compressor motor will not start.....

Discussion in 'General Electronics Chat' started by bigblock81, Feb 24, 2013.

  1. bigblock81

    Thread Starter New Member

    Feb 24, 2013
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    Hello to all and thank you in advance for any insight you can give me. I installed an outlet plug for my three wire 240v 30 amp air compressor today and when it turned on, I shut off the breaker to make sure I had the right circuit. I made the change, tried it and it was working fine. I did the same thing again, when it was running I tripped the breaker to reroute a wire. Now it will not work, nothing at all, not a sound. I have never used the breaker before to turn it off and am afraid I messed something up. It has power into the motor on the two hots according to my meter, pressure switch is fine. I tried the red reset button, spinning it by hand, and letting all air out. Please help.
     
  2. #12

    Expert

    Nov 30, 2010
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    Seems too simple from here. The 240 volts is being applied to the terminals of the motor and the motor doesn't even notice. The motor only has one job: to turn when 240 volts is applied to its power terminals, therefore, the motor has something wrong with it.

    (Spinning it by hand removes the capacitor from the equation.)
     
  3. bigblock81

    Thread Starter New Member

    Feb 24, 2013
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    Maybe I didn't say this right, I only moved the motor with a screw driver through the guard a few turns from where it was, not spun it over rapidly with power applied.

    I guess I was looking for something easy. Maybe something simple I am missing.
     
  4. #12

    Expert

    Nov 30, 2010
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    Well, I bought a cheap compressor from Harbor Freight and the wire fell off the capacitor. It wouldn't start, so I looked at the wiring and found the problem without a meter.
     
  5. bigblock81

    Thread Starter New Member

    Feb 24, 2013
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    Looks like I will do more detective work. Are both "humps" on the motor capacitors? I will look at all connections, and see if I can find instructions on how to test capacitors. I am an autobody tech with limited experience repairing ac motors.
     
  6. JDT

    Well-Known Member

    Feb 12, 2009
    658
    85
    Probably. If you have two capacitors, one is the starting capacitor and the other is the "run" capacitor.

    The starting capacitor is disconnected when the motor gets up to speed either by a centrifugal switch or an electronic circuit.
     
  7. tinkerman

    Member

    Jul 22, 2012
    136
    34

    Any sound from the motor when you apply power? If not there is an open circuit somewhere.
     
    Last edited: Feb 25, 2013
  8. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    Another thing fits your description. Are you using a double breaker?
    If you are using two single pole breakers and when you "re routed" your wire, you picked another breaker on the same phase it won't run.
    To check this put your voltmeter on ac volts and check across the two hots coming in. You should read your 220-240 volts. If you get no reading across the two hots, but get 120 to ground you have them connected to the same phase in the panel.
    According to code you need to be using a double pole breaker, or tie the handles together( a piece of wire through the holes in the handles)
     
  9. bigblock81

    Thread Starter New Member

    Feb 24, 2013
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    No sound at all.

    I will check about it being on the same phase. I ran out of room in my panel so I took out the regular 30 amp breaker and put in a space saver 30 amp breaker. It looked like it was on the same phase, so I will post my results.
     
  10. gerty

    AAC Fanatic!

    Aug 30, 2007
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    A space saver is 2 breakers on the same phase.

    edit: for those that aren't familiar with space savers, they give you 2 circuit breakers in one slot. Which means they are on the same phase and cannot be used for a 220 volt application.
     
  11. bigblock81

    Thread Starter New Member

    Feb 24, 2013
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    You sir are correct! When I bought the space saver breakers, one 30 amp and one 50 amp, the guy at the hardware store picked them out and said they would work for 220. WRONG! I should have stopped when it looked fishy as I was installing them and noticed they were on the same bar.

    I am glad gerty looked outside the box!

    I installed the old breaker and it works.

    I did not know to measure between the leads for 220v. I only went from each lead to ground. Thank you for the lesson!

    Thank you all for your input, I would have looked even more dumb taking the motor off and to a shop for them to tell me nothing is wrong with it!!:)
     
  12. #12

    Expert

    Nov 30, 2010
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    This is the statement where most of us assumed you merely rerouted the wire, not moved where it was connected in the breaker box.
     
  13. bigblock81

    Thread Starter New Member

    Feb 24, 2013
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    Yes, I threw you all off, I had no idea the breaker would have made this mess, I was too focused on the motor, and not what I had done. Lesson learned!
     
  14. gerty

    AAC Fanatic!

    Aug 30, 2007
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    Don'tcha love it when a plan comes together :D
     
    bigblock81 likes this.
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