Undercurrent Protection; Earth-Fault Protection - ABB REM 610 Technical Reference Manual

1MRS 752263-MUM
4.1.4.5.
4.1.4.6.
Motor protection Relay
Technical Reference Manual
Note!
If the PU scale has been set to 0.5, the maximum measured rated current (FLC) is 25
x In.
It is possible to block the tripping of the high-set overcurrent stage by applying a
digital input signal to the relay.
The high-set overcurrent stage can be set out of operation in SGF3 to prevent the
contactor in a contactor controlled drive from operating at too high phase currents.
This state will be indicated by dashes on the LCD and by "999" when the set start
value is read via serial communication.
Note!
When stage I>> starts during motor start up, no start signal will be generated.

Undercurrent protection

The non-directional undercurrent protection detects loss of load, caused by a
damaged pump or a broken conveyor, for instance, and can be used in applications
where undercurrent is considered a fault condition.
When all three phase currents fall below the set start value of stage I<, the stage will
generate a start signal after a ~ 300 ms' start time. When the set operate time elapses,
the stage will generate a trip signal. To avoid tripping a de-energized motor, stage
I< will be set out of operation when all phase currents fall below twelve per cent of
the FLC of the motor.
The undercurrent stage will be reset in 350 ms after one or several phase currents
have exceeded the set start value of the stage.
It is possible to block the tripping of the undercurrent stage by applying a digital
input signal to the relay.
Stage I< can be set out of operation in SGF3. This state will be indicated by dashes
on the LCD and by "999" when the set start value is read via serial communication.
Note!
When stage I< starts during motor start up, no start signal will be generated.

Earth-fault protection

The non-directional earth-fault current protection detects phase-to-earth currents,
caused by ageing and thermal cycling, for instance.
When the earth-fault current exceeds the set start value of stage I
generate a start signal after a ~ 50 ms' start time. When the set operate time at
definite-time characteristic elapses, the stage will generate a trip signal. The stage
can be given an instantaneous characteristic by setting the operate time to the
minimum, i.e. 0.05 s. The earth-fault stage will be reset in 50 ms after the
earth-fault current has fallen below the set start value of the stage.
It is possible to block the tripping of the earth-fault stage by applying a digital input
signal to the relay.
Stage I > can be set out of operation in SGF3. This state will be indicated by dashes
0
on the LCD and by "999" when the set start value is read via serial communication.
REM 610
>, the stage will
0
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