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Danfoss · VLT FC302Fault Code Alarm 4Warning

Danfoss VLT FC302 — Alarm 4 Mains Phase Loss

Raised when loss or severe imbalance of an input phase is detected. DC-link ripple increases.

Updated: 2026-07-05

Symptoms

  • Alarm 4 under load
  • Increased DC-link ripple
  • More vibration/noise

Probable Causes

  • Blown input fuse
  • Loose/oxidized mains terminal
  • Mains phase imbalance

Checkpoints

  • Measure all three input phases
  • Check fuses and terminals
  • Review mains-imbalance tolerance (par. 14-12)

Solution

If mains is healthy, inspect the input rectifier stage or DC-link capacitors.

Related Products

ABB ACS580Sürücüler (İnverter / VFD)ABB ACS880Sürücüler (İnverter / VFD)Siemens SINAMICS G120Sürücüler (İnverter / VFD)Danfoss VLT AutomationDrive FC302Sürücüler (İnverter / VFD)

Related Faults

ABB ACS580 — 3130 Input Phase LossABB · ACS5803130Siemens SINAMICS G120 — F30011 Line Phase LossSiemens · SINAMICS G120F30011

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