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How to carry out a basic electric motor inspection

There are a number of basic electric motor checks you can perform yourself to ascertain why the equipment has failed. Here are our suggestions for a quick motor assessment.

External checks

There may be some clues as to why the motor has failed on the outside of the unit.

Broken feet or mounting holes point to vibration issues which may have occurred as a result of the motor not being seated correctly.

Check any openings in the electric motor casing for signs of dirt and debris entering the windings.

Look out for discoloured paint on the housing, as this often indicates that the motor is overheating.

Fan checks

Examine the guard around the fan and ensure the grille isn’t clogged with dirt and debris, as this has a serious impact on the fan’s ability to cool the motor. The fan itself must spin freely, so be certain it isn’t bent, damaged or obstructed.

Bearing checks

Properly-functioning bearings should allow the rotor to move smoothly and quietly, so wear or damage can often be identified without dismantling the motor. To perform a quick bearing check, set the motor on an even surface and, with one hand on top of the motor, use the other to turn the shaft. You may be able to visually detect unevenness in the rotor’s movement, but you should also listen carefully for grinding or scraping sounds which would also suggest unbalance.

There may be a minimal amount of ‘play’ when pushing the shaft in and out of the frame, but if this exceeds 3mm then it’s possible the shaft is damaged.

Winding checks

If windings have shorted, the motor will tend to draw very high amps and trip the circuit breaker when activated. An ohmmeter or test lamp can be used to check resistance value and the presence or absence of voltage respectively.

If you’re unable to diagnose your equipment’s fault or require an electric motor rewind or repair, let us take care of it for you. Simply call 01621 868138 or email and our experienced Rewinds & Repairs division will take it from there.

Electric Motors


  • Date: 18 February 2015 ravikiran
    thaks for your valuable points on electric motor inspection.
    i want to know that what is minimal resistance drop alow in three phases.
  • Date: 19 February 2015 Gibbons Group
    Hi Ravi,

    Thanks for getting in touch. Paul Scott has emailed you regarding your enquiry, but if you require any further help then please do not hesitate to contact us.

    Kind regards
    Gibbons Group

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