TOPIC

DIRECT CURRENT (DC) GENERATOR

Prepared by – M. R. Mohanta

MSE, BARIPADA

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INTRODUCTION

• A direct current (DC) generator is a rotating machine that supplies an electrical output with unidirectional voltage and current.
• The basic principles of operation are the same as those for synchronous generator.
• The field is produced by direct current in field coils or by permanent magnets on the stator.

USED OF D C GENERATOR

• They are used in DC motor where speed control is necessary.
• They are used as portable generators where low power supply is required.
• They are used in motorcycle as dynamos,in toy such as remote control car and in appliances such as shavers.

How do DC Generator work?

• A DC generator transforms mechanical energy to electrical energy. This generator work on the principal of induced EMF(Electromative force) by the motion of a conductor through a magnetic field. This means that two essential parts of a DC generator are the magnetic field and conductors which can move in the field.

DC Generator

DC motor

D.C. GENERATORS PRINCIPLE OF OPERATION

• DC generator converts mechanical energy into electrical energy. when a conductor move in a magnetic field in such a way conductors cuts across a magnetic flux of lines and e.m.f. produces in a generator and it is defined by faradays law of electromagnetic induction e.m.f. causes current to flow if the conductor circuit is closed.

First Law :

  Whenever the magnetic flux linked with a circuit changes, an e.m.f. is always induced in it. 

                                        or

  Whenever a conductor cuts magnetic flux, an e.m.f. is induced in that conductor. 

Second Law :

  The magnitude of the induced e.m.f. is equal to the rate of change of flux linkages.

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Faradays Law of Electromagnetic Induction

A changing magnetic flux through a  loop or loops of wire induces an electromotive force (voltage) in each loop.

Lenz’s Law

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“The induced currents in a conductor are in such a direction as to oppose the change in magnetic field that produces them..”

“The direction of induced E.M.F in a coil (conductor) is such that it opposes the cause of producing it..”

OR

Fleming's Right Hand Rule

• The Thumb represents the direction of Motion of the conductor.
• The First finger (four finger) represents Field.
• The Second finger (Middle finger) represents Current

E.M.F

Fleming's Right Hand Rule

The following are the basic requirements to be satisfied for generation of E.M.F

• Magnetic field :-

Permanent Magnet

(or)

Electro Magnet (practical)

• Conductor :- Copper (or) Aluminum bars placed in

slots cut around the periphery of cylindrical rotor

• Relative motion:-

By Prime Mover

Turbine

I.C Engine (Internal combustion)

1.A uniform Magnetic field

2.A System of conductors

3.Relative motion between the magnetic field and conductors

• THANK YOU