Many industrial electrical components can operate from various voltages. Control transformers can operate from 240 volts with the two halves of the primary winding connected in parallel (24o volts across each winding) or 480 volts with the two halves of the primary winding connected series (240 volts across each winding). Electric motors can connect to various voltages in the same fashion.
Older factories have generally converted from 240 volts in the 1950s or 1960s to 480 volts as the power is the same, with double the voltage only half the current is required. Power loss is current squared multiplied by resistance so as the current is half as much only one forth of the power is lost in the wires. Cheaper, cooler and more efficient.
You should also know that 3-phase,reguardless of voltage level are 180 degrees out of sync. Meaning that if a scope meter was connected to each phase you would see that the sine waves only overlap at the 0v level. And it is critical that pwr generating stations maintain that separation as well as voltage levels on each phase.
1) The voltage value you show, 480/240 is not indicative of a 3-phase system. Perhaps you meant 480/277.
2) The three phases (eg, A,B,C or R,S,T etc) of a 3-phase system are 120 deg apart.
3) If by 180 deg out-of-sync you mean the displacement between two 3-phase sources, then that is the angle that will produce the highest current flow when the two sources are connected.
Contact me if you want the mathematical relationship for out-of-sync displacement!
