Old Hand Fault Finder

Siemens SINAMICS G120 F30011: Power unit: Line phase failure in main circuit

What it means DC link voltage ripple went over the allowed limit, usually because a line phase is missing or badly unbalanced.

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

Likely causes

  • Failed line phase
  • Blown main circuit fuse
  • Badly unbalanced phases
  • Failed motor phase

Checks, in order

  1. Check the main circuit fuses
  2. Measure all input phases
  3. Check for a single-phase load distorting the line

Source

Source (reworded, not copied): Siemens, SINAMICS G120 Control Units CU240B-2/CU240E-2 List Manual, 02/2023, A5E33839529, section 4.2 List of faults and alarms, PDF page 906. Official manual (PDF). Fault numbers and names can differ between firmware versions.