220-440v transformer

I would like to know what sorts of transformers are suitable for converting 220v to 440v. Specifically, can I use a step down
transformer in the opposite direction, or will it not work at all due to losses, etc?
My actual line voltage usually is 240-245 volts.
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Iggy,
Transformers are generaly "bi-directional" but work better in the direction they were designed for.
I would try and get "full power" out of one backwards but it will work. I've used 110-220 both ways and don "squirly" things with old 70Volt audio transformers.
--.- Dave

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Friggin fingers... That's a typo.. I meant I WOULDN'T try and get full power.. I usualy derate about 20%...

--.- Dave

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What I am afraid, is that out of this 440-220 transformer, I would get not 440v, but maybe 420 volts.
i
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Ignoramus23731 wrote:

Should be easy enough to check. You also ought to be able to change the taps around to get plus or minus five percent or so on the output. I'm assuming a three phase IO here.
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Just one phase.
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"Ignoramus23731"
message >

Just curious---what the heck runs on 440 single phase?
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An old Hypertherm 600 plasma cutter.
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Ignoramus23731 wrote:

Also useful for testing 440V VFDs presuming you have a 3 phase motor that can be strapped for 440V to go on the output of the VFD.
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If memory serves, at 440 one cannot use any direct action switches, and must instead use contactors in well-grounded metal boxes to turn things on and off.
Joe Gwinn
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On Sat, 31 May 2008 03:50:54 GMT, with neither quill nor qualm,

VERY fast motors, well, for a couple seconds, anyway. ;)
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wrote:

A 440 volt VFD that then powers a 440 v 3 phase motor?
Many or most 3-phase input VFDs can be wired for single-phase input, at some expense in derating.
Joe Gwinn
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Not a whole lot - But if you have 277V/480V 3-Phase 4-Wire Wye service there's a LOT that runs off a single 277V leg to Neutral. Overhead fluorescent and HID lighting, Emergency and EXIT lights, parking lot HID pole lights, and a lot more.
You can cover a 5,000 foot warehouse with two or three circuits of high-bay lighting at 277V or 10 circuits at 120V. Makes it go together a lot faster and easier, and a lot less wire.
--<< Bruce >>--
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Unless there is some serious Hysterisis loss, you'll get the 2-1 the transformer is wound for.
Hook it up and see.
--.- Dave
wrote:

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I think 10 percent variation is normal. Some transformers have voltage adjustment taps. I personally prefer a bit high over a bit low.
Wes
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On May 30, 6:06pm, Ignoramus23731 <ignoramus23...@NOSPAM. 23731.invalid> wrote:

http://en.wikipedia.org/wiki/Buck-boost_transformer
Jim Wilkins
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So when you put in 240 on the 220 input the losses might be ok. It depends on the 'regulation' of the transformer - how tightly the two windings are to each other.
Many transformers have multiple taps on the input and/or output for line regulation correction...
Martin
Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com /
Ignoramus23731 wrote:

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On Fri, 30 May 2008 17:06:56 -0500, Ignoramus23731

Even if you do..that 20 volts ..in the grand scheme of things..really wont mean shit at 400+ volts
Gunner
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Transformers will work both directions. However they are usually designed to boost the voltage slightly to compensate for the drop in voltage due to the resistance in the windings. So a 120 to 240 volt transformer with 120 volts in, might put out 243 volts with no load and 240 volts when loaded.
Dan
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Well I'd want one rated for the voltage I'm using. Then there is KVA rating. That has to be up to what you are trying to power. Higher power, to problem. 50 cycle, no problem.
I have never run into a warning that a transformer is only suitable for going one way.
The only issue I'd be concerned about is using a way bigger transformer than needed. Hysterisis losses might be high.
Wes
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