After some interesting reading I just have to get in on this discussion. I fail to see the difference between a 208-230 volt three phase US motor and a 3 phase motor used in Australia except the nominal RMS operating voltage and the frequency. A 208-230 volt single phase motor used in the US expects to see between 208 volts and 230 volts between it's two input terminals to operate around motor nameplate HP, current, and RPM (these are a function of motor load). Does this single phase motor know it has two separate phases as referenced to the neutral (AKA the midpoint of the transformer). Let's let one of the input phases (say L1) be the 0 volt reference point for L2. So now L2 referenced to L1 is a 208 to 230 volt sine wave at 60 Hz in the US. In my opinion that is why this is a single phase motor and not a two phase motor. Is the single phase motor in Australia any different? If we can rotate an unloaded 3 phase motor with single phase power in the US why can't they rotate an unloaded one in Australia with single phase power? Is anyone following my reasoning here?

Just wondering

Junker2
AKA Terry