GE 489 - Manual (Page 97)

GE Multilin 489 Generator Management Relay 4-47
4 SETPOINTS 4.8 S7 POWER ELEMENTS
4
4.8.3 REVERSE POWER
PATH: SETPOINTS ÖØ S7 POWER ELEMENTS ÖØ REVERSE POWER
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
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.
„ REVERSE POWER
„ [ENTER] for more
BLOCK REVERSE POWER
FROM ONLINE: 1 s
Range: 0 to 5000 s in steps of 1
REVERSE POWER
ALARM: Off
Range: Off, Latched, Unlatched
ASSIGN ALARM
RELAYS (2-5): ---5
Range: Any combination of Relays 2 to 5
REVERSE POWER ALARM
LEVEL: 0.05 x Rated MW
Range: 0.02 to 0.99 × Rated MW in steps of 0.01
REVERSE POWER ALARM
DELAY: 10.0 s
Range: 0.2 to 120.0 s in steps of 0.1
REVERSE POWER ALARM
EVENTS: Off
Range: On, Off
REVERSE POWER
TRIP: Off
Range: Off, Latched, Unlatched
ASSIGN TRIP
RELAYS (1-4): 1---
Range: Any combination of Relays 1 to 4
REVERSE POWER TRIP
LEVEL: 0.05 x Rated MW
Range: 0.02 to 0.99 × Rated MW in steps of 0.01
REVERSE POWER TRIP
DELAY: 20.0 s
Range: 0.2 to 120.0 s in steps of 0.1
ENTER
ESCAPE
р
р
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
MESSAGE
ESCAPE
NOTE