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Control a Fan With a VFD Based on Temp

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  • Control a Fan With a VFD Based on Temp

    I need to control a fan with a VFD based on temp. The temperature range will be from 0F - 80F and there will be a different frequency output based on the temperature being received from a weather station. I attached a basic program just to see what was possible so I may be going down the wrong path. Since there will be at least 10 different frequency outputs is there a better way to do this than using the compare function? Thank you
    Attached Files


  • #2
    1. I believe compare is about all that's available in a Click.
    2. If you're operating a GS drive, your write for speed reference should go to address 402331.
    Why worry? If you've done the best you can, worrying won't make it any better

    - Walt Disney

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    • #3
      If you want one of limited number of specific values I suppose a series of compares might be clearest, if there are only 10 then with copy and paste is shouldn't take long. The CLICK does have the "SEARCH" function, but that might just make the code harder to understand.
      If there is a mathematical relationship between temperature and frequency and you don't mind a continuous range of frequencies, you could just calculate the frequency on the fly, the CLICK has decent math capability.

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      • #4
        Use a temp transmitter that turns into analog signal which feeds back to vfd analog in. No plc.

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        • #5
          I agree.

          Feed the analog temp signal right into the VFD and let it do it's thing. No PLC.

          I can't tell if you need to do something temp input-speed proportional or whether you want to maintain a setpoint with a PID based on the info you gave.

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          • #6
            Thank you everyone for the feedback. The scope of the project is for climate control in a dairy barn. This includes fans that will adjust speed based on temp and curtains along the openings of the building that will open and close in increments based on temp and wind chill. If fans were the only item we would use a temp signal straight to the VFD. Opening and closing curtains is going to be done using stepper motors. We will also be incorporating a HMI so we need the PLC. I should be all set with the feedback given. Thanks again

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