Any electric motor gurus?

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Wolfdog
Posts: 76
Joined: Thu Jul 19, 2018 6:29 pm
Location: North Brevard

Any electric motor gurus?

Post by Wolfdog »

Shop has a 120 volt fan. Will not start on its own but will run if you kick start it, then motor heats up over time. Classic run cap failure. Problem is only marking on cap that survived the melt down is 370 volt. Plate on motor says 120 volt 3.32 amps. No luck trying to contact fan maker for info. Anyone know what size cap I need to make this thing work? It is hot out there.
Dave P
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Joined: Thu Jul 19, 2018 1:33 pm

Post by Dave P »

Lots of info online. But call your local elec supply house, see what they say.

They are only $5 or so, and I cant imagine the wrong one will cause serious problems. So maybe try a couple based on what the web says.

Do you also have a start cap and relay in there?
Wolfdog
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Joined: Thu Jul 19, 2018 6:29 pm
Location: North Brevard

Post by Wolfdog »

No 120 usually just have a run cap.
P5 Guy
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Post by P5 Guy »

delete I don't know what I'm talking about
Last edited by P5 Guy on Thu Jun 27, 2019 7:28 am, edited 1 time in total.
P5 Guy
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Post by P5 Guy »

Dave P
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Post by Dave P »

I am no expert, but "the capacitor adds torque to start the motor under load" does not sound correct.

I thought the start cap delays the voltage going to one set of windings (ELI the ICE man) to ensure the armature turns in the right direction.
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Bmup
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Post by Bmup »

All I know is that you never want to touch the two posts on a capacitor with a finger - even if it's an old one you think might be drained. I once won a $10 bet and almost got an ass whooping with this knowledge. :mrgreen:
"No society ever thrived because it had a large group of parasites living off those who produce." - Dr. Thomas Sowell
Wolfdog
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Joined: Thu Jul 19, 2018 6:29 pm
Location: North Brevard

Post by Wolfdog »

Got the info from Granger's tech department. 10 mf. put it in runs great.
Dave P
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Post by Dave P »

cool!
Dave P
Posts: 149
Joined: Thu Jul 19, 2018 1:33 pm

Post by Dave P »

P5 - the more I think about it, the more your answer of supplying torque is valid.

By delaying the power to one set of windings will definitely apply torque to the armature (so it turns in the proper direction).
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