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Switcher with 480VAC single phase input

Discussion in 'Electronic Design' started by Guy Macon, Mar 10, 2007.

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  1. Guy Macon

    Guy Macon Guest

    I am looking for an off-the-shelf 24VDC 25A switching power supply
    that will run off a 480VAC single phase input. Does anyone know
    of a vendor who makes such a beast? Just a name; I can do the
    searching given a hint as to what direction to go. Thanks!

    Guy Macon
  2. I have looked without success for such an animal. One idea I considered was
    using the 277 VAC L-N voltage, which may be close enough to the usual 264
    VAC maximum, or a small buck transformer could bring it down.

    Another possibility is to run two 240 VAC power supplies in series. You
    would probably need to add a voltage divider (maybe a 480 VAC CT
    autotransformer) to make sure the two supplies have about equal input
    voltages, and the outputs would probably need to be each 12 VDC and also
    wired in series to present an equal load.

    A third possibility is a phase fired SCR voltage controller, but it would
    cause some high current transients into the input capacitors, so a series
    inductor may be needed to reduce the current spikes.

    A custom design may be the only "clean" option.

  3. You can't transform down to 120 or 24 VAC first?
  4. Terry Given

    Terry Given Guest

    Hi Guy,

    you might have to modify one.

    Get a SMPS with a voltage doubler configuration for 110/220V operation.

    That way you can replace the two caps (usually 220V) with 400V caps, and
    use a suitably rated rectifier.

    Make sure it uses a FET for the primary switch, ideally in a TO-247
    package (they pretty much all do)

    Then remove the FET and replace it with a BU508 (or any Horizontal
    output transistor).

    Lift the emitter, and place a small LV FET in series with it (D--> E,
    S--> current sense resistor).

    connect the FET gate to the original gate output.

    lift the base, and place a 1W resistor to the smps supply, with an
    antiparallel diode (Kathode to supply, Anode to base). choose the
    resistor based on min Hfe.

    Voila, you now have an emitter-switched bipolar, which will eat up to 1500V.

    If there is sufficient duty cycle available, you wont need to vandalise
    the transformer at all.

    you will probably need to mangle the startup supply (higher R), and also
    the clamp network (diode voltage rating)

  5. jasen

    jasen Guest

    that could get kind of exciting with a pair of switchers with inputs in
    series, isolation could be an issue too.

  6. jasen

    jasen Guest

    a quick google search found me

    "Cabur CSG30P" (340-550VAC in , 24V @ 30A out)

    These are three-phase but will operate from 507-700VDC too.

    So, for single phase operation you'll need to add a capacitor
    and a rectifier.

  7. Guy Macon

    Guy Macon Guest

    This is the solution I chose. Thanks, Jasen!

    They cost $410.00 each and are available in the USA at:

    P.O. Box 1230 - CARLISLE, PA 17013 - USA
    Tel. +1 717 2495581 - Fax +1 717 2495542
    Contact: Mr. Mike Manning
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