Troubleshoot AC Motors – Part 3

Posted 3/22/2004

Problem C Motor overheats

C1: Is ambient temperature too high? Reduce ambient, increase ventilation or install larger motor.
C2: Is motor too small for present operating conditions? Install larger motor.
C3: Is motor started too frequently? Reduce starting cycle or use larger motor.
C4: Check external frame. Is it covered with dirt which acts as insulation and prevents proper cooling? Wipe, scrape or vacuum accumulated dirt from frame.
C5: Feel output from air exhaust openings. Is flow light or inconsistent indicating poor ventilation? Remove obstructions or dirt preventing free circulation of air flow. If needed,                        clean internal air passages.
C6: Check input current while driving load. Is it excessive indicating an overload? Go to Step C11.
C7: Is the driven equipment overload? Reduce load or install larger motor.
C8: Are misalignments, bad bearings or damaged component causing excessive friction in driven machine or power transmission system? Repair or replace bad components.
C9: Are motor bearings dry? Lubricate. Does motor still draw excessive current?
C10: Are damaged end bells, rubbing fan, bent shaft or rubbing rotor causing excessive internal friction? Repair or replace motor.
C11: Are bad bearings causing excessive friction? Determine cause of bad bearings (See Problem D).
C12: Check phase voltage. Does it vary between phases? Restore equal voltage on all phases.
C13: Is voltage more than 10% above or 10% below nameplate? Restore proper voltage or install motor built for the voltage.
C14: Check stator. Are any coils grounded or shorted? Repair coils or replace motor.