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?

 

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.

 

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.

 

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.

 

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.

 

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.

 

It's an interference suppressor and would connect like this:

 

Thank you very much. I can get some new caps now.

 

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.

 

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.