On 5/5/21 8:37 AM, Paul Koning via cctalk wrote: > Incidentally, a way to get three phase power at a frequency of your > choice is to use a "variable frequency drive". That's basically a > high power solid state inverter intended to drive three-phase motors > with a chosen frequency resulting in the RPM of your choice. > Depending on the model, those can go up to 120 Hz or so, or all the > way to somewhere around 400 Hz. I have a very cheap one at home that > runs on single phase 220 volt power, producing up to 3 kW or so at > anywhere up to 120 Hz. (Made by a company named Teco, amusingly.) > Most of these and especially the larger ones want three phase mains > input, though I'm told that even for those you can typically just > connect them to single phase power (between two of the three inputs, > leaving the third unconnected) at reduced power ratings. These > devices are surprisingly cheap, in particular they tend to be cheaper > than "rotary phase converters" which is how machine shops > traditionally produce three phase power when their mains is just > single phase.
Please forgive the null message--too fast with the mouse. A simple single-to-three phase converter used by many home shops is simply a 3-phase motor fed single-phase power to one pair and a large capacitor connected between the remaining lead and the "hot" side of the power line. Such a motor is an "idler", run no-load--basically a rotary transformer. Of course, you don't get a precise 120 degree phase relationship but it's adequate for powering a lathe or mill. --Chuck
