How can I tell a good motor from a bad motor

[beatcan]

(I already posted this in the pumps forum instead of electric motors by accident. Sorry if you get this thread twice).

Our company is sourcing motors from China for exhaust fans. These are PSC motors, ranging from 1/4HP to 1HP. What is the major determining factor that makes a good quality motor good. Is it the quality in materials (i.e.copper, laminations, slot liners etc.)? Workmanship? Engineering design? Any suggested tests to determine the quality and longevity of the motor.
We have purchased motors in the past that seemed to be good as far as I can tell (they looked and tested the same as our proven motors), however the failure rate was much higher than our standard motors. We always load motors well under the rated heat rise for the class of motor, under worst case conditions. Therefore we can assume that the motors did not fail because of our design. Any advise?

 

[acmotorengineer]

the only true measure is long term testing of a statistical meaningful batch of motors at the expected application conditions. you need to then evaluate root cause of failure. from this information you will be able to identify what needs to be addressed, i.e. design, material, workmanship ... etc ...


good quality is the sum of design + materials + workmanship + application. any weak link will cause failure no matter how robust the other links.

 

[jbartos]

Suggestion: If a motor look good, then the motor design including the motor materials may be culprits.

 

[bssrinivasa]

Mr. Beatcan,

List out causes of failure then you can pinpoint what could be problem with that motor.

If possible try to post some more information, so that any one of us can analyse and guide accordingly.

 

[dubairay]

Not much I can add to the previous suggestions but in the past we have had problems with the bearings in this type of motor which caused the motor to burn out. Have you checked this?

 

[jbartos]

Small encore: Sometimes a product has a specific flaw that could be remedied before the product is applied. The Bssrinivasa post is heading in the similar direction.