Why India has 50 Hz Power System....?

The choice between 50Hz and 60Hz frequency depends on a number of factors, including the specific electrical power transmission and distribution needs of a region, and the availability and cost of the electrical generating equipment. There is no inherent superiority of one frequency over the other.

The use of 50 Hz versus 60 Hz is purely due to historical reasons, with companies in the US making 60 Hz equipment and those in Europe making 50Hz equipment so that they have a monopoly. This rivalry led to the split you see today.

60 Hz was the result of engineering trade-offs by Nicolas Tesla working at Westinghouse, having to do with size of the generators and transformers needed, which get smaller with higher frequency and eddy current losses, which go up with frequency.

India got it's power systems initially imported from the Britsh, who used 50 Hz. So naturally they imported 50 Hz power systems to use with their British Appliances which were 50 Hz. 60 Hz is the US/North American standard.

We can say that the Supply of Pakistan or India is 50 Hz due to these following factors: Due to the Cost efficiency. Practical difficulties in using 60Hz supply.