Capacitor start motor

Discussion in 'General Electronics Chat' started by bwd111, Oct 10, 2013.

  1. bwd111

    Thread Starter Member

    Jul 24, 2013
    117
    1
    would the capacitor start motor fail to start when the cap is open,out of phase or shorted? Its hard to get to the cap but thinking open for sure its not going to start
     
    Last edited: Oct 10, 2013
  2. tinkerman

    Member

    Jul 22, 2012
    136
    34
    If it's open it will not start. You could wrap a string around the shaft and give it a spin while powering up the motor. That should get in running and prove there is something wrong with the start winding circuit. It could be the cap, open winding or bad start switch. It should still start with a shorted cap but lack starting torque. Out of phase?? no. The cap is used to increase the phase shift between the start and run windings and give the motor greater starting capabilities.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    Incidentally the string start method to test the start winding/switch can be done with a pull in either direction, if open start circuit is suspected.
    Max.
     
  4. BobTPH

    Active Member

    Jun 5, 2013
    782
    114
    And if it starts and pulls your hand into the rotating shaft... I'd be very careful with that method.

    Bob
     
  5. #12

    Expert

    Nov 30, 2010
    16,298
    6,810
    Using a bit of string is still better than trying to spin it with your bare fingers.:rolleyes:
     
  6. tinkerman

    Member

    Jul 22, 2012
    136
    34
    ya sure. I routinely check capacitors of this type by plugging them very quickly into an AC outlet and then immediatley short the terminals. People had a fit about that too when I posted this method.
     
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