Phase U to Grnd

What does 38 mean?

A phase-to-ground fault has been detected between the drive and the motor on output phase U. This indicates insulation breakdown or a direct short from output phase U to earth. This condition poses a significant risk of electrical shock and can cause severe damage to both the drive and the motor if not quickly identified and resolved.

Complete Troubleshooting Guide

1. 1

   Rotate the U/T1, V/T2, W/T3 motor connections at the drive. If the fault then moves to the new phase connected to the U terminal, suspect a problem with the motor or field wiring (e.g., damaged cable insulation, motor winding fault).

2. 2

   If the fault remains on phase U after rotating connections, suspect a problem with the drive's output stage for phase U.

3. 3

   Measure the insulation resistance of the motor windings and the motor cable to ground using a megger. Expect values greater than 1 MΩ.