Description : Why is transmission line 11kV, 33kV 66kV Not Is 10kV, 20kV, 30kV ?

**Answer** : 10kv plus to compensate losses in olden days 1kv were added and transmitted. Since all equipment used for transmission have a multiple of 11 from olden days, still that is being followed even though the losses are ... voltages, multiples of 11 is eazy for winding ratios.. i.e. 11kv to 33kv is 1:3.