RE: 3-Phase Electrical Service

Should check the codes in your area. I have been retired for 7+ years. I have connected them directly to the equipment when 3 phase generator was sized properly for it. If the output is larger than the maximum circuit rating on the equipment, you need to provide properly sized circuit protection; ie, subpanel. Sounds like you are running multiple machines and a subpanel is probably required to provide proper circuit protection. I am not familiar with Phase Perfect PT-355. It may have options. Lots of innovations in electronic controllers in the last couple of decades.