Scope of this technical record
Pre-power workflow for Alarm 16, drive-side Alarm 13 / 14 evidence or repaired VLT 2900 power-board hardware.
Do not energize a suspected output stage until the external short, static output and driver evidence are reconciled.
VLT 2900 pre-power driver route
The workflow protects replacement hardware from unresolved output or driver causes.
VLT 2900 gate-driver pre-power workflow
Pre-power evidence before another start
When a compact VLT has shown Alarm 16 or repeat output-stage symptoms, the safest service decision is made before live PWM tests. Static output checks, driver supply evidence and motor/cable proof come first.
A repaired module or donor board is not protected if the gate-driver channel, current feedback or external cable fault remains unresolved.
Pre-power checks
| Check | Purpose | Unsafe finding |
|---|---|---|
| Motor/cable disconnected and proven | Avoid powering into an external short | Any U/V/W short remains |
| Static phase-leg comparison | Find damaged output devices | One phase differs clearly |
| Driver supply present | Confirm gate driver can operate | Rail missing or pulsing |
| Driver channel comparison | Avoid repeat module failure | One channel damaged |
| Current-feedback zero | Avoid false-current trips | Current shown without motor |
Field record checklist
- External output proof
- Static output comparison
- Driver supply evidence
- Driver-channel evidence
- Current-feedback behavior
- 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.
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.
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.
Provides practical Alarm 14 separation between motor/cabling evidence and drive-side current-sensor evidence, including no-motor current observations and manual-initialization caution.
Linked records
Alarm 16 is a phase-to-phase short-circuit route. The first boundary is motor terminals and motor winding / cable evidence; if the external output is clear, the service route moves to gate-driver, feedback and output module evidence on the compact power board.
Alarm 13 means the inverter peak current limit has been exceeded. In service work the key is not the code text but the timing: mechanical lock, wrong motor sizing, aggressive ramp, load torque, motor cable condition, current feedback and output-stage evidence are different branches.
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.
Energy path for compact Danfoss cases where DC-link undervoltage, display instability or power-board suspicion must be separated from input fuses, rectifier, DC link and auxiliary supply behavior.
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