Scope of this technical record
Workflow for repair shops handling a VFD where a replacement IGBT/IPM failed again or may fail again on the next test.
Another power-up without driver, bus and load evidence can create destructive semiconductor failure. Use only qualified staged repair procedures.
Repeat module workflow route
The workflow turns a repeat module failure into a pre-power evidence package.
Repeated IGBT workflow image
Workflow goal
The workflow converts a repeat module failure into a pre-power evidence package. It prevents another expensive module from being installed while a weak driver supply, damaged gate component, biased current sensor, bus stress or external cable fault remains unresolved.
Pre-power stop-condition matrix
Any one of these unresolved findings is enough to stop a full-power test.
Repeat IGBT failure workflow
| Boundary | Evidence | Stop condition |
|---|---|---|
| Gate path | Gate resistor/driver/clamp mismatch | Do not energize module |
| Driver supply | Missing or weak isolated supply | Repair driver supply first |
| Current feedback | Biased sensor/channel | Fault protection is not trusted |
| DC link | Capacitor/chopper/snubber stress | Resolve bus stress |
| External load | Motor/cable fault remains | Do not connect repaired drive |
Evidence package for repair intake
The strongest submission includes original failure mode, module part number, photos of each phase driver channel, isolated supply evidence, snubber/current-sensor evidence and motor/cable insulation boundary.
Field record checklist
- Original failure mode
- Module replacement history
- Driver-channel photos
- Isolated supply evidence
- Current feedback evidence
- Motor/cable status
Technical basis and reference documents
This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.
Circuit path for module survival decisions.
Linked records
Repeat module failure usually means the original cause was not limited to the module; gate-drive, isolated supply, current detection, snubber/clamp, motor cable or load evidence must be reviewed.
Immediate overcurrent can be caused by load lock, motor/cable fault, wrong motor data, current-sensing error, gate-driver failure or a damaged output bridge. The trip text alone does not identify the failed component.
The route must separate motor lead, contactor, current sensor, gate-driver command and output power device evidence.
Connects PWM command, isolated driver supply, gate components, short-circuit protection and the output bridge to overcurrent and repeat-module-failure symptoms.
Routes incoming three-phase supply through protection, rectification, precharge and DC-link storage before the inverter stage is allowed to run.
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