Field-Breaker Discrepancy; Tachometer - GE 489 Instruction Manual

4.4 S3 DIGITAL INPUTS
T
FIELD-BKR DISCREP.
T
[ENTER] for more
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
T

TACHOMETER

T
[ENTER] for more
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
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.
4-14
ð
ASSIGN DIGITAL
ENTER
INPUT: None
ESCAPE
FIELD STATUS
ESCAPE
CONTACT: Auxiliary a
MESSAGE
ASSIGN TRIP
ESCAPE
RELAYS (1-4): 1---
MESSAGE
FIELD-BKR DISCREP.
ESCAPE
TRIP DELAY: 1.0 s
MESSAGE
ð
ASSIGN DIGITAL
ENTER
INPUT: None
ESCAPE
RATED SPEED:
ESCAPE
3600 RPM
MESSAGE
TACHOMETER
ESCAPE
ALARM: Off
MESSAGE
ASSIGN ALARM
ESCAPE
RELAYS (2-5): ---5
MESSAGE
TACHOMETER ALARM
ESCAPE
SPEED: 110% Rated
MESSAGE
TACHOMETER ALARM
ESCAPE
DELAY: 1 s
MESSAGE
TACHOMETER ALARM
ESCAPE
EVENTS: Off
MESSAGE
TACHOMETER
ESCAPE
TRIP: Off
MESSAGE
ASSIGN TRIP
ESCAPE
RELAYS (1-4): 1---
MESSAGE
TACHOMETER TRIP
ESCAPE
SPEED: 110% Rated
MESSAGE
TACHOMETER TRIP
ESCAPE
DELAY: 1 s
MESSAGE
A2 METERING DATA / SPEED / TACHOMETER
489 Generator Management Relay
4 SETPOINT PROGRAMMING

4.4.10 FIELD-BREAKER DISCREPANCY

Range: None, Input 1 to Input 7. If an input is assigned to
the Tachometer function, it may not be used here.
Range: Auxiliary a, Auxiliary b
Range: Any combination of Relays 1 to 4
Range: 0.1 to 500.0 s in steps of 0.1
4.4.11 TACHOMETER
Range: None, Inputs 4 to 7. Only Digital Inputs 4 to 7 may
be assigned to the Tachometer
Range: 100 to 3600 RPM in steps of 1
Range: Off, Latched, Unlatched
Range: Any combination of Relays 2 to 5
Range: 101 to 175% in steps of 1
Range: 1 to 250 s in steps of 1
Range: On, Off
Range: Off, Latched, Unlatched
Range: Any combination of Relays 1 to 4
Range: 101 to 175% in steps of 1
Range: 1 to 250 s in steps of 1
GE Power Management
actual value.