difficult to say with out some more info on the machine. A transformer would work but would be power hungry. Is the machine three phase or 400V (380) single phase?
would help if you could post a link mate, is it in greece? shouldn't be any worry of anyone sniping it out from under you if it is
are you shore how many cores has the supply cable got
Edit: Thought it was going to be a transformer machine but it's an inverter so wouldn't need such a big RPC.
Anyhoo, back to the welder before we go o/t, echidna, if you want a powerful tig consider an old miller or murex if you can find one, they're often single phase but people advertise them as 3 phase because they don't realise.