But the store has three phase. So does this machine need 208-220V on one wire? I've never heard of 208V single phase. I don't know, maybe it's from some other country that uses a different voltage? Thank you for your help.
Motors usually maintain full performance, but resistive heating appliances have to be derated 25% on 208v, I don't know about that welder, but its worth checking.
208v is common in multi-family houses and apartment buildings. Appliances are designed for 208 or 240, because they're both common, but boiling water, pre-heating the oven, water heater recovery all takes 33% longer on 208v.
Take a look at an electric water heater when you get a chance. You'll see the derated wattage at 208v on the label.