Re: Is single phase 120/240 really 2 phase ?
Instead of thinking in terms of how many wires there are or how they are connected, think of the electromagnetic and magnetomotive forces that are created in a single-phase system verses a 2-phase or 3-phase system.
In a single-phase transformer, the flux in the magnetic circuit are in phase, whereas a polyphase system has two or three magnetic circuits through the core and the flux in the various circuits are displaced in phase.
Its an issue of time. A 3-phase system as three alternating single-phase currents of equal frequency and amplitude, but differing in phase from each other by one-third of a period. The time period is the same with a 3-wire 120V/240V system.