strange capacitor

Discussion in 'General Electronics Chat' started by jamus, Jul 18, 2014.

  1. jamus

    Thread Starter Member

    Feb 11, 2013
    53
    0
    Does anyone know what the configuration is inside this capacitor? It is from the windings of a AC motor from the 1950's. Two wires go in, a ground lead comes out. Perhaps I should just tear it apart to find out?
     
    Last edited: Jul 18, 2014
  2. k7elp60

    Senior Member

    Nov 4, 2008
    478
    69
    It might be a special configuration. The ground lead you talk about just might connect to one of the other leads. It looks like a motor run capacitor, so an
    extra wire is possible.
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,049
    3,244
    It would appear to be a dual capacitor in one case with a common ground lead. If it's from a DC motor it may be to suppress EMI from the commutator sparking and/or increase the brush life.
     
  4. jamus

    Thread Starter Member

    Feb 11, 2013
    53
    0
    crutschow:
    Dual? It has three capacitance values on the casing

    I would like to replace the capacitor if possible. Tearing it apart didn't really give me any more clues. I will post a picture of the inside tomorrow.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,564
    2,379
    Too small to be a motor run cap, in value and physical size.
    Do you suspect anything wrong with it before tearing it apart.
    Is this a single phase, 3 phase or small shaded pole motor?
    Max.
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    It's a dual .075 uF cap to common ground. The third cap value (.006) is just an artifact of the cap construction, they list it on the label to be nice.

    I believe it's a brush arc suppressor like Crutschow said.
     
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,804
    1,105
    It's an interference suppressor and would connect like this:
     
  8. jamus

    Thread Starter Member

    Feb 11, 2013
    53
    0
    Thank you very much. I can get some new caps now.
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,564
    2,379
    What is the reason for replacing it? did it cause a problem? It should have no effect on the actual ability of the motor to run.
    Max.
     
  10. jamus

    Thread Starter Member

    Feb 11, 2013
    53
    0
    My problem is a mechanical one and I know how to fix it. The capacitor is 50 years old and leaking black gunk so I want to replace it.
     
Loading...