Switcher with 480VAC single phase input

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.

Paul

You can't transform down to 120 or 24 VAC first?

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)

Cheers Terry

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

Bye. Jasen

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.

Bye. Jasen

This is the solution I chose. Thanks, Jasen!

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

AUTOMATION SYSTEMS INTERCONNECT, Inc. P.O. Box 1230 - CARLISLE, PA 17013 - USA Tel. +1 717 2495581 - Fax +1 717 2495542 E-mail: snipped-for-privacy@asi-ez.com Internet: