In Single phase power supply system, there are two supply wires to connect single phase load to the distribution system among them one is phase and another is neutral. So the appeared voltage between a phase and neutral is 220 Volts.
But in three phase power supply system, there are three supply wires to connect three phase load to the distribution system. All three phase ac generator has three set of the armature winding and current following these phases of armature winding are shifted at the phase angle of 120 degrees from one another.
Also, the voltage generated between these phases are sinusoidal and 120 degree apart. So, the net voltage appeared between two phases in three phase ac power supply system is 440 Volts as potential of third phase is zero at a instant in accordance with the phase angle of 120 degree.
As phase is 120 degree apart so, voltage calculation is not normal. In this case vector addition is performed, the ac power has sinusoidal waveform means ac power has peak voltage and low voltage through-out the power system.
When positive peak voltage is checked at a period of time then only two peak voltages are seen. This will be same for negative half cycle so there will be only two peak voltages because they are 120 degree apart so that two phase will be high and other will be low and by vector addition it will be 440 volts not 660 volts.
Conclusion
Hope, you have clearly understand why 3 phase voltage is 440 volts not 660 volts, if single phase voltage is 220 volts. Make sure to Leave your Opinion and suggestion about this post in the Comment Section Below.