AC Motor are of two types, namely Induction motor and Synchronous motor. But still in majority of application Induction motor is used due to less maintenance cost and less wear and tear and good efficiency.
In Industrial application 3-phase induction motor are used but single phase motor are also available in market as they still find their use in some field.
To understand the working of Induction motor we first should know what is present inside the motor. Induction motor consists of stator and rotor and it works on the principal of Faraday law of electromagnetic induction. An electric motor turns due to this law only , where stator is a stationary magnet and rotor is rotating electro-magnet.
The basic working principal of AC induction motor is as follows:-
When a 3-phase power is supplied to the rotor a rotating and pulsating flux is produced inside stator and this in turn impose electromagnetic torque on the rotor and thus an electromagnetic locking is formed and the rotor turns .There is always a difference in between speed of rotor and speed of rotating flux and this difference is known as slip. In other words we can say that slip is necessary for an induction motor to rotate because if there will be no slip then there will be no magnetic interlocking and rotor will not rotate.
Slip = Ns – N r / Ns
Ns – is synchronous speed
In this way the Ac Induction Motor operates . In further sections we will see what are the different types of rotor and history of Induction Motors. Also we will put some light on construction of AC Induction motor.
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