i built me a rotary phase converter a few years ago, it is just a 2 hp motor, they work great and are very easy to build, mine cost me about 2 hours worth of time to assemble, that was after collection the capacitors, which i got from old outside central A/C units
i plan on building a bigger one someday
the thing about a roto phase is, you idle motor, which is in fact the phase converter itself, can run whatever size motor it is - if you get a 5 hp 3 phase motor and turn that into your roto phase (thats what i call them) you can run a 5 hp machine with no problems, now say you have 4 machines all with 3 phase motors, 1 or them is a 10 hp motor, you can run that by turning on the roto phase (5hp) plus starting another 5hp motor and let it just idle, then you should be able to turn on and run a 10 hp motor and run a full power
the hp adds up with all the idle motors
thats why i need a bigger roto phase, mine is 2hp i have a 7.5 hp cutoff saw, i hafta turn on all the 3 phase machines and let them idle so i can get my saw to work, i onl;y have 1 other 2hp motor and several 1hp motors, so i hafta turn my roto phase on, then the 2hp motor, then 3 other 1hp motors to get the saw to work, it just about max's out my amps by doing this, but it does work
you can buy one for several hundred dollars, or build one for cheap, and if you are good and resourceful at collecting things, you could build one for less than $25 maybe even free (like i did)
oh yeah, most small motors (like my 2hp) doesnt need a start up capacitor, most (not all) will start to turn just by adding the 2 single phase 120v power to it, then you use the capacitors to even out the 3rd leg of 120v to as close as the others as possible
bigger motors need the startup capacitors, or a pony motor and belt to get the bigger motors to start spinning, you can use a pull rope to start it spinning and then turn on the power, then is will start up,
ill look for the link i have about them, the guy lives here in Cincinnati, he sells a disc on ebay on how to build them, it is like $2 and he can email a down loadable file or for $5 he will send a C/D he also will help out as best he can thru email if you have problems building one
i bought him breakfast (from Mcdonalds) and he gave me a disc, has lots of info on them
i would try to send it to you but it has some type of copy write thing that makes it impossible to do
Ron