Anyone know electric motors?????

[Fuddy1952]

We removed the cupola fan in horse stable. It has a 3ft square wood mounting frame fan is attached to so we made a 36.25" square box out of 2"×10" lumber.
When first installed we tested it with extension cord, black & white wires poked into plug. It worked perfectly, running over an hour, even cycled on & off.
Then I ran 12-2 wire in plastic conduit up to it, tried, it never ran & tiny whiff of smoke.
I re-tried extension cord test, motor never ran. Blade spins free. Fan mounted in wood so no metal anywhere close.
So fan removed. I removed GE motor. Here is what I measured:
Starting cap 7.5ufd, measures 7.45ufd
Black to white 4.6 ohms
Black to green 1.9 ohms
White to green 6.5 ohms
Starting capacitor leads 87.9 ohms
As you see in pictures, with motor apart there are three windings...heavy copper, a small gauge copper and small gauge dark green. They wrapped string around, string burned in two places I'm pointing to.
Just for fun I put motor together, jumped it two wires black & white and (drum roll)...it ran!!!???!!!
Now I'm completely baffled, it makes absolutely no sense. I know basically nothing about electric motors, but the green (ground) wire measuring like it does to neutral or hot I don't understand. I thought that was ground for metal motor case?
Any assistance, thanks in advance...

 

[Ken45101]

it has a short to ground. When you tested it (white and black) there was no ground so no problem. However, it was dangerous, you could have been hurt f you touched it and ground at the same time.

When you wired it properly, you heavy current to ground.

It is defective, don't use it.

Ken

 

[Fuddy1952]

it has a short to ground. When you tested it (white and black) there was no ground so no problem. However, it was dangerous, you could have been hurt f you touched it and ground at the same time.

When you wired it properly, you heavy current to ground.

It is defective, don't use it.

Ken

Wow...thanks! I thought ground green wire to hot or neutral low resistance sounded weird.
It's 24ft in air so nothing will touch it but I won't use it. Thanks so much. I'll take measurements...hopefully I can find a motor & trash can this one.

 

[Ken45101]

Green (or bare wire in the Romex cable) is ground for the outside cover, the motor frame etc. On a 110v device, black is hot (+110) and white is neutral (the return circuit for the black 110.)

A DC ohm meter will not give you an accurate measurement of the AC impedance because you are measuring a coil and it provides more than just DC resistance.

You said you were using 12-2 wire. I assume that is 12-2 with ground.

 

[Fuddy1952]

Green (or bare wire in the Romex cable) is ground for the outside cover, the motor frame etc. On a 110v device, black is hot (+110) and white is neutral (the return circuit for the black 110.)

A DC ohm meter will not give you an accurate measurement of the AC impedance because you are measuring a coil and it provides more than just DC resistance.

You said you were using 12-2 wire. I assume that is 12-2 with ground.

Yes...3 wire. So should I:
Replace just the motor. I have two, the squirrel cage similar one & I have two industrial pedestal fans which same diameter blade, but 1/2hp bigger motor (2 speed)...they ohm out fine, work well, I'd just use one's motor, it will physically fit.
Or just buy another fan (about $400-$500).
Thanks...(I'm retired, plenty of free time)

 

[Fuddy1952]

Forgot pictures:

 

[Doughknob]

All that wire in the windings is “coated.” The burned area has this coating compromised. It likely does not touch wire to wire when cold or not vibrating. But when things warm up and/or vibrate then the compromised coating lets copper to copper in the winding touch. Maybe even touch the steel core slightly.

As others said, It’s toast.

 

[jaxs]

There shouldn't be continuity between green and either wire (much less both) tells you windings are shorted to ground. Not dead zero resistance short but shorted non the less.

 

[ponytug]

Sorry that it burned up. As @Ken45101 put it so well, it is toast. I doubt that it was anything that you did; it just wasn't made properly.

You might just look for your motor replacement online, or for something similar. E.g. Surpluscenter.com;

Fan & Air Conditioner Motors | AC Single Phase Motors | Electric Motors | www.surpluscenter.com

Fan & Air Conditioner Motors,AC Single Phase Motors,Electric Motors, Universal Electric Motor New, Universal Electric, three speed motor. Requires

www.surpluscenter.com

All the best,

Peter

 

[jigs_n_fixtures]

You can probably fit either of the motors you have. They are both 48 frames. Does the old motor have a name plate?