Breaker Failure - GE 750 Instruction Manual

17.7 PROTECTION SCHEMES
Rate:
1. With the V frequency at a level well below the Frequency Decay Pickup, drop the frequency of V
a
speed less than the
2. With the V frequency at a level well below the Frequency Decay Pickup, drop the frequency of V
a
speed greater than the
Indications and Operations are as outlined under Phase Time Overcurrent 1.
Blocking From Logic Inputs:
1. Decrease the V
2. Assert a logic input to provide a "Block Frequency Decay". The PICKUP indicator should immediately go
out.
3. Repeat steps 1 and 2 for logic input "Block 1 TRIP Relay" as required.
Timing:
1. Connect the Stop Trigger.
2. Preset the ramp-rate to a minimum of 110% of the pickup and reset the timer.
3. Inject the preset voltage into the V
4. Repeat step 3 four more times and obtain an average of the time intervals.
5. Disconnect the Stop Trigger.
Test Connections per Figure 17–1: RELAY TEST WIRING – WYE CONNECTION or Figure 17–2: RELAY
TEST WIRING – DELTA CONNECTION on page 17–4.
1. Ensure the wiring to the circuit breaker trip and close circuits is complete.
2. Energize the breaker trip and close circuits and close the breaker.
3. Carefully disconnect a wire to open the trip circuit.
17
4. Set a test current level 3% above the Breaker Failure Current setpoint and inject current into a phase cur-
rent input. (All O/C protection features are Disabled.)
5. Assert a Trip logic input, which cannot be performed by the breaker. After a delay the element should gen-
erate an output. (The delay time can be checked in the Event Recorder.) Turn the current off and Reset the
relay.
6. Reduce the current magnitude to 3% below the Breaker Failure Current setpoint and inject current into a
phase current input. Assert a Trip logic input, which cannot be performed by the breaker. The element
should not generate an output.
Indications and Operations are as outlined under Phase Time Overcurrent 1. This element has no Trip
function.
17-
42
Courtesy of NationalSwitchgear.com
FREQUENCY DECAY RATE
FREQUENCY DECAY RATE
frequency at a rate to cause a pickup.
a
bus voltage input and note the measured delay time. Reset the timer.
a
750/760 Feeder Management Relay
setting. The pickup indicator should remain off.
setting. The pickup indicator will come on.
17 COMMISSIONING
at a
a
at a
a

17.7.29 BREAKER FAILURE

GE Power Management