An induction motor which connects with a 3-stage supply called 3-stage induction motor. Example enthusiasts,three phase ac induction motor china blowers, cranes,traction .It is a ac electric motor. The primary drawback of DC motors may be the presence of commutator and brushes, which require regular maintenance and we can not use DC engine in explosive and dirty environment. But induction motors are cheaper,tough,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 swiftness control technique of induction electric motor is important

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