From the power generating stations, a large amount of AC supply is produced and is transmitted through transmission lines. The layout of a typical AC power supply system. The transmission is done caried by 3 phase 3 wire and 3 phase 4 wire systems. Other methods are also used for some special reasons.
Two types of transmission are
i. Primary transmission and
ii. Secondary transmission
In the primary transmission, the voltage produced from power plants, transmitted over the transmission lines to the substations with the help of step up transformer.
The voltage transmitted by the primary transmission is reduced by a step down transformer, and is transmitted to the sub-stations in the city.
Advantages of AC transmission
i. Alternate current can produce voltage (33 KV) at the highest level.
ii. The voltage can be increased or decreased.
iii. High voltage transmission reduces losses.
iv. It is easy to maintain sub-stations and less expensive.
Disadvantages of AC transmission
i. The AC line has the capactive and inductive effect.
ii. Due to skin effect, it requires more effective conductors.
iii. The construction of AC transmission is complicated.
iv. More copper conductors are required for transmitting AC.