An induction electric motor which connects with a 3-phase supply called 3-stage induction motor. Example followers,three phase ac induction motor china blowers, cranes,traction .It really is a ac motor. The main drawback of DC motors is the presence of commutator and brushes, which require regular maintenance and we can’t use DC motor in explosive and filthy environment. But induction motors are cheaper,rugged,lighter,smaller,require much less maintenance and may use in filthy and explosive environment. Slide s is the imp factor in this kind of motor.

There are 2 types of IM.

Squirrel cage IM
Slip ring IM
There are numerous 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 velocity control technique of induction electric motor is important

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