Danfoss fault record

Alarm 16: Current Short Circuit at Motor Terminals or Output Stage

The VLT 2800 / 2900 reports Alarm 16 on start, immediately after output enable, after motor work, after cable changes or after a prior power-stage repair.

Fault route10 min read

Scope of this technical record

Alarm 16 short-circuit route for VLT 2800 / 2900 cases where output terminals, cable, motor and gate-driver evidence must be separated before another power test.

Safety boundary

Alarm 16 is a stop condition. Do not reset and re-run until the short-circuit boundary has been found and the output stage is safe to energize.

VLT 2800 Alarm 16 route

1U/V/W
2Cable
3Motor
4Output accessories
5Driver / module

Alarm 16 is a stop condition until the short-circuit boundary is known.

VLT 2800 Alarm 16 route

Danfoss VLT 2800 Alarm 16 short circuit route terminals cable motor output driver module
Alarm 16 is handled as a short-circuit boundary before another power test.

Find the short before judging the board

Alarm 16 indicates a short-circuit at the motor terminals or in the motor path. The first action is not a parameter change. The first action is boundary finding: U/V/W terminals, motor cable, winding, output contactor, output filter and terminal-box condition.

If the external path is clear, the compact drive moves onto a pre-power gate-driver route. That route compares output phase legs, driver supplies and prior repair evidence before any live test.

Alarm 16 evidence path

BoundaryWhat to proveStop condition
U/V/W terminal blockNo phase-to-phase short or contaminationShort found at terminals
Motor cableNo damage, splice fault or moving-cable shortInsulation or continuity fault
Motor windingNo winding short or grounded terminal-box faultWinding fault remains
Output accessoriesContactor/filter/surge path not shortedAccessory fault remains
Power boardStatic output and driver channels compare correctlyDriver/module damage or prior repeat failure

Field record checklist

  • Fault timing
  • U/V/W inspection
  • Cable continuity
  • Motor winding evidence
  • Output contactor/filter status
  • Static output check
  • Driver channel comparison
  • Repair history

Technical basis and reference documents

This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.

Danfoss service tips for VLT alarm boundariesDanfoss

Confirms Alarm 13 overcurrent, Alarm 14 earth fault, Alarm 16 current short circuit, input-phase and DC-link alarm boundaries used to structure the first service routes.

VLT 2800 Series instruction manualDanfoss

Documents VLT 2800 warning and alarm text including Alarm 13 peak current, Alarm 14 ground fault, Alarm 15 switch-mode supply and Alarm 16 short-circuit cautions.

Danfoss earth-fault service notesDanfoss

Provides practical Alarm 14 separation between motor/cabling evidence and drive-side current-sensor evidence, including no-motor current observations and manual-initialization caution.

Diagnostic workflow

Evidence intake

Turn this record into a qualified service request

A repair decision is much more reliable when the request includes the exact identity of the drive, the first fault evidence and the machine condition when the symptom appeared.

  • Complete drive type code / MLFB or nameplate model
  • Fault code, fault value and first event before reset
  • When the event appears: power-up, enable, ramp, run, decel or stop
  • Motor/cable connected or isolated during the symptom
  • Visible board, option-card, module and connector identifiers
  • Previous repair history, replacement parts and repeat-failure pattern
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