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Thread: Compressor RLA

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  1. #1
    Join Date
    Sep 2007
    Location
    NH
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    1,157

    Compressor RLA

    Compressor LACA-031-TAC
    RLA 10.0A
    Case old open multi deck frozen meat Tyler d6f8
    Ref hp80

    Unit tripped breaker store reset and called in service call.
    I arrived and found compressor off on overload cooled off and found running high suction and high head like 40psi and 310psi and high amps 16a or so.
    Adjusted CPR down to 16.4psi (-22F) and 282psi and amps at 10.86A.
    suction psi in case 34psi. Case temp at 24*

    Looked up compressor on the copeland calculator and found amps dead on, but not outside opperating envelope.

    Compressor is inside opperating envelope until about 26psi and 282psi at 14.8A

    Question is how much over RLA can I run this compressor?? Or should I run it over RLA??

    Would like to run suction as high as I can, do to store being very hot and humid with the open frozen case... This thing is not going to win any races with the CPR holding back.

    Left case running over night to see how it pulls down.
    Last edited by Dchappa21; 08-02-2012 at 05:58 PM. Reason: forgot refer

  2. #2
    Join Date
    Apr 2012
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    Paper Street Soap Company
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    2,304
    service factor x RLA if you can find it.

  3. #3
    Join Date
    Mar 2007
    Location
    pittsburgh, pa
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    541
    I was told you can go 125% above rla.

  4. #4
    Join Date
    Jul 2000
    Location
    Guayaquil EC
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    10,392
    I checked Emerson's Online Product Info (OPI) and it look like the maximum continuous current (MCC) for that compressor is 12.9 A, so I'd feel safe just below that...like around 12 A.

  5. #5
    Join Date
    Sep 2007
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    NH
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    Sweet thanks Ice. An extra amp will help this thing out.

  6. #6
    Join Date
    Feb 2008
    Location
    California
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    2,066
    So all this time it's been taught to set the CPR to the compressor nameplate RLA.

    But it's actually proper to set the CPR to just below the MCC.

  7. #7
    Join Date
    Jul 2000
    Location
    Guayaquil EC
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    Quote Originally Posted by Phase Loss View Post
    So all this time it's been taught to set the CPR to the compressor nameplate RLA.

    But it's actually proper to set the CPR to just below the MCC.
    I didn't mean to say using the MCC was proper. It is possible however.

  8. #8
    Join Date
    Feb 2004
    Location
    British Columbia, Canada
    Posts
    527
    Quote Originally Posted by icemeister View Post
    I didn't mean to say using the MCC was proper. It is possible however.
    I too was taught to set at RLA but I can't see why using Ice's method wouldn't work. It is still "under" the max cc as stated by the manufacturer.

    "Winning the race" on some of these old waterlogged/deteriorated-insulation, inefficiently designed cases is needed to get and hold the proper temp as soon and as long as possible between defrosts and off cycles.
    So if a guy can tweak a little more refrig effect out of a compressor without tripping the breaker or intern/overload then it sure would help.

    It's a gamble that is at least an option.

  9. #9
    Join Date
    Sep 2007
    Location
    NH
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    1,157
    Yep. I have always gone just above rla in most cases, an amp at most.

    Never new about the MCC till ice mention it.

    Compressor ended up runing around 12a and will get below that an hour or so out of defrost.
    And it's enough to keep the meat frozen...

    So there happy. Tried talking em in to replacing the open frozen case with some glass doors. And a new cond unit to boot. Telling them how much money they would save, they said we can't do that we wouldn't have any air conditioning then.

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