Power System Protection. Vol.2: Systems and Methods

Table of Contents......Page 1
8.2 Types of Overcurrent System......Page 6
8.2.1 Overcurrent and Earth-fault Protection Systems......Page 8
8.2.2 Grading of Current Settings......Page 9
8.2.3 Grading of Time Settings: The Definite-time System......Page 10
8.2.4 Grading by Both Time and Current: Inverse-time Overcurrent Systems......Page 11
8.2.4.3 Fuse-shunted Trip Coils......Page 13
8.2.4.4 Inverse-time Overcurrent Relays......Page 17
8.3 Selection of Settings......Page 18
8.3.2 Grading of Relay Settings......Page 19
8.3.2.1 Grading for Definite-time Relays......Page 20
8.3.2.2 Grading for Inverse-time Relays......Page 21
8.3.2.4 Graphical Method of Grading......Page 29
8.3.3 Current Transformer Requirements......Page 32
8.3.3.1 Burdens......Page 34
8.3.3.3 Additional Burden......Page 35
8.3.3.4 Significance of Leads......Page 36
8.3.3.5 Burden of Earth-fault Schemes......Page 38
8.3.3.6 Effective Setting......Page 39
8.3.3.7 Time-grading of Earth-fault Relays......Page 42
8.3.3.8 Phase-fault Stability......Page 43
8.3.4 Sensitive Earth-fault Protection......Page 44
8.3.5 High-set Instantaneous Overcurrent Relays......Page 45
8.3.6 Relay Co-ordination with Fuses......Page 50
8.4 Directional Control......Page 51
8.4.1 Directional Relays......Page 53
8.4.2 Connections for Directional Phase-fault Relays......Page 55
8.4.2.1 30° Relay Connection: m.t.a. = 0°......Page 57
8.4.2.2 60° Relay Connection: m.t.a. = 0°......Page 58
8.4.2.3 90° Relay Connection......Page 61
8.4.3.1 Polarisation by Residual Voltage......Page 63
8.4.3.2 Polarisation by Neutral Current......Page 66
8.4.3.3 Dual Polarisation......Page 67
8.4.4 Grading of Ring Mains......Page 68
8.4.6 Parallel Feeders......Page 69
8.5 Bibliography......Page 70
9.2 Historical......Page 71
9.3.1 Impedance Measurement......Page 72
9.3.2 Derivation of Basic Measuring Quantities......Page 74
9.4.1 Presentation of Characteristics......Page 76
9.4.2 Derivation of Relay Characteristics......Page 78
9.4.3 Equivalence of Amplitude and Phase Comparators......Page 81
9.4.4 Basic Range of Impedance Characteristics......Page 83
9.4.5 Measuring Characteristics of Relay Schemes......Page 88
9.4.6 Mho Characteristics......Page 91
9.4.7 Practical Polarised Mho Characteristic......Page 95
9.5.1 Induction Cup......Page 97
9.5.2 Rectifier Bridge Moving Coil......Page 98
9.5.3 Electronic Relays: Introduction......Page 99
9.5.4 Comparator Development......Page 100
9.5.5 Practical Realisation of Static Phase Comparators......Page 105
9.6.1 Basis for Shaped Polar Characteristics......Page 112
9.6.3 Multicomparator Schemes......Page 113
9.6.4 Multi-input Comparators......Page 115
9.7.1 Requirements......Page 118
9.7.7 Dynamic Polar Characteristics......Page 0
9.8.1 Introduction......Page 132
9.8.2 Switched Distance Protection......Page 133
9.8.3 Polyphase Distance Protection......Page 140
9.9.1 General......Page 142
9.9.2.2 Permissive Intertrip-underreaching Schemes......Page 143
9.9.2.3 Permissive Intertrip-overeaching Systems......Page 146
9.9.3 Blocking Schemes......Page 147
9.9.3.1 Distance Protection Blocking Scheme......Page 148
9.9.3.2 Directional Comparison......Page 151
9.10.1 Fault Resistance......Page 152
9.10.2 Measuring Errors......Page 154
9.10.3 Healthy Phase Relays......Page 156
9.10.4 Load Encroachment......Page 158
9.10.5 Power Swing Encroachment......Page 160
9.10.6 Line Check......Page 163
9.10.7 Voltage Transformer Supervision......Page 164
9.11 Trends in Distance Protection Development......Page 165
9.12 Bibliography......Page 168
10.1 General Background and Introduction......Page 169
10.2 Some Basic Concepts of Unit Protection for Feeders......Page 170
10.3.1 Pilot Wires......Page 171
10.4 Types of Information Used......Page 172
10.5 Starting Relays......Page 173
10.6.1 General Philosophy......Page 177
10.6.2 Interconnections of Current Transformers......Page 178
10.6.3 Summation Transformers......Page 179
10.7 Elementary Theory of Longitudinal Differential Protection......Page 181
10.7.1 Longitudinal Differential Protection with Biased Relays......Page 182
10.7.2 Phase-comparison Principles......Page 185
10.7.3 Nonlinear Differential Systems......Page 187
10.7.5 Current Sources and Voltage Sources......Page 189
10.7.6 Nonlinearity and Limiting......Page 192
10.8.1 Basic Principles......Page 196
10.8.2 Practical Relay Circuits......Page 198
10.8.3 Summation Circuits......Page 199
10.8.4 Basic Discrimination Factor......Page 200
10.8.5 Typical Pilot Circuits......Page 205
10.8.6 Typical Systems for Privately Owned Pilots......Page 206
10.8.7 Use of Rented Pilots......Page 219
10.8.8 Typical Systems for use with Rented Pilots......Page 226
10.8.9 V.F. Phase-comparison Protection (Reyrolle Protection)......Page 232
10.9.1 General......Page 235
10.9.2 Current Transformer Requirements......Page 237
10.9.4 Fault Settings......Page 239
10.9.5 Protection Characteristics......Page 243
10.10.1 Introduction......Page 245
10.10.2 Types of Information Transmitted......Page 246
10.10.3 Basic Principles of Phase-comparison Protection......Page 248
10.10.4 Summation Networks......Page 249
10.10.5 Modulation of H.F. Signal......Page 254
10.10.6 Junction Between Transmitted and Received Signals......Page 256
10.10.7 Receiver......Page 257
10.10.8 Tripping Circuit......Page 259
10.10.9 Starting Circuits......Page 261
10.10.10 Telephase T3......Page 262
10.10.11 Contraphase P10......Page 263
10.10.12 Marginal Guard......Page 264
10.10.13 Checking and Testing......Page 266
10.11.1 General......Page 267
10.11.4 Fault Settings Related to Capacitance Current......Page 268
10.12.1 General......Page 272
10.12.2 Basic Principles......Page 273
10.12.4 Directional Relays......Page 274
10.12.5 Fault Detecting......Page 275
10.12.6 Change of Fault Direction......Page 277
10.13.1 General......Page 278
10.14 Bibliography......Page 279
11.1.1 External Overvoltages (Lightning)......Page 281
11.1.2 Internal Overvoltages......Page 283
11.2.1 Wave Propagation Along a Transmission Line without Losses......Page 290
11.2.3 Discontinuities in Surge Impedance and Junctions with Infinitely Long Lines......Page 291
11.3.1 Fundamental Principles of Surge Protection and Insulation Co-ordination......Page 293
11.3.4 Relation Between Overvoltage Tests and Service Conditions......Page 294
11.3.5 Practical Choice of Insulation Levels......Page 296
11.4.1 Shielding of Overhead Lines and Substations......Page 297
11.4.2 Surge Protection by Effective System Layout......Page 300
11.4.3 Voltage Limiting Devices......Page 301
11.5.1 Protection Against Switching Transients......Page 307
11.5.3 Protection Against Internal Temporary Overvoltages......Page 310
11.6.1 Effect of System Neutral Earthing on Insulation Requirements......Page 311
11.6.2 Choice of Surge Arresters and Derivation of Basic Impulse Insulation Levels......Page 313
11.6.3 Clearances to Earth Between Phases and Across Isolating Gaps......Page 314
11.6.4 Standard Insulation Levels, Clearances with Recommended Co-ordinating Gap Settings, or Surge Arrester Ratings, or Both......Page 315
11.6.5 Effect of Rain, Humidity and Atmospheric Pollution......Page 316
11.7.1 Statistical Aspects of Overvoltages and Insulation Strength......Page 317
11.7.2 Application of Statistical Distribution to Insulation Co-ordination......Page 320
11.8 Economic Aspects......Page 321
11.9 Bibliography......Page 322
C......Page 327
D......Page 328
O......Page 329
P......Page 330
U......Page 331