Troubleshooting
VFD undervoltage
Check incoming supply, connections, DC bus behavior, loading, and event history.
Undervoltage can originate upstream, in the DC bus, from weak connections, or during source/load transients.
Review
- Fault timestamp and operating state.
- Incoming voltage rating, phase condition, source capacity, and shared loads.
Tests
- Inspect input connections and protective devices de-energized.
- Qualified persons may trend line voltage and DC bus during the event using rated equipment.
Corrections
- Repair supply/connection issues, adjust ride-through settings only when appropriate, and address excessive source impedance or load transients.
Verification
- Repeat the triggering sequence and confirm stable input/DC bus values without masking a supply problem.