Page 397 - Practical Power System and Protective Relays Commissioning

Index 385

of high-voltage transmission feeders, residual voltage-broken delta-connection,
262 263 208f
setting ring main circuit overcurrent and
high-impedance differential protection directional relays grading, 208
setting, 301 306 Directionality test, 326, 367
interposing transformer in transformer Discharging of new battery, 160
differential protection, 296f Disconnect switch (DS), 133, 141, 143, 145f
low-impedance differential protection, contact resistance measurement, 138f
294 300, 295f DS/ES tests, 138 139
relay operate bias characteristic, 297f high-speed earthing switches, 136 137
tap changers, 274 load break switches, 134 135
transformer connections, 273 Disconnector switch. See Disconnect switch
Differential voltage pickup test, 357 (DS)
Digital bay control unit, 146 Discrimination
Digital channels, 142 by current, 203 204
Digital relays, 194, 367 368. See also by time, 203 204, 203f
Directional relays Distance protection, 217 220, 289. See also
Direct current (DC). See also Alternative Overcurrent protection (OC protection)
current (AC) application setting, 289f, 290f, 291f
contact resistance of cable phase basic principles, 210 211, 211f
conductors, 73, 74f circuit analysis, 211 212, 211f
distribution panels commissioning tests compensation factor, 291f
electrical tests, 29 distance protection setting for parallel lines,
visual check, 29 219 220
injection method, 246 effect SIR on distance protection
insulation sheath test, 74 measurements, 218 219
power circuits, 157 measurements, 218 219
protection system, 83 secondary injection test, 332 338
schematic elementary diagram, 9, 15f Mho-relay characteristic for pH-E faults,
transmission, 69, 78 333f
components, 81 82, 82f relay characteristic of directional OC
construction, 80 81 relay, 331f
Direct transfer trip scheme, 221 222, 221f, relay power swing characteristic, 336f
222f relay test connections, 334f
Direct transformer connections, relay test sheet, 335t, 336t
147, 150f SOTF Logic in distance protection, 337f
Directional comparison scheme, 223 telecommunication schemes, 221 226
Directional load tests, 337 acceleration scheme, 224 225
Directional overcurrent (DOC), 330 blocking overreach transfer scheme,
relay testing and commissioning, 330 331, 225 226
330f direct transfer trip scheme, 221 222
Directional relays, 204 208. See also permissive overreach scheme, 223
Distance relays; Protection relays permissive underreach scheme, 222
30 degrees connection maximum torque power swing blocking relay, 228
angle, 207f stub protection function, 230 231
90 degrees connection switch to fault feature in distance relay,
30 degrees maximum torque angle, 206f, 230
206t, 207t voltage transformer supervision,
45 degrees maximum torque angle, 205f, 228 229
206t zone extension scheme, 223 224
connections, 208f weak infeed in permissive overreach
grading, 208 scheme, 220