ABB fault record

ff51 / LINE CONV: Line Converter Fault Indication

The drive reports LINE CONV / ff51 or points the technician toward the input/line-converter side rather than the motor output side.

Meaning of the indication

The indication belongs to the line converter or input-side conversion boundary. On larger ABB systems this may require distinguishing the motor-side control panel context from the line-side converter control context.

Checking order

  1. Identify whether the installation is a simple standard drive or part of a larger converter/cabinet arrangement.
  2. Confirm input supply, fuses, precharge and line-converter status before investigating the motor-side output bridge.
  3. Check whether the panel or fault reference is currently addressing a line-side unit.
  4. Inspect line-side boards, contactors and supply feedback only after safe isolation.
  5. Collect type-code and cabinet photos before quoting a replacement board.

Suspect areas

Line converterInput supply pathLine-side control boardPrecharge/contactor sequencePanel unit selection
Fault-specific caution

Do not jump from LINE CONV to motor-module replacement; the fault route begins on the input conversion side.

Diagnostic workflow