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6 FUNCTIONAL TESTS (USER SETTINGS)
6.4 BACKUP PROTECTION TESTS
1. Protection Settings:
OVERCURRNT
(601)
50 = YES
(602)
50_DIRCNL = NO
(603)
50PICKUP = [_________] amps,
50 is calculated with the following equation:
50 = ( I
– I
) or ( I
A
B
B
where 50 is the difference in phase-to-phase current. The test current, I
returned through another to simulate a phase-to-phase fault. When an AB fault is applied, the difference
( I
– I
) equals ( I
– (– I
A
B
op
2. Connect the relay as shown in Figure 5–1: PHASE-TO-PHASE TEST CONNECTIONS on page 5–7, for a
phase AB, BC, or CA fault.
3. Set the relay into test mode 43 (Phase Overcurrent). The LUI should display
INST PHS OVRC ON
4. Set I
= 0.5·50 + 0.05·50 = [________] amps rms and apply to the relay. The A1 contact should close.
op
Lower I
to 0.5·50 – (0.05·50) = [________] amps rms; the A1 contact should open.
op
5. Reduce I
to zero.
op
1. Protection Settings:
OVERCURRNT
(605) 50G = YES
(606) 50G_DIRCNL = NO
(607) 50GPICKUP = [_________] amps,
50G is given by
×
50G =
3 I
0.9
–
0
where I
is the zero-sequence current and I
0
Since the test current, I
I
= I
/ 3
(eq. 6–13)
0
op
Substituting Equations 6–13 and 6–14 into Equation 6–12 yields
50G
= I
– 0.3 I
op
Therefore IPT will pick up when I
2. Connect the relay as shown in Figure 4–3: PHASE TO GROUND TEST CONNECTIONS on page 4–14.
3. Set the relay into test mode 44 (Ground Overcurrent). The LUI displays
INST GND OVRC ON
4. Set I
to (50G / 0.7) + 0.5 = [________] amps rms and apply to the relay. The A1 contact should close.
op
Lower I
to (50G / 0.7) – 0.5 = [________] amps rms; the A1 contact should open.
op
5. Reduce I
to zero.
op
6. Change the setting of 50G_DIRCNL back to YES to restore directional control, if required.
GE Power Management
6.4.1 T9 – PHASE INSTANTANEOUS OVERCURRENT 50
– I
) or ( I
– I
)
C
C
A
)) = 2 I
. Therefore 50 will pick up when I
op
op
6.4.2 T10 – GROUND INSTANTANEOUS OVERCURRENT 50G
×
I
(eq. 6–12)
1
is the positive-sequence current.
1
, is single-phase, I
and I
op
0
and
I1 = I
= 0.7 I
(eq. 6–15)
op
op
= 50G / 0.7.
op
LPS-D Line Protection System
6.4 BACKUP PROTECTION TESTS
(eq. 6–11)
, is connected to one phase and
op
= 0.5 x 50
op
are given by
1
/ 3
(eq. 6–14)
op
6
6-
9
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