IndustrialDriveDataDrive Board & Diagnostic Database
Danfoss fault record

Overvoltage / DC link high: DC Link Overvoltage During Deceleration

The VLT trips on overvoltage when the machine slows down, stops a high-inertia load or lowers a regenerative load.

Meaning of the indication

Regenerated energy is raising the DC-link voltage faster than the ramp/brake path can handle it.

Checking order

  1. Confirm whether the trip occurs only during deceleration or load lowering.
  2. Lengthen the deceleration ramp as a diagnostic test where safe.
  3. Check brake resistor, brake chopper setting and wiring where fitted.
  4. Review load inertia and regenerative duty.
  5. Measure input line voltage and DC-link behaviour under qualified procedure.

Suspect areas

Short rampRegenerative loadBrake resistorBrake chopperHigh line voltageDC-link measurement
Fault-specific caution

High DC-link voltage remains hazardous after shutdown; verify discharge before access.

Diagnostic workflow

Workflow
Danfoss VLT Deceleration Overvoltage Workflow

Danfoss VLT trips on overvoltage during deceleration, stop or load lowering.

Open →