GE 489 Instruction Manual page 104

4.11 S10 MONITORING
If 52 Open/Closed is selected, the trip coil supervision circuitry monitors the trip coil circuit for continuity at all times regard-
less of breaker state. This requires an alternate path around the 52a contacts in series with the trip coil when the breaker is
open. See the figure below for modifications to the wiring and proper resistor selection. If that continuity is broken, a Starter
Failure alarm will indicate Trip Coil Supervision.
E11
TRIP COIL
SUPERVISION
F11
E2
R1 TRIP
CONTACT
F1
TRIP COIL CLOSED SUPERVISION
"52 Closed"
4
T
VT FUSE FAILURE
T
[ENTER] for more
A fuse failure is detected when there are significant levels of negative sequence voltage without correspondingly significant
levels of negative sequence current measured at the output CTs. Also, if the generator is online and there is not a signifi-
cant amount of positive sequence voltage, it could indicate that all the VT fuses have been pulled or the VTs have been
racked out. If the alarm is enabled and a VT fuse failure has been detected elements that could nuisance operate will be
blocked and an alarm will occur. Those elements that will be blocked include voltage restraint for the phase overcurrent,
undervoltage, phase reversal, and all power elements.
V > 0.05 x Full Scale
1
Breaker Status = Online
V < 0.05
1
4-66
TRIP COIL
SUPERVISION
R1 TRIP
CONTACT
52a
TRIP COIL
OPEN/CLOSED
SUPERVISION
TRIP
"52 Open/Closed"
COIL
WITH MULTIPLE
BREAKER AUX
CONTACTS
Figure 4–19: TRIP COIL SUPERVISION
ð
VT FUSE FAILURE
ENTER
ALARM: Off
ESCAPE
ASSIGN ALARM
ESCAPE
RELAYS (2-5): ---5
MESSAGE
VT FUSE FAILURE
ESCAPE
ALARM EVENTS: Off
MESSAGE
I / I < 20%
2 1
V / V > 25%
2 1
I > 0.075 x CT AND
1
AND
×
Full Scale
Figure 4–20: VT FUSE FAILURE
489 Generator Management Relay
E11
TRIP COIL
SUPERVISION
F11
E2
R1 TRIP
CONTACT
F1
52a
TRIP
COIL
52a TRIP COIL OPEN/CLOSED SUPERVISION
Range: Off, Latched, Unlatched
Range: Any combination of Relays 2 to 5
Range: On, Off
99ms
0
OR
99ms
0
4 SETPOINT PROGRAMMING
E11
F11
E2
F1
52a
TRIP
COIL
"52 Open/Closed"
VALUE OF RESISTOR 'R'
SUPPLY
OHMS WATTS
48 VDC
10 K 2
125 VDC 25 K 5
250 VDC
50 K 5
4.11.4 VT FUSE FAILURE
Block
Appropriate
Elements
&
Operate
Alarm
Relay
GE Power Management