What are the advantages and disadvantages of three phase induction motor?

Advantages are:

(i) It has simple and rugged construction.

(ii) It is relatively cheap.

(iii) It requires little maintenance.

(iv) It has high efficiency and reasonably good power factor.

(v) It has self-starting torque.

Disadvantages are:

(i) It is essentially a constant speed motor and its speed cannot be changed easily.

(ii) Its starting torque is inferior to d.c. shunt motor.