Page 402 - Practical Power System and Protective Relays Commissioning

390 Index

Manufacturer message specification (MMS), O
183 OC protection. See Overcurrent protection
Maximum torque angle (MTA), 205 (OC protection)
MCBs. See Miniature circuit breakers (MCBs) Ocean energy, 34
Megger tester, 72 OCT. See Optical current transformer (OCT)
Merz-price differential protection, 263f OFAF. See Oil forced air forced (OFAF)
Message integrity, 184 Offset-Mho characteristic, 214 215
Metering current transformer accuracy classes, Offset-Mho distance relay, 244
109 OFWF cooling. See Oil forced water forced
Metrosils resistance. See Nonlinear resistance cooling (OFWF cooling)
MHI. See Machine-Human-Interface-Display Ohm relay characteristic, 359
(MHI) Ohmic impedance, 174
Mho characteristic, 212 Oil CB, 88, 89f
Miniature circuit breakers (MCBs), 26 Oil forced air forced (OFAF), 51, 51f,52t
Minimum bias, 296 Oil forced water forced cooling (OFWF
Minimum zone protection, 230 231
cooling), 51, 52f,52t
MMS. See Manufacturer message
Oil natural air forced (ONAF), 52t
specification (MMS)
Oil natural air natural (ONAN), 52t
Moisture content, 91
Old-type pilot wire differential protection
Momentary overload test,
testing, 339 342
44
On-load
Monitoring relays, 189
stability test, 367 368
Monopolar links, 80, 80f tap changer
Motor faults, 320 321 using reactor, 54f
Motor protection, 250 251 using resistor, 55f
mechanisms, 133 tests, 326
setting, 320 ONAF. See Oil natural air forced (ONAF)
worked examples, 320 323 ONAN. See Oil natural air natural (ONAN)
MTA. See Maximum torque angle (MTA) One and half breaker arrangement, 13 14,
Multishot reclosing, 232 18f
MVA, 174 Open circuit characteristic test, 43 44
Open circuited secondary winding, CT, 111
Opening time of CB, 232
N Operating time
National control center (NCC), 24, 93 in cycles, 85 86
electricity control center, 379 of protection, 232
SCADA system, 142 Optical current transformer (OCT), 115 118,
Negative sequence, 163 164, 165f 128 129
Negative-phase sequence current I 2 protection, Optical high-voltage CTs, 116 118, 117f
246 Optical instrument advantages, 116 118
Negative-sequence principle, Optical sensors, 129
228 Optical voltage transformer (OVT), 115 118,
Neutral impedance compensation, 227 128 129
No-load Optimal coordination time, 201
circuit losses test, 62 Out-of-step protection, 244 245, 246f
current, 62, 63f for synchronous motors, 323
Noise level test, 44 Out-of-step relay testing and commissioning,
Nondirectional overcurrent, 202 203 359 360
relays testing, 327 329 relay connection, 360
Nonlinear resistance, 258, 303 304 test procedure, 360
Nuclear generation stations, 1 Over speed test, 44
Nuclear power stations, 31 Over-frequency protection, 247