developments in gas-filled power apparatus, present-day trends in the use replacement of liquid insulating materials, the latest applications of new solid dielectrics in high voltage engineering, vacuum technology and liquid insulating materials, and more. This edition features a brand-new case study exploring the estimation of clearance requirements for 25 kV electric traction. Readers will also find the new edition: - Provides new coverage of advances in the field, such as the application of polymer insulators and the use of SF6 gas and its mixtures in gas-insulated systems/substations (GIS) - Uses a novel approach that explores the field dependent behavior of dielectrics - Explains the “weakly nonuniform field,” a unique concept introduced both conceptually and analytically in Germany - A separate chapter provides the new approach to the mechanism of lightning phenomenon, which also includes the phenomenon of “Ball Lightning” - The dielectric properties of vacuum and the development in the application of vacuum technology in power circuit breakers is covered in an exclusive chapter - In-depth coverage of the performance of the sulphur-hexafluoride gas and its mixtures applicable to the design of Gas Insulated Systems including dry power transformers
High Voltage and Electrical Insulation Engineering, Second Edition, remains the perfect textbook for graduate students, teachers, academic researchers, and utility and power industry engineers and scientists involved in the field.</p.
Table of Contents
Author Biographies xv
Preface xix
Acknowledgments xxiii
1 Introduction 1
1.1 Electric Charge, Discharge, Current, and Potential 2
1.2 Electric and Magnetic Fields 4
1.3 Electromagnetism 4
1.4 Dielectric and Electrical Insulation 6
1.5 Electrical Breakdown 6
1.5.1 Global Breakdown 7
1.5.2 Local Breakdown or Partial Breakdown 7
1.5.3 Breakdown Strength or Electric Strength 7
1.6 Corona, Streamer, Star, and Leader 7
1.6.1 Aurora 9
1.6.2 Electric Arc 10
1.7 Capacitance and Capacitor 10
1.7.1 Stray Capacitance 11
1.8 Forms of Voltages and Currents 12
1.8.1 TravelingWaves 13
1.8.2 Neutral and Ground 13
References 13
2 Electric Fields, Their Control and Estimation 15
2.1 Electric Field Intensity, “E” 15
2.2 Breakdown and Electric Strength of Dielectrics, “Eb” 18
2.2.1 Partial Breakdown in Dielectrics 18
2.3 Classification of Electric Fields 19
2.3.1 Degree of Uniformity of Electric Fields 21
2.3.1.1 Effect of Grounding on Field Configuration 23
2.4 Control of Electric Field Intensity (Stress Control) 25
2.5 Estimation of Electric Field Intensity 30
2.5.1 Basic Equations for Potential and Field Intensity in Electrostatic Fields 31
2.5.2 Analytical Methods for the Estimation of Electric Field Intensity in Homogeneous Isotropic Single Dielectric 34
2.5.2.1 Direct Solution of Laplace Equation 35
2.5.2.2 “Gaussian Surface” Enclosed Charge Techniques for the Estimation and Optimization of Field 39
2.5.3 Analysis of Electric Field Intensity in Isotropic Multidielectric System 46
2.5.3.1 Field with Longitudinal Interface 46
2.5.3.2 Field with Perpendicular Interface 48
2.5.3.3 Field with Diagonal Interface 53
2.5.4 Numerical Methods for the Estimation of Electric Field Intensity 54
2.5.4.1 Finite Element Method (FEM) 55
2.5.4.2 Charge Simulation Method (CSM) 62
2.5.5 Numerical Optimization of Electric Fields 69
2.5.5.1 Optimization by Displacement of Contour Points 70
2.5.5.2 Optimization by Changing the Positions of Optimization Charges and Contour Points 71
2.5.5.3 Optimization by Modification of “Contour Elements” 73
2.6 Conclusion 75
References 76
3 Field Dependent Behavior of Air and Other Gaseous Dielectrics 79
3.1 Fundamental Process of Field Assisted Generation of Charge Carriers 83
3.1.1 Impact Ionization 85
3.1.2 Thermal Ionization 86
3.1.3 Photoionization and Interaction of Metastables with Molecules 86
3.2 Breakdown of Atmospheric Air in Uniform andWeakly Nonuniform Fields 88
3.2.1 Uniform Field with Space Charge 89
3.2.2 Development of Electron Avalanche 91
3.2.3 Development of Streamer or “Kanal Discharge” 96
3.2.4 Breakdown Mechanisms 99
3.2.4.1 Breakdown in Uniform Fields with Small Gap Distances (Townsend Mechanism) 99
3.2.4.2 Breakdown with Streamer (Streamer or Kanal Mechanism) 106
3.2.5 Breakdown Voltage Characteristics in Uniform Fields (Paschen’s Law) 111
3.2.6 Breakdown Voltage Characteristics inWeakly Nonuniform Fields 122
3.3 Breakdown in Extremely Nonuniform Fields and Corona 123
3.3.1 Development of Avalanche Discharge of Below Critical Amplification 124
3.3.1.1 Positive Needle-Plane Electrode Configuration (Positive or Anode Star Corona) 125
3.3.1.2 Negative Needle-Plane Electrode Configuration (Negative or Cathode Star Corona) 127
3.3.2 Development of Streamer or Kanal Discharge 129
3.3.2.1 Positive Rod-Plane Electrode (Positive Streamer Corona) 129
3.3.2.2 Negative Rod-Plane Electrode (Negative Streamer Corona) 134
3.3.2.3 Symmetrical Positive and Negative Electrode Configurations in Extremely Nonuniform Fields 136
3.3.3 Development of Stem and Leader Corona 137
3.3.3.1 Development and Propagation of Positive Leader Corona 141
3.3.3.2 Development and Propagation of Negative Leader Corona and the Phenomenon of Space Leader 144
3.3.3.3 Electromagnetic Interference (EMI) Produced by Corona 147
3.3.4 Summary of the Development of Breakdown in Extremely Nonuniform Fields 148
3.3.5 Breakdown Voltage Characteristics of Air in Extremely Nonuniform Fields 150
3.3.5.1 Breakdown Preceded with Stable Star Corona 152
3.3.5.2 Breakdown Preceded with Stable Streamer Corona 156
3.3.5.3 Breakdown Preceded with Stable Streamer and Leader Coronas (Long Air Gaps) 163
3.3.5.4 The Requirement of Time for the Formation of Spark Breakdown with Impulse Voltages 168
3.3.5.5 Effect of Wave Shape on Breakdown with Impulse Voltages 171
3.3.5.6 Conclusions from Measured Breakdown Characteristics in Extremely Nonuniform Fields 175
3.3.5.7 Estimation of Breakdown Voltage in Extremely Nonuniform Fields in Long Air Gaps 176
3.3.6 Effects of Partial Breakdown or Corona in Atmospheric Air 178
3.3.6.1 Chemical Decomposition of Air by Corona 179
3.3.6.2 Corona Power Loss in Transmission Lines 182
3.3.6.3 Electromagnetic Interference (EMI) and Audible Noise (AN) Produced by Power System Network 184
3.3.6.4 Other Effects of High Voltage Transmission Lines and Corona on the Environment 187
3.4 Electric Arcs and Their Characteristics 188
3.4.1 Static Voltage-Current, U-I, Characteristics of Arcs in Air 189
3.4.2 Dynamic U-I Characteristics of Arcs 192
3.4.3 Extinction of Arcs 194
3.5 Properties of Sulfurhexafluoride, SF6, Gas, and Its Application in Electrical Installations 194
3.5.1 Properties of Sulfurhexafluoride, SF6 Gas 197
3.5.1.1 Physical Properties 199
3.5.1.2 Property of Electron Attachment 199
3.5.2 Breakdown in Uniform and Weakly Nonuniform Fields with SF6 Insulation 201
3.5.3 External Factors Affecting Breakdown Characteristics in Compressed Gases 210
3.5.3.1 Effect of Electrode Materials and Their Surface Roughness on Breakdown 210
3.5.3.2 Effect of Particle Contaminants in Gas Insulated Systems (GIS) 212
3.5.3.3 Particle Initiated PB and Breakdown Measurements in GIS 219
3.5.3.4 Preventive Measures for the Effect of Particles in GIS 222
3.5.4 Breakdown in Extremely Nonuniform and Distorted Weakly Nonuniform Fields with Stable PB in SF6 Gas Insulation 222
3.5.5 Electrical Strength of Mixtures of SF6 with Other Gases 226
3.5.6 Decomposition of SF6 and Its Mixtures in Gas Insulated Equipment 230
3.5.7 SF6 Gas and Environment 234
3.5.8 Development in Gas Insulated Power Apparatus 236
3.5.9 Mineral Oils Versus SF6 Gas 236
3.5.10 Basic Electrical Insulation Requirements for GITs 238
3.5.11 SF6 Gas Insulation, a Replacement for Oils 239
3.5.12 Basic Cooling Requirements Met by Gas for GITs 240
3.5.13 Environment Concerns and Future Trends 241
3.6 Investigations for the Requirement of Optimum Clearance for 25 kV Electric Traction: A Case Study 242
3.6.1 Field Estimation for the Traction Overhead Conductor at 25 kV 243
3.6.2 Measurement of Breakdown/Withstand Voltage Characteristics 247
3.6.3 Measurements with ac Power Frequency Voltage 247
3.6.4 Measurements Under FairWeather, Natural Fog, and Natural Rain Conditions 248
3.6.5 Measurements Under Artificial Rain 249
3.6.6 Investigation of the Performance of Air-Gap Under System Overvoltages 250
3.6.7 Measurements with Impulse Voltages 252
3.6.8 Measurements with Insulating-Barrier in the Gap 253
3.6.9 Choice of Solid Insulating Barrier 253
3.6.10 Positioning and Fastening of the Solid Insulating Barrier in the Gap 254
3.6.11 Measurement Results with Teflon Sheet as a Barrier 254
3.7 Conclusions and Recommendations 255
References 257
4 Lightning and Ball Lightning, Development Mechanisms, Deleterious Effects, Protection 267
4.1 The Globe, a Capacitor 268
4.1.1 The Earth’s Atmosphere and the Clouds 269
4.1.1.1 The Troposphere 270
4.1.1.2 The Stratosphere 270
4.1.1.3 The Ionosphere 271
4.1.2 Clouds and Their Important Role 271
4.1.2.1 Classification of Clouds 271
4.1.3 Static Electric Charge in the Atmosphere 273
4.1.3.1 External Source of Electric Charge 273
4.1.3.2 Charges Due to Ionization Within the Atmospheric Air 275
4.1.3.3 Charging Mechanisms and Thunderstorms 276
4.2 Mechanisms of Lightning Strike 278
4.2.1 Mechanism of Breakdown in Long Air Gap 278
4.2.2 Mechanisms of Lightning Strike on the Ground 280
4.2.3 Preference of Locations for the Lightning to Strike 282
4.3 Deleterious Effects of Lightning 284
4.3.1 Loss of Life of the Living Beings 284
4.3.2 Fire Hazards Due to Lightning 284
4.3.3 Blast Created by Lightning 285
4.3.4 Development of Transient Over-Voltage Due to Lightning Strike on the Electric Power System Network and Its Protection 286
4.4 Protection from Lightning 288
4.4.1 Protection of Lives 289
4.4.2 Protection of Buildings and Structures 290
4.4.2.1 Air Termination Network 291
4.4.2.2 Down Conductor 292
4.4.2.3 Earth Termination System 292
4.4.3 The Protected Area 292
4.4.3.1 Protected Volume Determined by a Cone 292
4.4.3.2 Protected Volume Evolved by Rolling a Sphere 293
4.5 Ball Lightning 295
4.5.1 The Phenomenon of Ball Lightning 295
4.5.2 Injurious Effects of Ball Lightning 296
4.5.3 Models and Physics of Ball Lightning 296
4.5.4 Ball Lightning Without Lightning Strike 298
4.5.4.1 TheWeather and Climatic Conditions 299
4.5.4.2 The Man Made Sources of Charge/Current 299
4.5.5 Ball Lightning, a Mythological Legend in India 300
4.6 Lightning, a Truthful Myth 301
4.6.1 Examples of Known and Widely Accepted Myths 301
4.6.2 The Mythology of “Bijli Mahadev” 302
4.6.3 Geographical Location and the Construction of the Temple 302
4.6.4 The Mechanism of Destruction of the Deity 304
References 304
5 Electrical Properties of Vacuum as High Voltage Insulation 307
5.1 Pre-breakdown Electron Emission in Vacuum 308
5.1.1 Mechanism of Electron Emission from Metallic Surfaces 308
5.1.2 Non-metallic Electron Emission Mechanisms 311
5.2 Pre-breakdown Conduction and Spark Breakdown in Vacuum 316
5.2.1 Electrical Breakdown in Vacuum Interrupters 324
5.2.1.1 High Current Arc Quenching in Vacuum 324
5.2.1.2 Delayed Re-ignition of Arcs 325
5.2.1.3 Effect of Insulator Surface Phenomena 326
5.2.2 Effect of Conditioning of Electrodes on Breakdown Voltage 326
5.2.3 Effect of Area of Electrodes on Breakdown in Vacuum 328
5.3 Vacuum as Insulation in Space Applications 329
5.3.1 Vacuum-Insulated Power Supplies for Space 329
5.3.2 Vacuum Related Problems in Low Earth Orbit Plasma Environment 330
5.4 Development in Vacuum Technology Applications in Power System Switchgears 331
5.4.1 Development in Actuator Mechanism for the Interrupter Units 333
5.4.2 Development of 245 kV Vacuum Circuit Breaker 334
5.5 Conclusion 335
References 336
6 Liquid Dielectrics, Their Classification, Properties, and Breakdown Strength 339
6.1 Classification of Liquid Dielectrics 340
6.1.1 Mineral Insulating Oils 341
6.1.1.1 Mineral Insulating Oil in Transformers 342
6.1.2 Vegetable Oils 344
6.1.3 Synthetic Liquid Dielectrics, the Chlorinated Diphenyls 344
6.1.3.1 Halogen-Free Synthetic Oils 345
6.1.4 Inorganic Liquids as Insulation 346
6.1.5 Polar and Nonpolar Dielectrics 347
6.2 Dielectric Properties of Insulating Materials 347
6.2.1 Insulation Resistance Offered by Dielectrics 347
6.2.2 Permittivity of Insulating Materials 349
6.2.3 Polarization in Insulating Materials 350
6.2.3.1 Effect of Time on Polarization 352
6.2.3.2 Polarization Under Alternating Voltages and the Eigen-Frequency of Dielectrics 355
6.2.3.3 High Frequency High Voltage Application of Dielectrics 358
6.2.4 Dielectric Power Losses in Insulating Materials 360
6.3 Breakdown in Liquid Dielectrics 363
6.3.1 Electric Conduction in Insulating Liquids 364
6.3.1.1 Liquid Dielectrics in Motion and Electrohydrodynamics (EHD) 367
6.3.2 Intrinsic Breakdown Strength 369
6.3.3 Practical Breakdown Strength Measurement at Near Uniform Fields 370
6.3.3.1 Effect of Moisture and Temperature on Breakdown Strength 372
6.3.4 Breakdown in Extremely Nonuniform Fields and the Development of Streamer 376
6.4 Aging in Mineral Insulating Oils 382
References 384
7 Solid Dielectrics, Their Sources, Properties, and Behavior in Electric Fields 387
7.1 Classification of Solid Insulating Materials 388
7.1.1 Inorganic Insulating Materials 388
7.1.1.1 Ceramic Insulating Materials 388
7.1.1.2 Glass as an Insulating Material 392
7.1.2 Polymeric Organic Materials 392
7.1.2.1 Thermoplastic Polymers 393
7.1.2.2 Thermoset Polymers 393
7.1.2.3 Polymer Compounds 394
7.1.2.4 Polyvinylchloride (PVC) 394
7.1.2.5 Polyethylene (PE) 395
7.1.2.6 Epoxy Resins (EP-Resins) 400
7.1.2.7 Natural and Synthetic Rubber 402
7.1.3 Composite Insulating System 403
7.1.3.1 Impregnated Paper as a Composite Insulation System 403
7.1.3.2 Insulating Board Materials 407
7.1.3.3 Fiber Reinforced Plastics (FRP) 407
7.2 Partial Breakdown in Solid Dielectrics 408
7.2.1 Internal Partial Breakdown 409
7.2.2 Surface Discharge (Tracking) 416
7.2.3 Degradation of Solid Dielectrics Caused by PB 419
7.2.3.1 Inhibition of Partial Breakdown/Treeing in Solid Dielectrics 420
7.2.4 Partial Breakdown Detection and Measurement 422
7.2.4.1 Indirect Methods of PB Detection 422
7.2.4.2 Direct Methods of PB Detection and Measurement 423
7.3 Breakdown and Pre-breakdown Phenomena in Solid Dielectrics 424
7.3.1 Intrinsic Breakdown Strength of Solid Dielectrics 426
7.3.2 Thermal Breakdown 429
7.3.3 Mechanism of Breakdown in Extremely Nonuniform Fields 433
7.3.4 “Treeing” a Pre-breakdown Phenomenon in Polymeric Dielectrics 434
7.3.4.1 Forms of Treeing Patterns 434
7.3.4.2 Classification of Treeing Process 434
7.3.5 Requirement of Time for Breakdown 437
7.3.6 Estimation of Life Expectancy Characteristics 440
7.3.7 Practical Breakdown Strength and Electric Stress in Service of Solid Dielectrics 443
7.4 Development and Application of Solid Dielectric Line Insulators in High Voltage Power System 444
7.4.1 Polymeric, also known as Composite Dielectric Insulators 445
7.4.2 Design and Construction of Polymeric Insulators 446
7.4.2.1 The Core or the Rod 446
7.4.2.2 Metallic End Fittings 446
7.4.2.3 The Weather Sheds 447
7.4.3 Hollow Core Polymer Insulators 449
7.4.4 Properties of Silicone Rubber and Fiber-Glass Reinforced Polymers 450
7.4.4.1 Hydrophobicity 450
7.4.5 Electrical Properties and Specified Tests 452
7.4.5.1 Water Diffusion Test 452
7.4.5.2 Water Immersion Test 452
7.5 Condition Monitoring of Electrical Insulation 453
7.5.1 Offline Single Measurement Techniques 454
7.5.2 Online Continuous Measurement Techniques 455
7.5.3 Construction of Large Rotating Electrical Machines 456
7.5.3.1 Typical Nature of Insulation in Electrical Machines 456
7.5.4 Partial Breakdown (PB) Monitoring Techniques Applied on Large Rotating Machines 458
7.5.5 PB Measurements with VHF and UHF Sensors/Couplers 460
7.5.5.1 Capacitive PB Couplers 461
7.5.5.2 Inductive PB Couplers 461
7.5.5.3 Electro-Magnetic (EM) PB Couplers 462
References 464
Index 469
