Loss Of Load Protection Loflptuc; Phase Reversal Protection Prevptoc - ABB RELION 630 Series Applications Manual

1MRS756785 G
3.2.6.5
3.2.6.6
REM630
Application Manual
GUID-658AB3F3-DFE0-4896-BA9B-BFDDCFC4905B V2 EN
Figure 10: Motor load jam protection

Loss of load protection LOFLPTUC

The loss of load protection is used for detecting sudden load loss which is considered
as a fault condition.
The set of three phase currents, I3P, is connected to the inputs and the function
operates when all the phase currents fall below the set level but stay above the set de-
energization level. It operates with definite time (DT) characteristics. The operate
signal is used to trigger the disturbance recorder.

Phase reversal protection PREVPTOC

The phase reversal protection is used for detecting the reversed connection of the
phases to a three-phase motor by monitoring the negative-phase sequence current of
the motor.
The operation of the function is based on the detection of very high negative-sequence
currents during motor start up due to incorrect phase connections to the motor. The
condition causes the motor to rotate in the reverse direction. The function starts and
Section 3
REM630 variants
33