|>> | An 3 phase welder should have had 4 wires, 3 hots and a ground. |>>
|>> How would a 3 phase welder put all three phases at the welding rod? |>> The only way I could see this happening is if it is really converting |>> everything to DC. Or else it is not drawing current on all three. |>>
|>> I was once thinking about how to make an arc lamp with the light source |>> being as small a point as possible, as bright as possible, and powered |>> with three phase well balanced. The only thing that seems plausible is |>> 3 arc rods at 120 degree angles. |>>
|> here it is
|> or here
|> yup, looks like is a DC only welder. |>
|> 4 wire with the ground left dangling :) maybe it's in Mexico?
It's simply a DC welder. The word "only" tells ho it behaves. It gives output as DC. And it is 3-phase. So at 50 Hz, that means you'll see the DC pulsing at 300 Hz. But it won't reach zero crossing due to the DC rectification from 3-phase. And it looks like a substantial welder on that esab.co.uk site ... 35 kW.
3-phase is a plus when you are doing such a high amperage. But you do have to recitify it to DC to get it all coming in through one rod.
Also, this will put some hefty harmonics on the power line. Since it is listed as 380 volts, it's obviously getting it's power without using the neutral wire (e.g. phase to phase). But an upstream transformer wired in star (wye in the US) configuration (as they almost always are in the UK) could have 2 to 3 times the current going through its common point for the three secondary windings. If it is a small transformer dedicated to this circuit, it needs to be double rated. If it is a big transformer for much more load, it is likely to be no problem.