Due to following reasons, AC systems are preferred over DC
systems:
a. It is easy to maintain and change the voltage of AC
electricity for transmission and distribution.
b. Plant cost for AC transmission (circuit breakers,
transformers etc) is much lower than the equivalent DC
transmission
c. From power stations, AC is produced so it is better to use
AC then DC instead of converting it.
d. When a large fault occurs in a network, it is easier to
interrupt in an AC system, as the sine wave current will
naturally tend to zero at some point making the current easier
to interrupt.