GE Power Management 750/760 Feeder Management Relay 17-
31
17 COMMISSIONING 17.7 PROTECTION SCHEMES
17
17.7.14 GROUND INSTANTANEOUS OVERCURRENT
The procedure to test this element is identical to that outlined for Section 17.7.3: PHASE TIME OVERCUR-
RENT 1 on page 17–21, with the following exceptions.
Current is injected into the ground input terminals, and the element is not subject to the test "phases required
for operation" and not subject to the tests “linear reset timing” and “voltage restrained time overcurrent”.
Blocking From Logic Inputs:
1. Inject current to cause a pickup.
2. Assert a logic input to provide a "Block Ground Inst". The PICKUP indicator should immediately go out.
3. Repeat steps 1 and 2 for logic inputs "Block Ground O/C", "Block All O/C" and “Block 1 TRIP Relay” as
required.
17.7.15 GROUND DIRECTIONAL OVERCURRENT
The procedure to test this element is identical to that outlined for Section 17.7.12: NEUTRAL DIRECTIONAL
OVERCURRENT on page 17–28, except the operating current is the ground current. Also, Ground Directional
may only be voltage polarized.
17.7.16 SENSITIVE GROUND TIME OVERCURRENT
The procedure to test this element is identical to that outlined for Section 17.7.3: PHASE TIME OVERCUR-
RENT 1 on page 17–21, with the following exceptions.
Current is injected into the sensitive ground input terminals, and the element is not subject to the "phases
required for operation" and “voltage restrained time overcurrent” tests.
Blocking From Logic Inputs
1. Inject current to cause a pickup.
2. Assert a logic input to provide a "Blk Sens Gnd Time". The PICKUP indicator should immediately go out.
3. Repeat steps 1 and 2 for logic inputs "Block Sens Gnd O/C", "Block All O/C" and “Block 1 TRIP Relay” as
required.
17.7.17 SENSITIVE GROUND INSTANTANEOUS OVERCURRENT
The procedure to test this element is identical to that outlined for Section 17.7.5: PHASE INSTANTANEOUS
OVERCURRENT 1 on page 17–24, with the following exceptions.
Current is injected into the sensitive ground input terminals, and the element is not subject to the test "phases
required for operation" and not subject to the tests “linear reset timing” and “voltage restrained time overcur-
rent”.
Blocking From Logic Inputs:
1. Inject current to cause a pickup.
2. Assert a logic input to provide a "Blk Sens Gnd Inst". The PICKUP indicator should immediately go out.
3. Repeat steps 1 and 2 for logic inputs "Block Sens Gnd O/C", "Block All O/C" and “Block 1 TRIP Relay” as
required.
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