Preface	6
	Contents	8
	Chapter 1: Introduction	13
	1.1 Definition and Content of Gas Discharge	13
	1.2 History of Electrical Discharge Research	14
	1.3 Classification of the Discharge	16
	1.4 Application of the Discharge	18
	1.5 Definition and Content of Gas Insulation	20
	1.6 History and Application of Sulfur Hexafluoride	21
	1.7 Situation and Development of Environmentally Friendly Insulating Gas	24
	References	29
	Chapter 2: Fundamentals of Gas Discharge	30
	2.1 Charged Particles in the Process of Gas Discharge	30
	2.1.1 Photons	31
	2.1.2 Electrons	32
	2.1.3 Ground State Atoms (or Molecules) and Excited Atoms (or Molecules)	33
	2.1.4 Positive and Negative Ions	36
	2.2 Movement of Charged Particles	37
	2.2.1 Thermal Motion of Charged Particles	37
	2.2.2 Diffusion Motion of Charged Particles	39
	2.2.3 Drift Motion of Charged Particles	40
	2.3 Collision Interactions of Charged Particles	45
	2.3.1 Classification of Collision Between Particles	45
	2.3.2 Collision Energy Transfer	46
	2.3.2.1 Energy Transfer in Elastic Collision	46
	2.3.2.2 Energy Transfer in Inelastic Collision	47
	2.3.3 Collision Characteristic Parameters	47
	2.3.3.1 Collision Cross Section	47
	2.3.3.2 Probability of Collision and Collision Frequency	49
	2.3.4 Elastic Collisions of Electrons, Ions and Atoms	49
	2.3.5 Excitation and Ionization of Gas Atoms	50
	2.3.6 Gas Particle Excitation Transferring	52
	2.3.7 Disappearance of Charged Particles	53
	2.3.7.1 Charged Particles´ Recombination	53
	2.3.7.2 Charged Particles´ Diffusion	54
	2.3.7.3 Charge Transferring of Charged Particles	55
	2.3.7.4 Anion Formation and Attachment Process	55
	References	56
	Chapter 3: Fundamental Theory of Townsend Discharge	57
	3.1 Formation and Development of Electronic Avalanche	57
	3.1.1 Formation of Electronic Avalanche	57
	3.1.2 ? Process	60
	3.1.3 gamma Process	63
	3.2 Self-Sustaining Discharge Criterion	64
	3.2.1 Gas Discharge Volt-Ampere Characteristics	64
	3.2.2 From Non-Self-Sustaining to Self-Sustaining Discharge	67
	3.2.3 The Condition of Self-Sustained Discharge	68
	3.3 Paschen´s Law	69
	3.3.1 Paschen´s Law	69
	3.3.2 The Impact of Impurity Gases on the Breakdown Potential	72
	3.3.3 The Impact of Electrodes on Breakdown Voltage	77
	3.3.4 The Impact of Electric Field Distribution on Breakdown Voltage	78
	3.3.5 The Impact of External Ionization Source on Breakdown Potential	79
	3.4 Townsend Discharge Experiments	79
	3.4.1 The Steady-State Townsend Experiment (SST)	80
	3.4.1.1 SST Experimental Principles and Measuring Circuit [3]	81
	3.4.1.2 The Establishment of SST Mathematical Model and Solving Method of Discharging Parameters	83
	3.4.1.3 SST Experimental Apparatus	85
	3.4.2 Pulse Townsend Method (PT)	87
	3.4.2.1 Principle Law and Basic Circuit of PT Method	88
	3.4.2.2 The Establishment of PT Mathematical Model [3, 4]	90
	3.4.2.3 The Calculation of Initial Electrons Distribution	94
	3.4.2.4 Solution Method of Electrons Avalanche Parameters	94
	3.4.2.5 Experimental Apparatus of PT Method [3]	95
	References	98
	Chapter 4: Fundamental Theory of Streamer and Leader Discharge	99
	4.1 Streamer Discharge Mechanism	99
	4.1.1 Basic Properties of Spark Discharge	100
	4.1.1.1 Characteristics of Spark Discharge	100
	4.1.1.2 Types of Spark Discharge	100
	4.1.1.3 Streamer	101
	4.1.1.4 Common Circuits for Spark Discharge	101
	4.1.2 Streamer Discharge	103
	4.1.2.1 Limitation of Townsend Discharge Theory	103
	4.1.2.2 Introduction of Streamer Theory	105
	4.1.2.3 Criterions of Streamer	106
	4.1.2.4 Qualitative Description of Streamer Theory	110
	4.1.2.5 Mechanism of Streamer Formation	115
	4.1.2.6 Explanations for Different Phenomena by Streamer Theory	119
	4.1.2.7 The Effect of Water Molecules on the Streamer Development	120
	4.1.2.8 Transition Between Townsend Discharge and Streamer Discharge	121
	4.2 Long Gap and Leader Discharge	123
	4.2.1 Experimental Study on the Long Gap Discharge in Air	123
	4.2.2 Discharge Process in Non-uniform Electric Field	124
	References	131
	Chapter 5: Theoretic Analysis Methods for Modeling Gas Discharge	132
	5.1 Monte Carlo Simulation	132
	5.1.1 Introduction of General Monte Carlo Simulation	132
	5.1.1.1 Monte Carlo Simulation Model for Electron Avalanche in a Single Gas	132
	5.1.1.2 Monte Carlo Simulation Model for Electron Avalanche in Gas Mixtures	136
	5.1.2 Monte Carlo Simulation of Electron Avalanche Development	137
	5.1.2.1 Initializing of the Simulated Electron	137
	5.1.2.2 The Null-Collision Technique	137
	5.1.2.3 Determining the Probability and the Type of Collision	138
	5.1.2.4 The Scattering Parameters After Collision	138
	5.1.2.5 Sampling the Electron Swarm Parameters	139
	5.1.3 Electron Swarm Parameters from Monte Carlo Simulation	140
	5.1.3.1 Simulation of Avalanche Discharge in SF6	140
	5.1.3.2 Simulation of Avalanche Discharge in c-C4F8 Gas Mixtures	142
	5.2 Boltzmann Equation Method	149
	5.2.1 Introduction to Boltzmann Equation Method	149
	5.2.2 Electron Swarm Parameters Calculated by Boltzmann Equation Method	151
	5.2.2.1 Collision Cross Sections of CO2 and SF6	152
	5.2.2.2 Comparison Between the Calculated and Experimental Results of Electron Swarm Parameters in Pure SF6 Gas and SF6/CO2 Ga...	153
	References	155
	Chapter 6: Dielectric Strength of Atmosphere Air	157
	6.1 Breakdown Voltage Characteristics in Uniform and Quasi-uniform Electric Fields	158
	6.1.1 Breakdown Characteristics Under Continuous Voltages	158
	6.1.2 Breakdown Characteristics Under Lightning Impulse Voltages	162
	6.1.2.1 Basic Conceptions of Lightning Discharge	162
	6.1.2.2 Lightning Impulse Voltage Standard Waveform	165
	6.1.2.3 Discharge Time Lag	166
	6.1.2.4 Fifty Percent Breakdown Voltage	168
	6.1.2.5 Breakdown Characteristics in Uniform and Weakly Nonuniform Electric Fields	169
	6.1.3 Breakdown Characteristics Under Operating Impulse Voltage	169
	6.1.3.1 Formation of the Operating Impulse Voltage	169
	6.1.3.2 Operating Impulse Voltage Standard Waveform	170
	6.1.3.3 Breakdown Characteristics in Uniform and Weakly Nonuniform Electric Fields	171
	6.2 Breakdown Characteristics in Extremely Nonuniform Electric Fields	172
	6.2.1 Breakdown Characteristics Under Continuous Voltage	172
	6.2.1.1 Breakdown Voltage Under DC Voltage	172
	6.2.1.2 Breakdown Voltage Under Power Frequency AC Voltage	174
	6.2.2 Breakdown Characteristics Under Lightning Impulse Voltage	176
	6.2.2.1 Breakdown Voltage in Extremely Nonuniform Electric Fields	176
	6.2.2.2 Volt-Second Characteristics	178
	6.2.3 Breakdown Voltage Under Operating Impulse Voltage	184
	6.2.3.1 Polarity Effect	184
	6.2.3.2 Influence of the Electric Field Distribution	185
	6.2.3.3 Influence of the Waveform and U-Shaped Curve	185
	6.2.3.4 Large Dispersion	187
	6.2.3.5 Saturation	187
	6.2.3.6 Empirical Formula for the Minimum Breakdown Voltage	187
	6.3 Methods to Improve Insulation Strength in Air	188
	6.3.1 Improve the Shape of Electrodes	188
	6.3.2 Use of Electric Field Distortion by Space Charges	190
	6.3.3 Use of Barrier in Extremely Nonuniform Electric Fields	193
	6.3.4 Solid Insulating Coating Layer	197
	6.3.5 Use of High Pressure	197
	6.3.6 Use of High Vacuum	199
	6.3.7 Use of High-Dielectric-Strength Gases	200
	6.3.7.1 High-Dielectric-Strength Gases	200
	6.3.7.2 Reasons for the High Dielectric Strength of Halide Gas	201
	References	202
	Chapter 7: Insulation Characteristics of Sulfur Hexafluoride (SF6)	203
	7.1 Basic Physical and Chemical Properties of SF6	203
	7.1.1 Molecular Structure	203
	7.1.2 Gas State Parameters	204
	7.1.3 Electronegativity and Thermal Performance	207
	7.1.4 Decomposition of SF6	209
	7.2 Breakdown Characteristics of SF6	212
	7.2.1 Breakdown Characteristics in Uniform Electric Fields	212
	7.2.2 Breakdown Characteristics in Quasi-uniform Fields	213
	7.2.3 Breakdown Characteristics in Extremely Non-uniform Fields	214
	7.3 Surface Discharge Characteristics of Solid Insulators in SF6	217
	7.3.1 Effects of Electric Field Distribution	218
	7.3.2 Other Factors Affecting Solid Surface Discharge Characteristics	220
	7.4 Factors Affecting Insulation Properties of SF6	226
	7.4.1 Effects of Gas Pressure on Breakdown Voltage of SF6	226
	7.4.2 Effect of Electric Field Uniformity on Breakdown Voltage of SF6 [4]	228
	7.4.3 Effect of Polarity on Breakdown Voltage of SF6	230
	7.4.4 Effect of Surface Roughness on Breakdown Voltage of SF6	234
	References	237
	Chapter 8: Insulating Characteristics of SF6 Gas Mixtures	238
	8.1 Improvements of Gas Mixtures on Defects of SF6	238
	8.1.1 Liquefaction Temperature	238
	8.1.2 Insulating Properties	240
	8.1.2.1 Relative Electric Strength	240
	8.1.2.2 Influence of Electric Field Uniformity	243
	8.1.2.3 Very Fast Transient Overvoltage Problems of GIS	244
	8.1.3 Cost of Gas	244
	8.1.4 Environmental Protection	245
	8.2 Mixing Characteristics of SF6 Gas Mixtures	245
	8.2.1 Mixing Ratio	245
	8.2.2 Changes of Mixing Ratio with Height	246
	8.2.3 Mixing Process	248
	8.2.4 Recovery of Gas Mixtures	248
	8.2.4.1 Liquefaction Method	248
	8.2.4.2 PSA Method	249
	8.2.4.3 Polymer Film Method	249
	8.3 Insulation Properties of Binary Mixtures of SF6 with Other Gases [2]	250
	8.3.1 Electrical Strength of SF6/N2 Gas Mixtures	250
	8.3.1.1 Uniform Electric Field	250
	8.3.1.2 Non-Uniform Electric Field	255
	8.3.1.3 Practical Application	257
	8.3.2 Electrical Strength of SF6/CO2 Gas Mixtures	257
	8.3.2.1 Uniform Electric Field	257
	8.3.2.2 Non-Uniform Electric Field	262
	8.3.3 Contrast Between SF6/N2 and SF6/CO2	263
	8.4 Other Multivariate SF6 Gas Mixtures	264
	8.4.1 SF6/He and SF6/Ne Gas Mixtures	264
	8.4.2 SF6/Ar, SF6/Kr and SF6/Xe Gas Mixtures	267
	8.4.3 Gas Mixtures Consisting of SF6 and Gases Containing Halogen Elements	272
	8.4.3.1 Perfluorocarbon (CF4)	272
	8.4.3.2 Octafluorocyclobutane (c-C4F8)	275
	References	277
	Chapter 9: Insulating Characteristics of Potential Alternatives to Pure SF6	278
	9.1 Research Advances on Substitutes for SF6	278
	9.1.1 Significance of Research	278
	9.1.2 Current Research on Alternatives to SF6 Gas	281
	9.1.2.1 Current Research Around the World	281
	9.1.2.2 Research in China	283
	9.2 Insulation Properties of c-C4F8 and Its Gas Mixtures	284
	9.2.1 c-C4F8/CO2 Discharge Characteristics and Analysis	285
	9.2.2 c-C4F8/CF4 Discharge Characteristics and Analysis	288
	9.2.3 c-C4F8/N2 Discharge Characteristics and Analysis	290
	9.2.4 c-C4F8/N2O Discharge Characteristics and Analysis	292
	9.2.5 The Influence of CO2, CF4, N2 and N2O on the (E/N)lim of c-C4F8	295
	9.3 Insulation Performance of CF3I and Its Gas Mixtures	296
	9.3.1 Insulation Performance Analysis of CF3I	297
	9.3.2 Feasibility Analysis of CF3I and Its Gas Mixtures Used in C-GIS	301
	9.4 Insulation Performance of Other Potential Alternative Gas	304
	9.4.1 Perfluoropropane (C3F8)	304
	9.4.1.1 C3F8/N2 Gas Mixture	307
	9.4.1.2 Pay Attention To Problems in Practical Application	309
	9.4.2 Nitrous Oxide (N2O)	310
	9.4.3 Trifluoromethane (CHF3)	311
	9.4.4 Fluorinated Carbon (CF4)	313
	Reference	316
	Chapter 10: Development Prospects of Gas Insulation	317
	10.1 Three Stages of Development of Gas Insulation	317
	10.1.1 Application and Development of Pure SF6 Gas	320
	10.1.2 Application and Development of SF6 Gas Mixtures	322
	10.1.3 Development of Research on Environmentally Friendly Insulation Gas	324
	10.2 Research and Development of c-C4F8 and Its Gas Mixtures	330
	10.2.1 Properties of c-C4F8	330
	10.2.2 Further Research on c-C4F8 and Its Mixtures Discharge Mechanism	333
	10.2.2.1 Electrical Breakdown Model of Gas Mixtures	334
	10.2.2.2 Improved Electrical Breakdown Model of Gas Mixtures	336
	10.2.2.3 Proof of Gas Mixtures Breakdown Voltage Model	341
	10.2.2.4 Boiling Point of c-C4F8 Mixture	343
	10.2.2.5 Calculation of GWP Value in Gas Mixtures	343
	10.2.2.6 AC Breakdown Voltage as a Function of Gas Pressure in c-C4F8 and N2 Gas Mixtures	344
	10.2.2.7 AC Breakdown Voltage as a Function of Gas Pressure in c-C4F8/CO2 Gas Mixtures	348
	10.2.2.8 Comparison of Dielectric Strength as a Function of Pressure in c-C4F8 Gas Mixtures and SF6/N2 Gas Mixtures	351
	10.2.2.9 Comparison of Dielectric Strength in c-C4F8 Gas Mixtures and SF6/N2 at Different Mixing Ratios	353
	10.2.3 The Application and Development of c-C4F8 and Its Gas Mixtures	355
	10.3 Study and Development of CF3I and Its Gas Mixtures	357
	10.3.1 Physical Properties of CF3I Gas	357
	10.3.2 Further Study on Insulation Properties of CF3I Gas	358
	10.3.3 Research Tendency and Application of CF3I and Its Gas Mixtures	363
	References	365
	Index	366