What causes fault code CONV-MOTOR-OT (Conveyor Motor Overtemperature — RTD/Thermistor Trip)?

Motor overloaded — conveyor carrying more weight than motor is rated for. Motor cooling obstructed — TEFC fan shroud clogged, fan broken, or motor mounted in enclosed space. Ambient temperature too high — motor in hot environment near ovens, boilers, or sun exposure. Motor running at reduced speed on VFD — self-cooled motor loses cooling capacity below 30Hz. Motor bearings failing — increased friction generates heat

How do I fix fault code CONV-MOTOR-OT?

Stop the motor and let it cool — do not restart until temperature drops below the reset threshold. Check motor fan and fan shroud — clean debris, verify fan rotation. Measure motor current with clamp meter — compare to nameplate FLA. Check ambient temperature around motor — improve ventilation if in an enclosed area. If running on VFD at low speed, install a separately-powered cooling fan. Check motor bearings — feel for roughness when rotating shaft by hand. If motor trips repeatedly with normal load and good cooling, motor windings may be partially shorted — megger test

Conveyor Motor Overtemperature — RTD/Thermistor Trip

CONV-MOTOR-OT

Conveyor motor embedded temperature sensor (RTD, PTC thermistor, or thermostat) has tripped. Motor has exceeded its safe operating temperature.

high conveyor packaging palletizer

conveyor motor overtemperature rtd thermistor cooling fan

Probable Causes (ranked)

Motor overloaded — conveyor carrying more weight than motor is rated for
Motor cooling obstructed — TEFC fan shroud clogged, fan broken, or motor mounted in enclosed space
Ambient temperature too high — motor in hot environment near ovens, boilers, or sun exposure
Motor running at reduced speed on VFD — self-cooled motor loses cooling capacity below 30Hz
Motor bearings failing — increased friction generates heat

Fix Steps

1 Stop the motor and let it cool — do not restart until temperature drops below the reset threshold
2 Check motor fan and fan shroud — clean debris, verify fan rotation
3 Measure motor current with clamp meter — compare to nameplate FLA
4 Check ambient temperature around motor — improve ventilation if in an enclosed area
5 If running on VFD at low speed, install a separately-powered cooling fan
6 Check motor bearings — feel for roughness when rotating shaft by hand
7 If motor trips repeatedly with normal load and good cooling, motor windings may be partially shorted — megger test

Field Trick

When a motor trips on overtemp and the load is normal, check the bearing closest to the fan end. That bearing runs hotter than the drive end because it's enclosed in the fan shroud. A failing fan-end bearing can heat up the motor enough to trip the thermistor without the drive-end bearing showing any symptoms.

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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