An induction electric motor which connects with a 3-stage supply called 3-phase induction motor. Example fans,blowers, cranes,traction .It really is a ac motor. The main drawback of DC motors is the existence of commutator and brushes, which require frequent maintenance and we can’t use DC engine in explosive and dirty environment. But induction motors are cheaper,rugged,lighter,smaller,require less maintenance and may use in dirty and explosive environment. Slip s is the imp element in this type of motor.

There are 2 types of IM.

Squirrel cage IM
Slip ring IM
There are various three phase ac induction motor starting and braking condition.

Important starting methods are

Star-delta starter
Auto transformer starter
Ac voltage controller starter
Rotor resistance starter
Important braking methods are

Regenerative braking
Plugging or invert voltage braking
Dynamic braking
But one thing swiftness control technique of induction motor is important

Pole changing
Stator voltage control
V/f control
Slip power recovery
Rotor resistance control