Power Fail Test - GE Multilin MM3 Motor Manager 3 Instruction Manual

FUNCTIONAL TESTS
7.2.6

Power Fail Test

7–6
With the thermistor resistance initially set to zero, begin increasing resistance until a
thermistor trip occurs. Note that the Tripped and Stopped LEDs are lit, the contactor A
relay has de-energized, the Running LED is off, and a
displayed. Use an ohmmeter to verify that the thermistor resistance value agrees with the
setpoint value. Decrease the thermistor resistance below the
THERMISTOR HOT
value but not below the
THERMISTOR HOT
and verify that the MM3 Motor Manager 3 still indicates a trip. Reduce thermistor
resistance below the
THERMISTOR COLD
Tripped LED turns off and the default display message returns. Issue a Start A command
via the keypad or switch input and note that contactor A contacts now close and the
Running LED is lit.
To test the power fail circuit, connect the supply voltage to the MM3 Motor Manager 3
through a variac and begin decreasing control voltage. When the control voltage drops
below 80 V for 120 V AC input or 150 V for 240 V AC input, the fault light comes on and the
MM3 Motor Manager 3 ceases to operate. The MM3 Motor Manager 3 has insufficient
voltage to continue accurately monitoring the motor. All output relays will change to their
power off state. Decrease control voltage to zero and then return voltage to its normal
operating level. Verify that the MM3 Motor Manager 3 resumes its normal operation. Check
the power fail memory circuit by verifying that setpoints and statistical data have not been
altered.
THERMISTOR TRIP
value. Press the RESET key
THERMISTOR COLD
value. Press the RESET key again, noting that the
MM3 MOTOR MANAGER 3 – INSTRUCTION MANUAL
CHAPTER 7: TESTING
message is