What the MFD?

Old 06-18-05, 10:38 PM
Too Hot in MD
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What the MFD?

As i replace the motor in my heat pump I am also replacing the capacitor. Grainger lists a compatable capacitor with a 7.5 MFD and then lists an alternate capacitor with identical specs and a 5 MFD.

What is MFD?

I could make a few guesses, but there is no call for profanity.

Old 06-19-05, 05:33 AM
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Too Hot in MD,

I have not seen a capacitor run motor with two choices of capacitor.
Make sure the "alternate" capacitor is not for use with a different voltage or frequency.
Chose the primary rating if unsure.
Old 06-19-05, 08:13 AM
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Too Hot in MD

Farad (F): The basic unit for capacitance. A capacitor has a value of one farad when it has stored one coulomb of charge with one volt across it.

Microfarad (mfd, MFD, or mfd): One millionth of a farad.
Old 06-19-05, 11:10 AM
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Guess having a measurement of capacitance makes sence.
As for the alternate. . . Not sure why one wouldn't go with what was actually recommended.

Thanks, I learned something.
Old 06-19-05, 05:32 PM
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Some motors use different capacitors to yield different horsepower ratings. For example: One motor I use will yield 1/3 HP with a 10 mfd cap & 1/2 HP with a 15 mfd cap.
Tip: If the motor you are getting specs a 370 volt cap, use a 440 volt cap at the same mfd rating. For some reason they hold up better & metal cased caps seem to last better than plastic cased ones.

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