Motor Readings

J

jmellc

Senior Member
Location
Durham, NC
Occupation
Facility Maintenance Tech. Licensed Electrician
Just got in 3 new hand dryer motors. We use them on 208V and 277V dryers. Manufacturer uses this motor for either, Motor is labeled 240V.
Motor 1, I get 24 to 28 ohms at different times.
Motor 2, 18 ohms.
Motor 3, 14 ohms.

I don't understand getting 2 different readings moments apart on #1. I don't understand getting such lower readings on 2 and 3. I might think the 4 ohm difference between those 2 might be that 1 got more windings than the other somehow. But how does #1 have double #3 and nearly double #2? Adding to the confusion, I recently got an 11 ohm reading on a new dryer unit.

What am I missing here? Shouldn't the 3 be close to each other or does production vary that much? I was hoping I could use ohm readings as a guide for checking motors from units we replace. We try to save usable parts and make 1 or 2 rebuilds to have on hand. New dryers are expensive.
 
ActionDave said:
If the winding isn't burnt it's fine. Usually it is the bearings that cause problems. There is a way to get to the wicking and add a few drops of oil if you get to them before the shaft is locked up.
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But that has nothing to do with getting widely varied ohm readings on new unused motors.
 
the different resistance readings would depend upon what type of motors they are. brush-motors could give you any kind of different readings.

why did you bother to check brand new motors? is there something else going on that made you feel the need to check them?

if i were concerned about wasting time installing potentially bad units, i would take them back to my workbench, hook them up to power, and see how they amp-out.
 
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