Introduction to Induction Motor

Induction Motor

In DC motor we need to provide electric supply for stator and field winding but in induction motor it works on single supply to stator with its secondary short circuited i.e. principle is similar to the transformer i.e. electromagnetic mutual induction principle

Induction motor also called a synchronous motor because it always runs at a speed less than synchronous speed (rmf speed in stator)

Two types depending upon type of input supply 1 phase, 3 phase or divided upon type of rotor squirrel cage induction motor

Squirrel cage Induction motor

When supply is given to Induction motor Alternating flux will be produced called (rmf field) this alternating flux will rotate at synchronous speed now there is a relative speed between stator mmf (rmf ) & rotor conductors as per mutual induction principle Induced emf is generated in short circuited rotor conductors  so, rotor current in rotor will also produce alternating flux

This rotor flux lags behind the stator flux according to lenz law the direction of induced emf is in such a way that it opposes the cause  of its production here that cause of production of rotor current is relative speed between the rotor and stator flux so, the rotor try to catch up the stator emf & rotor rotates in same direction as that of stator flux to minimize the relative speed rotor& stator flux it never catches the synchronous speed