I've had no experience of using static or rotary converters but I'm sure I have read you may need to use one that's 50 to 100% over size to have enough in reserve for the start up surge of starting your machine


the other point to watch out for is to connect the machines control to the two mains supply terminals from the converters 240 to 420V step up transformer and not the phantom / wild phase

is there no recommendations from the machines manufacturer ?

digital converters will have the advantage of having built in protection to protect its self and your machine


John

PS

I forgot to add
digital converters regulate the output voltage which will be an advantage if your on a rural supply that may not be a tightly controlled as most of the UK grid