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AZ Miner
Associate

Join Date: Jan 2009
Posts: 43

Motor Startup

06/27/2012 11:13 PM

I have an old electric motor that is driving a gear reduction unit. It is old enough and has been used enough that the Mfg. info is not discernible. It is 115 v - 60 Hz - 1 phase - 5.6 amp - 1725 rpm.

When it is switched on it groans to start until I turn the shank by hand fast enough to get it started. Then it runs fine, no problem.

Since it is so old I probably should just replace it. However, I was curious about why or what was wrong with it. I took it apart to see if I could figure it out. It was really grimy and dirty inside, so much so, after cleaning I was sure it would work better. But it didn't, I checked lubrication of gears, good. Rotor and Stator were good no breaks in wiring. Replaced the starting capacitor, no improvement.

So I'm wondering why, if all the above are in order; what could be causing it to start so hard? Is it a mechanical or an electrical problem?
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SimpleMind
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Join Date: Sep 2009
Posts: 1056
Good Answers: 88
#1

Re: Motor startup

06/28/2012 2:10 AM

Have any means (multimeter etc) to measure the capacitor only current without getting electrocuted, before and after you spin it? Something is wrong with starting coil, capacitor (hope you replaced with a new one) and bad or wrong connection. There is no nr. 4. with the symptoms you describe. S.M.

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SolarEagle
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Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33392
Good Answers: 1817
#2

Re: Motor Startup

06/28/2012 12:11 PM

Your starting circuit is not functioning properly...It could be the start cap or potential relay, or a wiring connection or an improperly wired relay...If it is a start/run cap setup, the cap might be weak or bad or improperly wired...Follow link to find wiring type and use capacitor tester to check cap strength...This should be a 1/3 hp motor and take a 7.5 cap...just a guess...

http://www.brighthub.com/engineering/electrical/articles/44951.aspx

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bigg
Guru

Join Date: Jun 2010
Posts: 1296
Good Answers: 104
#3

Re: Motor Startup

06/28/2012 1:58 PM

Does this motor have a centrifugal start switch? If so, maybe the contacts are burnt and not making contact.
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AZ Miner
Associate

Join Date: Jan 2009
Posts: 43
#4
In reply to #3

Re: Motor Startup

06/28/2012 7:37 PM

Thanks, that did the trick.

Thanks everyone for your input, I really do appreciate it.
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bigg
Guru

Join Date: Jun 2010
Posts: 1296
Good Answers: 104
#5
In reply to #4

Re: Motor Startup

06/29/2012 8:13 AM

You're welcome, and thanks for the feedback.
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Carl Van Wormer
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Join Date: Mar 2012
Posts: 42
Good Answers: 5
#6
In reply to #4

Re: Motor Startup

06/29/2012 12:51 PM

Which of the multiple offered solutions did the trick? Was it the capacitor, contacts, wiring, or something else?
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AZ Miner
Associate

Join Date: Jan 2009
Posts: 43
#7
In reply to #6

Re: Motor Startup

06/29/2012 1:12 PM

It was the contacts.
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alpha
Active Contributor

Join Date: Feb 2012
Location: Manila, Philippines
Posts: 24
#8

Re: Motor Startup

06/30/2012 10:09 AM

did you clean the motor winding? if yes, have your re-insulated the motor winding?

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AZ Miner
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Join Date: Jan 2009
Posts: 43
#9
In reply to #8

Re: Motor Startup

06/30/2012 11:59 AM

Yes and no. I did clean the windings and there was a lot of what appeared to be old pieces of insulation in the gupe. I did not think to re-insulate as I would not know how to do that, unless there is a spray or liquid I could use. Is there such a thing? and if so, where would I find it?

Thanks
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alpha
Active Contributor

Join Date: Feb 2012
Location: Manila, Philippines
Posts: 24
#10
In reply to #9

Re: Motor Startup

06/30/2012 1:48 PM

Yes there is a insulation varnish use to reinsulated the old windings. yes it is a spray type of varnish.

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Users who posted comments:

alpha (2); AZ Miner (3); bigg (2); Carl Van Wormer (1); SimpleMind (1); SolarEagle (1)

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