Three key points about 3 phase induction motors: 1. They have a stator winding that produces a rotating magnetic field when powered by a 3 phase voltage supply. This rotating field induces current in the rotor to generate torque. 2. The main types are squirrel cage and wound rotor induction motors. Squirrel cage motors have conductor bars embedded in the rotor, while wound rotor motors have windings on the rotor. 3. Key parts include the stator, rotor, and shaft. The stator produces the rotating magnetic field. The rotor rotates due to electromagnetic induction from the stator field. The shaft transmits the rotational power outside the motor.