Advantages of three phase system over single phase system
a) Rotating magnetic field can be set up, by passing three-phase current by stationary coils.
b) Polyphase system is extra capable and reliable than single - phase system.
c) Parallel operation of three - phase alternators is easy as compared that of single- phase alternators due to of pulsating reaction in single- phase alternators.
Therefore, three-phase operation is not as practical for domestic applications where motors are mainly smaller than 1 kW and where lighting circuits supply most of the load.