i. Electric power is produced in a large scale at electric power stations with the help of AC generators. These power stations are classified based on the type of fuel used as thermal, hydro electric and nuclear power stations.
ii. Most of these stations are located at remote places. Hence the electric power generated is transmitted over long distances through transmission lines to reach towns or cities where idt is actually consumed. This process is called power transmission.
iii. But there is a difficulty during power transmission. A sizable fraction of electric power is lost due to joule heating `(i^(2)R)` in the transmission lines which are hundreds of kilometer long.
iv. This power loss can tackled either by reducing current i or by reducing resistance R of the transmission lines.
v. The resistance R can be reduced with thick wires of copper or aluminium. But this increases the cost of production of transmission lines and reducing power loss is not economically viable.
vi. Since power produced is alternating in nature, there is a way out. The most important property of alternating voltage that it can be stepped up and stepped down by using transformers could be exploited in reducing current and thereby reducing power losses to a greater extent.
vii. At the transmitting point, the voltage is increased and the corresponding current is decreased by using step-up transformer.
viii. Then it is transmitted through transmission lines. This reduced current at high voltage reaches the destination without any apprciable loss.
ix. At the receiving point, the voltage is decreased and the current is increased to appropriate values by using step-down transformer and then it is given to consumers. Thus power transmission is done efficiently and economically.
