Baldor 5hp Compressor Motor Help

Discussion in 'General Electronics Chat' started by ric44, Jul 1, 2010.

  1. ric44

    Thread Starter New Member

    Jul 1, 2010
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    Im new here but have a question Id like to ask those in the know if I may. I just replaced the motor on my Ingersoll-Rand T-30 air compressor at considerable expense. I thought the motor was fried because it got slower and slower to start then finally would not start at all and gave a puff of smoke. I thought it was odd that the motor would give up the ghost like that as Ive always taken care of it and it didnt have a lot of hours on it although it is about 23 or so years old. As I was changing the motor out today I noticed some oily residue leaking out from under the top cover where the capacitors sit. Upon closer inspection I see where the two starting capacitors have been leaking and they smelled burnt. The run capacitor however looked ok. Is it possible the start capacitors have been my problem all along and that my motor windings are ok ? I can order the two new capacitors for about 30 bucks but dont want to if the motor windings are shot . Id like to get the old motor back up for a spare. I did sniff around the louvered end plate but really didnt smell anything burnt there............what say you? Thanks, Rick
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Yup..
    You need to change those caps.
    I advise you to change all of 'em just to be on the safe side
    Check for proper ratings and capacity
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    The caps are bad. If one went, the other is likely not far behind.

    Letting a motor run under duress until you see "a puff of smoke" is usually not a good thing, as smoke usually causes large bills to fly out of your wallet.

    Most motors have a thermal switch in the frame to cut power if they are overloaded.

    I'd certainly replace the caps with same-rated new ones, and give it a try.

    Do you have a motor rebuild shop nearby? If so, you might have them megger the windings to make sure it's not shorted internally. If it is, then new caps would be a waste.
     
  4. ric44

    Thread Starter New Member

    Jul 1, 2010
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    NO motor rebuilder near me so I may go ahead and invest a few bucks to see if it will spin.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Don't buy caps from an auction site. Use a factory-authorized distributor.

    Auction site sellers may be posting "new old stock", which is basically why yours failed in the first place.

    Make certain that the new caps meet or exceed the voltage rating.
    The capacitance values are very important, too. If they are wrong, you will use a lot more power than if they were correct.
     
  6. ric44

    Thread Starter New Member

    Jul 1, 2010
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    My starting caps are 216-259 mfd 250v according to my motor frame no. that I googled. I intended to buy them on ebay but will ask the seller if they are fresh stock before I do. Thanks for the tip sgtwookie. PS.............this compressor is over 25 years old I suppose thats why the caps went bad.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Like I said, don't buy the caps on an auction site. Use a large authorized distributor like Mouser, Digikey, Newark, Avnet Express, Allied, etc.

    That way you can be certain that you are getting what you are paying for. An E-bay seller will likely have NO idea how long the caps have been sitting around; they bought them as surplus to begin with. Unless you have a cap tester that also has a re-forming feature, save your money and buy known-fresh caps from one of the distributors I suggested.
     
  8. retched

    AAC Fanatic!

    Dec 5, 2009
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    I second that. You really do not want to go the auction route for Electrolytics.
     
  9. VoodooMojo

    Active Member

    Nov 28, 2009
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  10. Hagen

    Active Member

    May 8, 2010
    30
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    Make sure that the compressor is properly bleeding off the air pressure in the head every time the pressure switch opens. You should hear air escape as the motor stops.

    The oil may be from the run cap, since they are oil-filled, and will leak if ruptured.

    Are you running the motor on 230 volts? It is generally recommended to run any motor 1 HP or bigger on 230. The reason is that the inrush current tends to drop the supply voltage at the motor, which can drastically reduce starting torque, which in turn causes the starting caps to remain in the circuit longer. Inrush current on 230 volts is half the 125 vac inrush current.
     
  11. Dx3

    Member

    Jun 19, 2010
    87
    7
    It is generally recommended that you run the motor on the voltage it is rated for. DO NOT connect a 120 volt motor to 230 volts!
     
  12. 5&under=sorcery

    New Member

    Jul 4, 2010
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    Run your common ohmmeter across from the case to each of the motor leads. If it is badly burned internally, or even if the rotor has been wobbling due to wear, you would probably show less than infinite resistance. Try rotating the shaft as you take your readings. I have found most burned motors are ground faulted and don't require anything as exotic as meggering.
     
  13. ric44

    Thread Starter New Member

    Jul 1, 2010
    4
    0
    Will give that a try thanks.
     
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