GE 750 - Bus Undervoltage 1 (2)

17-
34
750/760 Feeder Management Relay GE Power Management
17.7 PROTECTION SCHEMES 17 COMMISSIONING
17
17.7.23 BUS UNDERVOLTAGE 1 (2)
a) FOR WYE VTs
Test Connections per Figure 17–1: RELAY TEST WIRING – WYE CONNECTION on page 17–4.
Pickup with One Phase For Operation:
1. Inject
V
an
= V
bn
= V
cn
= nominal voltage into the bus voltage input of the relay. The PICKUP indicator
should be off.
2. Slowly lower
V
an
until the PICKUP indicator comes on. This is the pickup voltage.
3. Continue to lower
V
an
until the PICKUP indicator goes out. This is the programmed Minimum Operating
Voltage level minus 2% of VT.
4. Raise
V
an
until the PICKUP indicator comes on, and continue to increase until the indicator goes out. This
is the reset voltage, which should be the pickup value plus 2% of VT.
5. Repeat steps 1 through 4 except adjust
V
bn
and V
cn
in turn.
Pickup with Two Phases For Operation:
1. Inject
V
cn
= nominal voltage and V
an
= V
bn
= a voltage between the Minimum Operating Voltage and the
pickup voltage into the bus voltage input of the relay. The PICKUP indicator should be on.
2. Slowly raise
V
an
until the PICKUP indicator goes out. This is the reset voltage, which should be the pickup
value plus 2% of VT.
3. Reduce
V
an
until the PICKUP indicator comes on. This is the pickup voltage of V
an
.
4. Continue to lower
V
an
until the PICKUP indicator goes out. This is the programmed Minimum Operating
Voltage of
V
an
minus 2% of VT.
5. Slowly raise
V
an
until the PICKUP indicator comes on, then reduce V
bn
until the PICKUP indicator goes
out. This is the programmed Minimum Operating Voltage of V
bn
minus 2% VT.
6. Slowly raise
V
bn
until the PICKUP indicator first comes on and then goes out. This is the reset voltage,
which should be the pickup value plus 2% of VT.
7. Lower
V
bn
until the PICKUP indicator comes on. This is the pickup voltage of V
bn
.
8. Repeat steps 1 through 7, substituting
V
cn
for V
an
, V
an
for V
bn
and V
bn
for V
cn
.
9. Repeat steps 1 through 7, substituting
V
bn
for V
an
, V
cn
for V
bn
and V
an
for V
cn
.
Pickup with Three Phases For Operation:
1. Inject
V
an
= V
bn
= V
cn
= a voltage between the Minimum Operating Voltage and the pickup voltage into the
bus voltage input of the relay. The PICKUP indicator should be on.
2. Slowly raise
V
an
until the PICKUP indicator goes out. This is the reset voltage, which should be the pickup
value plus 2% of VT.
3. Reduce
V
an
until the PICKUP indicator comes on. This is the pickup voltage of V
an
.
4. Slowly raise
V
bn
until the PICKUP indicator goes out. This is the reset voltage, which should be the pickup
value plus 2% of VT.
5. Reduce
V
bn
until the PICKUP indicator comes on. This is the pickup voltage of V
bn
6. Slowly raise V
cn
until the PICKUP indicator goes out. This is the reset voltage, which should be the pickup
value plus 2% of VT.
7. Reduce
V
cn
until the PICKUP indicator comes on. This is the pickup voltage of V
cn
.