GE 469

CHAPTER 5: SETTINGS
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL 5–31
These settings apply only if the INPUT 1(4) FUNCTION is “Tachometer”.
Once the tachometer is chosen for a digital input, the settings shown here follow the
assignment message. The period of time between each switch closure is measured and
converted to an RPM value based on one closure per revolution.
A trip and alarm may be configured such that the motor or load must be at a certain speed
within a set period of time from the motor starting. The tachometer trip and alarm features
are configured such that the specified speed (
TACHOMETER TRIP SPEED or TACHOMETER
ALARM SPEED) must be reached in the specified time (TACHOMETER TRIP DELAY or
TACHOMETER ALARM DELAY), otherwise the element operates. Initially, the time delay
begins when the motor is started and resets when the desired speed is reached. Once the
motor is running and the speed drops below the set threshold, the time delay restarts and
the designated output contact will operate if the motor fails to reach the set speed in the
allotted time. This element is active when motor is running and ignored while the motor is
stopped. The RPM value may be viewed with the
A2 METERING ZV SPEED Z TACHOMETER
actual value.
For example, an inductive proximity probe or hall effect gear tooth sensor may be used to
sense the key on the motor. The probe could be powered from the +24 V from the input
switch power supply. The NPN transistor output could be taken to one of the assignable
switch inputs configured as a tachometer.
MESSAGE
TACHOMETER
ALARM: Off
Range: Off, Latched, Unlatched
MESSAGE
ASSIGN ALARM
RELAYS:
Range: Alarm, Alarm & Auxiliary2,
Alarm & Aux2 & Aux3, Alarm &
Auxiliary3, Auxiliary2, Aux2 &
Aux3, Auxiliary3
MESSAGE
TACHOMETER ALARM
SPEED: 10% Rated
Range: 5 to 100% in steps of 1
MESSAGE
TACHOMETER ALARM
DELAY: 1 s
Range: 1 to 250 s in steps of 1
MESSAGE
TACHOMETER ALARM
EVENTS: Off
Range: On, Off
MESSAGE
TACHOMETER
TRIP: Off
Range: Off, Latched, Unlatched
MESSAGE
ASSIGN TRIP
RELAYS:
Range: Trip, Trip & Auxiliary2, Trip &
Aux2 & Aux3, Trip & Auxiliary3
MESSAGE
TACHOMETER TRIP
SPEED: 10% Rated
Range: 5 to 95% in steps of 1
MESSAGE
TACHOMETER TRIP
DELAY: 1 s
Range: 1 to 250 s in steps of 1