New Synchro 250dx....Old question

[blackwire]

I ordered a new 250dx and need to know about breaker size.About the highest I will run the machine is 250amps@68En.I figure the draw will be about the same as 270 balanced or so. If I run a 100amp breaker will the machine kick off first?Or will the breaker trip in panel box.I obviously want machine to trip first,leaving fan on.My present wire is #6 TEC armoured cable which I feel will run the 100amp Ok,but if I need a 125amp breaker I will run a bigger cable.Anyone have any experience on this?

Thanks

[clint738]

Don't know if you have the manual yet.
http://www.millerwelds.com/om/o359q_mil.pdf

Page 30 shows the electrical service recommendations.
125A is the Max recommended circuit breaker for 220V input without PFC.
Minimum input conductor is 6 AWG wire

With PFC the breaker is smaller, 90A for 220V input and 80A for 230V input voltage.
Minimum input conductor is 8 AWG wire

Page 13 shows the input current for single-phase 60Hz.
It makes a pretty good difference if your model has Power Factor Correction (PFC) built in or not.

At 250Amps AC balanced- 40% duty cycle at 230V input the Current input is as follows:
No PFC - 96A - (2.8A while idling)
With PFC - 71A - (49.5A while idling)

Hope that helps.