Typical supplies are:
Single phase, 3 wire: 120/240V
3 phase, 3 wire: 240 volt or 480 volt or 600 volt
3 phase, 4 wire: 208Y/120 volt or 480Y/277 volt
Usually only one supply would be provided to a site (due to cost and/or availability)
The 240V is the only winding which is split (to provide 120V). The coils for other voltages are not usually split.
277 volts is convenient for fluorescent lights as it allows a simpler (cheaper) magnetic ballast