An induction electric motor which connects with a 3-phase supply called 3-phase induction motor. Example fans,blowers, cranes,traction .It really is a ac engine. The primary drawback of DC motors is the presence of three phase ac induction motor china commutator and brushes, which require frequent maintenance and we can’t use DC motor in explosive and dirty environment. But induction motors are cheaper,tough,lighter,smaller,require much less maintenance and may use in dirty and explosive environment. Slide s may be the imp factor in this type of motor.

There are 2 types of IM.

Squirrel cage IM
Slip ring IM
There are many 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 reverse voltage braking
Dynamic braking
But one thing speed control technique of induction motor is important

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