Investigation sequence
Separate timing
Record whether the trip occurs at enable, at first PWM output, during ramp, at a speed threshold or only under mechanical load.
Inspect external output path
Check motor cable, terminal box, output contactors, reactors and load lock evidence before board-level conclusions.
Verify parameter and feedback conditions
Wrong motor data, short acceleration time, encoder mismatch or incorrect control mode can force a trip without a failed module.
Check static inverter evidence
Before energizing, check for obvious phase-leg shorts, damaged bus parts and repeat-failure signs using qualified bench methods.
Escalate to driver/current sensing
If external and parameter evidence is clean, inspect gate-drive supply, gate components, desaturation/current feedback and power module condition.
Stop conditions
- Trip becomes a short-circuit indication
- Module measures shorted
- Motor insulation is suspect
- Unknown previous repair history
Linked records
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.
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.
Connects PWM command, isolated driver supply, gate components, short-circuit protection and the output bridge to overcurrent and repeat-module-failure symptoms.
Separates motor insulation, cable leakage, terminal contamination, output filters and internal sensing when a drive trips only after output voltage is applied.