There are many advantages of using three phase power, such as –
Constant Power: Three phase power delivered to a resistive load is perfectly constant at all the times. That means, not even minor fluctuations and vibrations.
Net power in all three phases,
P = sin2θ + sin2(θ – 2π/3) + sin2(θ – 4π/3) = 1.5
Single phase, two phase or four phase system etc. will have a sinusoidal component in the resultant power. Thus, vibrations and fluctuations are introduced.
Low neutral current: In case of a balanced system, no neutral current flows, hence no neutral wire is required. With non-linear or unbalanced loads, the neutral current in three phase system is very low. So, size of the neutral conductor is practically reduced.
Higher phases will require more number of conductors: Since, three phases can give a constant power, who would you go for higher phases when you will require increased number of conductors for transmission?
Easily get single phase supply: Three phase power supply is used for transmission and distribution. It is very easy to obtain single phase supply by taking connection from any one phase and the neutral.