
7-2
LED Display
Description
Cause
Possible Solutions
Ground Fault
The ground fault exceeds
50% of the AC Drive rated
output current (If 08-23 = 1,
GF function is enabled).
● Motor damaged (insulation).
● Wire damage or deterioration.
● AC Drive DCCT sensors defect.
● Replace motor.
● Check motor wiring.
● Disconnect motor and try
running AC Drive.
● Check resistance between
cables and ground.
● Reduce carrier frequency.
Over Voltage
DC bus voltage exceeds the
OV detection level:
240V class: 410Vdc
480V class: 820Vdc
● Deceleration time set too short,
resulting in regenerative energy
flowing back from motor to the
AC Drive.
● The AC Drive input voltage is
too high.
● Use of power factor correction
capacitors.
● Excessive braking load.
● Braking transistor or resistor
defective.
● Speed search parameters set
incorrectly.
● Increase deceleration time
● Reduce input voltage to
comply with the input
voltage requirements or
install an AC line reactor to
lower the input voltage.
● Remove the power factor
correction capacitor.
● Use dynamic braking unit.
● Replace braking transistor
or resistor.
● Adjust speed search
parameters.
Low Voltage
DC bus voltage is lower than
the UV detection level or the
pre-charge contactor is not
active while the AC Drive is
running.
240V class: 190Vdc
480V class: 380Vdc
(The detection value can be
adjusted by 07-13).
● The input voltage is too low.
● Input phase loss.
● Acceleration time set too short.
● Input voltage fluctuation.
● Pre-charge contactor damaged.
● DC bus voltage feedback signal
value incorrect.
● Check the input voltage.
● Check input wiring.
● Increase acceleration time.
● Check power source
● Replace pre-charge
contactor
● Replace control board or
AC Drive.
Input Phase
Loss
Phase loss at the input side
of the AC Drive or input
voltage imbalance, active
when 08-09 = 1 (enabled).
● Loose wire at AC Drive input
terminal.
● Momentary power loss.
● Input voltage imbalance.
● Check input wiring.
● Fasten wire terminal
screws.
● Check power supply.
Output Phase
Loss
Phase loss at the output side
of the AC Drive, active when
08-10 = 1 (enabled).
● Wiring loose at AC Drive output
terminal.
● Motor rated current is less than
10% of the AC Drive rated
current.
● Check output wiring /
fasten screws.
● Check motor & AC Drive
rating.
OH1 Heatsink
Overheat
The temperature of the heat
sink is too high.
Note
: When OH1 fault occurs
three times within five
minutes, user must wait 10
minutes before the AC Drive
can be reset.
● Ambient temperature too high.
● Cooling fan failed.
● Carrier frequency set too high.
● Load too heavy.
● Install fan or AC to cool
surroundings.
● Replace cooling fan.
● Reduce carrier frequency.
● Reduce load / Measure
output current
OH4 Motor
Overheating
Motor overheating, PTC
(Positive Temperature
Coefficient) exceeds the
overheat protection level.
● The surrounding temperature of
the motor is too high.
● The PTC input (Positive
Temperature Coefficient)
exceeds the overheat
protection level.
● Check the surrounding
temperature of the motor.
● Check the motor and GND
terminal wiring.