In INDIA the standrad of electricity generation , transmission and distribution and system voltage is 11kv, 33kv, 66kv , 110, 132kv, 220kv, 440kv, 750kv, at 50 hz .why not 40kv,50,60,300kv, like this.
M.Yogindranath
The initial voltages which you mention are typical of the hereditary UK transmission system.
Presumably it is because the British started building the infrastructure like railways, electricity, etc. in the commonwealth days before independence, that India has inherited the British system.
Clearly there is little practicable difference in using 33kV and 66kV instead of 40 and 50kV it really just depends on who made and supplied the equipment.
I must confess I'm not even aware that there is a European standard for transmission voltages, never mind a world wide standard, as we have only just agreed the distribution voltages (400v & 230V).
This is just my guess so I wait to be enlightened by other contributors.