Rotary phase convertor sizing

[No Plan]

I have 200 amp 220v single phase in my garage/shop. Just bought a 3ph 5hp mill. Can get a 20hp rpconvertor for about $900, or a 10hp for $850. Will the 20hp cost a lot more to run? Only other 3ph machine I will buy is a 3hp lathe, & never run both at same time. Is it dumb to put in 2x the capacity I'll ever need?

 

[larry_g]

In my experience you will not need the 20hp. I also think it's naive to think these will be the only 3 phase machines you will have. You want to be able to balance the output on the RPC to match the load you are running. So if you go way overboard then the generated leg will be way high. I believe that if you do a bit of research at the American Rotary site they have some tutorials on sizing a RPC. https://www.americanrotary.com/

lg
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