Film-Tech Forum ARCHIVE: 4k rectifier A.C. question

This is topic 4k rectifier A.C. question in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Jonathan Bodge (Member # 4072) on 04-29-2013, 02:18 PM:

Does anyone know how much (with single phase 220) amperage a rectifier would draw for a 4000 watt bulb? Or, is 3 phase the only option with this high wattage bulb. Thanks!

Posted by Louis Bornwasser (Member # 3063) on 04-29-2013, 04:55 PM:

Unless you find a switcher, you are looking at 3 phase. It is possible to strap 2-2000 watt units in parallel for 4k. If you lose one, you are likely to lose the other since it is then overloaded a bit. 3-2000 watt units works better. I use Strong high reactance rectifiers: Each: 30 amps/230volt. Louis

Posted by Jim Cassedy (Member # 4115) on 04-29-2013, 05:43 PM:

I know of a couple of theatres here in SF that are running 3phase
rectifiers (power supplies) on single phase by using a bank of large capacitors
to create a 'phantom' 3rd phase. You can find info on how to do this online.
They're lamps are only 2K though. But I assume if you had large enough capacitors,
you could go higher.

There are some trade-offs though. You won't be able to get full rated power
output, due to efficiency losses.

- - and the rectifier makes a very loud annoying buzz at about 120hz, which
might be a problem if your booth isn't too soundproof.

But they've been running with this arrangement for over 20 years.