GE MM3, Instruction Manual, Page: 96 / 230

5–16 MM3 MOTOR MANAGER 3 – INSTRUCTION MANUAL
S2 PROTECTION CHAPTER 5: SETPOINTS
5.3.2 Motor
Protection:
Ground Fault
PATH: S2 PROTECTION ÖØ MOTOR PROTECTION GROUND FAULT
Care must be taken when enabling the ground fault trip feature. If the interrupting device
(contactor or circuit breaker) is not rated to break ground fault current (low resistance or
solidly grounded systems), the feature should be disabled. Alternately, the feature may be
assigned to an auxiliary relay and connected such that it trips an upstream device capable
of breaking the fault current. Be aware that the MM3 Motor Manager 3 will energize the
auxiliary relay and de-energize contactor A at the same time when the ground fault trip
occurs. Unless a contactor trip delay setting has been chosen (see
Auxiliary Relay
Configuration on page 5–32 for details).
The motor protection (ground fault) settings are programmed as follows:
• GROUND FAULT ALARM LEVEL : Set the
GROUND FAULT ALARM LEVEL
to some
arbitrary amount below the GROUND FAULT TRIP LEVEL to get an early warning of
insulation breakdown. For maximum sensitivity, the value selected should be just high
enough to prevent nuisance alarms. If the “RESIDUAL” value is selected, the level is
calculated as a percentage of the
FULL LOAD CURRENT
setting (see ranges above).
• GROUND ALARM DELAY ON RUN : This delay is used when the motor is in a running
condition. If the ground current is equal to or above the GROUND PRIMARY ALARM
PICKUP
setpoint value and remains this way for the time delay programmed in this
setpoint while the motor is running, the alarm relay will activate and the “GROUND
ALARM” message will be displayed. Refer to
Load Protection on page 5–19 for details
on how the MM3 Motor Manager 3 detects a start condition.
When the phase current increases from 0 A, the GROUND ALARM DELAY ON START
setpoint described below is used until the MM3 Motor Manager 3 determines whether
the motor is running or starting.
• GROUND ALARM DELAY ON START : This delay is used when the motor is in a
STARTING condition. If the ground current is equal to or above the
GROUND PRIMARY
ALARM PICKUP setpoint value and remains this way for the time delay programmed in
this setpoint while the motor is starting, the alarm relay will activate and the “GROUND
ALARM” message will be displayed. Refer to
Load Protection on page 5–19 for details
on how the MM3 Motor Manager 3 detects a start condition
When the phase current increases from 0 A, this delay is used until the MM3 Motor
Manager 3
determines whether the motor is running or starting.
] MOTOR PROTECTION
] GROUND FAULT GROUND FAULT ALARM
LEVEL:
OFF A
Range: 0.1 to 15.0 A or Off in steps of
0.1 A (see below) or 10 to 100%
FLC or Off in steps of 1
GROUND ALARM
DELAY ON RUN: 10 s Range: 1 to 60 s in steps of 1
GROUND ALARM:
DELAY ON START: 10 s Range: 1 to 60 s in steps of 1
GROUND FAULT TRIP
LEVEL:
OFF A
Range: 0.1 to 15.0 A or Off in steps of
0.1 A (see below) or 10 to 100%
FLC or Off in steps of 1
GROUND TRIP
DELAY ON RUN: 1.0 s Range: 0.0 to 5.0 s in steps of 0.1
GROUND TRIP
DELAY ON START: 1.0s Range: 0.0 to 10.0 s in steps of 0.1
NOTE
NOTE
NOTE