Switching in Electrical Transmission and Distribution Systems presents the issues and technological solutions associated with switching in power systems, from medium to ultra-high voltage. The book systematically discusses the electrical aspects of switching, details the way load and fault currents are interrupted, the impact of fault currents, and compares switching equipment in particular circuit-breakers. The authors also explain all examples of practical switching phenomena by examining real measurements from switching tests. Other highlights include: up to date commentary on new developments in transmission and distribution technology such as ultra-high voltage systems, vacuum switchgear for high-voltage, generator circuit-breakers, distributed generation, DC-interruption, aspects of cable systems, disconnector switching, very fast transients, and circuit-breaker reliability studies. Key features: Summarises the issues and technological solutions associated with the switching of currents in   transmission and distribution systems. Introduces and explains recent developments such as vacuum switchgear for transmission systems, SF6 environmental consequences and alternatives,  and circuit-breaker testing. Provides practical guidance on how to deal with unacceptable switching transients. Details the worldwide IEC (International Electrotechnical Commission) standards on switching equipment, illustrating current circuit-breaker applications. Features many figures and tables originating from full-power tests and established training courses, or from measurements in real networks. Focuses on practical and application issues relevant to practicing engineers. Essential reading for electrical engineers, utility engineers, power system application engineers, consultants and power systems asset managers, postgraduates and final year power system undergraduates.

Table of Contents:
Preface xv 1 Switching in Power Systems 1 1.1 Introduction 1 1.2 Organization of this Book 2 1.3 Power-System Analysis 5 1.4 Purpose of Switching 8 1.4.1 Isolation and Earthing 8 1.4.2 Busbar-Transfer Switching 8 1.4.3 Load Switching 8 1.4.4 Fault-Current Interruption 9 1.5 The Switching Arc 10 1.6 Transient Recovery Voltage (TRV) 14 1.6.1 TRV Description 14 1.6.2 TRV Composed of Load- and Source-Side Contributions 16 1.7 Switching Devices 19 1.8 Classification of Circuit-Breakers 22 References 27 2 Faults in Power Systems 28 2.1 Introduction 28 2.2 Asymmetrical Current 30 2.2.1 General Terms 30 2.2.2 DC Time Constant 33 2.2.3 Asymmetrical Current in Three-Phase Systems 34 2.3 Short-Circuit Current Impact on System and Components 35 2.4 Fault Statistics 43 2.4.1 Occurrence and Nature of Short-Circuits 43 2.4.2 Magnitude of Short-Circuit Current 45 References 46 3 Fault-Current Breaking and Making 48 3.1 Introduction 48 3.2 Fault-Current Interruption 48 3.3 Terminal Faults 49 3.3.1 Introduction 49 3.3.2 Three-Phase Current Interruption 51 3.4 Transformer-Limited Faults 58 3.4.1 Transformer Modelling for TRV Calculation 59 3.4.2 External Capacitances 61 3.5 Reactor-Limited Faults 62 3.6 Faults on Overhead Lines 64 3.6.1 Short-Line Faults 64 3.6.2 Long-Line Faults 81 3.7 Out-of-Phase Switching 81 3.7.1 Introduction 81 3.7.2 Switching between Generator and System 83 3.7.3 Switching between Two Systems 85 3.8 Fault-Current Making 86 3.8.1 Impact of Making a Short-Circuit Current on the Circuit-Breaker 86 3.8.2 Switching-Voltage Transients at Making in Three-Phase Systems 88 References 93 4 Load Switching 96 4.1 Normal-Load Switching 96 4.2 Capacitive-Load Switching 97 4.2.1 Introduction 97 4.2.2 Single-Phase Capacitive-Load Switching 98 4.2.3 Three-Phase Capacitive-Load Switching 104 4.2.4 Late Breakdown Phenomena 104 4.2.5 Overhead-Line Switching 114 4.2.6 Capacitor-Bank Energization 118 4.3 Inductive-Load Switching 122 4.3.1 Current Chopping 124 4.3.2 Implication of Current Chopping 125 4.3.3 Inductive-Load Switching Duties 127 References 138 5 Calculation of Switching Transients 141 5.1 Analytical Calculation 141 5.1.1 Introduction 141 5.1.2 Switching LR Circuits 142 5.1.3 Switching RLC Circuits 147 5.2 Numerical Simulation of Transients 153 5.2.1 Historical Overview 153 5.2.2 The Electromagnetic Transients Program 154 5.2.3 Overview of Electrical Programs for Transient Simulation 159 5.3 Representation of Network Elements when Calculating Transients 160 References 162 6 Current Interruption in Gaseous Media 164 6.1 Introduction 164 6.2 Air as an Interrupting Medium 166 6.2.1 General 166 6.2.2 Fault-Current Interruption by Arc Elongation 167 6.2.3 Arc Chutes 171 6.2.4 Arcs in Open Air 174 6.2.5 Current Interruption by Compressed Air 175 6.3 Oil as an Interrupting Medium 176 6.3.1 Introduction 176 6.3.2 Current Interruption in Bulk-Oil Circuit-Breakers 177 6.3.3 Current Interruption in Minimum-Oil Circuit-Breakers 180 6.4 Sulfur Hexafluoride (SF6) as an Interrupting Medium 181 6.4.1 Introduction 181 6.4.2 Physical Properties 182 6.4.3 SF6 Decomposition Products 186 6.4.4 Environmental Effects of SF6 189 6.4.5 SF6 Substitutes 195 6.5 SF6 – N2 Mixtures 197 References 198 7 Gas Circuit-Breakers 202 7.1 Oil Circuit-Breakers 202 7.2 Air Circuit-Breakers 205 7.3 SF6 Circuit-Breakers 207 7.3.1 Introduction 207 7.3.2 Double-Pressure SF6 Circuit-Breakers 210 7.3.3 Puffer-Type SF6 Circuit-Breakers 210 7.3.4 Self-Blast SF6 Circuit-Breakers 215 7.3.5 Double-Motion Principle 218 7.3.6 Double-Speed Principle 220 7.3.7 SF6 Circuit-Breakers with Magnetic Arc Rotation 221 References 222 8 Current Interruption in Vacuum 223 8.1 Introduction 223 8.2 Vacuum as an Interruption Environment 223 8.3 Vacuum Arcs 227 8.3.1 Introduction 227 8.3.2 Cathode- and Anode Sheath 229 8.3.3 The Diffuse Vacuum Arc 230 8.3.4 The Constricted Vacuum Arc 234 8.3.5 Vacuum-Arc Control by Magnetic Field 235 References 241 9 Vacuum Circuit-Breakers 243 9.1 General Features of Vacuum Interrupters 243 9.2 Contact Material for Vacuum Switchgear 246 9.2.1 Pure Metals 247 9.2.2 Alloys 247 9.3 Reliability of Vacuum Switchgear 248 9.4 Electrical Lifetime 249 9.5 Mechanical Lifetime 249 9.6 Breaking Capacity 251 9.7 Dielectric Withstand Capability 251 9.8 Current Conduction 252 9.9 Vacuum Quality 252 9.10 Vacuum Switchgear for HV Systems 253 9.10.1 Introduction 253 9.10.2 Development of HV Vacuum Circuit-Breakers 254 9.10.3 Actual Application of HV Vacuum Circuit-Breakers 255 9.10.4 X-ray Emission 256 9.10.5 Comparison of HV Vacuum- and HV SF6 Circuit-Breakers 257 References 258 10 Special Switching Situations 261 10.1 Generator-Current Breaking 261 10.1.1 Introduction 261 10.1.2 Generator Circuit-Breakers 266 10.2 Delayed Current Zero in Transmission Systems 267 10.3 Disconnector Switching 267 10.3.1 Introduction 267 10.3.2 No-Load-Current Switching 268 10.3.3 Bus-Transfer Switching 278 10.4 Earthing 279 10.4.1 Earthing Switches 279 10.4.2 High-Speed Earthing Switches 280 10.5 Switching Related to Series Capacitor Banks 282 10.5.1 Series Capacitor-Bank Protection 282 10.5.2 By-Pass Switch 283 10.6 Switching Leading to Ferroresonance 285 10.7 Fault-Current Interruption Near Shunt Capacitor Banks 286 10.8 Switching in Ultra-High-Voltage (UHV) Systems 288 10.8.1 Insulation Levels 289 10.8.2 UHV System Characteristics Related to Switching 289 10.9 High-Voltage AC Cable System Characteristics 291 10.9.1 Background 291 10.9.2 Current Situation 291 10.10 Switching in DC Systems 295 10.10.1 Introduction 295 10.10.2 Low- and Medium Voltage DC Interruption 295 10.10.3 High-Voltage DC Interruption 297 10.11 Distributed Generation and Switching Transients 298 10.11.1 General Considerations 298 10.11.2 Out-of-Phase Conditions 300 10.12 Switching with Non-Mechanical Devices 301 10.12.1 Fault-Current Limitation 301 10.12.2 Fuses 301 10.12.3 IS Limiters 303 References 304 11 Switching Overvoltages and Their Mitigation 310 11.1 Overvoltages 310 11.2 Switching Overvoltages 312 11.3 Switching-Voltage Mitigation 313 11.3.1 Principles of Mitigation 313 11.3.2 Mitigation by Closing Resistors 314 11.3.3 Mitigation by Surge Arresters 316 11.3.4 Fast Insertion of Shunt Reactors 319 11.4 Mitigation by Controlled Switching 320 11.4.1 Principles of Controlled Switching 320 11.4.2 Controlled Opening 321 11.4.3 Controlled Closing 323 11.4.4 Staggered Pole Closing 324 11.4.5 Applications of Controlled Switching 324 11.4.6 Comparison of Various Measures 334 11.4.7 Influence of Metal-Oxide Surge Arresters on Circuit-Breaker TRVs 336 11.4.8 Functional Requirements for Circuit-Breakers 337 11.4.9 Reliability Aspects 340 11.5 Practical Values of Switching Overvoltages 341 11.5.1 Overhead Lines 341 11.5.2 Shunt Capacitor Banks and Shunt Reactors 342 References 344 12 Reliability Studies of Switchgear 347 12.1 CIGRE Studies on Reliability of Switchgear 347 12.1.1 Reliability 347 12.1.2 Worldwide Surveys 348 12.1.3 Population and Failure Statistics 349 12.2 Electrical and Mechanical Endurance 354 12.2.1 Degradation Due to Arcing 354 12.2.2 Electrical-Endurance Verification 356 12.2.3 Mechanical Endurance 358 12.3 CIGRE Studies on Life Management of Circuit-Breakers 359 12.3.1 Maintenance 359 12.3.2 Monitoring and Diagnostics 360 12.3.3 Life Management of Circuit-Breakers for Frequent Load-Switching 362 12.4 Substation and System Reliability Studies 362 References 363 13 Standards, Specification, and Commissioning 365 13.1 Standards for Fault-Current Breaking Tests 365 13.1.1 Background and History of the Standardized IEC TRV Description 366 13.1.2 IEC TRV Description 368 13.1.3 IEC Test-Duties 370 13.1.4 IEC TRV Parameters Selection and Application 373 13.2 IEC Standardized Tests for Capacitive-Current Switching 373 13.3 IEC Standardized Tests for Inductive-Load Switching 377 13.3.1 Shunt-Reactor Switching 378 13.3.2 Medium-Voltage Motor Switching 381 13.4 Specification and Commissioning 381 13.4.1 General Specifications 381 13.4.2 Circuit-Breaker Specification 383 13.4.3 Information to be given with Requests for Offers 384 13.4.4 Information to be provided with Submitted Offers 384 13.4.5 Circuit-Breaker Selection 384 13.4.6 Circuit-Breaker Commissioning 384 References 385 14 Testing 386 14.1 Introduction 386 14.2 High-Power Tests 387 14.2.1 Introduction 387 14.2.2 Direct Tests 391 14.2.3 Synthetic Tests 395 References 411 List of Abbreviations 413 Index 417