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3 Phase Variable Power Supply

  1. Jun 15, 2012 #1
    Hello all,

    I have a 3 phase Variable frequence drive that requires an input voltage of 380-480VAC. I would like to test what would happen if I apply 300VAC to the drive.

    I have access to 208V and 440V. Is there anything I can do to obtain 300V? I have thought about a variable power supply but at that voltage they are hard to find.

  2. jcsd
  3. Jun 15, 2012 #2
    Why can't you simply step down the 440V to 300V with a transformer?
  4. Jun 15, 2012 #3

    Because I cannot find a 480 to 300V transformer. Also would I need a transformer for each phase?
  5. Jun 15, 2012 #4


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    Gold Member

    Yes you would need a transformer for each phase

    If you stepped voltage down that way
  6. Jun 15, 2012 #5


    User Avatar
    Gold Member

    Why not use VARIAC's products?

    "Three phase Wye variable transformers:
    240VAC 3 PH input, 0-280VAC output
    240VAC 3 PH input, 0-560VAC output
    480VAC 3 PH input, 0-560VAC output"

  7. Jun 15, 2012 #6

    jim hardy

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    Science Advisor
    Gold Member

    How much current do you need?

    Enough to run the motor, presumably tens of amps,
    or just a few milliamps to fool some electronics into thinking power is pesent?

    A good stereo audio amplifier IC and small 3 phase instrument transformer will do the latter.
    Make two sinewaves 60 degrees apart and use them for open delta into step up transformer.
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