Question

describe fully about electric generator

Answer 1

In electricity generation, a generator is a device that converts motive power into electrical power for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines and even hand cranks. The first electromagnetic generator, the Faraday disk, was invented in 1831 by British scientist Michael Faraday. Generators provide nearly all of the power for electric power grids.  The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be mechanically driven to generate electricity and frequently make acceptable manual generators.

Answer 2

$\bf{\: principal}$

It is based on the principle of electromagnetic induction . when a coil is rotated about an axis perpendicular to the direction of uniform magnetic field, an indused emf produced across it.

$\bf{construction}$

The AC generator consists of the following parts :

$\sf{1. \: armature}$

A rectangular coil ABCD consisting of a large number of turns wound over a soft iron core is called armature. the soft iron core is used to increase the magnetic flux.

$\sf{2. \: field \: magnet}$

it is a strong magnet having concave poles. the armature is rotated between the two poles of this magnet so that axis of armature is perpendicular to magnetic field lines. in a small AC generator the magnet is the permanent magnet but in Big AC generators it is an electromagnet.

$\sf{3. \: slip \: rings}$

the leads from the arms of armature AC connected to two slip rings S, which rotate with the loop .

$\sf{4. \: brushes}$

the rings slide against stationery contacts called brushes . these brushes are made up of carbon. these brushes are connected to the output terminals p and q.

$\bf{working}$

the working of AC generator can be understood with the help of various positions of the armature .

suppose at time 't' =0 , the plane of the loop is perpendicular to B . as the loop rotate from position t=0 to position t=T/2 , induced EMF changes from zero to maximum value and then becomes zero again, hence induced EMF is zero. as the loop moves from position t =T /2 to position t=T , the EMF again changes from zero to maximum value and then again becomes zero .

Thus the output of the AC generator varries sinusoidally with time . The induced EMF does not depend upon the shape of the loop but depends only upon area of the loop..