460-480 V Plasma: HELP PLEASE

[bruchi]

I got on ebay a brand new ESAB 825 plasma cutter, shipping it to Puerto Rico was not cheap and then I find out the thing, according to the techs at ESAB will only run on 460-480 volts, only got 208 at the shop.

An electrician told me I need a 208 to 460/80 volt transformer around 10KVA, all I found are huge, very heavy and expensive.

The guy that sold me the thing told me after not mentioning it was a 480V unit that transformers for it to work on 208V where affordable an manageable regarding size and weight.

What are my options here? Can't sell the thing locally, too expensive to ship elsewhere and I want to use the thing! It has been sitting around for almost a year now.

[awright]

Check with ESAB Service or your operator's manual regarding the permissible range of input voltage. If you can feed it 416 VAC (about 10% low, which may be tolerable, especially if you never intend to use it at maximum output), you may be able to get by with a 208-208 VAC or 230-230 VAC isolation transformer with secondary current rating as great as or greater than the maximum input current of your unit (either voltage indication would be suitable. If you can find such an animal, it will be cheaper and about 1/2 the weight and bulk of a 230/460 VAC transformer of the same current rating. This is because the transformer is supplying only half of the the input power demanded by the ESAB unit. The transformer you use can be rated for either 208 volts or 230 as long as it is rated for the maximum current you would ever use.

Connect your new transformer as an autotransformer, i.e., with the primary and secondary in series aiding (voltages adding, not subtracting). In this configuration, the transformer is supplying the full current, but only 1/2 the voltage demanded by the ESAB input and, thus, can be 1/2 the power handling capability of a transformer supplying the entire input power demand of the ESAB.

Good luck.

awright

[MAC702]

Another expensive option would be the Bobcat 3-Phase generator. It provides 10kVA of 480V.

[Shane@profab]

guess who's back.....from coming down that very road..

You need to advise what configuration that machine is (single or three phase or worse two phase)
The next thing, listen to the guys here (except me!) they know plenty!
If you are in luck and its single phase, check out the amp draw and multiply that by the 460 voltage, then divide your existing supply voltage into that number at you will get the current draw at the lower voltage. Check this against whats in your DB at home/shop, you may well find that you are limited to about 60 or 80 amps at 230V or whatever your local supply is.

My tip for the day, scratch around in old machines for a suitable transformer, I goy a 380-220 15kva for a swop out on an old cellphone....still smile about that!

Shane

[bruchi]

Thanks for the answers, keep 'em comming please, the unit will work either single or 3 phase, I got 3 phase at the shop. Any leads to a suitable and AFFORDABLE transformer are most welcomed, ebay works fine for me, ugly, used but working fine too.

Don't have the manual, can't find a download for it at ESAB.

An electrician (I can wire a wall outlet but I am far from being one) got out his toolbox a table, did the math and tells me that I need a 9KVA 208-460/480 transformer

Not familiar with transformers at all so for my education, how big, heavy and expensive a 208 to 460/480 10-15 KVA transformer is?

I might have access, a freebie, to a 208 to 360-90? transformer.

[bruchi]

If you are in luck and its single phase, check out the amp draw and multiply that by the 460 voltage, then divide your existing supply voltage into that number at you will get the current draw at the lower voltage. Check this against whats in your DB at home/shop, you may well find that you are limited to about 60 or 80 amps at 230V or whatever your local supply is.

Okay the unit draws at the max setting, 60 amps, I did the math and comes to 133 amps at 208 volts, got 200 amps per line at the shop. Now the question is how do I set this up and how far should I be from the unit when I fire it up the first time?

[Sandy]

EATON and/or Cutler Hammer should to have something in the universal step-up/step-down group. Not cheap of course, but if you're in a bind you may not have much choice. See if some electrical supply can get EATON products without too high of a shipping penalty. At least it'll give you some ideas.

An example here in the states would be if you wanted to build your own power line and needed the higher voltage for practicle transport. The power company steps it down to normal voltage, you runs it through your meter for billing, then you step it back up for longer distance transport then step it back down again for houseld usage. They'll use the same universal dry transformer on both ends to simplify the spares or replacement problem. I've seen them with a variety of taps up to about 560 volts. There are some fairly high energy losses in dry type transformers that have to be calculated into a a family budget but those folks doing these types of things also drive multiple Hum Vs and don't sweat the small stuff. For intermittent use as for a shop machine I doubt that it would be too big of a deal.

[bruchi]

Happy to report that today I got (from ebay again) a transformer so I can get the plasma to work, this time I checked first with a certified electrician to make sure I get the right unit and talked on the phone with the seller to make sure it was what I needed, seems that in a couple of weeks I'll be a happy metal cutting fool.

Got a good deal too, used unit including shipping, for a third the cost of one here and it has twice the juice I need.

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