What is Electric Motor ?

namely the electromagnetic interaction by Hans Christian Ørsted in 1820 much progress was soon made. It only

took a few weeks for André-Marie Ampère to develop the first formulation of the electromagnetic interaction and

present the Ampère's force law, that described the production of mechanical force by the interaction of an electric current and a

magnetic field.[6] The first demonstration of the effect with a rotary motion was given by Michael Faraday in 1821. A free-hanging

wire was dipped into a pool of mercury, on which a permanent magnet (PM) was placed. When a current was passed through the

wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire.[7]

This motor is often demonstrated in physics experiments, substituting brine for (toxic) mercury. Though Barlow's wheel was an

early refinement to this Faraday demonstration, these and similar homopolar motors remained unsuited to practical application

until late in the century.

Electric motor, any of a class of devices that convert electrical energy to mechanical energy, usually by employing electromagnetic phenomena.

In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils. After Jedlik solved the technical

Most electric motors develop their mechanical torque by the interaction of conductors carrying current in a direction at right angles to a magnetic field.

problems of continuous rotation with the invention of the commutator, he called his early devices "electromagnetic self-rotors".

The various types of electric motor differ in the ways in which the conductors and the field are arranged and also in the control that can be exercised over mechanical output torque, speed, and position

Although they were used only for teaching, in 1828 Jedlik demonstrated the first device to contain the three main components of

The simplest type of induction motor is shown in cross section in the figure

A three-phase set of stator windings is inserted in slots in the stator iron

practical DC motors: the stator, rotor and commutator. The device employed no permanent magnets, as the magnetic fields of

These windings may be connected either in a wye configuration, normally without external connection to the neutral point, or in a delta configuration

The rotor consists of a cylindrical iron core with conductors placed in slots around the surface.

both the stationary and revolving components were produced solely by the currents flowing through their

In the most usual form, these rotor conductors are connected together at each end of the rotor by a conducting end ring.

windings.[9][10][11][12][13][14][15]

he basis of operation of the induction motor may be developed by first assuming that the stator windings are connected to a three-phase electric supply

that a set of three sinusoidal currents of the form shown in the figure flow in the stator windings.