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Fault tracing
What this chapter contains
This chapter gives the troubleshooting information.
Troubleshooting hints
Trouble
Unit operates illogically
despite all connections and
parameters are correct.
BUF OUT signal from
RSYC board is constantly
low i.e.0 ... 1 V DC.
Drive output frequency
remains too close to 50 Hz
and occasional short
synchronization pulses
take place.
The speed control is
unstable.
Excessive motor current
peak at synchronization.
Cause
The board is affected by radiated
interference. BUF OUT signal is not
stable and as a consequence
synchronization is not possible.
Signals from synchronizing
transformers are cross-connected at
the RSYC unit.
Too small value for parameter 40.17
TRIM RANGE ADJUST. Drive
cannot control the speed (and output
frequency) loosely enough.
Too large value for parameter 40.17
TRIM RANGE ADJUST causes the
control to overcompensate.
Rotor decelerates too fast and
phase difference between stator and
motor fluxes increase too much.
Motor flux decreases too much
during the operation of change-over
contactors. High current is needed to
remagnetize the motor.
Supply line (motor) and drive output
are 180º out of phase due to wrong
connection of the synchronization
transformer.
Supply line and drive output are 180º
out of phase since the phasing
between motor and supply line
differs from the phasing between
motor and drive output.
Remedy
Ensure all cables that connect to the RSYC unit
are shielded and shields are properly grounded.
Install an additional metal shield between the
emission source and the unit.
Change location of the unit, i.e. arrange more
space between the emission source (drive module
or motor cables) unit.
Check and correct connections.
Increase the value of parameter 40.17.
Decrease the value of parameter 40.17.
Make contactors operate faster if possible.
Contactors can operate simultaneously.
Connect a serial inductor (3 phase choke) to the
motor AC input during switching of change-over
contactors. Equip the choke with a by-pass
contactor (the choke does not need to be
dimensioned according to continuous current, only
the contactor). The choke must not saturate
through. See Connection diagram on page 11.
Check and correct the transformer connection.
Check and correct the transformer connection.
Check and change the connections.
21
Fault tracing
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