Old Hand Fault Finder

Allen-Bradley PowerFlex 525 F004: UnderVoltage

Cites the manual · line-by-line check pending

What it means DC bus voltage fell below the drive's minimum.

Likely causes

  • Low line voltage
  • Sagging transformer
  • One phase missing

Checks, in order

  1. Measure line under load
  2. Check transformer tap
  3. Check input phases

Source

Source (reworded, not copied): Rockwell Automation, PowerFlex 520-Series AC Drives User Manual, publication 520-UM001O-EN-E (September 2025), Chapter 4 Troubleshooting. Official manual (PDF). Fault numbers and names can differ between firmware versions.