burnt start capacitor on air compressor
 

Hi, ran into a little problem with my air compressor. Discovered that this capacitor (start capacitor I believe) was burning. This was from a Husky 80 gallon compressor with a 4HP motor.
The capacitor itself had this stuff on the label. Some of it was a little hard for me to read so this may not be 100%.

45.F +/- 5% PO 50/60 HZ
400V ~B <10000h>
440V ~C <3000h> SH
L622851 19/04/06
IEC 60252 61048/61049
Made in Brazil 25/85/2

The brand might be WED but hard to read. Google isn't finding me any exact matches. I pulled up the parts list for the compressor but they only list the whole motor which is $$$. This capacitor is easily replaceable so not sure why they don't list a part number.

Question is which of this information is key if I look for a replacement? Is there any good reason to expect that something else went bad causing this to burn up? Anyone know a good source for these?

Thanks!

Re: burnt start capacitor on air compressor
 

45 micofarad and 400 to 440 volt rating. Is this on a 240 volt single phase application? If so, a 330 to 450 or even 500 volt cap in the 45 mF range will work. Caps aren't necessarily an exact science. The larger the mF rating the more punch it has at startup.

Re: burnt start capacitor on air compressor
 

Also, if you can get one with close to the same footprint so it will mount.

Re: burnt start capacitor on air compressor
 

A cap of similar size and rating should be fine. Doesn't have to be exact.

Re: burnt start capacitor on air compressor
 

On thing that can put a tremendous load on startup is tank pressure going backwards into the cylinder head. A check valve with a blow off is best so after shutdown it can bleed off the remaining head pressure so the motor doesn't have to fight it. Usually after shut down you will hear a hissing sound.

Re: burnt start capacitor on air compressor
 

Thank you for your responses. Found this one, but I don't understand the "Single Microfarad" in the description. The rest looks like a match and the dimensions are right.

Fasco C4RS45 Proline 45 Mfd/440-volt Single Microfarad Capacitor with 2-Inch Base Size and 3.88-Inch Case Height

Re: burnt start capacitor on air compressor
 

Some caps are double. They will have 2 different size caps in one package with 3 terminals. One for each cap and a common. These are commonly used in an application that needs a start and run cap.

Re: burnt start capacitor on air compressor
 

You might check with SurplusCenter for a future choice.

http://www.surpluscenter.com/Electrical/Capacitors/

Re: burnt start capacitor on air compressor
 

That capacitor will work just fine.

Re: burnt start capacitor on air compressor
 

Sorry, I usually am pretty good about coming back and giving an update on my threads, but forgot on this one. I did get that capacitor. It was a little large to fit back under the cover, but I made it work and the compressor is working fine. Thanks for all the help!