Turns ratio causes a transformer to step up or reduce voltage. Take a transformer with 100 turns in one winding and 200 in another. Voltage connected to the 100 turns will be double when measured at 200 turn winding.
Norm
:how do you get 277/480 voltages on a transformer? what makes this happen?
Those are three-phase voltages. Do you mean "why does 277 plus 277 add up to 480? Because they're 120 degrees out of phase.