GE 750 User Manual

GE Power Management 750/760 Feeder Management Relay 17-
41
17 COMMISSIONING 17.7 PROTECTION SCHEMES
17
17.7.28 FREQUENCY DECAY
Test Connections per Figure 17–1: RELAY TEST WIRING – WYE CONNECTION or Figure 17–2: RELAY
TEST WIRING – DELTA CONNECTION on page 17–4.
Procedure To Check:
Minimum Operating Voltage Supervision:
1. Inject voltage into the
V
a
bus voltage input at a level well below the Minimum Operating Voltage level. Also
inject
I
a
= I
b
= I
c
at a level well above the Minimum Operating Current level. Starting with the V
a
frequency
at a level well below the Frequency Decay Pickup, drop the frequency of
V
a
at a speed greater than the
FREQUENCY DECAY RATE
setting. The pickup indicator should remain off.
2. Inject voltage into the
V
a
bus voltage input at a level well above the Minimum Operating Voltage level. Also
inject
I
a
= I
b
= I
c
at a level well above the Minimum Operating Current level. Starting with the V
a
frequency
at a level well below the Frequency Decay Pickup, drop the frequency of
V
a
at a speed greater than the
FREQUENCY DECAY RATE
setting. The pickup indicator should come on while the V
a
frequency is dropping.
Minimum Operating Current Supervision:
1. Inject voltage into the
V
a
bus voltage input at a level well above the Minimum Operating Voltage level. Also
inject
I
a
= I
b
= I
c
at a level well below the Minimum Operating Current level. Starting with the V
a
frequency
at a level well below the Frequency Decay Pickup, drop the frequency of
V
a
at a speed greater than the
FREQUENCY DECAY RATE
setting. The pickup indicator should remain off.
2. With the
V
a
voltage at a level well above the Minimum Operating Voltage level, increase I
a
to a level well
above the Minimum Operating Current level. Currents
I
b
and I
c
should be well below the Minimum Operat-
ing Current level. Starting with the
V
a
frequency at a level well below the Frequency Decay Pickup, drop
the frequency of
V
a
at a speed greater than the
FREQUENCY DECAY RATE
setting. The pickup indicator
should come on while the
V
a
frequency is dropping.
3. With the
V
a
voltage at a level well above the Minimum Operating Voltage level, increase I
b
to a level well
above the Minimum Operating Current level. Currents
I
a
and I
c
should be well below the Minimum Operat-
ing Current level. Starting with the
V
a
frequency at a level well below the Frequency Decay Pickup, drop
the frequency of
V
a
at a speed greater than the
FREQUENCY DECAY RATE
setting. The pickup indicator
should come on while the
V
a
frequency is dropping.
4. With the
V
a
voltage at a level well above the Minimum Operating Voltage level, increase I
c
to a level well
above the Minimum Operating Current level. Currents
I
a
and I
b
should be well below the Minimum Operat-
ing Current level. Starting with the
V
a
frequency at a level well below the Frequency Decay Pickup, drop
the frequency of
V
a
at a speed greater than the
FREQUENCY DECAY RATE
setting. The pickup indicator
should come on while the
V
a
frequency is dropping.
For all procedures following, the injected voltage and currents are always above the minimum
operating levels.
Pickup:
1. Starting with the
V
a
frequency at a level well above the Frequency Decay Pickup, drop the frequency of V
a
at a speed greater than the Frequency Decay Rate setting, to a level still well above the Frequency Decay
Pickup. The pickup indicator should remain off.
2. Continue dropping the
V
a
frequency at a speed greater than the Frequency Decay Rate. When the fre-
quency drops below the Frequency Decay Pickup the PICKUP indicator will come on.
NOTE

GE 750 Specifications

General

Brand	GE
Model	750
Category	Relays
Language	English