By your own label..it say's 70/78 amps on single phase to pull 280, that's a lot of amps on single phase, most welder plugs are 50 amps,,,you will be lucky to get 210 to 230 amps out of it on single phase,,,regardless of what the dial say's,,,To get 300 & 400 you need 3 phase and large breakers...My 3 phase comes in a 208 volts which sucks when you hook up to it on single phase,,,it ups the amp draw as you can see from the label, when you compare to 230 or 240 volts.
Some of those lies people tell about me, are true