Dayton AC fan motor getting HOT!

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pishta

pishta

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20" Dayton ELECTRIC FAN in a round cage with a stand, floor mount. Has 1/6 HP 'clam shell' 1600-1300 RPM motor with integral sleeve bearings. The back of the motor gets hot, like 140F on a laser thermometer and trips the thermal cutout after a while. Will reset after about 30 seconds and will trip again in 5 minutes. I lube the crap out of the sleeve bearing even putting a zerk fitting on the back and loading rear bearing pocket with moly grease. I think the bearings are not the issue. How do I check the windings for faults? What else could cause the AC motor to heat like this? This fan is not old looking but it was taken from a 24/7 on environment for who knows how long (comm gear cooling indoors).
 
Did the fan used to have louvers or dampers or directional vanes of any kind that have been removed? Sounds like a classic case of motor overload.
 
6PakBee said:
Did the fan used to have louvers or dampers or directional vanes of any kind that have been removed? Sounds like a classic case of motor overload.
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I assume this motor does not use a run capacitor?


^^THIS^^...........Example, you can not run a blower like a furnace/ AC squirrel cage OUT OF the ducted evironment it was designed for, without reducing motor power (speed wires selection) They will "over current."

Also is it possible the motor was wrongly replaced (too small or too high RPM) or likewise blades replaced with wrong blades?

Other than that you may have a partially shorted winding, which is very difficult to test for
 
67Dart273 said:
Other than that you may have a partially shorted winding, which is very difficult to test for
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All stock, just pulled from the E-waste heap at work. We toss loads of stuff (procurement is pretty lax!) that only needs lube or a new battery. This blade would only buzz when I first plugged it in and decided to lube the bearings. That got them spinning pretty good again and it worked but then started to trip the thermal cut out. On a single phase motor how many windings does it have? Could I detect it from the plug resistance? I cant seem to find a comparable motor for this online.
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maybe something close to this style but flatter
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First off, I am guessing it's a capacitor run motor. Most of those small fractional horsepower fan motors are. As to it not working, there was a reason it ended up in the junk pile!
 
6PakBee said:
First off, I am guessing it's a capacitor run motor. Most of those small fractional horsepower fan motors are. As to it not working, there was a reason it ended up in the junk pile!
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No. It is likely something like a simple induction motor. One winding, no start switch, and no caps. Just one winding.

I would guess either one group whatever they are called or "pole" is somewhat shorted, or else the bearings are still a problem. It may also be that it was dragging the rotor against the stator, which damages the two, and screws up the magnetic field. "Eddy currents" or whatever.

If you are certain it is all factory, and the bearings seem free, it's time to look for a replacement motor
 
There are two main ways of generating excess heat in a motor ( assuming you have the proper load). Pulling too much current, or mechanical friction. One could cause the other also, to make it even more confusing. Can you measure the current draw? Is the plug or the cord getting hot?
 
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