What causes fault code VFD-STALL1 (VFD Stall Detection — Motor Not Rotating)?

Motor shaft mechanically locked — seized bearing, jammed coupling, or frozen load. VFD output contactor (if used) not closed — motor not connected to drive output. Motor winding open on one phase — single-phasing, motor hums but won't spin. Coupling between motor and load sheared — motor spins but load doesn't move. VFD boost voltage too low for breakaway torque — motor can't overcome static friction

How do I fix fault code VFD-STALL1?

Disconnect motor from load and try to run motor alone — confirms motor vs load issue. Check motor rotation by hand — should spin freely without grinding. Measure resistance on all three motor windings T1-T2, T2-T3, T1-T3 — should be equal within 5%. If output contactor is used, verify it pulls in before VFD run command. Increase VFD start boost/torque boost parameter if motor can't break away from standstill. Check coupling between motor and load — inspect keyway, set screws, and coupling spider

VFD Stall Detection — Motor Not Rotating

VFD-STALL1

VFD detected that the motor is not rotating despite output being commanded. Current is flowing but no speed feedback confirmed.

high vfd conveyor packaging palletizer

vfd stall motor rotation coupling

Probable Causes (ranked)

Motor shaft mechanically locked — seized bearing, jammed coupling, or frozen load
VFD output contactor (if used) not closed — motor not connected to drive output
Motor winding open on one phase — single-phasing, motor hums but won't spin
Coupling between motor and load sheared — motor spins but load doesn't move
VFD boost voltage too low for breakaway torque — motor can't overcome static friction

Fix Steps

1 Disconnect motor from load and try to run motor alone — confirms motor vs load issue
2 Check motor rotation by hand — should spin freely without grinding
3 Measure resistance on all three motor windings T1-T2, T2-T3, T1-T3 — should be equal within 5%
4 If output contactor is used, verify it pulls in before VFD run command
5 Increase VFD start boost/torque boost parameter if motor can't break away from standstill
6 Check coupling between motor and load — inspect keyway, set screws, and coupling spider

Field Trick

A motor that hums loudly but won't spin is almost always a single-phase condition — one winding is open. Check all three lead connections in the motor junction box. A loose wire nut on one lead causes this 90% of the time.

Suggested Replacement Parts

Parts matched to fault category: Motor

Baldor/ABB 1HP TEFC Motor P/N: EM3554T 1HP, 1765RPM, 143TC frame, 230/460V, TEFC, premium efficiency

AutomationDirect $285.00 Amazon $310.00 Grainger $345.00

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

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