Power transmission line from power generating stations to the city consumers
Step 1
Power is generated at 11kV 50Hz
Step 2
The voltage is stepped up to 132kV using a step up transformer. This is because for a given power, greater the voltage, lesser is the current flowing through the wire (P=VI) and lesser current means less loss power due to heating effect ( H=I²Rt).
Step 3
Voltage is stepped down from 132kV to 33kV . Some of it is used by heavy industries.
Step 4
33kV is stepped down to 11kV and some of it is used by light industries
Step 5
11kV is stepped down to 220V for city consumers.
The above circuit shows the steps in power transmission line. The yellow and red switches symbolize heavy and light industries respectively.
Summing up
11kV AC to 132kV AC to 33kV AC to 11kV AC to 220V AC
