113
Compressor Drive VFD Troubleshooting Chart
Problem
Potential Cause
Corrective Action
Earth Fault
There is current from the output
phases to ground (earth) in the
cables, or the motor.
Check the cables from the converter to the compressor.
Check for continuity from the compressor terminals to
ground. There should be no continuity.
Control Word
Timeout
There is no communication to
the frequency converter. Only
active if setting 8-04 is NOT set
to [0] OFF.
Verify wiring, and connections are correct.
Check cable connections to the converter.
Increase the Control Word Timeout time setting 8-03.
Check the communication components.
Over Current
This fault can be caused by
shock loading, or quick
acceleration with high inertia
load.
Make sure the unit is OFF. Verify the motor shaft can
be turned.
Check the motor size matches the frequency converter.
Check parameters 1-20 to 1-25 for correct setup.
Torque Limit
The torque has exceeded the
value in setting 4-16 or 4-17.
Check for excessive current draw on the motor.
If the motor torque limit is exceeded during ramp-up,
extend ramp up time.
If the generator torque limit is exceeded during ramp
down, extend ramp downtime.
If torque limit occurs while running, increase the torque
limit. Verify the system operation can operate safely at
a higher torque.
Inverter
Overload
The converter is about to cut
out because of an overload.
The thermal protection issues a
warning at 98% and an alarm at
100%. This converter cannot be
reset until the counter is at 90%.
Compare current output from LCP to the converter’s
rated current.
Compare the output shown from the LCP with
measured motor current.
Verify the drive load on the LCP. Monitor the value. The
counter will increase when running above the
continuous current rating. The counter will decrease
when running below the continuous current rating.
DC Under Volt
If the intermediate circuit
voltage drops below the under-
voltage limit, the frequency
converter checks if a
24V DC
backup supply is connected. If
no
24V DC
backup supply is
connected, the converter trips
after a fixed time delay. The
time delay varies with unit size.
Check that the supply voltage matches the frequency
converter voltage.
Perform input voltage test.
DC Over Volt
If the intermediate circuit
voltage exceeds the limit, the
converter trips after a time.
Connect a brake resistor.
Extend the ramp time.
Change the ramp type.
Activate the functions in 2-10 Brake Function.
Increase 14-26 Trip Delay at Inverter Fault.
If the alarm/warning occurs during a power sag, the
solution is to use kinetic back-up (14-10 Mains Failure).
Short Circuit
There is short-circuiting in the
motor or motor wiring.
Remove power to the frequency converter and repair
the short circuit.
