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  1. #1
    Join Date
    Jun 2008
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    EXV and Compressor Variable speed drive


    Hi,

    can someone please explain on how EXV and Compressor VSD work together? Will EXV send signals to the compressor VSD to regulate the flow rate?

    please advice.

    Thanks
    -jp



  2. #2
    Join Date
    Mar 2008
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    Re: EXV and Compressor Variable speed drive

    Hi JP,

    From my experience, the required cooling load will be worked out by the main control unit for the chiller/refrigeration machine, from the leaving water/air temperature and the time it took to reduce the temperature.
    The control unit will then send a signal to both the compressor and EXV to regulate the refrigerant flow and pressure difference to match the required cooling capacity; if possible.

    I hope this helps, though it is a bit vague. I have done a lot of work with Turbocor units, and they generally work on this principle.

    Thanks,

    Bash

  3. #3
    Join Date
    May 2006
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    India
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    Re: EXV and Compressor Variable speed drive

    The vsd needs a signal to change the frequency of vsd . The signal is either from a pressure transducer mounted on the casing of compressor . In other words, the suction pressure change due to fall in load is sensed by pressure transducer & it is converted in a 4 to 20 milliamp signal .the signal changes the frequency & hence the speed .
    You can install a temperature transmitter to achieve the frequency change .the exv will respond on the pressure differential across it`s port

  4. #4
    Join Date
    Mar 2006
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    Merate (LC) - Italy
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    Re: EXV and Compressor Variable speed drive

    EXV and VSD do not necessarily know what they are doing one another. They are on different control loops. EXV is regulated on superheating, VSD on heat load.

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