Reverse Power - GE 489 Instruction Manual

4 SETPOINTS
PATH: SETPOINTS S7 POWER ELEMENTS

REVERSE POWER

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If enabled, once the magnitude of 3-phase total power exceeds the Pickup Level in the reverse direction (negative MW) for
a period of time specified by the Delay, a trip or alarm will occur. The level is programmed in per unit of generator rated MW
calculated from the rated MVA and rated power factor. If the generator is accelerated from the power system rather than the
prime mover, the reverse power element may be blocked from start for a specified period of time. A value of zero for the
block time indicates that the reverse power protection is active as soon as both current and voltage are measured regard-
less of whether the generator is online or offline. If the VT type is selected as "None" or VT fuse loss is detected, the
reverse power protection is disabled.
The minimum magnitude of power measurement is determined by the phase CT minimum of 2% rated CT primary.
If the level for reverse power is set below that level, a trip or alarm will only occur once the phase current exceeds
NOTE the 2% cutoff.
Users are cautioned that a reverse power element may not provide reliable indication when set to a very low setting, partic-
ularly under conditions of large reactive loading on the generator. Under such conditions, low forward power is a more reli-
able element.
GE Multilin
REVERSE POWER
ð
BLOCK REVERSE POWER
ENTER
ð
ESCAPE FROM ONLINE: 1 s
REVERSE POWER
ESCAPE
ALARM: Off
MESSAGE
ASSIGN ALARM
ESCAPE
RELAYS (2-5): ---5
MESSAGE
REVERSE POWER ALARM
ESCAPE
LEVEL: 0.05 x Rated MW
MESSAGE
REVERSE POWER ALARM
ESCAPE
DELAY: 10.0 s
MESSAGE
REVERSE POWER ALARM
ESCAPE
EVENTS: Off
MESSAGE
REVERSE POWER
ESCAPE
TRIP: Off
MESSAGE
ASSIGN TRIP
ESCAPE
RELAYS (1-4): 1---
MESSAGE
REVERSE POWER TRIP
ESCAPE
LEVEL: 0.05 x Rated MW
MESSAGE
REVERSE POWER TRIP
ESCAPE
DELAY: 20.0 s
MESSAGE
489 Generator Management Relay
4.8 S7 POWER ELEMENTS
4.8.3 REVERSE POWER
Range: 0 to 5000 s in steps of 1
Range: Off, Latched, Unlatched
Range: Any combination of Relays 2 to 5
Range: 0.02 to 0.99 × Rated MW in steps of 0.01
Range: 0.2 to 120.0 s in steps of 0.1
Range: On, Off
Range: Off, Latched, Unlatched
Range: Any combination of Relays 1 to 4
Range: 0.02 to 0.99 × Rated MW in steps of 0.01
Range: 0.2 to 120.0 s in steps of 0.1
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