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  1. #1
    Join Date
    May 2015
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    ABB VFD for Air handling unit

    Dear all,
    can any one how i choose a vfd for fan motor
    because i think is undersize please help me to understand. is it suitable VFD installed?
    VFD specs:
    model: ACH550-01-012A-4
    volts 380-480
    Amp 11.9A
    power 5.5KW
    and motor specs are:
    Voltage:415
    Amperage:27.9
    RPM:1472
    Motor power:KW15

  2. #2
    Join Date
    Nov 2006
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    This is the general forum.

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  3. #3
    Join Date
    Sep 2007
    Location
    edmonds wa
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    I would have the distributor where you plan on buying from, help you size it.
    UA Local 32

  4. #4
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    Mar 2015
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    Canada
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    Quote Originally Posted by buford View Post
    I would have the distributor where you plan on buying from, help you size it.
    I agree! But why do you think it's undersized? Does it not work? The motor is a bit bigger for the vfd, but most vfd drives monitor current and adjust their waveform to compensate. I would suspect that if the vfd and motor came as a package, especially if it's in a unit, there's a good reason for it.

  5. #5
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    Sep 2007
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    edmonds wa
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    That match he described it is way too low of output on that drive anyway, Like 1/3 of what is needed, unless someone really does not need that much motor or just really screwed up.
    UA Local 32

  6. #6
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    Mar 2015
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    Canada
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    Could have been a cheaper motor, but didn't need the power from it. Logistics is funny sometimes. I'm just saying, if it's in a package, it's *usually* not screwed up. If it's not working, tripping limits, etc, etc. Then for sure someone screwed up.

  7. #7
    Join Date
    May 2015
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    Yes dear motor frequently tripping and even the frequency doesn't match with the percentage of operation
    and i am worry about going to run it at 100%
    shouldn't be the drive little bigger than the motor? like 25% more or not
    what you advice me.

  8. #8
    Join Date
    Mar 2015
    Location
    Canada
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    Usually when i run into problems with vfds it's because people haven't set it up right, or just don't know how to. I do apologize, for trying to get to the basics first. 😊
    The drive does look a bit small at first glance. And a distributor/manufacturer should be able to tell you what you need, compared to what's available there.

    With that said, the drive should run at capacity without issue. (100% of drive) If this allows the motor to do the work required, then you should be able to adjust your settings to make it work well. Be careful however of your ramp speed. A lot of drives come out of the box at something stupid, like 5sec ramp up or down. I usually set them between 30-90sec, application dependant. Also if your drive has programmable limits, set your Max output Hz so that you don't pass your drive Max capacity. If all that fails, or the motor just won't do whatever your asking it to do, then go to your distributer. Someone screwed up. I'd go slightly oversized. 5-10% 25% would be nice if those drives weren't so expensive. Lol. Good luck.

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  10. #9
    Join Date
    May 2015
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    Many thanks for your advice i will see the nearest ABB specialist
    for the moment device is running because vfd control do not exceed 40% and most of VAV are partially closed
    however i feel curious to try it at full speed because i still have 6 other units having the same problems
    and the 10 units witch have a higher vfd amps and KW not showing any performance troubles.
    that's why it look like your 1st reply and Mr''Buford'' is true it's wrong installed by the contractor.

  11. #10
    Join Date
    Sep 2007
    Location
    edmonds wa
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    So there is 6 other units matched up the same way? It kinda sounds like maybe the VFDs were not factory installed?
    UA Local 32

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