GE LPS-O - T7: Ground Instantaneous Overcurrent Test

GE Power Management LPS-O Line Protection System 6-
5
6 FUNCTIONAL TESTS (USER SETTINGS) 6.2 MEASURING UNIT TESTS
6
3. Set the relay into test mode 27 (Phase Overcurrent). The LUI should display
INST PHS OVRC ON
4. Set
I
op
to 0.55 x
50PICKUP
= [________] A rms and apply to the relay. The A1 contact should close.
Lower
I
op
to 0.45 x
50PICKUP
= [________] A rms, at which point the A1 contact should open.
5. Reduce
I
op
to 0 A.
6.2.7 T7 – GROUND INSTANTANEOUS OVERCURRENT TEST
1. Protection settings:
OVERCURRNT
(605)
50G
= YES
(606)
50G_DIRCNL
= NO
(607)
50GPICKUP
= [________] Amps
(610)
51G
= NO
LINEPICKUP
(801)
LINEPICKUP
= NO
The
50G
function is given by:
50G
= 3
I
0
+ 0.9 I
1
(eq. 6–1)
where
I
0
is the zero-sequence current and I
1
is the positive-sequence current. Since the test current I
op
is
single phase,
I
0
and I
1
are given by:
Substituting Equations 6–2 and 6–3 into Equation 6–1 yields:
50G
=
I
op
– 0.3 I
op
= 0.7 I
op
(eq. 6–4)
Therefore,
I
PT
will pick up when:
2. Connect the relay as shown in Figure 4–3: PHASE TO GROUND TEST CONNECTIONS on page 4–16.
3. Set the relay into test mode 28 (Ground Overcurrent). The LUI displays
INST GND OVRC ON
4. Set
I
op
to (50GPICKUP / 0.7) + 0.5 = [________] A rms and apply to the relay. The A1 contact should
close. Lower
I
op
to (50GPICKUP / 0.7) – 0.5 = [________] A rms, at which point the A1 contact should
open.
5. Reduce
I
op
to 0 A.
I
0
I
op
3
-------
=
(eq. 6–2) and
I
1
I
op
3
-------
(eq. 6–3)
=
I
PT
50GPICKUP
0.7
---------------------------------
≥