What causes fault code VFD-OC1 (VFD Overcurrent Trip)?

Short circuit in motor cable — check with megger between phases and to ground. Motor windings shorted — measure phase-to-phase resistance with motor disconnected. Incorrect motor parameters — verify nameplate amps match drive settings. Mechanical load jam — motor cannot turn, stall current exceeds OC threshold. IGBT module degrading — drive trips at low loads where it previously ran fine. Cable too long without output reactor — capacitive charging current triggers OC

How do I fix fault code VFD-OC1?

Disconnect motor cables at drive output terminals — if fault clears on start, problem is external. Megger motor cables: phase-to-phase and phase-to-ground, must be >1 MΩ. Check motor windings with LCR meter — phase balance within 5%. Verify drive parameter: motor rated current matches nameplate FLA. Inspect for mechanical binding — try to turn motor shaft by hand. Check acceleration time — too fast ramp causes current spike. If cable run >100ft, add output line reactor (3-5% impedance). Replace drive if IGBT test fails (many drives have self-test in diagnostics menu)

VFD Overcurrent Trip

VFD-OC1

Drive tripped on instantaneous overcurrent. Output current exceeded the hardware limit, shutting down to protect IGBTs.

high vfd conveyor packaging palletizer

vfd overcurrent igbt motor trip

Probable Causes (ranked)

Short circuit in motor cable — check with megger between phases and to ground
Motor windings shorted — measure phase-to-phase resistance with motor disconnected
Incorrect motor parameters — verify nameplate amps match drive settings
Mechanical load jam — motor cannot turn, stall current exceeds OC threshold
IGBT module degrading — drive trips at low loads where it previously ran fine
Cable too long without output reactor — capacitive charging current triggers OC

Fix Steps

1 Disconnect motor cables at drive output terminals — if fault clears on start, problem is external
2 Megger motor cables: phase-to-phase and phase-to-ground, must be >1 MΩ
3 Check motor windings with LCR meter — phase balance within 5%
4 Verify drive parameter: motor rated current matches nameplate FLA
5 Inspect for mechanical binding — try to turn motor shaft by hand
6 Check acceleration time — too fast ramp causes current spike
7 If cable run >100ft, add output line reactor (3-5% impedance)
8 Replace drive if IGBT test fails (many drives have self-test in diagnostics menu)

Field Trick

Disconnect motor leads at the drive. If it still faults on start with nothing connected, the drive IGBTs are shot.

Suggested Replacement Parts

Parts matched to fault category: Vfd Drive

Allen-Bradley PowerFlex 525 AC Drive 1HP P/N: 25B-D2P3N114 1HP, 480V, 3-phase, built-in EtherNet/IP, EMC filter

AutomationDirect $395.00 Amazon $450.00 Grainger $520.00

ABB ACS580 General Purpose Drive 2HP P/N: ACS580-01-05A7-4 2HP, 480V, built-in safe torque off, adaptive programming

AutomationDirect $425.00 Amazon $480.00 Grainger $550.00

GS20 AC Drive 1HP (Budget Option) P/N: GS20-20P5 1HP, 230V, sensorless vector, compact size — good replacement for testing

AutomationDirect $149.00 Amazon $175.00

Prices are estimates. Verify part numbers match your equipment before ordering.

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