04

Under Voltage Fault

Allen-Bradley · 160 AC Drive

What does 04 mean?

This fault occurs when the DC Bus voltage drops below a minimum threshold during operation. For 200-240V AC rated controllers, this trip happens at 210V DC bus (150V AC incoming); for 380-460V AC rated controllers, it's 390V DC bus (275V AC incoming). Persistent undervoltage can cause erratic controller behavior and motor performance issues.

Complete Troubleshooting Guide

  1. 1

    Monitor the incoming AC line voltage to ensure it stays within the specified operating range.

  2. 2

    Inspect the AC power supply for sags, brownouts, or interruptions.

Source: Allen-Bradley Manual