Question

) Give two reasons why a three-phase system is normally used for the transmission and distribution of electrical energy when an AC system is used

Answer 1

1. power delivered is constant. In single phase circuit the power delivered is pulsating and objectionable for many applications. so we go through three phase for transmission and distrubtion.

2. For transmitting the same amount of power at the same voltage, a thrre phase transmission line requires less conductor for material than a single phase line . The three phase transmission system is so cheaper.

3.If a fault occurs in any winding of a 3 phase transformer , the rest of two winding can be used in the open delta to serve the 3 phase load.

4.Three phase system can produce a rotating magnetic field with a specified direction and constant magnitude, which simplifies the design of electric motors, as no starting circuit is required.