Soft Charge Circuit Fault

What does UV3 mean?

The pre-charge contactor, responsible for managing the initial charging of the DC bus capacitors, opened unexpectedly while the drive was running. This often indicates a mechanical issue with the contactor itself, such as dirty or worn contacts, preventing proper mechanical operation or causing premature opening.

Complete Troubleshooting Guide

1. 1

   Cycle power to the drive to attempt to re-engage the soft charge circuit and confirm if the contactor operates.

2. 2

   Visually inspect the soft charge contactor for signs of physical damage, dirt, carbon buildup on its contacts, or mechanical sticking.

3. 3

   If the contactor is physically damaged or fails to operate correctly, repair or replace the contactor or the associated Power PCB/Gate Drive PCB, which may contain the contactor control circuit.