An induction electric motor which connects with a 3-phase supply called 3-stage induction motor. Example supporters,blowers, cranes,traction .It is a ac electric motor. The main drawback of DC three phase ac induction motor china motors may be the presence of commutator and brushes, which require frequent maintenance and we can not use DC motor in explosive and filthy environment. But induction motors are cheaper,durable,lighter,smaller,require less maintenance and may use in filthy and explosive environment. Slip s may be the imp element in this kind of motor.

There are 2 types of IM.

Squirrel cage IM
Slip ring IM
There are various 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 rate control technique of induction engine is important

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