The primary areas from where electricity is generated for regular usage are via thermal or nuclear power stations sand hydroelectric stations. Given that these stations are located at an ample distance in comparison to load centers from where it is generated, so to ensure that there is presence of a strong power supply there has to be strong connection between consumer and plant loads.
It is very important to have a strong conveyance connection from the place from where this electricity is generated (central stations) to the area to where it is required (consumers). The primary areas where it is required are: factories, commercial buildings, and pumping stations.
It is to be noted that amount of power that has to be transmittedvia lines of transmission is quite high, and chances are there that power loss associated with this transmission is quite high. In such areas, with the help of a step-up transformer, voltage is stepped up to a higher value in case of those sub-stations.
In comparison to maximum voltage in foreign countries to be around 33 kV, in India, it comes down to 11kV. Also, generally it is the 132 kV, 220 kV and 400kv voltage that functions on a regular basis. With the help of transmission lines that have high voltage, from power generating stations, electric power is transmitted to the receiving end of these sub-stations. In such cases, voltage is kept within a range of 33-66 kV.
To form a connective link between the secondary sub-station receiving points and main receiving points of sub-stations, there is need of a secondary transmission system. It so happens that as per connective standards, either 11 kV or 33 kV distribution lines ends up at distribution sub-stations starting off from secondary sub-stations. So, the step-down transformers that are present in distribution sub-stations and from that area power will be supplied. These sub-stations are distributed in such a manner, contain certain pole transformers that are mounted and hence their voltage is kept down at 400 kV.
The distribution lines normally have a voltage of 400V, and they are tapped off by using distributors, as they are placed along roads and other side fence areas. Since they come in a 3 wire and phase format, so there is need for a neutral wire that helps in supplying to domestic and commercial areas the required power. This whole thing comes in a grid format.