GE 489 - Manual (Page 69)

GE Multilin 489 Generator Management Relay 4-19
4 SETPOINTS 4.4 S3 DIGITAL INPUTS
4
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 ÖØ SPEED ÖØ 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.
4.4.11 WAVEFORM CAPTURE
PATH: SETPOINTS ÖØ S3 DIGITAL INPUTS ÖØ WAVEFORM CAPTURE
This feature may be used to trigger the waveform capture from an external contact. When one of the inputs is assigned to
the Waveform Capture function, shorting that input will trigger the waveform.
4.4.12 GROUND SWITCH STATUS
PATH: SETPOINTS ÖØ S3 DIGITAL INPUTS ÖØ GND SWITCH STATUS
This function is used to detect the status of a grounding switch for the generator for which the relay is installed. Refer to
Appendix B for Application Notes.
„ WAVEFORM CAPTURE
„ [ENTER] for more
ASSIGN DIGITAL
INPUT: None
Range: None, Input 1 to Input 7. If an input is assigned to
the Tachometer, it may not be used here.
„ GND SWITCH STATUS
„ [ENTER] for more
ASSIGN DIGITAL
INPUT: None
Range: None, Input 1 to Input 7. If an input is assigned to
the Tachometer, it may not be used here.
GROUND SWITCH
CONTACT: Auxiliary a
Range: Auxiliary a, Auxiliary b
ENTER
ESCAPE
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ENTER
ESCAPE
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MESSAGE
ESCAPE