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8 COMMISSIONING TESTS
3.
Calculate the 3V
(neutral voltage, i.e. residual voltage) being supplied to the relay using the formula:
0
4.
Repeat Steps 1 through 3 except adjust V
The following procedure tests Blocking From Logic Inputs:
1.
Cause a pickup of the Neutral Displacement element.
2.
Assert a logic input to provide a "Blk Ntr Displacement". 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 tests element Timing:
1.
Connect the Stop Trigger.
2.
Preset the neutral (residual) voltage to be 150% of the pickup setting.
3.
Inject the preset neutral (residual) voltage into the relay and note the delay time. Reset the timer.
4.
Repeat Step 3 four more times and obtain an average of the time intervals. Disconnect the stop trigger when finished.
a) UNDERFREQUENCY
To test Underfrequency, use the test connections specified in Figure 8–1: Relay Test Wiring – Wye Connection or Figure 8–
2: Relay Test Wiring – Delta Connection on page 8–3. The Indications and Operations are as outlined for Phase TOC 1 on
page 8–16.
The following procedure checks Minimum Operating Voltage Supervision:
1.
Set the injection source well below the pickup frequency. Inject V
I
= I
above the Minimum Operating Current level. The Pickup LED should be off.
b
c
2.
Slowly increase the voltage in Phase A until the Pickup LED comes on. Check that the pickup voltage is the selected
Minimum Operating Voltage.
3.
Slowly reduce the voltage. Note the voltage at which the Pickup LED goes out. Check that this dropout voltage is the
pickup voltage minus 2 x VT nominal. Turn the injection voltage off.
The following procedure checks Minimum Operating Current Supervision:
1.
Set the injection source well below the pickup frequency. Inject V
into the phase current inputs of the relay. The Pickup LED should be off.
2.
Slowly increase the voltage in Phase A above the selected Minimum Operating Voltage. The Pickup LED should
remain off.
3.
Slowly increase the Phase A current until the Pickup LED turns on. This is the Minimum Operating Current level. Now
reduce the current until the Pickup LED turns off. Note the dropout level, which should be 2% of CT less than the Mini-
mum Operating Current level when the level is ≤ CT. When the Minimum Operating Current level is > CT, the dropout
level should be 97 to 98% of the Minimum Operating Current level.
4.
Slowly increase the Phase B current until the Pickup LED turns on. This is the Minimum Operating Current level. Now
reduce the current until the Pickup LED turns off. Note the dropout level, which should be 2% of CT less than the Mini-
mum Operating Current level when the level is ≤ CT. When the Minimum Operating Current level is > CT, the dropout
level should be 97 to 98% of the Minimum Operating Current level.
5.
Slowly increase the Phase C current until the Pickup LED turns on. This is the Minimum Operating Current level. Now
reduce the current until the Pickup LED turns off. Note the dropout level, which should be 2% of CT less than the Mini-
mum Operating Current level when the level is ≤ CT. When the Minimum Operating Current level is > CT, the dropout
level should be 97 to 98% of the Minimum Operating Current level.
For the following Underfrequency test procedures, the injected voltage and currents are always above the
minimum operating levels.
NOTE
GE Multilin
Courtesy of NationalSwitchgear.com
3V
V
V
V
=
+
+
0
a
b
c
and V
in turn.
bn
cn
= 0 V into the bus voltage input of the relay with I
a
= 0 V into the bus voltage input and I
a
750/760 Feeder Management Relay
8.4 PROTECTION SCHEMES
(EQ 8.2)
8.4.7 FREQUENCY
= I
= I
= 0 A
a
b
c
8-29
=
a
8
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