EHV and HV transformer size

Not from those figures. Units of kW and MW would be needed.

Refer to IEC 60076 or some standard trafo manufacturer.

Standard : IEC 600076

Capacity: 100 MVA

Type of cooling : ONAF

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Power transformer rating is not a function of the voltage level, instead, the amount of power needed to be evacuated/transmitted shall be the determing factor for transformer rating. Which in turn, depends upon the installed capacity of generating station.

Generally, there are three levels of a power system network -

1. Transmission - Normally at EHV voltage levels

2. Subtransmission - Normally at HV/MV levels

3. Distribution - MV/LV levels

Finally, after stepping down the voltage, power supply is connected to consumer premises through cable etc in case of LV consumers, whereas for bulk consumers, power supply is given at higher voltage level(s) to consumer's grid substation.

The rating of transformers may vary from 11 KV, 25 KVA to say.. 400 KV, 500 MVA depending upon manufacturer.

As righly pointed out by Mr. B.N. Das, you can refer the IEC standard and for specific information regarding the capacities of transformers meant for various voltage levels, contact manufacturers.