JapScrap 
The make 50 volt DC + or - about 5 volt power using a electric motor driven off the mains voltage.
Theres the possibility that someone wanting to generate 48 DC power could use that part of the welder as a generator.
Normally they like 48 volt generators because it can be stepped up to the line voltage of 110 AC or 240 AC by only 2 or 3 steps using a invertor. Making it more efficient than 24V or 12V.
Otherwise they are popular as a DC power source for Arc air gouging of heavy metals. You can cut the metal using a carbon arc like welding rod & then blast compressed air under it to blow the liquid metal away.
It'll cut thru 1/2 inch plate. Any condition.
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