Thanks all, for your advice I found Kemppis address and emailed them, I got a reply back in a few hours, I'm impressed with their aftersales service (even if it wasn't what I wanted to hear)
------------------------------------------ From the rating plate on this machine, the mains supply is norminal value is
1phase 230v ( 198v - 254v) the rated fuse is 16amp slow blow The input current is proportional to the output value set on the current dial.
At max output the power is 6200 VA (6.2Kva) power factor 0.75 therefore output power in watts is 8267 watts At 75 amps output the power is 2900 VA so an estimate of power in watts (pf approx 0.6) is 4833 watts
Therefore we would NOT recommend using your battery/inverter supply to power this equipment because of the in-rush and surge currents even at the low output and using
1.6mm electrodes.
The generator supply is probably also not large enough, unless it has a very well regulated output, again due to the in-rush and surge currents even at the low output and using 1.6mm electrodes.
We recommend a minimum generator of 6.2Kva.
Best Regards Martin Forster Service Technician
Kemppi UK Ltd _________________________________________________