Motor Phase Failure

What does -OPF mean?

This fault indicates a loss of one or more phases at the output of the drive controller, meaning the motor is not receiving power on all its windings. This can be caused by loose motor connections, a damaged motor cable, or if the drive is significantly oversized for a small motor (making phase loss harder to detect). Operating with a missing motor phase will cause excessive heating and damage to the motor windings and potentially the drive.

Complete Troubleshooting Guide

1. 1

   Power down the drive and visually inspect all connections from the drive output terminals (U/T1, V/T2, W/T3) to the motor for tightness, corrosion, or damage.

2. 2

   Using a multimeter, check the resistance across motor phases (U-V, V-W, W-U) to confirm continuity and balance in the motor windings. Also, check for shorts to ground.

3. 3

   If the drive is significantly oversized for the motor, consider disabling the OPL (Motor Phase Failure Detection) parameter (see page 65) and installing an external motor overload protection device directly at the motor.