the lower the voltage the higher of amperage cable needed on the supply . use 240 volt and a half decent size to the machineIt didn’t work,even off 20m 240v cable,is this due to being 110 welder,years ago,I had a Migatronic 240v inverter,ran that fine off of 45m cable.
D Napier & son, Acton, London. Also built the Sabre aero engine used in the Tempest & Typhoon, another odd ‘X’ configuration. Taken over by English Electric during the war. It’s worth looking at Wiki & the Napier Power heritage trust for the history, quite interesting.Is that the same(Robert ?) Napier’s of shipbuilding and marine engineering fame ?