Old Hand Fault Finder

Yaskawa GA500 PF: Input Phase Loss

What it means There is a phase loss or bad imbalance in the drive input power.

✓ Checked against the manual (Oct 2026): meaning and actions match the official fault table. Manual page.

Likely causes

  • Blown fuse or open phase
  • Loose input terminal
  • Unstable supply voltage
  • Unbalanced phases

Checks, in order

  1. Measure supply phases
  2. Tighten input terminals
  3. Check the input power and main contactor

Source

Source (reworded, not copied): Yaskawa, GA500 Drive Maintenance & Troubleshooting Manual, TOEPYAIGA5001A, Faults, PDF page 62. Official manual (PDF). Fault numbers and names can differ between firmware versions.