There are many important reasons why 400 KV not directly Stepped Down to 33 KV. First, the 440 KV stepped down to 132 KV, then 132 KV to 66 KV, and then 66 KV to 33KV.  The step up and step down of voltage is depending upon the Transformer. When transformers are designed, many factors are kept in mind. So, the answer to this question mostly depends on the transformer. In this article, we will discuss, what are the problems are to be faced if 400 KV directly stepped down to 33KV or 11KV.

Reason 1

We know that when we step down the voltage using a transformer the current will increase. So in this case, if we step down the 440KV to 33KV, current will increase. But as here a big difference between primary and secondary voltage, so the difference between primary and secondary current will be high.

In this case, the secondary current would be 12 to 13 times higher than the primary current. As the current increases, the very very thick conductor should be used. For this reason, the size of the transformer will be extremely high.

Reason 2

The different transmission voltages are selected according to the distance of transmission. For very very large distance transmission purpose 440 KV is used and for short transmission purpose, 33KV is used.

So if we transmit electrical power in the medium distance, we must select a voltage level between 440 KV and 33KV such as 132 KV, 66K V, etc. Because if we transmit electrical power at 33 KV voltage level in the medium distance the loss will be high and if we select 440 KV voltage level for medium distance the cost will be high compared to the distance which is not economical.

Reason 3

As there is a big difference between the primary and secondary voltage so the difference between no. of turns in the primary and secondary winding will be high. For this reason, the placement of windings, insulation arrangement, connections, tappings may be impractical. So the manufacturing of 440/33 KV transformer may not be possible.

Reason 4

If we step down the 440 KV directly to 33 KV and operate them with very low load current, then a huge no. of transformers are to be installed in distribution substation or receiver end. If we transmit power at 440 KV voltage level in all places, the size of the towers will be big and the gap between ground and conductors must be kept very high. So this high voltage transmission consumes very large areas.