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3 Phase AC Electric Motors Working Principles

An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding.An induction motor can therefore be made without electrical connections to the rotor.

source/image(PrtSc): The Engineering Mindset

Learn from the basics how an electric motor works, where they are used, why they are used, the main parts, the electrical wiring connections, induction motor, alternating current AC, electrical machines, rotating magnetic field, star delta, wye delta.

Three-phase squirrel-cage induction motors are widely used as industrial drives because they are self-starting, reliable and economical.The operating principle of a 3 phase induction motor is based on the production of a rotating magnetic field.The induction motor stator’s magnetic field is therefore changing or rotating relative to the rotor. This induces an opposing current in the induction motor’s rotor.


The induced currents in the rotor windings in turn create magnetic fields in the rotor that react against the stator field.The stator of an induction motor consists of a number of overlapping windings offset by an electrical angle of 120°. When the primary winding or stator is connected to a 3 phase A.C. supply, it establishes a rotating magnetic field which rotates at a synchronous speed./wikipedia