Why normally Generator rating are between 11Kv to 22Kv?

Because if we use a generator of 33kv or higher then the radii must be of 2-3 meters that is not good. And also the area of the generator will be very high and losses and heat paameters will also be high.

The main point is that we use 11kv generator at power plants and we have to step up the power to 220KV or 500KV etc. So we use 11kv or 22kv instead of 33 kv or higher..

By doing so we save the cost of area required, radii of rotor, and losses produced by higher power generators.