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CHAPTER 4 Troubleshooting and Fault Information
The VFD-L AC drive has a comprehensive fault diagnostic system that includes several different
alarms and fault messages. Once a fault is detected, the corresponding protective functions will be
activated. The following faults are displayed on the AC drive digital keypad. The six most recent
faults can be read on the digital keypad display by viewing Pr.6-07 to Pr.6-12.
NOTE: faults can be cleared by pressing the Reset key on the keypad or Input Terminal.
Common Problems and Solutions:
Fault
Name
Fault Descriptions
Corrective Actions
The AC drive detects an abnormal
increase in current.
1. Check whether the motors horsepower
corresponds to the AC drive output power.
2. Check the wiring connections between the
AC drive and motor for possible short circuits.
3. Increase the Acceleration time (Pr.1-09,
Pr.1-11).
4. Check for possible excessive loading
conditions at the motor.
5. If there are any abnormal conditions when
operating the AC drive after the short-circuit
is removed, the drive should be sent back to
manufacturer.
The AC drive detects that the DC bus
voltage has exceeded its maximum
allowable value.
1. Check whether the input voltage falls within
the rated AC drive input voltage.
2. Check for possible voltage transients.
3. Bus over-voltage may also be caused by
motor regeneration. Increase the decel time.
The AC drive temperature sensor
detects excessive heat.
1. Ensure that the ambient temperature falls
within the specified temperature range.
2. Make sure that the ventilation holes are not
obstructed.
3. Remove any foreign objects on the heat sink
and check for possible dirty heat-sink fins.
4. Provide enough spacing for adequate
ventilation.
The AC drive detects that the DC bus
voltage has fallen below its minimum
value.
Check whether the input voltage falls within the
rated AC drive’s input voltage.
Internal electronic overload trip
1. Check for possible motor overload.
2. Check electronic thermal overload setting.
3. Increase motor capacity.
4. Reduce the current level so that the drive
output current does not exceed the value set
by the Motor Rated Current Pr.7-00.
The external terminal EF-GND goes
from OFF to ON.
When external terminal EF-GND is closed, the
output will be turned off. (under N.O.
E.F.)
Motor overload. Check the
parameter settings ( Pr.6-03 to
Pr.6-05)
1. Reduce the motor load.
2. Adjust the over-torque detection setting to an
appropriate setting.
