Why AC systems are more used or preferred over DC systems? answer in short points please

AC is widely used for Power Generation, Transmission and Distribution because it is easy and practical to transform. While for small voltages requirement such as for Electronics, DC is also widely used.

1.         It is comparably easy to maintain and modify the voltage of AC electricity for transmission and distribution than it is for DC electricity.

2.         The entire plant cost, ie, circuit breakers, isolators, transformers, etc is much lower in comparison to that of DC transmission.

3.         All the power stations produce AC electricity, and hence it is advantageous and also easy to use AC rather than converting it and using DC.

4.         AC is practically a sine wave current, and hence in case of a large fault in the network, the sine wave will naturally tend to zero at some point and hence it is very easy to interrupt it in an AC system rather than in a DC system.

for generation and transmit the power we should decrease or increase the voltage. and so we should use transformers for this purpose. we cant use dc power for transformers  and just ac power can be used in transformers

Because of the transmitting power is A.C over D.C .it is easy to vary the voltage .A flexible alternating current transmission system (FACTS) is a system composed of static equipment used for the AC transmission of electrical energy. It is meant to enhance controllability and increase power transfer capability of the network. It is generally a power electronics-based system.

AC system is more preferred over Dc systems because

1: It is easy in  AC systems to regulate the value of voltages by stepping up or stepping down.

2: AC system is also not harmful for electronic appliances, however DC systems is also preferrable.

3: The value of sine wave at some point tends to be zero in AC system, so it is easy to interrupt the AC system.

Primarily because it is much easier to step up or step down voltage for AC as compared to DC. 

1) Generating Plant produce  AC Voltage conversion of DC is very costly( AC Voltage is High inverter capacity required high)

2) Maintenance cost is very with respect to AC System (Breakers Relays transformer).

3)AC Generators and motors are cheaper than DC.

4) Easy to maintain.

5) In AC system Current tend to zero so we can interrupt.