HOW DOES A POWER GENERATOR WORK ?

A generator is an electrical device used to convert mechanical energy to electrical energy. It operates on the principle of electromagnetic INDUCTION. The generator moves a conductor through a magnetic field and directs the current produced by the induced voltage to an external circuit. In the simplest generator the conductor is an open coil of wire rotating between the poles of a permanent magnet. During a single rotation, one side of the coil passes through the magnetic field, first in one direction and then in the other, so that the induced current is alternating current (AC), moving first in one direction, then in the other. Each end of the coil is attached to a separate metal slip ring that rotates with the coil. Brushes resting on the slip ring pass the current to the external circuit. To obtain direct current (DC), i.e., current that flows in only one direction, a commutator is used in place of slip rings. The commutator is a single slip ring split into left and right halves that are insulated from each other and attracted to opposite ends of the coil. Current leaves the generator through the brushes in only one direction and pulsates from no flow to maximum flow and back again. In practice, generators have many coils and several magnets. The whole assembly carrying the coils is called the armature, or rotor; the stationary parts constitute the stator. Except for magnetos, which use permanent magnets, AC and DC generators use electromagnets. AC generators are often called alternators. Source:The Concise Columbia Electronic Encyclopedia, Third Edition