Phase Overcurrent - GE 750 Instruction Manual

750/760
Feeder Management Relay

Phase Overcurrent

NOTE
7–18
Once one of the above strategies is selected, the following procedures are used to
test protection elements.
a) Phase TOC 1
For these tests, refer to the figures on page 7–4 for test connections.
The following procedures, other than the check for Linear Reset Timing, are based
on the "Instantaneous" reset time characteristic. If the "Linear" reset time
characteristic is required, ensure that there is sufficient time between test current
injections, or cycle relay power OFF and ON to discharge the energy measurement
accumulator to 0.
The following procedure checks Pickup with one phase for operation:
1. Inject current at a level below the pickup level into Phase A.
2. Slowly increase the current until the Pickup LED comes on. Note the pickup
value.
3. Slowly reduce the current until the Pickup LED goes out. Note the dropout level,
which should be 2% of CT less than pickup when pickup
pickup when pickup CT.
>
4. Repeat Steps 1 through 3 for Phases B and C.
The following procedure checks indications and operations caused by a Trip function,
with front panel RESET key resetting:
1. Inject current to cause a pickup and wait until the element times to Trip.
2. Check that the Trip and Message LEDs are flashing, the Last Trip message is
displayed, and the Output Relay 1 and any others programmed to operate (as
well as their associated LED indicators) operate.
3. Slowly reduce the current until the Pickup LED goes out. Check that the Trip and
Message LEDs are flashing, and that the Output Relay 1 and any others
programmed to operate (as well as their associated LEDs) reset.
4. Press the front panel RESET key. Check that the Trip and Message LEDs go off,
and the Last Trip message is no longer displayed. Turn current off.
The following procedure checks indications and operations caused by a Trip function,
with Logic Input resetting:
1. Ensure that the reset logic input control function has been assigned to a logic
input.
2. Inject current to cause a pickup and wait until the element times to Trip.
3. Check that the Trip and Message LEDs are flashing, the Last Trip message is
displayed, and the Output Relay 1 and any others programmed to operate (as
well as their associated LED indicators) operate.
4. Slowly reduce the current until the Pickup LED goes out. Check that the Trip and
Message LEDs are flashing, and that the Output Relay 1 and any others
programmed to operate (as well as their associated LEDs) reset.
5. Assert a logic input to provide a reset. Check that the Trip and Message LEDs
are now off, and the Last Trip message is no longer displayed. Turn current off.
The following procedure checks indications and operations caused by an Alarm
function:
1. Inject current to cause a pickup and wait until the element times to Alarm.
2. Check that the Alarm and Message LEDs are flashing, the Active Alarm message
is displayed, and any output relays programmed to operate (as well as their
associated LEDs) operate.
3. Slowly reduce the current until the Pickup LED goes out.
4. Verify that the Alarm and Message LEDs go off, and that any output relays
programmed to operate (as well as their associated LEDs) reset, and the Active
Alarm message is no longer displayed.
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Protection Schemes
CT or 97 to 98% of
≤
GE Multilin