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IndustryArena Forum > CNC Electronics > Phase Converters > 3 phase input VFD for single phase input?
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  1. #1
    Join Date
    Feb 2008
    Posts
    3

    3 phase input VFD for single phase input?

    I need a VFD that will power a 4HP 3 phase motor from a 220V single phase source. From reading this and other forums, it looks like I can use a 3 phase input VFD for this purpose, but I must derate the power by approx 1/2. So I can find many 7.5HP 3 phase input VFD's......Will these work for my application? The main reason for the VFD is it is so much quieter than the rotary phase converters that I have been looking at in the past. Only one machine will be hooked up to the VFD.

    A real concern is that VFD's look very intimidating to set up and use. All that I want to do is turn on the machine and turn it off. Nothing fancy at all.

    Mike

  2. #2
    Join Date
    Dec 2003
    Posts
    24216
    I think a 50% de-rate is too much, more like 20-30% if any.
    WEG make some that are non-derate-able, just a bit higher cost.
    I have several 2HP VFD's running 2hp motors with no problem.
    With a higher end model you can probably get away with a 5HP, which is usually the highest 1ph input model for most makes.
    Sounds like you are just intending to run at 60hz?
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  3. #3
    Join Date
    Feb 2008
    Posts
    3

    Yes 60HZ only

    Yes 60HZ is all that i need for this tool. Thanks for the comments about derating HP. I really do not want to spend any more than possible, but don't want junk either. This application will be an on for short periods of time" (maybe 5 minutes max normally). The tool may get turned on 3-5 times in a 4 hour period, but generally short period of time, once or twice each day.

    Mike

  4. #4
    Join Date
    Dec 2003
    Posts
    24216
    It is the current factor that is the limit, if you do not run the motor near the FLA, Full load amps, then it is not normally problem.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  5. #5
    Join Date
    Feb 2008
    Posts
    3

    Thanks Al

    Really appreciate the quick responses.

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