Breaker Failure - GE 750 Instruction Manual

Protection Schemes
NOTE

Breaker Failure

GE Multilin
4. With the V voltage at a level well above the Minimum Operating Voltage level,
a
increase I to a level well above the Minimum Operating Current level. Currents
c
I and I should be well below the Minimum Operating Current level. Starting
a b
with the V frequency at a level well below the
a
frequency of V at a speed greater than the
a
LED should come on while the V
For the following Frequency Decay test procedures, the injected voltage
and currents are always above the minimum operating levels.
The following procedure checks the Frequency Decay Pickup:
1. Starting with the V frequency at a level well above the
a
the frequency of V at a speed greater than the
a
level still well above the
2. Continue dropping the V
. When the frequency drops below the
RATE
will come on.
The following procedure checks the Frequency Decay Rate:
1. With the V frequency at a level well below the
a
quency of V at a speed less than the
a
cator should remain off.
2. With the V frequency at a level well below the
a
frequency of V at a speed greater than the
a
indicator will come on.
The following procedure checks Blocking From Logic Inputs:
1. Decrease the Va frequency at a rate to cause a pickup.
2. Assert a logic input to provide a "Block Frequency Decay". The Pickup LED
should immediately go out.
3. Repeat Steps 1 and 2 for logic input "Block 1 Trip Relay" as required.
The following procedure checks the Frequency Decay 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
delay time. Reset the timer.
4. Repeat Step 3 four more times and obtain an average of the time intervals.
5. Disconnect the Stop Trigger.
To test Breaker Failure, use the test connections specified in FIGURE 7–1: Relay Test
Wiring – Wye Connection or FIGURE 7–2: Relay Test Wiring – Delta Connection on
page 7–4. The Indications and Operations are as outlined for Phase TOC 1 on page
7–18. This element has no Trip function.
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.
4. Set a test current level 3% above the
current into a phase current input (all overcurrent protection features are
"Disabled").
5. Assert a Trip logic input, which cannot be performed by the breaker. After a
delay the element should generate 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
and inject current into a phase current input. Assert a Trip logic input, which
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FREQ DECAY PICKUP
FREQ DECAY RATE
frequency is dropping.
a
FREQ DECAY RATE
. The Pickup LED should remain off.
FREQ DECAY PICKUP
frequency at a speed greater than the
a
FREQ DECAY PICKUP
FREQ DECAY PICKUP
FREQ DECAY RATE
FREQ DECAY PICKUP
FREQ DECAY RATE
bus voltage input and note the measured
a
BRKR FAILURE CURRENT
BRKR FAILURE CURRENT
750/760
Feeder Management Relay
, drop the
setting. The Pickup
, drop
FREQ DECAY PICKUP
setting, to a
FREQ DECAY
, the Pickup LED
, drop the fre-
setting. The pickup indi-
, drop the
setting. The pickup
setpoint and inject
setpoint
7–35