A.C GENERATOR

D.C GENERATOR

“A.C generator” means “Alternating current generator”

That is, an A.C generator produces alternating current , which reverses its direction continuously A.C generator is also known as an alternator .

A.C Generator

A Simple A.C Generator consist of a rectangle coil ABCD which can be rotated rapidly between the poles N and S of a strong horseshoe-type permanent magnet .

The coil is made of a large number of turns of insulator copper wire .

Construction of an A.C Generator

The two ends A and D of rectangular coil are connected to two circular piece of copper metal called slip rings R 1 and R 2 .

As the slip rings R1 and R2 rotate with the coil, the two fixed pieces of carbon called carbon brushes B1 and B2 keep contract with them.

So, the current produce in the rotating coil can be tapped out through slip rings into the carbon brushes.

The outer ends of carbon brushes are connected to a galvanometer to show the flow of current in the external circuit.

Suppose that the generator coil ABCD is initially in the horizontal position

Again suppose that the coil ABCD is being rotated in the anticlockwise direction between the poles N and S of the horses-type magnet by rotating its shaft.

Working of an A.C generator

1. a s the coil rotates in the anticlockwise direction , the side AB of the coil moves down cutting the magnetic field lines near the N- pole of the magnet , and side CD moves up , cutting the magnetic field near the S- pole of the magnet . Due to this , induced current is produced in the sides AB and CD of the coil. On applying Fleming` s right - hand rule to the sides AB and CD of the coil, we find that the current are in the direction B to A and D to C.

Thus, the induced current in two sides of coil

Are in same direction ‘and we get an effective induced currents in the direction BAD C thus in the first half revolution of coil ’, the current in the external circuit flows from brush B1 to B2 .

2.After half resolution, the sides AB and CD of the coil will inter change their positions. The side AB will come on the right hand side and side CD will come on the left side. So, after half a revolution , side AB s tarts moving up and side CD starts moving down. As a result of this , the direction of induced current in each side of the coil is reserved after half a revolution giving rise to the net induced current in the direction CDAB …. .……….

Field current and motion

D.C Generator

Constructor 1.Armature coil . It

consist of large number of insulated copper wire wound on iron core in the form of a rectangle coil . Rectangle coil ABCD is an armature coil.

Strong field magnet .Armature coil is

placed between Two pole pieces ( N and S poles ) of a strong magnet . This magnet provides a strong magnetic field.

3.Split-ring Type Commutator . It consist of two halves (R1 and R2) of a metallic ring . The output is by the glowing bulb connected across the carbon brushes.

When the coil of d.c. generator rotates in the magnetic field, induced potential difference is produced in the coil . The induced potential difference gives rise to the flow of current through the bulb and hence the bulb glows.

Working of D.C generator

In d.c. generator , the flow of current in the circuit is in the same direction as long as the coil rotates in the magnetic field . This is because one brush is always in contact with the arm of the armature moving up and the other brush is in contact with the arm of the armature moving downwards in the magnetic field

Submitted to :- Miss Jayanti

Submitted by:- Carol Ekka

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