In A.C. motors, rotor receives electric power by induction in exactly the same way as the secondary of a two-winding transformer receives its power from the primary. The vector diagram for the split phase induction motor is shown in the Figure B. This article discusses-What is Three Phase Induction Motor, Working Principle, Construction, Advantages, and Disadvantages. In this article, I am discussing about three phase induction motor construction. Induction machines are also called asynchronous machines i.e. A 3 phase induction motor can be used for different applications with various speed and load requirements. Construction of Three Phase Induction Motor: Figure 8.1 shows the construction of three phase induction motor.A 3 phase induction motor has two main parts (i) stator and (ii) rotor.The rotor is separated from the stator by a small air-gap which ranges from 0.4 mm to 4 mm, depending on the power of the motor. Whenever we say induction machine we mean to say induction motor. Hence such motors are known as a rotating transformer i.e. Therefore when we say induction motor it is a rotating device based on the principle of induction. Working Principle of Three Phase Induction Motor An induction motor (also known as an asynchronous motor) is a commonly used AC electric motor.In an induction motor, the electric current in the rotor needed to produce torque is obtained via electromagnetic induction from the rotating magnetic field of the stator winding. For industrial and mining applications, 3-phase AC induction motors are the prime movers for the vast majority of machines. The rotor of an induction motor can be a squirrel cage rotor or wound type rotor. The interaction of the magnetic fields creates the torque that rotates the rotor and the load. These motors can be operated either directly from the mains or from adjustable variable frequency drives. Construction : Conversion of electrical power into mechanical power takes place in the rotating part of an electric motor. The popularity of 3 phase induction motors on board ships is because of their simple, robust construction, and high-reliability factor in the sea environment. What is an Induction Motor? the machines which never run at a synchronous speed. Like all motors, a three-phase induction motor contains a stator (the stationary part) and a rotor (which rotates). As the winding resistance of starting winding is high, the angle between voltage and current I s is small. Induction motors may be single-phase or three-phase. The motor is known to be associated with motion. Each contains electrical windings that carry current and thus creates a magnetic field. 3-phase AC induction motors.