What causes fault code VFD-OV1 (VFD DC Bus Overvoltage)?

Deceleration time too short — motor regenerates energy faster than bus can absorb. Braking resistor disconnected or open — no path to dissipate regen energy. Incoming line voltage too high — measure at drive input terminals. Large inertia load — motor acts as generator during coast-down. Braking transistor failed — cannot switch regen energy to resistor

How do I fix fault code VFD-OV1?

Increase deceleration time — double it and test. Verify braking resistor: measure resistance, check wiring to drive BR terminals. Measure incoming voltage at drive input — should be within ±10% of drive rating. Enable coast-to-stop if application allows — eliminates regen entirely. Check drive DC bus voltage on parameter display — should be ~1.35x line voltage at rest. For high-inertia loads, size braking resistor for continuous duty. Verify braking transistor with drive diagnostic test

VFD DC Bus Overvoltage

VFD-OV1

DC bus voltage exceeded safe threshold. Typically caused by regenerative energy from the motor during deceleration.

high vfd conveyor palletizer

vfd overvoltage dc bus braking regeneration

Probable Causes (ranked)

Deceleration time too short — motor regenerates energy faster than bus can absorb
Braking resistor disconnected or open — no path to dissipate regen energy
Incoming line voltage too high — measure at drive input terminals
Large inertia load — motor acts as generator during coast-down
Braking transistor failed — cannot switch regen energy to resistor

Fix Steps

1 Increase deceleration time — double it and test
2 Verify braking resistor: measure resistance, check wiring to drive BR terminals
3 Measure incoming voltage at drive input — should be within ±10% of drive rating
4 Enable coast-to-stop if application allows — eliminates regen entirely
5 Check drive DC bus voltage on parameter display — should be ~1.35x line voltage at rest
6 For high-inertia loads, size braking resistor for continuous duty
7 Verify braking transistor with drive diagnostic test

Field Trick

Set decel time to 999 seconds temporarily. If OV goes away, it's a regen problem. Size a braking resistor.

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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