Anyone educated with capacitors???

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Old 05-25-12, 09:53 AM
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Anyone educated with capacitors???

I have a capacitor off of a air compressor, I'm assumiong it is bad cause the compressor motor will try to start for a few seconds then trip the reset button.
I don't even know if it is a start? run? start&run? capacitor. Here is what is on it.
CBB65A
130uf +_ 5% SH
250v ac 50/60Hz
40/85/21 C P1
internally protected
10000AFC PB1 300

E302127

I've looked for it but can not find. Is there something else I can use that is close and will work?
Thanks for the help.... Oh, the compressor is 2.5HP motor.
 
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Old 05-25-12, 10:47 AM
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Only two terminals? The terminals MAY be doubled but if there are only two then it is definitely a starting capacitor. Replace it with another 130 mfd (or uf) capacitor with a voltage rating of at least 250 volts. The mfd/uf rating may be as low as 123.5 or as high as 136.5 and the voltage rating 250 volts or higher.

Actually pretty common and available from most motor repair shops or from Grainger.
 
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Old 05-25-12, 10:50 AM
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If I remember correctly, it is generally the starters that go on those compressors.
 
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Old 05-25-12, 11:32 AM
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yes only 2 terminals. So I can use a 123.5 - 136.5 250v or higher? I have not been able to find an exact 130 except for the small ones, not the big round silver ones.

If it was good it would hold voltage and spark when crossing terminals correct?
 
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Old 05-25-12, 12:20 PM
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Use a multi-meter to test it.
Caps discharge really quickly (some quicker then others), so it may have lost it's charge by the time you cross the terminals (which is not a safe way to test btw).
 
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Old 05-25-12, 01:09 PM
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When I was finishing up a Residential and Commercial diploma course back in the early 90's I tried to help out the newbies as much as possible. One guy was a know-it-all jerk. He was stumped on capacitors, and just didn't understand. I told him to go pick up one of our test caps off the shelf. Mind you test terminals are sticking straight up. Well now HE knows more about capacitors than he wanted to I heard the snap across the room.
 
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Old 05-25-12, 02:08 PM
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The original capacitor has an internal bleed resistor so it won't hold a charge and it also cannot be tested with the "kick" of a multimeter.

Grainger has one that will probably work just fine as long as the dimensions allow it to fit in the enclosure.

Start Capacitor, 124-149mfd, 220-250 V, Rnd - Capacitors - Motor Supplies - 2MET1 : Grainger Industrial Supply

Understand that a faulty capacitor is not the only reason that your motor may not run. It could be a damaged centrifugal switch or burnt-out starting (or running) winding or broken internal connections.
 
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Old 05-25-12, 02:11 PM
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Originally Posted by chandler View Post
When I was finishing up a Residential and Commercial diploma course back in the early 90's I tried to help out the newbies as much as possible. One guy was a know-it-all jerk. He was stumped on capacitors, and just didn't understand. I told him to go pick up one of our test caps off the shelf. Mind you test terminals are sticking straight up. Well now HE knows more about capacitors than he wanted to I heard the snap across the room.
Oh man that brings me back to high school electronics class when we'd charge up axial-lead caps and toss them to someone.. "Here, catch!"
 
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