GE 489 User Manual

4-14 489 Generator Management Relay
GE Power Management
4.4 S3 DIGITAL INPUTS 4 SETPOINT PROGRAMMING
4
4.4.10 FIELD-BREAKER DISCREPANCY
The field-breaker discrepancy function is intended for use with synchronous generators. If a digital input is assigned to this
function, any time the field status contact indicates the field is not applied and the breaker status input indicates that the
generator is online, a trip will occur once the time delay has expired. The time delay should be used to prevent possible nui-
sance tripping during shutdown. The field status contact may be chosen as "Auxiliary a", open signifying the field breaker or
contactor is open and shorted signifying the field breaker or contactor is closed. Conversely, the field status contact may be
chosen as "Auxiliary b", shorted signifying the field breaker or contactor is open and open signifying it is closed.
4.4.11 TACHOMETER
One of assignable digital inputs 4 to 7 may be assigned to the tachometer function to measure mechanical speed. The time
between each input closure is measured and converted to an RPM value based on one closure per revolution. If an over-
speed trip or alarm is enabled, and the measured RPM exceeds the threshold setpoint for the time specified by the delay, a
trip or alarm will occur. The RPM value can be viewed with the
A2 METERING DATA / SPEED / TACHOMETER
actual value.
For example, an inductive proximity probe or hall effect gear tooth sensor may be used to sense the key on the generator.
The probe could be powered from the +24V from the digital input power supply. The NPN transistor output could be taken
to one of the assignable digital inputs assigned to the tachometer function.

FIELD-BKR DISCREP.

[ENTER] for more
ASSIGN DIGITAL
INPUT: None
Range: None, Input 1 to Input 7. If an input is assigned to
the Tachometer function, it may not be used here.
FIELD STATUS
CONTACT: Auxiliary a
Range: Auxiliary a, Auxiliary b
ASSIGN TRIP
RELAYS (1-4): 1---
Range: Any combination of Relays 1 to 4
FIELD-BKR DISCREP.
TRIP DELAY: 1.0 s
Range: 0.1 to 500.0 s in steps of 0.1

TACHOMETER

[ENTER] for more
ASSIGN DIGITAL
INPUT: None
Range: None, Inputs 4 to 7. Only Digital Inputs 4 to 7 may
be assigned to the Tachometer
RATED SPEED:
3600 RPM
Range: 100 to 3600 RPM in steps of 1
TACHOMETER
ALARM: Off
Range: Off, Latched, Unlatched
ASSIGN ALARM
RELAYS (2-5): ---5
Range: Any combination of Relays 2 to 5
TACHOMETER ALARM
SPEED: 110% Rated
Range: 101 to 175% in steps of 1
TACHOMETER ALARM
DELAY: 1 s
Range: 1 to 250 s in steps of 1
TACHOMETER ALARM
EVENTS: Off
Range: On, Off
TACHOMETER
TRIP: Off
Range: Off, Latched, Unlatched
ASSIGN TRIP
RELAYS (1-4): 1---
Range: Any combination of Relays 1 to 4
TACHOMETER TRIP
SPEED: 110% Rated
Range: 101 to 175% in steps of 1
TACHOMETER TRIP
DELAY: 1 s
Range: 1 to 250 s in steps of 1
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GE 489 Specifications

General

Brand	GE
Model	489
Category	Relays
Language	English