Hi,
maybe solved by now. Step down I think ? 3kv = +- 3000w ? 110/25 or 220/15 to 40v/65a ? not that 110v/25a is reasonable. and 40v is open circuit voltage and might drop to 12v? under load . I have been thinking about this stuff also. If size/power consumption is not primary criteria,a transformer conversion from microwaves like the diy welder guys make might do .
Regards,Ed