I have inherited a large Oxford 250 amp welder. On connecting it up to what I thought was a suitable supply, it trips a 32 amp breaker, when I input between the 0 and 240 volt terminals, there are also connection for 400 and 415 volts ac.
I have conected the 240 vac to the 0 and 415 connections, to see what happens and the set does not blow the breaker, so I do not think there is much wrong with it. The voltages across all the taps and the secondary seem to be about the right levels given that the 240 volts is a lot less than the primary connection that I am connecting to.
This is a really heavy machine and has lots of adjustments and is oil filled. However I am a bit worried by going up to an even heavier breaker, without a bit of advice. What would be the allowable size for a transformer of 7.5 KVA which is only 32 amps on full load and I am starting it off load, of course. How can I calculate the starting surge?
Any comments would be welcome.
Thanks George.