Vt Fuse Failure - GE 489 Instruction Manual

4 SETPOINTS
PATH: SETPOINTS S10 MONITORING

VT FUSE FAILURE

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A fuse failure is detected when there are significant levels of negative sequence voltage without corresponding levels of
negative sequence current measured at the output CTs. Also, if the generator is online and there is not significant positive
sequence voltage, it could indicate that all VT fuses have been pulled or the VTs are racked out. If the alarm is enabled and
a VT fuse failure detected, elements that could nuisance operation are blocked and an alarm occurs. These blocked ele-
ments include voltage restraint for the phase overcurrent, undervoltage, phase reversal, and all power elements.
I / I < 20%
2 1
V / V > 25%
2 1
I > 0.075 x CT
1
V > 0.05 x Full Scale
1
Breaker Status = Online
×
V < 0.05 Full Scale
1
GE Multilin
VT FUSE FAILURE
ð
VT FUSE FAILURE
ENTER
ð
ESCAPE ALARM: Off
ASSIGN ALARM
ESCAPE
RELAYS (2-5): ---5
MESSAGE
VT FUSE FAILURE
ESCAPE
ALARM EVENTS: Off
MESSAGE
AND
AND
Figure 4–20: VT FUSE FAILURE LOGIC
489 Generator Management Relay
Range: Off, Latched, Unlatched
Range: Any combination of Relays 2 to 5
Range: On, Off
99ms
0
OR
99ms
0
4.11 S10 MONITORING
4.11.4 VT FUSE FAILURE
Block
Appropriate
Elements
&
Operate
Alarm
Relay
4-71
4