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 Posted: Wed Nov 21st, 2018 01:09 am
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Randy Pierce
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Polar cub shaded pole motor, 2 separate windings, not the usual winding on the bottom.  Pulled it apart to change the cord, and the winding tape was so shot, i pulled the coils, pulled the old tape off and retaped, put the windings back in and it ran great for about an hour then it went up in smoke.  Did I pull some of the wire coating off and cause high resistance leading to failure?  I just don't see what caused this.  Any ideas?

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 Posted: Wed Nov 21st, 2018 11:11 am
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Lane Shirey
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I’ve found it best not to disturb stator coils if at all possible. If anything I wrap new tape over top of the crumbling tape. It’s likely that you cracked or flaked off a piece of the old magnet wire varnish, causing them to short out. 
The other possibility is that the original paper tape overheated and crumbled due to an already failing coil, and your disturbing it just put the final nail in the coffin. 

While it can’t hurt to do a little exploratory digging to figure out what went wrong, it’s likely that the stator can’t be salvaged. 

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 Posted: Wed Nov 21st, 2018 12:53 pm
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Randy Pierce
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Thanks Lane,

Your advice will be gospel on this.  What I unknowingly caused resulted in an actual fire inside the fan, with pops and lots of smoke, and had I not been there to cut power, it may have caused damage beyond the fan itself and been catastrophic to the surroundings.  Thank you again Lane....this lesson is well learned, thanks to you sir,

Randy

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 Posted: Wed Nov 21st, 2018 03:13 pm
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John McComas
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Hey!  At least you were there and got to see the fireworks show!  :-)
...Sorry for your loss...

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 Posted: Wed Nov 21st, 2018 04:39 pm
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Randy Pierce
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That's funny John, and thanks for that!  The good is nobody died, I learned a lot, and even got to celebrate with sparklers.  The rest of the good is I just ordered some 32 gauge winding wire and tho I have no winding equip, i can build a fixture to spin in the lathe and feed wire to it.  I just have to figure out somehow how much wire to wind on it.
[No bingo parlor stuff to pass time for this guy]

Cheers, Randy

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 Posted: Wed Nov 21st, 2018 05:02 pm
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David Allen
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Randy Pierce wrote: That's funny John, and thanks for that!  The good is nobody died, I learned a lot, and even got to celebrate with sparklers.  The rest of the good is I just ordered some 32 gauge winding wire and tho I have no winding equip, i can build a fixture to spin in the lathe and feed wire to it.  I just have to figure out somehow how much wire to wind on it.

[No bingo parlor stuff to pass time for this guy]



Cheers, Randy


Hi Randy. The other guys pretty well summed it up already but I want to add to it.

When the winding is newly made, the individual wraps of wire are free and separate from one another. When the wire is new, the coating is flexible and resists cracking and chipping off. It's easy and harmless to flex and bend the coil to put it into the motor.

Normally, the winding coil is soaked with varnish after it's installed in the motor. That glues all the wraps of wire together and makes the motor quieter. Unfortunately, it also makes the coils one-time-use. If you bend and flex them to remove them from the motor, it will crack the bonds between the wraps of wire. By this age, the insulation coating is brittle. It will flake off and now you have bare spots touching, internally in the coil. That's "shorted turns" in the coil, which creates a magnetic heating effect and leads to burning out of the coil.

I always like to soak the winding with new varnish to ensure it's not going to be easily disturbed before trying to do much with the lead wires, to hopefully keep this from happening; but wouldn't attempt to remove and re-use an old coil.

Did you have a chance to see my Vornado rewind video? That is the first motor (and only motor) I have rewound. I also used a lathe, and made a wood form to wind the coil on. The first one was too small and I had to start over, but in the end, it turned out well and the fan runs like a top.  Again, I am not an expert, have only done this once, and don't really know what I'm doing!  But watching me fumble with it might help! https://www.youtube.com/watch?v=xjxLlDxgxKg 

Also, to prevent the motor from becoming an odious, smoldering fireball if something goes wrong again; you can install an inline fuse in the circuit. This should be a time-delay (slow-blow) fuse rated just above the motor's running current, when it's cold and just up to speed. If the winding starts to fail with shorted turns, it will cause the fuse to blow before the motor can actually catch fire.

Sincerely,
David

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 Posted: Wed Nov 21st, 2018 06:48 pm
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Randy Pierce
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David, I will check out your video and do plan on using wood as a form to wind onto.  I know I can do it no problem.  Your assessment is perfect and pertinent, so thanks so much for your time to help me with this.  If it wasn't for good guys willing to help and share knowledge,  it would be way too frustrating and sometimes too expensive to get done what we want done.  This is great stuff what you are sharing, and thanks so much,

Randy

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 Posted: Wed Nov 21st, 2018 09:08 pm
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David Allen
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Randy Pierce wrote: David, I will check out your video and do plan on using wood as a form to wind onto.  I know I can do it no problem.  Your assessment is perfect and pertinent, so thanks so much for your time to help me with this.  If it wasn't for good guys willing to help and share knowledge,  it would be way too frustrating and sometimes too expensive to get done what we want done.  This is great stuff what you are sharing, and thanks so much,



Randy


You're more than welcome. Hope your rewind goes smoothly!

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 Posted: Thu Nov 22nd, 2018 03:12 pm
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Randy Pierce
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David, your video is awesome! thanks for sharing....Randy

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 Posted: Thu Nov 22nd, 2018 04:22 pm
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David Allen
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Randy Pierce wrote: David, your video is awesome! thanks for sharing....Randy
Thank you sir! Hope yours turns out well, as well!

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