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.
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
Friggin fingers... That's a typo.. I meant I WOULDN'T try and get full power.. I usualy derate about 20%...
--.- Dave
What I am afraid, is that out of this 440-220 transformer, I would get not 440v, but maybe 420 volts.
i
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
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.
Unless there is some serious Hysterisis loss, you'll get the 2-1 the transformer is wound for.
Hook it up and see.
--.- Dave
I think 10 percent variation is normal. Some transformers have voltage adjustment taps. I personally prefer a bit high over a bit low.
Wes
Sure they will work backwards but the flux leakage will be a tad higher so derate a little 15 or 20 % . ...lew...
Just one phase.
"Ignoramus23731" wrote in message >
Just curious---what the heck runs on 440 single phase?
An old Hypertherm 600 plasma cutter.
On Sat, 31 May 2008 03:50:54 GMT, with neither quill nor qualm, "BillM" quickly quoth:
VERY fast motors, well, for a couple seconds, anyway. ;)
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.
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
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
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
Do you have a reference to that? Always interested in learning something.
Wes
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