Underfrequency - GE Multilin 489 Instruction Manual

CHAPTER 5: SETPOINTS
5.7.5

Underfrequency

1 UNDERFREQUENCY
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
and the phase rotation is not the same as the setpoint. Loss of VT fuses cannot be
detected when the generator is offline and could lead to maloperation of this element. If
the VT type is selected as "None", the phase reversal protection is disabled.
PATH: SETPOINTS S6 VOLTAGE ELEM.
[ ] BLOCK UNDERFREQUENCY
FROM ONLINE: 1 s
VOLTAGE LEVEL
MESSAGE
CUTOFF: 0.50 x Rated
UNDERFREQUENCY
MESSAGE
ALARM: Off
ASSIGN ALARM
MESSAGE
RELAYS (2-5): ---5
UNDERFREQUENCY
MESSAGE
ALARM LEVEL: 59.50 Hz
UNDERFREQUENCY
MESSAGE
ALARM DELAY: 5.0 s
UNDERFREQUENCY
MESSAGE
ALARM EVENTS: Off
UNDERFREQUENCY
MESSAGE
TRIP: Off
ASSIGN TRIP
MESSAGE
RELAYS (1-4): 1---
UNDERFREQUENCY
MESSAGE
TRIP LEVEL1: 59.50 Hz
UNDERFREQUENCY
MESSAGE
TRIP DELAY1: 60.0 s
UNDERFREQUENCY
MESSAGE
TRIP LEVEL2: 58.00 Hz
UNDERFREQUENCY
MESSAGE
TRIP DELAY2: 30.0 s
It may be undesirable to enable the underfrequency elements until the generator is online.
This feature can be blocked until the generator is online and the block time expires. From
that point forward, the underfrequency trip and alarm elements will be active. A value of
zero for the block time indicates that the underfrequency protection is active as soon as
voltage exceeds the cutoff level (programmed as a multiple of the generator rated phase-
phase voltage). Frequency is then measured. Once the frequency of Vab is less than the
underfrequency setpoints, for the period of time specified, a trip or alarm will occur. There
are dual level and time setpoints for the trip element.
UNDERFREQUENCY
Range: 0 to 5 s in steps of 1
Range: 0.50 to 0.99 × Rated in steps of
0.01
Range: Off, Latched, Unlatched
Range: Any combination of Relays 2 to
5
Range: 20.00 to 60.00 Hz in steps of
0.01
Range: 0.1 to 5000.0 s in steps of 0.1
Range: On, Off
Range: Off, Latched, Unlatched
Range: Any combination of Relays 1 to
4
Range: 20.00 to 60.00 Hz in steps of
0.01
Range: 0.1 to 5000.0 s in steps of 0.1
Range: 20.00 to 60.00 Hz in steps of
0.01
Range: 0.1 to 5000.0 s in steps of 0.1
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