GE MM3 Instruction Manual page 42

4.3 S2 PROTECTION
GROUND FAULT TRIP
MESSAGE
LEVEL: OFF %FLC
GROUND FAULT TRIP
MESSAGE
LEVEL: OFF A
4
GROUND FAULT TRIP
MESSAGE
DELAY ON RUN: 1.0 s
GROUND FAULT TRIP
MESSAGE
DELAY ON START: 1.0s
4-12
Range: 10 to 100% FLC or OFF; Step: 1% FLC
This message will appear if the GROUND FAULT CT INPUT is set to RESIDUAL.
Some leakage current will always flow between the 3 phases and ground
due to capacitance, insulation, resistance, etc. On resistance limited
ground systems, the value selected must be below the maximum
resistance limited current that can flow or a trip will never occur. If no
optimum value is known, monitor actual leakage current then enter a
OR current somewhat above this value. Ground Fault Trips at a later time
would indicate a deterioration in the system and insulation integrity
should be verified. Persistent, high values of leakage current pose a
threat to personnel and equipment and should not be left unchecked. If
the RESIDUAL value is selected, the level is calculated as a percentage of
the Full Load Current setting. Settings below 1 A are not recommended.
Range: 0.1 to 15.0 A or OFF; Step: 0.1 A
This message will appear if the Ground Fault CT Input is set to 50:0.025
CBCT. See description for GROUND FAULT TRIP LEVEL (%FLC) for details.
Range: 0.0 to 5.0 seconds; Step: 0.1 second
This delay is used when the motor is in a RUNNING condition. If the
ground current is equal to or above the GROUND PRIMARY TRIP PICKUP
setpoint value and remains this way for the time delay programmed in
this setpoint while the motor is running, the assigned relay(s) will activate
and the CAUSE OF TRIP: GROUND FAULT message will be displayed.
When the phase current increases from 0 A, the GROUND
TRIP DELAY ON START setpoint described below is used until
the MM3 determines whether the motor is RUNNING or
NOTE
STARTING.
Refer to the ACCELERATION TIME setpoint in Section 4.3.5: LOAD
PROTECTION for details on how the MM3 detects a start condition.
Range: 0.0 to 10.0 seconds; Step: 0.1 second
This delay is used when the motor is in a STARTING condition. If the
ground current is equal to or above the GROUND PRIMARY TRIP PICKUP
setpoint value and remains this way for the time delay programmed in
this setpoint while the motor is starting, the assigned relay(s) will activate
and the CAUSE OF TRIP: GROUND FAULT message will be displayed.
When the phase current increases from 0, this delay is
used until the MM3 determines whether the motor is RUN-
NING or STARTING.
NOTE
Refer to the ACCELERATION TIME setpoint in Section 4.3.5: LOAD
PROTECTION for details on how the MM3 detects a start condition.
MM3 Motor Manager 3
4 SETPOINTS
GE Power Management