Question

explain the construction working and principle of ac generator​

Answer 1

An AC Generator essentially consists of two main parts: Stator and Rotor. Stator is the stationary part of machine whereas rotor is rotating part. A prime mover is coupled to this rotor to supply mechanical energy.

Stator:

Stator is stationary component on which armature winding is wound. Armature winding is the winding which carries load current. Here load means any device or equipment which consumes electrical power. This stator is stack of laminated steel assembled to form a cylindrical structure. Steel lamination are used to minimize the eddy current loss.

Slots for housing stator winding (armature winding) are cut along the periphery of the stator.

Rotor:

Rotor is the rotating component of AC Generator. It is also made of laminated steel. DC Field winding or exciting winding is wound on the rotor to create magnetic poles i.e. North and South Poles. This exciting winding is supplied DC current through an assembly of slip ring and carbon brush.

There are basically to designs for rotor. One is Salient Pole Rotor and another is Cylindrical Rotor.

Working Principle of AC Generator:

The basic working principle of AC Generator is based on faraday’s law. When the rotor of AC Generator is rotated by prime-mover, the magnetic flux linkage with the stationary armature winding (mounted on Stator) changes. Due to this an emf is induced in the armature winding. If load is connected, an AC current starts flowing through the load due to the induced emf. This is how an AC Generator works.  

Let us consider the figure below to better understand the AC generator working principle. In the figure, a single armature winding is considered for the sake of simplicity. A permanent magnet is taken as rotor instead of rotor with field winding. Rotor is assumed to be rotating in clockwise direction.the rotor field axis and armature winding axis coincides. Therefore the flux linkage is maximum at this instant of time and hence maximum emf will be induced. Consequently, maximum current will flow through the load RL. The direction of current is governed by lenz’s law. The current will flow from D-A-B-C-D.At this instant, rotor axis and armature winding axis are perpendicular to each other. Therefore, there will not be any mutual coupling between them. Thus no emf will be induced in the stator (armature winding). Hence no current will flow through the load RL at this instant.

A further rotation of rotor by 90 degree causes stator axis and rotor axis to coincide again. Hence flux linkage will again be maximum. Subsequently, maximum current will flow through the load.

Answer 2

Explanation:

Explanation:

Step-by-step explanation:

$\huge \bf\red{\mid{\overline{\underline{ANSWER}}\mid}}$

$\bf{\: principal}$

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..