Induction Motors

Introduction:
                     AC motors are called Induction motors. In AC motors , the rotor does not receive electrical power by conduction but by the induction in same way as primary induce power in secondary of a transformer. This is the reason why AC motors are called Induction motors.

Here  is a video of basic function of  Induction motor.

                                              
Construction:                  
                     There are two main parts of motor

1. Stator
2. Rotor

It is made up of  number of stampings. It has a winding on which supply is given ( 3 or single phase). It is wound on the definite number of poles on which speed of motor depends, greater the number of poles lesser will be the speed.
Rotor:
          It is that part of motor which rotate inside the frame. The axel is made of cast steel alloy to withstand tearing and shearing stress. Its dia is mechanical design and it is coupled on one end to a device which carries mechanical energy in a form of rotational energy.
Rotor consist of

• Shaft
• Cores 
• Slots
• Winding

There are two types of rotor,

1. Squirrel cage
2. Wound rotor

Squirrel cage:
                       90% of motors used in industries are of squirrel cage type.It is a normal design crossection area having  a shaft in the center and over it ring shaped electromagnetic laminated sheets. There are slots along the length of rotor. The conductors are placed inside the slots because it is the safest place. The conductor laced inside the rotor in this condition are look like a cage that is why its is called squirrel cage rotor.

Wound rotor:    
                      The rotor has slots and wound with insulated conductors the stator way. The ends of theconductors are brought to be connected with slip rings which will now connected to three phase rheostat.