why does india have 50 hz as ac frequency but america as 60 hz? any advantage ??

Answer 1

Responses without sources aren't answers, just opinions.

A higher frequency results in a smaller lighter transformer (hence usually less expensive) for the same capacity.

To indiantrumpet: nice to see that you posted a verifiable source.

Answer 2

I like how you just gave a source on transformers from wikipedia and said exactly the same thing the previous guy did after criticizing his answer. India uses a 240V standard where here in the US we use a 110 V standard. Difference is the amperage in the transmission lines. The more the line current, the higher the losses. Because of the relationship: P=V*I and knowing that lower currents cause lesser problems (both in power loss and safety), it would be better to have appliances that require higher voltage rather than higher current for equal power consumption. However, power consumption is not equal in both countries. 50 Hz is cheaper than 60 Hz. India conserves power better than the US does.

Answer 3

Theres no real advantage either way, Europe also uses 50hz AC. In theory higher frequency is more efficient in transfering energy when using transformers because the field is changing more rapidly, thus transfering more power from primary to secondary (analogous to a generator spinning faster, and the coils experiencing more phase shift per unit time).

Realistically, theres no huge difference. Im not sure about overall efficiency in grids that use 50hz AC, but I doubt it would be significantly lower.

As to why some countries use 50hz and some use 60, im not sure exactly, but there are many variances in grids from place to place, including transmissing and distribution voltage, HVDC lines, etc.