Transmission and Distribution Electrical Engineering Second Edition-1.pdf
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| Transmission and Distribution Electrical Engineering Second Edition-1.pdf |
Drawings and Diagrams
List of Contributors xxi
Preface xxiii
1 System Studies 1
1.1 Introduction 1
1.2 Load flow 1
1.2.1 Purpose 1
1.2.2 Sample study 2
1.3 System stability 8
1.3.1 Introduction 8
1.3.2 Analytical aspects 10
1.3.3 Steady state stability 14
1.3.4 Transient stability 17
1.3.5 Dynamic stability 28
1.3.6 Effect of induction motors 28
1.3.7 Data requirements and interpretation of transient
stability studies 29
1.3.8 Case studies 34
1.4 Short circuit analysis 42
1.4.1 Purpose 42
1.4.2 Sample study 42
2 Drawings and Diagrams 50
2.1 Introduction 50
| 2.2 Block diagrams | 50 |
| 2.3 Schematic diagrams | 51 |
| 2.3.1 Method of representation | 51 |
| 2.3.2 Main circuits | 55 |
| 2.3.3 Control, signalling and monitoring circuits | 55 |
| 2.4 Manufacturers’ drawings | 55 |
| 2.4.1 Combined wiring/cabling diagrams | 55 |
| 2.4.2 British practice | 61 |
| 2.4.3 European practice | 63 |
| 2.4.4 Other systems | 68 |
| 2.5 Computer aided design (CAD) | 68 |
| 2.6 Case study | 69 |
| 2.7 Graphical symbols | 70 |
| Appendix A—Relay identification—numerical codes Appendix B—Comparison between German, British, US/Canadian and international symbols | 72 |
| 82 | |
| B1 General circuit elements | 83 |
| B2 Operating mechanisms | 86 |
| B3 Switchgear | 89 |
| 3 Substation Layouts | 92 |
| 3.1 Introduction | 92 |
| 3.2 Substation design considerations | 92 |
| 3.2.1 Security of supply | 92 |
| 3.2.2 Extendibility | 93 |
| 3.2.3 Maintainability | 93 |
| 3.2.4 Operational flexibility | 94 |
| 3.2.5 Protection arrangements | 94 |
| 3.2.6 Short circuit limitations | 94 |
| 3.2.7 Land area | 94 |
| 3.2.8 Cost | 95 |
| 3.3 Alternative layouts | 95 |
| 3.3.1 Single busbar | 95 |
| 3.3.2 Transformer feeder | 97 |
| 3.3.3 Mesh | 101 |
| 3.3.4 Ring | 103 |
| 3.3.5 Double busbar | 104 |
| 3.3.6 1 Circuit breaker | 106 |
| 3.4 Space requirements | 106 |
| 3.4.1 Introduction | 106 |
| 3.4.2 Safety clearances | 108 |
| 3.4.3 Phase-phase and phase-earth clearances | 109 |
| 4Substation Auxiliary Power Supplies 115 | |
| 4.1 Introduction 115 | |
| 4.2 DC supplies | 115 |
| 4.2.1 Battery/battery charger configurations | 115 |
| 4.2.2 Battery charger components | 118 |
vi Contents
4.2.3 Installation requirements 121
4.2.4 Typical enquiry data—DC switchboard 124
4.3 Batteries 125
4.3.1 Introduction 125
4.3.2 Battery capacity 125
4.3.3 Characteristics of batteries 128
4.3.4 Battery sizing calculations 129
| 4.3.5 Typical enquiry data | 132 |
| 4.4 AC supplies 134 | |
| 4.4.1 Power sources 134 | |
| 4.4.2 LVAC switchboard fault level | 134 |
4.4.3 Auxiliary transformer LV connections 134
| 4.4.4 Allowance for future extension | 136 |
| 4.4.5 Typical enquiry data | 138 |
| 4.4.6 Earthing transformer selection | 139 |
| 4.4.7 Uninterruptible power supplies | 143 |
5 Current and Voltage Transformers 147
5.1 Introduction 147
5.2 Current transformers 147
5.2.1 Introduction 147
5.2.2 Protection CT classifications 147
5.2.3 Metering CTs 151
5.2.4 Design and construction considerations 152
5.2.5 Terminal markings 154
5.2.6 Specifications 155
5.3 Voltage transformers 155
5.3.1 Introduction 155
5.3.2 Electromagnetic VTs 155
5.3.3 Capacitor VTs 156
5.3.4 Specifications 157
6 Insulators 160
6.1 Introduction 160
6.2 Insulator materials 160
6.2.1 Polymeric and resin materials 160
6.2.2 Glass and porcelain 161
6.3 Insulator types 161
6.3.1 Post insulators 161
6.3.2 Cap and pin insulators 165
6.3.3 Long rod 166
6.4 Pollution control 167
6.4.1 Environment/creepage distances 167
6.4.2 Remedial measures 169
Contents vii
6.4.3 Calculation of specific creepage path 170
6.5 Insulator specification 171
6.5.1 Standards 171
6.5.2 Design characteristics 175
6.6 Tests 176
6.6.1 Sample and routine tests 176
6.6.2 Technical particulars 177
7 Substation Building Services 179
7.1 Introduction 179
7.2 Lighting 179
7.2.1 Terminology 179
7.2.2 Internal lighting 185
7.2.3 External lighting 187
7.2.4 Control 195
7.3 Distribution characterization 196
7.4 Heating, ventilation and air conditioning 199
7.4.1 Air circulation 199
7.4.2 Air conditioning 201
7.4.3 Heating 206
7.5 Fire detection and suppression 206
7.5.1 Introduction 206
7.5.2 Fire extinguishers 207
7.5.3 Access, first aid and safety 207
7.5.4 Fire detection 208
7.5.5 Fire suppression 211
7.5.6 Cables, control panels and power supplies 212
8 Earthing and Bonding 214
8.1 Introduction 214
8.2 Design criteria 215
8.2.1 Time/current zones of effects of AC currents on persons 215
8.2.2 Touch and step voltages 215
8.2.3 Comparison of touch and step potential design criteria 217
8.3 Substation earthing calculation methodology 220
8.3.1 Boundary conditions 220
8.3.2 Earthing materials 222
8.3.3 Earthing impedance and earthing voltage 225
8.3.4 Hazard voltage tolerable limits 226
8.4 Computer generated results 228
8.4.1 Introduction 228
8.4.2 Case study 231
References 232
9 Insulation Co-ordination 234
9.1 Introduction 234
9.2 System voltages 234
9.2.1 Power frequency voltages 234
9.2.2 Overvoltages 235
9.3 Clearances 245
9.3.1 Air 245
9.3.2 SF
246
9.4 Procedures for co-ordination 247
9.4.1 Statistical approach 247
9.4.2 Non-statistical approach 248
9.5 Surge protection 248
9.5.1 Rod or spark gaps 248
9.5.2 Surge arresters 250
References 265
10 Relay Protection 266
10.1 Introduction 266
10.2 System configurations 267
10.2.1 Faults 267
10.2.2 Unearthed systems 267
10.2.3 Impedance earthed systems 267
10.2.4 Solidly earthed systems 268
10.2.5 Network arrangements 268
10.3 Power system protection principles 271
10.3.1 Discrimination by time 271
10.3.2 Discrimination by current magnitude 272
10.3.3 Discrimination by time and fault direction 272
10.3.4 Unit protection 272
10.3.5 Signalling channel assistance 273
10.4 Current relays 274
10.4.1 Introduction 274
10.4.2 Inverse definite minimum time lag (IDMTL) relays 274
10.4.3 Alternative characteristic curves 277
10.4.4 Plotting relay curves on log/log graph paper 277
10.4.5 Current relay application examples 278
10.5 Differential protection schemes 289
10.5.1 Biased differential protection 289
10.5.2 High impedance protection 292
10.5.3 Transformer protection application examples 293
10.5.4 Pilot wire unit protection 297
10.5.5 Busbar protection 300
10.6 Distance relays 303
10.6.1 Introduction 303
Contents ix
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10.6.2 Basic principles 304
10.6.3 Relay characteristics 305
10.6.4 Zones of protection 309
10.6.5 Switched relays 311
10.6.6 Typical overhead transmission line protection schemes 312
10.7 Auxiliary relays 316
10.7.1 Tripping and auxiliary 316
10.7.2 AC auxiliary relays 321
10.7.3 Timers 321
10.7.4 Undervoltage 321
10.7.5 Underfrequency 322
10.8 Computer assisted grading exercise 325
10.8.1 Basic input data 325
10.8.2 Network fault levels 325
10.8.3 CT ratios and protection devices 326
10.8.4 Relay settings 326
10.9 Practical distribution network case study 326
10.9.1 Introduction 326
10.9.2 Main substation protection 328
10.9.3 Traction system protection 328
10.9.4 21 kV distribution system and protection philosophy 331
10.9.5 21 kV pilot wire unit protection 332
10.9.6 21 kV system backup protection 333
10.9.7 Use of earth fault indicators 335
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