GE Power Management
MM2 Motor Manager 2 7-5
7 TESTING 7.2 FUNCTIONAL TESTS
7
7.2.3 GROUND FAULT CURRENT FUNCTIONS
Test the Ground Fault CT (Residual / 50:0.025) in a similar manner to phase currents for accuracy at
various injected current levels. To check alarm and trip levels, make the following settings:
S1 CONFIGURATION \ CT/VT INPUTS \ GROUND FAULT CT INPUT: Residual
S2 PROTECTION \ MOTOR PROTECTION GROUND FAULT \ GROUND FAULT ALARM LEVEL = 40 %FLC
S2 PROTECTION \ MOTOR PROTECTION GROUND FAULT \ GROUND FAULT TRIP LEVEL = 80 %FLC
S2 PROTECTION \ MOTOR PROTECTION THERMAL\ FULL LOAD CURRENT = 100 A
While displaying A1 DATA \ MOTOR DATA \ GROUND CURRENT, begin injecting current into the 5 A Ground
Fault CT input. The Alarm LED lights and the AUX Relay 1 change state at 40 A corresponding to the
40% FLC alarm setting. Change the display back to GROUND CURRENT and continue increasing
injected secondary current. When the measured Ground Current reaches 80 A, a Ground Fault Trip
occurs. This trip causes the MM2 to change its indicators and output relay status. The Running LED
turns off, the Tripped and Stopped LEDs turn on, and the Contactor A relay de-energizes. The AUX
Relay 1 remains energized as long as the alarm is present and AUX Relay 2 energizes after the
ground fault trip. The MM2 displays a Ground Fault Trip message. Turn the Ground Fault current off
and press the reset key to reset the trip.
7.2.4 INPUT FUNCTIONS
Operation of each MM2 switch input can be verified on the display. Go to A3 INPUTS \ INPUT CONTACT
STATUS and using the MESSAGE LEFT/RIGHT keys, view the status of each input one at a time.
Open and close each switch input and note that the display reflects the present status of the input
terminals. The status is shown as either OPEN or CLOSED.
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