GE 750 Instruction Manual page 360

PROTECTION SCHEMES
7.4.3 Neutral
Overcurrent
7 - 32
 Repeat the last 5 steps for current angle adjusted in each of Phases B and
C.
Neutral TOC 1
The procedure to test this element is identical to that outlined in Phase TOC 1 on page 7–
25, except that current is injected into any one phase, and the element is not subject to the
"phases required for operation" and "voltage restrained time overcurrent" tests.
The blocking from logic inputs check is different from that for Phase TOC 1 and is
performed as follows:
 Inject current to cause a pickup.
 Assert logic input to provide a "Block Neutral Time 1".
The Pickup LED should immediately turn off.
 Repeat Steps 1 and 2 for logic inputs "Block Neutral O/C", "Block All
O/C" and "Block 1 Trip Relay" as required.
Neutral TOC 2
The procedure to test this element is identical to that outlined in Phase TOC 1 on page 7–
25, except that current is injected into any one phase, and the element is not subject to the
"phases required for operation" and "voltage restrained time overcurrent" checks.
The blocking from logic inputs check is different from that for Phase TOC 1 and is
performed as follows:
 Inject current to cause a pickup.
 Assert logic input to provide a "Block Neutral Time 2".
The Pickup LED should immediately go out.
 Repeat last 2 steps for logic inputs "Block Neutral O/C", "Block All O/
C" and "Block 1 Trip Relay" as required.
Neutral IOC 1
The procedure to test this element is identical to that outlined in Phase TOC 1 on page 7–
25, except that current is injected into any one phase, and the element is not subject to the
"phases required for operation", "linear reset timing", and "voltage restrained time
overcurrent" tests.
The blocking from logic inputs check is different from that for Phase TOC 1 and is
performed as follows:
 Inject current to cause a pickup.
 Assert a logic input to provide a "Block Neutral Inst 1".
The Pickup LED should immediately go out.
 Repeat last 2 steps for logic inputs "Block Neutral O/C", "Block All O/
C" and "Block 1 Trip Relay" as required.
CHAPTER 7: COMMISSIONING
750 FEEDER MANAGEMENT RELAY – INSTRUCTION MANUAL