Fault display Type Enable Potential causes and corrective actions
Failed to magnetize F/A SOP Cause
This occurs only with induction motors due to high magnetizing current or
poor power factor. The trip occurs when I
ds
or magnetizing current is
greater than the magnetizing threshold of the rated current for a duration
more than ve times the ux ramp rate parameter setting.
Note: This threshold is set by parameter set by the "Mag current thresh"
(1061) and is nominally set to 80% for most induction motors. For motors
with higher pole count of with lower power factor (less ecient) this
number may be much higher (was set to 95% for motors with 10 poles or
higher).
With induction motors, this trip normally occurs only when starting, either
due to incorrect settings for Stator resistance (1080) and Cable resistance
(2940), i.e. settings that are higher than actual value, or due to the incor‐
rect setup of the spinning load. Once the motor is magnetized and run‐
ning, such an event is unlikely to occur.
Note: During high starting torque mode, the trip time used is the ux ramp
rate.
Action
1. Increase the ux ramp time to give more time for magnetizing current
to settle down at startup.
2. Verify if parameter Stator resistance (1080) is set too high for the
application; reduce it if continuous operation at very low speed is not
desired. Check that spinning load is set correctly.
Back EMF timeout F Fixed The software timed out waiting for the motor back EMF voltage to decay
to a safe level for bypass or turn-on (drive enable). The safe voltage is the
amount of voltage that the drive can support. The back EMF is the motor
voltage when the drive is not active. If an induction machine has a long
time constant, or if a synchronous machine has not disabled its eld, and
in either case the machine is spinning, the timeout threshold will cause a
fault. This is also possible for parallel drives connected to a single motor.
Troubleshooting Faults and Alarms
11.5 Drive Faults and Alarms Motor/Output Related
NXGPro+ Control Manual
Operating Manual, A5E50491925A 453
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