AC Generator - Definition, Diagram, Characteristics, Types & Uses

Divya Kare

| Updated: Mar 2, 2023 12:39 IST

An electric machine that converts mechanical energy into electrical energy in the form of voltage and current is known as a generator. It is based on the principle of electromagnetic induction. For e.g.- a wind turbine, hydroelectric turbine, photovoltaic, etc. Generator was invented in August 1831 by British scientist Michael Faraday. It was known as Faraday Disk. Generators are of two kinds: AC generator and DC generator.

In this article, we will be studying about AC generators, the working principles of AC generators, types, and uses of AC generators.

AC Generator

A generator that converts mechanical energy into alternating electrical energy i.e. alternating current and alternating emf is known as an AC generator. The emf generated is dependent on the number of armature coil turns, magnetic field strength and the speed of the rotating field. AC generators are based on the principle of electromagnetic induction. The first AC generator was developed in 1887 by F. Augus Haselwander in Europe.

Diagram of an AC Generator

Components of an AC Generator

Field- The field is composed of coils of conductors that receive voltage from the source and produce magnetic flux. This magnetic flux in the magnetic field cuts the armature to produce a voltage.
Armature- Armature consists of wire coils, large enough to carry full load current for the generator.
Prime Mover- Prime mover is a component used to drive the AC generator. It is either a diesel engine, a motor or a steam turbine.
Rotor- The rotating machine in the generator is known as a rotor. It is driven by the generator’s prime mover.
Stator- The stator, a stationary part, the core comprises a lamination of steel alloys or magnetic iron to minimize losses due to eddy currents.
Slip Rings- The slip rings are electrical connections used to transfer power to and fro from the rotor of the generator. Slip rings are designed to conduct the flow of current from a stationary device to a rotating device.

Working Principle of AC Generator

The armature in the AC generator rotates between poles of the magnet upon the axis perpendicular to the magnetic field. The flux linkage of the armature changes continuously. This results in a magnetic effect of electric current flowing through the galvanometer. Slip rings and brushes. There is movement in the galvanometer’s needle. This indicates the flow of an alternating current through the galvanometer. By using Fleming’s Right-Hand Rule, we can find the direction of induced current.

Types of AC Generator

AC generators are generally of two types- single-phase AC generator & three-phase AC generator

Single-Phase AC Generator– A single-phase AC generator is an electric machine that converts mechanical power into 1- phase electric power alternating current by the process of electromagnetic induction.
Three-Phase AC Generator– A three-phase AC generator is an electrical machine that converts mechanical power into three-phase power alternating current by the process of electromagnetic induction.

Difference Between AC and DC Generator

The differences between an AC generator and a DC generator are as follows:

AC GeneratorDC GeneratorA generator that converts mechanical energy into alternating electrical energy i.e. alternating currents and alternating emf is known as an AC generator.A generator that converts mechanical energy into direct electrical energy i.e direct currents and direct emf is known as an DC generator.Slip-rings have a smooth and uninterrupted surface, therefore they do not wear quickly and are highly efficient.Brushes and commutators of a DC generator wear out quickly and therefore are less efficient.The brushes have high-efficiency chances of a short circuit is very unlikelyThe brushes and commutators wear out quickly, so the possibility of sparking and short circuits is very high.AC generators are easy to maintain and are quite reliable.DC generators require high maintenance and are less reliable.

Uses of AC Generator

AC generators are widely used and have various applications. The applications of AC generators are listed below:

Diesel-electric locomotive alternators – Locomotives need electric and mechanical power simultaneously, and this power is provided by AC generators
Marine alternators – These alternators are used for generating power in marine equipment.
Brushless alternators –These alternators are the main source of power in electrical power plants.
Automotive alternators – Automobiles use generators for electric power. This electric power in the vehicles and charging battery is generated in AC generators.
Radio alternators – These are used for transmission of radio frequency in low bands.

You can also check out other Physics topics too. Get help from the experts to prepare for the exams with selective study material, mock tests and valuable insights all designed to help you score better marks in the exam. Download the free Testbook App to grab some exclusive offers now.

FAQs on AC Generator

Q.1 What is the principle of an AC generator?

Ans.1 . AC generators are based on the principle of electromagnetic induction.

Q.2 Can we convert a DC generator to an AC generator?

Ans.2 Yes, an AC generator can be converted into a DC generator by using half-split slit rings.

Q.3 Where AC generator is used?

Ans.3 AC generators are widely used diesel-electric locomotive alternators, marine alternators, brushless alternators, automotive alternators and radio alternators.

Q.4 Why are AC generators better than DC?

Ans.4 AC generators are better than DC because they have a high-efficiency, they do not wear down quickly, they are easy to maintain and are more reliable than DC generators

Q.5 What are the advantages of an AC generator?

Ans.5 Following are the advantages of an AC generator:
Slip-rings have a smooth and uninterrupted surface, therefore they do not wear quickly and are highly efficient.
The brushes have a high efficiency so the chances of short circuit are very unlikely
AC generators are easy to maintain and are quite reliable

Testbook Logo