Rotary Phase Converter (Create 3-phase power from a single phase source)

[Frank S]

The one thing that caused this thread to travel down the road top perdition is the fact that there are folks all around the globe with differing electrical power services available to them, plus the fact that not everyone understands that when something is written up or explained it can mean the nominal voltage, as with the term of single phase. In the USA single phase 220/240 volts requires 2 hot lines of 120 volts (nominal) in other places this is done by a single hot leg and the neutral. In many places such as Europe or in particular the Middle east 3 phase power is supplied to many homes in the form of 415v across any 2 of the phases
While I was working in Kuwait we often installed overhead doors made in Denmark that were powered by small 3 ph motors but only used a single hot leg and the common. this was accomplished via a very compact box which contained a small center tapped transformer and a couple of capacitors and not a whole lot else except for maybe a few resistors and a 5 amp fuse and a reversing switch.
I do onw a set of rhengineer's rotary phase converter plans and although his method of construction differs from the way I made my RPC years ago they are a valid set of plans. But no as they are written up they do not address differing voltages or energy production methods around the world. any more than a friend of mine who lives in New Zealand on another form who a long time ago made his own buck and boost transformer would have worked as made in the USA However he later created a spread sheet calculator which if a person understood enough about how electromagnetic currents are created could build their own
I've posted a few times on this thread of how a solution to achieving 3 ph from 1 ph could be accomplished, as wqell as a couple of others who have posted as well. This is not to say that my way or another's way is better or the only way they are simply a means to reach a suitable outcome.
When it comes to a RPC for small ones I prefer to simply add the required amount of capacitors to the idler motor when the become larger say over 7.5 HP the addition of a pony motor to serve as a means to start the idler motor turning reduces the inrush current of the locked rotor condition call it reducing amperage spike. However I still prefer to have a bank of capacitors across the phases of the idler motor to smooth out the 120° 3 ph offset from the 180° of a 2 hot line single phase.
You still need a way of creating 2 hot legs though in order for any 3 ph motor to be started and run even with the addition of capacitors or a pony motor, no matter what the desired output voltage is to be. The 1 exception might be and I say this only becaus I have never had the opportunity to try it, would be a motor with 12 or 18 wires, instead of the more common 9 wire motors