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  1. #1
    Join Date
    Dec 2007
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    49

    Why dont we see more run caps on commercial...

    ...refrigeration compressors. yea I see a few now and then but it not like a residential AC unit where EVERY unit has a run cap (to increase power factor). Maybe the mfg's (copeland, tecumseh, aspera, etc) dont have as strict of governmental guidlines as AC mfg's do with SEER ratings and all............hmmm. Both motors, AC or refer, use motors that are large inductive loads. You would think we would see all referigeration compressors with run caps.

    Any thoughts..........

  2. #2
    Join Date
    May 2009
    Location
    The Pas, Manitoba Canada
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    3 phase

  3. #3
    Join Date
    Dec 2007
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    49
    I'm mainly referring to 1 ph compressors..

    BTW...power factor correction devices (capacitors) can be installed on 3 phase equipment

  4. #4
    Join Date
    Feb 2004
    Location
    Medford Oregon
    Posts
    807
    "3 Phase"
    I used run capacitors on 3PH for years, especially with low voltage problems
    they have to be properly sized but can increase power factor
    see Copeland AE9-1249 at: http://www.hvacrinfo.com/cope_ae_bulletins/TAE1249.PDF

  5. #5
    Join Date
    May 2009
    Location
    The Pas, Manitoba Canada
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    212
    I stand corrected. How much can power factor be improved on systems with proper voltage? Does 1 capacitor burning out cause any damage to the motor windings?

  6. #6
    Join Date
    Jun 2005
    Location
    Las Vegas NV
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    1,152
    Quote Originally Posted by vettehead View Post
    then but it not like a residential AC unit where EVERY unit has a run cap
    The residential units don't use fractional HP compressors (with the exception of mini-splits). Most, not all, fractionals through 3/4 HP have an "Induction Run - Capacitor Start" type motor.

    The 1 HP and larger compressors, A/C and Refrigeration, have either a "Capacitor Run - Capacitor Start" or "Capacitor Run - Permanent Split Capacitor" type mptor.

  7. #7
    Join Date
    Dec 2007
    Posts
    49
    If the capacitor has failed the motor (compressor) usually doesn't run at all. If it is weak the motor will run at a higher amperage and will run hotter. Either way it's a no good sitcheeation.

    Great link Rocket. Thank you !
    Last edited by vettehead; 09-08-2010 at 12:40 PM.

  8. #8
    Join Date
    Jun 2003
    Location
    Chicago, IL
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    4,357
    Quote Originally Posted by powell View Post
    The residential units don't use fractional HP compressors (with the exception of mini-splits). Most, not all, fractionals through 3/4 HP have an "Induction Run - Capacitor Start" type motor.
    many residential refrigeration compressors 1/4 hp and smaller have run caps now. I think the reason is to meet energystar requirements that are required for the appliances to qualify for various rebate programs. many of these units even have VS ECM evaporator motors that vary their speed with the required cooling load and some have ECM condenser motors

  9. #9
    Join Date
    Dec 2007
    Posts
    49
    Gosh isn't that the truth. I started in this business in 1979 doing nothing but domestic refrigerators. (NO I'm not an appliance repair person, I'm a refrigeration man..dammit!) Thru the 80's amp draw on the cooling cycle was 5-6 amps...on 25 cu. ft. fridges... further.. many defrost cycles were drawing MORE power! (anyone remenber the ol GE s/s with the triple heaters?). I used to tell customers it takes more power to defrost your fridge than it does to cool it!

    Now the same 25 cu ft s/s is drawing less than 2 amps in cooling mode! Tremendous improvement because of things like run caps on the fractional hp compressors, solid state controls, thermisters, etc. The biz used to be easy....

  10. #10
    Join Date
    Jun 2005
    Location
    Las Vegas NV
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    1,152
    Quote Originally Posted by craig1 View Post
    many residential refrigeration compressors 1/4 hp and smaller have run caps now.
    craig,

    Being that you referenced my post directly and rejected my statement let me say that vettehead did not mention domestic. He was comparing A/C to commercial refrigeration from what I read in the content of his post.

    You've brought domestic into the picture which is a different world, as you noted.

  11. #11
    Join Date
    Jun 2003
    Location
    Chicago, IL
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    4,357
    Quote Originally Posted by powell View Post
    craig,

    Being that you referenced my post directly and rejected my statement let me say that vettehead did not mention domestic. He was comparing A/C to commercial refrigeration from what I read in the content of his post.

    You've brought domestic into the picture which is a different world, as you noted.
    I read the original post on my phone and then replied from my computer later on without re-reading the OP. Somehow I remembered it as comparing resi to commercial refrigeration.

  12. #12
    Join Date
    Jun 2005
    Location
    Las Vegas NV
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    1,152
    I don't see much domestic business. So they're actually using compressors with run caps? They usually just have a current relay.
    Last edited by powell; 09-09-2010 at 03:09 AM.

  13. #13
    Join Date
    Apr 2002
    Location
    Dallas, TX
    Posts
    2,987
    Quote Originally Posted by powell View Post
    I don't see much domestic business. So they're actually using compressors with run caps? They usually just have a current relay.
    Domestic refrigerator/freezer market is still a dog eat dog world. RSIR motors are still popular.
    If the only tool you have is a hammer, you tend to see every problem as a nail. – Abraham Maslow

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