IndustrialDriveDataDrive Board & Diagnostic Database
Diagnostic workflow

Danfoss VLT Alarm 14 / Alarm 16 Earth and Short Diagnostic Workflow

Entry symptom: Danfoss VLT reports alarm 14 earth fault or alarm 16 short circuit.

Safety controls before proceeding
  • Isolate supply and verify discharge before output work.
  • Do not megger through the drive.
  • Do not repeat starts into a suspected short.

Investigation sequence

1

Classify alarm and timing

Record alarm number and whether it appears at enable, acceleration or load.

2

Inspect output wiring

Look for moisture, damaged cable, loose strands, wrong accessories or contamination.

3

Isolate motor/cable

Perform insulation testing only after correct isolation from the drive.

4

Check with output disconnected

If the alarm persists without motor/cable, internal power-stage or sensing investigation becomes likely.

5

Review repair history

Repeated module failure requires gate-driver and current-feedback checks before another powered test.

Stop conditions

  • Motor/cable not isolated
  • Insulation procedure unavailable
  • Alarm remains with output disconnected
  • Prior module repair is undocumented

Linked records

Alarm 14
Earth Fault / Ground Fault

The drive has detected an earth/ground fault path. The first split is motor/cable insulation versus output-stage leakage or damaged power electronics.

Open →Alarm 16
Short Circuit

The fault route is output short-circuit evidence: cable, motor, output terminals, output accessories, IGBT module and driver/current-sense circuitry.

Open →Circuit
Danfoss VLT Output Earth-Fault and Short-Circuit Path

Routes alarm 14 and alarm 16 through output insulation, terminal contamination, motor cable damage, IGBT module, gate driver and current-feedback path.

Open →