GE 750 Instruction Manual page 274

750/760
Feeder Management Relay
7–20
1. Apply three-phase nominal voltage to the relay.
2. Inject current below the pickup level into Phase A and slowly increase until the
Pickup LED is on. Note the pickup value is the pickup current of the Curve in
use.
3. Slowly reduce the current into Phase A until the Pickup LED goes off and note
the dropout level, which should be 2% of CT less than pickup when pickup
or 97 to 98% of pickup when pickup
4. Reduce the current to zero.
5. Repeat Steps 2 to 4 for current injected into Phases B and C.
6. Set all input voltages to 0 and slowly increase Phase A current until the Pickup
LED comes on. Check that this current is 9 to 11% of the measured full voltage
pickup current.
7. Increase input voltage V
11% of the nominal phase-phase voltage. This test establishes the lower knee
of the operating characteristic.
8. With the Pickup LED still off, increase voltage V
phase voltage.
9. Increase the Phase A current until the Pickup LED comes on. This should be at
59 to 61% of the full voltage measured pickup current.
10. With the Pickup LED still off, increase voltage V
11. Increase Phase A current to 90% of normal pickup and hold this value. Slowly
decrease V until the Pickup LED just comes on. This should be at 89 to 91% of
ab
nominal V . This establishes the upper knee of the characteristic, and shows
ab
the pickup is not altered above 90% voltage.
12. Reduce current and voltages to 0.
13. Repeat Steps 6 through 12 for current injected in Phase B and controlling
voltage V .
cb
14. Repeat Steps 6 through 12 for current injected in Phase C and controlling
voltage V .
ca
To check trip timing with voltage restraint, set the input voltage to a given level,
establishing a new pickup current, and then following the procedure outlined earlier
under Timing.
b) Phase TOC 2
The procedure to test this element is identical to that for Phase TOC 1, except for
the blocking from logic inputs, in which case the following procedure should be
used:
1. Inject current to cause a Pickup.
2. Assert a logic input to provide a "Block Phase Time 2". The Pickup LED should
immediately go out.
3. Repeat Steps 1 and 2 for logic inputs "Block Phase O/C", "Block All O/C" and
"Block 1 Trip Relay" as required.
c) Phase IOC 1
The procedure to test this element is identical for Phase TOC 1, except for the
procedures below. Pickup, indication and operation are subject to the "phases
required for operation" test, but not subject to the "linear reset timing" and "voltage
restrained Phase TOC" tests.
The following procedure checks pickup with two phases for operation:
1. Inject current into Phase B at 150% of pickup.
2. Inject current at a level below the pickup level into Phase A.
3. Slowly increase the Phase A current until the Pickup LED comes on and note the
pickup value.
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CT.
>
until the Pickup LED goes out. This should be at 9 to
ab
to 60% of the nominal phase-
ab
to 130% of nominal.
ab
Protection Schemes
CT
≤
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