I am retrofitting an old (1980's) Bridgeport BOSS 5 kneemill with a new controller and new steppers. That part is well under way and I am at the point of jettisonning a lot of the old control hardware and electronics. My question is, can I get rid of the old power equipment (huge transformers, starting relays and 'reactors" (whatever they are, they look like transformers to me), and replace all that old stuff with a VFD. I have seen ads for VFD units rated in Kw, but I am not sure how to translate that into useable amps. I should mention that I also do not have 3-phase electricity at my shop and currently (no pun intended) use a 10 hp rated rotary phase convertor. If a VFD is possible, what size should I be looking at? The spindle motor is the only part that will remain that will need 3-phase current, so the load would be exactly one 2hp motor. I have never attempted to do a swap like this, so any information would be helpful.
So you will need a 1 phase input vfd, for 2hp or 1.5kW 230 vac output 3 phase. Should be around 8 amps output rated. Input current would be around 15 amps. I would recommend a constant torque, sensorless vector model for the spindle.
Thank you, that helps a lot. Now I know quite a bit more about VFDs than I did 5 minutes ago. Much appreciated..
