Mitsubishi Electric VFD fault codes

Common causes

• Acceleration or deceleration too fast
• Output short circuit or earth fault
• Damaged IGBT

What to check

• Disconnect the motor cable and run the drive without load: if the fault stays, the drive itself is faulty
• Megger the motor and cable for insulation or phase-to-phase faults
• Increase acceleration/deceleration time; check for mechanical jams

Common causes

• Deceleration too fast
• Load driving the motor
• Brake resistor fault

What to check

• Increase the deceleration time or enable the stall/overvoltage prevention function
• Check the braking resistor and braking transistor (if fitted)
• Measure the supply voltage – it should be within the drive's rating

Common causes

• Load too high for the inverter

What to check

• Reduce load or use a larger inverter

Common causes

• Motor overloaded
• Wrong electronic thermal setting (Pr. 9)

What to check

• Check Pr. 9 and the motor load

Common causes

• Fan failure
• Blocked heatsink
• High panel temperature

What to check

• Clean the heatsink and check that the cooling fan runs
• Check the panel temperature and ventilation
• Reduce the load or carrier frequency

Common causes

• Low supply voltage
• Faulty pre-charge circuit

What to check

• Measure all three input phases under load
• Check input fuses, contactor and loose terminals
• If the supply is fine, check the DC bus capacitors and pre-charge circuit

Common causes

• Missing supply phase

What to check

• Measure all three input phases under load
• Check input fuses, contactor and loose terminals
• If the supply is fine, check the DC bus capacitors and pre-charge circuit

Common causes

• Broken motor cable or winding

What to check

• Check motor cable continuity and windings

Common causes

• Motor or cable insulation failure

What to check

• Megger the motor and cable to earth
• Check for water or dust in the motor terminal box
• If insulation is fine, the output IGBT or current sensor may be faulty

Common causes

• Brake transistor damaged
• Brake resistor value too low

What to check

• Check the brake resistor value
• Brake transistor failure needs power board repair

Common causes

• Control board fault
• Strong electrical noise

What to check

• Check grounding; repeating E.CPU needs control board repair