GE 750, Instruction Manual

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750/760 Feeder Management Relay GE Power Management
17.9 CONTROL SCHEMES 17 COMMISSIONING
17
17.9.4 COLD LOAD PICKUP FEATURE BLOCKING
Test Connections per Figure 17–1: RELAY TEST WIRING – WYE CONNECTION or Figure 17–2: RELAY
TEST WIRING – DELTA CONNECTION on page 17–4.
Procedure To Check:
Function and Timer Control:
1. Enable the Cold Load Pickup setpoint to cause the relay to go into cold load pickup operation after the set-
point Outage Time Before Cold Load expires. Check that any selected output relays have operated. If the
function is selected as Alarm, the alarm message and LED should also be turned on.
2. Inject a current in any phase below 10% of nominal, and slowly increase. The relay should go into cold
load operation when the current is above 10% of nominal. The alarm message and LED should reset and
any output relays programmed to operate should dropout after a time interval equal to the cold load pickup
block time. This interval can be checked in the Event Recorder.
3. Reduce this current to 3% of nominal and simultaneously start a timer. This feature should generate an
output at the end of the
OUTAGE TIME BEFORE COLD LOAD
setting.
a) CONTROL OF O/C PROTECTION FEATURES
Phase Inst OC 1 Blocking
1. Set a test current, in the number of phases required to generate an output, to a level above the pickup of
this element then turn the current off.
2. Assert a Cold Load Pickup logic input, and immediately apply the test current to the relay. The element will
not pickup as it is blocked by cold load pickup blocking. Wait until the element operates, as shown by the
PICKUP indicator coming on at the end of the programmed Cold Load Pickup Block Time.
3. Turn the current off. The time interval can be checked in the Event Recorder.
Neutral Inst OC 1 Blocking
Follow the procedure described for Phase Inst OC 1 Blocking, injecting current as appropriate.
Ground Inst OC Blocking
Follow the procedure described for Phase Inst OC 1 Blocking, injecting current as appropriate.
Sensitive Ground Inst OC Blocking
Follow the procedure described for Phase Inst OC 1 Blocking, injecting current as appropriate.
Neg Seq Inst OC Blocking
Follow the procedure described for Phase Inst OC 1 Blocking, injecting current as appropriate.
Phase Time OC 1 Raised Pickup
1. Ensure all other O/C features are Disabled.
2. Cold Load Pickup Blocking will raise the pickup setting of the Curve normally used by the programmed per-
centage. Set a test current to a level between the normal pickup setting and the raised setting, (at least 5%
of nominal current) then turn the current off.
3. Assert a Cold Load Pickup logic input and immediately inject the test current into the relay. Phase Time O/
C 1 will not pickup as the pickup current is raised. Increase the injection current until the PICKUP indicator