Generators, Working Principle of Generator, Types of Generators (For CBSE, ICSE, IAS, NET, NRA 2022)

Doorsteptutor material for competitive exams is prepared by world's top subject experts: get questions, notes, tests, video lectures and more- for all subjects of your exam.

Generators

About Generator

  • It is mechanical equipment which converts mechanical form of energy into electrical energy.
  • Generators find application in agricultural and industrial production.
  • The frequently used principle for the construction of generator is based on the law of electromagnetic force.

Working Principle of Generator

Working Principle of Generator
  • The structure consists of a rectangular coil with a number of copper wires wound over an iron core. The coil is called the armature.
  • It is used to increase the magnetic flux.
  • A strong permanent magnet is placed and the armature is rotated between the magnets where the magnetic lines are perpendicular to the axis of the armature.
  • There are two slip rings connected to the arms of the armature. They are used to provide movable contact.
  • Two metallic brushes are connected to the slip rings to pass current from the armature to the slip rings.
  • Current is passed through a load resistance, which is connected across the slip rings.
  • At different intervals of time, the position of the armature keeps changing.
  • When the magnetic field lines are perpendicular to the coil, the coil is rotated in the magnetic field and the induced e. m. f produced increases.
  • This happens in this position because of the number of intercepting magnetic field lines maximum.

Types of Generators

Following are the types of generators:

  • AC generator
  • DC generator

AC Generators

  • These are also called alternators.
  • It is the most important means of producing electrical power in many of the places since all the consumers are using AC.
  • It works based on the principle of electromagnetic induction.
  • These are of two types
    • An induction generator
    • A synchronous generator.
  • The induction generator requires no separate DC excitation, regulator controls, frequency control, or governor. This concept takes place when conductor coils turn in a magnetic field actuating a current and a voltage.

Working Principle of AC Generator

  • The working principle is based on the electromagnetic induction.
  • The armature rotates between the poles of the magnet which is perpendicular to the magnetic field.
  • If there is a changed in the flux produced by the armature, emf is induced producing electric current with the help of galvanometer, slip rings, and brushes.
  • The flow of alternating current through the galvanometer can be observed when the galvanometer oscillates between positive and negative poles.

Types of AC Generators

  • Synchronous generators
  • Induction generators

Advantages of AC Generators

  • The time spent on maintenance is very less as there are no brushes.
  • When compared to DC generator, the size of A generators is small.
  • Minimal amount of losses are there.
  • The breakers used are relatively smaller when compared to DC generators.

DC Generator

It is used for converting mechanical energy onto direct current electricity

Working Principle of DC Generator

  • The working principle is based on Faraday՚s laws of electromagnetic induction.
  • When a conductor is placed in the varying field, an e. m. f is induced in the conductor.
  • The magnitude of the e. m. f induced can be calculated with the help of e. m. f equation of DC generator.
  • The circulation of induced current takes place within the closed path.
  • The direction of induced current can be determined by the help of Fleming՚s right-hand rule
  • equation of e. m. f of DC generator is given as:

Where,

  • P is the number of field poles
  • is the flux produced per pole in Weber?
  • Z is the total number of armature conductors
  • A is the number of parallel paths in armature
  • N is the rotational speed of the armature in rpm

Types of DC Generators

  • Permanent magnet DC generator
  • Separately excited DC generator
  • Self-excited Dc generator
    • Series wound generator
    • Shunt wound generator
    • Compound wound generator

Advantages of DC Generators

  • The operating characteristics of DC generator depends on the field winding
  • Cable cost will be less as there is no shielding from radiation.
  • Prevention of DC to the next circuit in the DC transformers.
  • The fluctuations in the generator can be reduced by constant arrangement the coils.

Developed by: