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  1. #1
    Join Date
    Nov 2004
    Location
    SW FL
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    6,387

    Cool

    Please verify the heat load for 60 HP Electric Motor.

    Six NEW pump motors are located in a small building at a water teratment facility.

    The BTUh load seems Quite significant along with the heating due to 93'F DB / 77'F WB in this area.

    Thanks in advance for "the Check".

    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  2. #2
    Join Date
    Sep 2002
    Location
    South Dakota
    Posts
    6,579


    Unless you know the efficiency ratings of each motor you can't figure out the waste heat they produce. If they were "zero" percent efficient (not realistic but just giving you the numbers), they would produce 3.42 btu of heat per watt. In other words they would be heaters rather than motors.

    If they were 100% efficient, they would not produce any waste heat at all. Instead, they would be putting all the input watts into mechanical rotational work out the motor shaft. This is also not possible.

    So, you need to know the motor efficiency in order to figure out the waste heat.

    Norm

  3. #3
    Join Date
    Sep 2002
    Location
    South Dakota
    Posts
    6,579


    BTW, the pumps the motors drive also produce additional heat due to friction. Yet another calculation.


  4. #4
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,387

    Efficiency of 60 HP

    Right !

    Efficiency is likely > 90% ...
    But How Much more?

    Only Experienced writers need apply ( write ).


    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  5. #5
    Join Date
    Sep 2002
    Location
    South Dakota
    Posts
    6,579

    If the motor efficiency is not listed on the motor data plate you can figure it out if the data plate lists the following information"

    voltage
    amperage
    power factor

    From there you can figure the waste motor heat.

  6. #6
    Join Date
    Sep 2002
    Location
    South Dakota
    Posts
    6,579




    %EFF = HP X 746 / V X A X PF X 1.73


    Use motor name plate data in the above equation and you will get the efficiency rating that the motor manufacturer did not list on the data plate.

    Don't bother using some average efficiency that you can find in some books. This equation gives you EXACTLY the right efficiency.

    Norm

  7. #7
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,387

    Thumbs up Thanks

    Originally posted by NormChris
    %EFF = HP * 746 / V * A * PF * 1.73

    Use motor name plate data in the above equation and you will get the Efficiency rating that the motor manufacturer did not list on the data plate.
    T H A N K S for the REALity Check.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

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