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Capacitors

I would not reduce the voltage rating, even temporarily. The comp. would over load, how much, depends. The compressor is too expensive and the clean up after a burn out is something you would want to avoid. Leave it down until the proper parts are obtained.

Comments

  • Barrington White
    Barrington White Member Posts: 37
    Run Capacitors

    Lets say you are working on a compressor that is rated to have a 60 microfarad 440 Volt capacitor and all you had was 70 microfarad 370 Volt capacitor so you decided to put it in. What would happen to the Compressor?

    Lets say you had half the amount of refrigerant that was suppose to be in there, do you think the compressor could overcome that load and start with that same capacitor?

    Lets say you had a fully charged system, do you think that compressor would over come that load and start, with that same capacitor?
  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,549
    Wow

    You've got a lot of questions Nate. The capacitor can exceed voltage (a 440v cap will work in place of a 370v cap). The MFD can vary by 10%, which basically means you need the right MFD cap. What will happen if it's wrong? I don't know. Don't find out. Use the right parts for the job. I'd guess the compressor would run less efficiently/draw more amps. Just a guess.
  • lee_7
    lee_7 Member Posts: 458


    like paul stated a 440 v will work in place of a 370 v, but a 370 v won't work in place of a 440 v
  • Techman
    Techman Member Posts: 2,144
    WOW also

    Nate,as Dan H says "IT DEPENDS".There's alot of maybe's or could be's in your Q.The bottom line is DON"T DO IT!The comp may start and run BUT for how long AND at what damage to the comp.For 2 minutes? 2 hours? 2 days? Once damage is done it can't be undone!
  • Rich W
    Rich W Member Posts: 175
    ELI the ICE man

    > Lets say you are working on a compressor that is

    > rated to have a 60 microfarad 440 Volt capacitor

    > and all you had was 70 microfarad 370 Volt

    > capacitor so you decided to put it in. What

    > would happen to the Compressor?

    >

    > Lets say you

    > had half the amount of refrigerant that was

    > suppose to be in there, do you think the

    > compressor could overcome that load and start

    > with that same capacitor?

    >

    > Lets say you had a

    > fully charged system, do you think that

    > compressor would over come that load and start,

    > with that same capacitor?



  • Rich W
    Rich W Member Posts: 175
    ELI the ICE man

    You're right on target about starting torque.

    The motor coil is an inductor.

    Voltage (E) leads current (I) in an inductive (L) circuit-that's ELI.

    When voltage and current are out of phase like this, your torque drops.

    Adding just the right capacitance brings the voltage and current back in phase for max starting torque...

    FYI Current leads voltage in a capacitive (C) circuit. ICE
  • JackEnnisMartin
    JackEnnisMartin Member Posts: 70
    Running Caps.

    Hello
    I have been asked this question many times and I will say it again: USE A CAP. WITH A HIGHER RATING OR THE ORIGINAL VOLTAGE NEVER-- EVER USE A CAP. WITH A LOWER VOLTAGE RATING.I have seen the cap that is undersized in voltage instantly bulge causing winding damage and once - I hope it is only once the cap. blew a crack in the metal of the cap. Not a pretty or safe result. The cap. voltage is rated at the inrush voltage of the machine and is carefully engineerd for safe orperation. Good luck and remember -- WEAR SAFETY GLASSES WHENEVER YOU DO THIS KIND OF WORK -- you are gifted with one pair of eyes. Good luck
    and all the best -- hug your kids we are the past they are the future.
    Jack Ennis Martin
  • Techman
    Techman Member Posts: 2,144
    370 0r 440

    Hi Nate,the next chance you get,go to a unit that you KNOW is running GOOD,and do a running voltage test.First ,turn off the unit by means of the disconnect and remove the comp terminal block cover.Then restart the unit. Then test for line voltage at the line side or load side of the contactor.Then check the voltage on the comp terminal block,First test C-R and you will get the same voltage that you had at the contactor.Then test the voltage on C-S and you will get a higher than line voltage reading.Some comp's will have 320vac or so,some will have 280vac or so thus the required 370vac run cap.Then some comp's will have 390vac or so ,some will have 415vac or so, thus the required 440vac run cap.So you cannot put a 370vac run cap on a comp that "produces" 415vac on the start winding.Every comp w/ a run cap is this way.Test away and see!
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    Very Important Terry

    Sounds like you can now teach a lesson on how potential magnetic relays work!
  • Barrington White
    Barrington White Member Posts: 37


    > Hi Nate,the next chance you get,go to a unit that

    > you KNOW is running GOOD,and do a running voltage

    > test.First ,turn off the unit by means of the

    > disconnect and remove the comp terminal block

    > cover.Then restart the unit. Then test for line

    > voltage at the line side or load side of the

    > contactor.Then check the voltage on the comp

    > terminal block,First test C-R and you will get

    > the same voltage that you had at the

    > contactor.Then test the voltage on C-S and you

    > will get a higher than line voltage reading.Some

    > comp's will have 320vac or so,some will have

    > 280vac or so thus the required 370vac run

    > cap.Then some comp's will have 390vac or so ,some

    > will have 415vac or so, thus the required 440vac

    > run cap.So you cannot put a 370vac run cap on a

    > comp that "produces" 415vac on the start

    > winding.Every comp w/ a run cap is this way.Test

    > away and see!



    I've tried that and I end up burning the tips on my volt meter leads
  • Techman
    Techman Member Posts: 2,144
    Darn!

    What kind of meter do you have ? I hope you didn't touch probe tip to probe tip[L1 to L2], which would be a direct short !I test C-S all the time and NO problems!If it is physically hard to test at the comp terminal block ,then test at the run cap,from the wire that goes from the cap to the start winding and the other leg of line.And have the meter set on the 600vac setting,since you are testing for up to 440v. DARN!
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