OL trips under normal-seeming load, sometimes only when hot or after running a while.
1
OL heaters/electronic OL sized incorrectly
CheckCompare heater table or electronic OL setting to motor nameplate FLA (115–125% typical, per NEC/OEM).
FixCorrect heater elements or reprogram electronic overload to nameplate FLA.
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2
Ambient temperature differs from panel vs motor location
CheckIf OL is in a hot panel and motor is in cooler ambient (or vice versa), compensation may be needed.
FixUse ambient-compensated overload or relocate/adjust per OEM guidance.
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3
Ventilation blocked, motor running hot
CheckCheck motor frame temperature and cooling fan/shroud for debris.
FixClean motor, restore airflow, verify duty cycle vs nameplate rating.
ToolsIR thermometer
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4
Bearing drag or mechanical bind increasing running amps
highCheckWith power confirmed off (LOTO), bar over airend/motor by hand; feel for roughness or excess drag.
FixReplace bearings or address mechanical bind; recheck amps after repair.
SafetyLOTO and bleed stored air pressure to 0 PSI before barring over.
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5
High resistance connection heating OL/contactor
CheckIR scan connections under load; check torque at lugs.
FixClean and re-torque terminations to spec.
ToolsIR thermometer or thermal camera
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Safety
Lockout/tagout before opening enclosures. Verify zero energy. Bleed system pressure before opening any pneumatic connection.