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An induction is also called as asynchronous motor is an Alternating Current motor, when current is induced in the stator winding producing magnetic field to the stator winding, by electromagnetic induction. They don't require the moving electric contacts, like a commutator or slip rings, which are necessary to transfer current to the rotor winding in other types of motor such as the universal motor. Rotor windings consist of short-circuited loops of conductors and they are 2 types: The wound rotor and the squirrel-cage rotor.
Three-phase squirrel-cage induction motors, The industries are mostly depend on induction motor for rotating force, They are widely used in industrial drives because they are cliffy, dependable and efficient. Single-phase induction motors are used extensive for small loads, such as household widget like fans. The simple induction motor is a fixed-speed device, Because they used variable-frequency drive systems, The device allowed to vary the speed. Variable-Frequency Drive Systems bring out especially important energy savings opportunities for existing induction motors in variable-torque centrifugal fan, pump and compressor load usage. Squirrel cage induction motors are very widely used in both fixed-speed and variable-frequency drive applications.
Pricipal of induction motor:
As a general rule, conversion of electrical power into mechanical power takes place in the rotating part of an electric motor. In d.c. motors, the electric power is conducted directly to the armature through brushes and commutator. Therefore, In this sense, a d.c. motor also called as conduction motor. However, in A.C. motors, the rotors, the rotor doesn't receive electric power by conduction but only with induction in exactly the same way, The secondary of a 2-winding receives its power from the primary. that's why such motors are known as induction motors. An induction motor can be treated as a rotating transformer i.e. one in which primary winding is stationary but the secondary is free to rotate. Of all the A.C. motors, the polyphase induction motor is the one which is sweeping used for various categories of industrial drives.
