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8.6 CONTROL SCHEMES
3.
Turn the current off. The time interval can be checked in the Event Recorder.
For Neutral IOC 1 Blocking, Ground IOC Blocking, Sensitive Ground IOC Blocking, and Neg Seq IOC Blocking, follow the
procedure described above for Phase IOC 1 Blocking, injecting current as appropriate.
The following procedure checks Phase TOC 1 Raised Pickup for Cold Load Blocking:
1.
Ensure all other overcurrent features are "Disabled".
2.
Cold Load Pickup Blocking will raise the pickup setting of the curve normally used by the programmed percentage. 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 TOC 1 will not
pickup as the pickup current is raised. Increase the injection current until the Pickup LED comes on, before the cold
load pickup blocking feature times-out and returns the pickup to normal. Check that the raised pickup level is correct.
Turn current off, and wait until the alarm is removed from the display.
4.
Set a test current to a level between the normal pickup setting and the raised setting, then turn the current off.
5.
Assert a Cold Load Pickup logic input and immediately inject the test current into the relay. Phase TOC 1 will not
pickup as the pickup current is raised.
6.
At the end of the programmed
has returned to normal. When this happens, reduce the injection current until the Pickup LED goes out. The
LOAD PICKUP BLOCK TIME
For Neutral TOC 1 Raised Pickup, Ground TOC Raised Pickup, Sensitive Ground TOC Raised Pickup, and Neg Seq TOC
Raised Pickup, follow the procedure outlined for Phase TOC 1 Raised Pickup, injecting current as appropriate.
To check the Select Setpoint Group for Cold Load Blocking, apply a Cold Load Pickup logic input and verify that the
selected setpoint group becomes active. Verify that settings return to the previous setpoint group after the Cold
interval expires.
PICKUP BLOCK TIME
Make 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 following procedure checks Logic and Timers for Undervoltage Restoration:
1.
Program the Undervoltage 1 function as "Trip" and the Undervoltage 2 function as "Disabled".
2.
Assert or De-assert a logic input to simulate a closed breaker.
3.
Inject a balanced three-phase voltage at nominal voltage and frequency into the bus voltage input.
4.
Initially set the undervoltage restoration function setpoint to Alarm, and other setpoints as required.
5.
Turn the voltage off. After the programmed delay Undervoltage 1 should cause a trip, which should not initiate under-
voltage restoration as the breaker is closed. Diagnostic message "Uvolt Restore Init" should not be displayed.
6.
Assert or De-assert a logic input to simulate an open breaker, initiating undervoltage restoration. The diagnostic alarm
message and LED should be displayed, and output relays programmed to operate for this condition should operate.
8
7.
Change the Undervoltage Restoration function setpoint to Control, and the diagnostic message should change to con-
trol and the Alarm LED should turn off. Return this setpoint to Alarm.
8.
Assert logic input Block Restoration. The diagnostic alarm message and LED should be removed from the display, and
any output relays that operated should reset.
9.
De-assert the logic input. The alarm message and LED should again be displayed and output relays operated. After
the delay programmed in Incomplete Sequence Time the alarm message and LED should be removed from the display
and output relays reset.
10. Return the reduced voltage to nominal, resetting both the undervoltage trip condition and undervoltage restoration.
11. Reduce voltage until Undervoltage 1 trips, then immediately return the voltage to nominal. The diagnostic alarm mes-
sage and LED should be displayed, and output relays operated.
12. Provide a Reset to the relay, and the alarm message and LED should be removed from the display and output relays
reset. Remove the Reset.
8-44
Courtesy of NationalSwitchgear.com
COLD LOAD PICKUP BLOCK TIME
interval can be checked in the Event Recorder.
750/760 Feeder Management Relay
8 COMMISSIONING TESTS
the Pickup LED should come on, as the pickup setting
8.6.5 UNDERVOLTAGE RESTORATION
COLD
LOAD
GE Multilin
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