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Output power stage / current feedback

Danfoss VLT 2900 Gate-Driver and Current Feedback Path

Output-stage route for Alarm 13, Alarm 14 and Alarm 16 cases after external motor, cable and terminal evidence has been collected. The route connects gate-drive channels, driver supply, current feedback and output module decisions.

Circuit path10 min read

Scope of this technical record

Gate-driver and current-feedback route for compact VLT 2900 output faults after external motor/cable evidence has been collected.

Safety boundary

Qualified repair personnel only. Do not power the output stage with unknown driver or motor/cable condition.

VLT 2900 gate-driver / feedback route

1PWM
→
2Driver supply
→
3Gate channels
→
4Output module
→
5Current feedback

The route separates current feedback and driver evidence before another power test.

VLT 2900 gate-driver feedback path

Danfoss VLT 2900 gate driver feedback path PWM driver supply output module current feedback
The path shows the driver and current-feedback boundary for compact output faults.

Output faults need driver and feedback evidence

Alarm 13, Alarm 14 and Alarm 16 can all reach the output-stage boundary, but they reach it through different evidence. Trip timing, no-motor current, static phase-leg comparison and driver supply behavior decide whether the case belongs to feedback, driver or output hardware.

The safest repair package compares phase legs and driver channels before another output module or board is installed.

Output-stage evidence

EvidenceWhat it meansNext route
No-motor current near zeroCurrent feedback likely usableReturn to external load path
No-motor current presentFeedback/sensor boundary suspectBoard evidence
One phase-leg abnormalOutput hardware boundaryModule / board decision
Driver supply missingDriver cannot be trustedAuxiliary / driver rail route
Driver channel mismatchRepeat failure riskPre-power stop condition

Field record checklist

  • Trip timing
  • No-motor current
  • Static output checks
  • Driver supply
  • Driver channel comparison
  • Board label
  • 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.

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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