ECN | State any two advantages of polyphase circuit over single phase circuit.

 i) Three-phase transmission is more economical than single-phase transmission. It requires less copper material.  

ii) Parallel operation of 3-phase alternators is easier than that of single-phase alternators.  

iii) Single-phase loads can be connected along with 3-ph loads in a 3-ph system. 

iv) Instead of pulsating power of single-phase supply, constant power is obtained in 3-phase system. 

v) Three-phase induction motors are self-starting. They have high efficiency, better power factor and uniform torque. 

vi) The power rating of 3-phase machine is higher than that of 1-phase machine of  the same size. 

vii) The size of 3-phase machine is smaller than that of 1-phase machine of the same power rating. 

viii) Three-phase supply produces a rotating magnetic field in 3-phase rotating machines which gives uniform torque and less noise.