Electric Power Transmission and Distribution System is based on three main topics. These are-
Power Generation or Power Generation Transmission or Power Distribution and Delivery of Power Distribution
That is, the power is being made first; Then it is being sent to distant distance. Finally, using a system to make them useful.
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Let's talk about our country. Where power or electricity is being produced, it is available from 11 kV volts. If we want to send it to the whole country or away somewhere, then sending it to 11 kilovolts, electrical engineer reading engineers will be able to sit in the saddle with electricity but electricity can not be found. 
Before sending it for a while it was taken up by step. It should be noted here that due to some specifications, this 11 kilowatt electricity was stepped up in 132 or 230 or 400 kilowolts. I do not mention it again because my previous article has written about the step up response to some important questions related to the transformer.
Then it is crossed through the transmission line, far away. Now suppose the need to connect the electricity to one place. So the line was taken down to 11 kilowolts down from 132/30/400 kilowolts to give a connection to the connection. If this is a big match, or an industrial company, then the direct access to the 11 kilovolt line goes out. Then they make it useful by reducing or increasing it.
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Well then let's come home, what happens? Very Simple Now the 11 kilovolts are again stepped down to 0.44 kilowatt or 440 volts. And it is sent to a home or a small consumer. From there it used to be transformed in 220-240 volts as needed.