Caution – LG C Series User Manual

Page 119

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Chapter 13. Troubleshooting & Maintenance

13.2 Fault Remedy

Protective

functions

Cause Remedy

CAUTION:

When an overcurrent fault occurs, operation must be started after the cause is removed to
avoid damage to IGBT inside the inverter.

Overcurrent

z Accel/Decel time is too short compared to

the GD

2

of the load.

z Load is greater than the inverter rating

z Inverter output is issued when the motor is

free running.

z Output short circuit or ground fault has

occurred.

z Mechanical brake of the motor is operating

too fast.

)

Increase the Accel/Decel time.

)

Replace the inverter with appropriate

capacity.

)

Resume operation after stopping the motor

or use H22 (Speed search) in Function group
2.

)

Check output wiring.

)

Check the mechanical brake.

Ground fault

current

z Ground fault has occurred at the output

wiring of the inverter

z The insulation of the motor is damaged due

to heat.

)

Check the wiring of the output terminal.

)

Replace the motor.

Inverter

overload

Overload trip

z Load is greater than the inverter rating.

z Inverter capacity is incorrectly selected.

z Torque boost scale is set too large.

)

Upgrade the capacity of motor and inverter

or reduce the load weight.

)

Select correct inverter capacity.

)

Reduce torque boost scale.

Heat sink

overheat

z Cooling system has faults.

z An old cooling fan is not replaced with a

new one.

z Ambient temperature is too high.

)

Check for alien substances clogged in the

heat sink.

)

Replace the old cooling fan with a new one.

)

Keep ambient temperature under 40

°C.

Output Phase

loss

z Faulty contact of magnetic switch at output
z Faulty

output

wiring

)

Make connection of magnetic switch at

output of the inverter securely.

)

Check output wiring.

Cooling fan

fault

z An alien substance is clogged in a

ventilating slot.

z Inverter has been in use without changing a

cooling fan.

)

Check the ventilating slot and remove the

clogged substances.

)

Replace the cooling fan.

Over voltage

z Decel time is too short compared to the

GD

2

of the load.

z Regenerative load is at the inverter output.
z Line voltage is too high.

)

Increase the Decel time.

)

Use Dynamic Brake Unit.

)

Check whether line voltage exceeds its

rating.

Low voltage

z Line voltage is low.

z Load larger than line capacity is connected

to line (ex: welding machine, motor with high
starting current connected to the commercial
line).

z Faulty magnetic switch at the input side of

the inverter.

)

Check whether line voltage is below its

rating.

)

Check the incoming AC line. Adjust the line

capacity corresponding to the load.

)

Change a magnetic switch.

Electronic

thermal

z Motor has overheated.
z Load is greater than inverter rating.
z ETH level is set too low.
z Inverter capacity is incorrectly selected.
z Inverter has been operated at low speed for

too long.

)

Reduce load weight and operating duty.

)

Change inverter with higher capacity.

)

Adjust ETH level to an appropriate level.

)

Select correct inverter capacity.

)

Install a cooling fan with a separate power

supply.

119

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