Motor Phase VW Short Circuit

What does F43 mean?

This fault detects a short circuit condition between motor phases V and W at the drive output. This implies an insulation failure within the motor windings or a direct short in the cabling connecting the drive to the motor.

• Motor winding insulation breakdown between phase V and W due to excessive vibration, chemical exposure, or prolonged high temperature.
• Mechanical damage to the motor cable insulation between phase V and W conductors, leading to a direct short.
• Arcing or conductive foreign material (e.g., carbon dust) bridging phases V and W within the drive's output stage or motor terminal box.
• Output filter inductor failure or drive internal IGBT module short between phase V and W.

Click steps to track your progress.

1. 1

   De-energize the drive and motor circuit. Disconnect motor leads V and W from the drive output terminals (T2, T3).

2. 2

   Use a multimeter to measure resistance between motor phases V and W at the motor terminal block. A reading of 0Ω or very low resistance indicates a short.

3. 3

   Conduct an insulation resistance test (megger) at 500VDC or 1000VDC between motor phases V and W at the motor terminal block. A reading <1 MΩ indicates insulation failure.

4. 4

   Carefully inspect the motor cables for abrasions, pinch points, or cuts between phases V and W conductors. Verify secure terminal connections.

5. 5

   If motor and cables pass inspection, check resistance between drive output terminals V and W (T2, T3) with the motor disconnected. If a short is detected, replace the drive.