GE 750 - Line Undervolt 3 (4)

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17-

750/760 Feeder Management Relay GE Power Management

17.7 PROTECTION SCHEMES 17 COMMISSIONING

c) FOR WYE and DELTA VTs

Test Connections per Figure 17–1: RELAY TEST WIRING – WYE CONNECTION or Figure 17–2: RELAY

TEST WIRING – DELTA CONNECTION on page 17–4.

Indications and Operations are as outlined under Phase Time Overcurrent 1.

Blocking From Logic Inputs:

1. Inject voltage into the required number of phases to cause a pickup.

2. Assert a logic input to provide a "Block Undervolt 1 (2)". 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. Set the voltage source to nominal voltage.

3. Reset the timer. Turn the voltage off in the required number of phases, and measure the operating time.

4. Repeat steps 2 and 3 four more times and obtain an average of the time intervals.

5. Reset the relay and disconnect the “Stop Trigger.”

17.7.24 LINE UNDERVOLT 3 (4)

Pickup

1. Inject nominal voltage into the line voltage input of the relay. The PICKUP indicator should be off.

2. Slowly lower the voltage until the PICKUP indicator comes on. This is the pickup voltage.

3. Continue to lower the voltage until the PICKUP indicator goes out. This is the programmed Minimum Oper-

ating Voltage minus 2% of VT.

4. Raise the voltage until the PICKUP indicator comes on, and continue to increase until the indicator goes

out. This is the reset voltage, which should be the pickup value plus 2% of VT.

Indications and Operations are as outlined under Phase Time Overcurrent 1.

Blocking From Logic Inputs:

1. Inject voltage to cause a pickup.

2. Assert a logic input to provide a "Block Undervolt 3 (4)". The PICKUP indicator should immediately go out.