I've made several static phase converters, including an extremely big one, but have only ever bought Transwave commercial rotary ones. Firstly I had a 3 kW static one that I used to power my Bridgeport Mill, and Colchester Student lathe. Then I bought a Transwave 5 kW rotary to run the whole workshop, then a 15 kW one to run the 10 kW chiller unit for my 100 kW induction furnace (furnace ran off a generator).
All the commercial ones managed their own start up sequences, and there was no need to interfere. (Though I did once manage to blow the 100 amp 240 volt company fuse with too much running at once)
When I was running off static converters the trick to starting big machines was to have a large (or several large) unloaded motors run up to speed before trying to start the machine in question
Amusingly my first really big static that I made, which was to run my Bridgeport Moog Hydropoint 1000 NC mill and it's huge compressor, I sold to the late Tim Leech (of Dutton Dock fame) and then later saw it advertised on eBay
![:lol:](https://madmodder.net/Smileys/default/kranke_200-1.gif)