They do suck a lot of power... But on the other hand 125 amp service is a lot of power.

There are a couple of repair guys on the forum here... Hopefully they will chime in.

Could be the breaker, especially if the breaker has been used as a switch after some time it may not be able to carry its rated current.
Bill

That machine will probably draw over 125 A @ 230V at max output. I think they draw about 100A or a bit more at the rated 300 A output, and max output is somewhere in the 375-400 A range. I would suggest checking with an amprobe to see what the actual line draw is, and if the wiring is big enough You might be able to increase the breaker size if You really need full output. If the breaker is popping below the rated amperage, be sure the conections are tight, as resistance heating of the connections can set the breaker off before full load is reached. As mentioned the breaker might be faulty as well. If the machine is supposed to be power factor corected, make sure the capacitors have not been unhooked, and that they still work.