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Generators are widely used for converting mechanical energy of motive power into electricity, which is then used in electric circuits. These devices, often called generators, are utilised to convert mechanical energy to electrical energy. The electrical energy produced is used in the external circuit to generate electricity. Various mechanical energy sources are available, such as turbines (gas, water, wind).
The electrical energy produced by the generator is used at domestic, industrial, and commercial levels. The generator works on the principle of magnetic induction, discovered by Michael Faraday in 1831-32. The most important components of a generator are a magnetic field, conductor and motor. A generator can be of two types:- AC and DC generators.
Types of Generators
There are two main generator types:
- Alternating Current (AC) Generator
- Direct Current (DC) Generator
Both types of generators work based on electromagnetic induction that leads to electricity generation. However, the major difference lies in their process of generating electricity. The principle used for the operation of a DC generator is the same as that of synchronous generators.
AC generators create an electric current that changes its direction periodically. At the same time, DC generators produce an electric current that moves in the same direction.
Differentiate Between Alternating Current and Direct Current Generators
AC GENERATOR Companies utilise these generators to transform mechanical energy into AC electrical energy. | DC GENERATOR Converts mechanical energy into DC electrical energy. |
The direction of the current that will flow through in a conductor would be used to produce electricity. | The current flows in the same direction. |
AC generators are used to set up a small appliance or a power supply. | DC generators are used to supply power to large industrial motors. |
Define DC Generators?
A DC generator is a rotating device that generates electricity by the unidirectional movement of current and voltage. It works on the principle of electromagnetic induction, based on Faraday’s law.
Working Principle of a DC Generator
According to Faraday’s law of magnetic flux, we can say that any conductor placed through a fluctuating magnetic field or a simple conductor moved along a magnetic field will be an induction of emf. The magnitude of induced emf can be estimated using the dc generator’s emf equation. The induced emf will circulate within the conductor if provided with a closed circuit.
Field coils generate an electromagnetic field in a power source, and the armature conductors rotate into it.
Consequently, the armature windings generate an electromagnetically induced emf. The right-hand principle of Fleming defines the direction of the current.
Structure of a DC Generator
The basic components of a DC generator are the magnetic field system, brush gear, commutator, and armature. Magnetic frame and yoke, pole core and pole shoes, field or exciting coils, armature core and windings, brushes, end housings, bearings, and shafts are the other components of a DC Generator.
State Different Types of DC Generators
DC generators are classified into three main categories based on their excitation methods.
- Permanent magnet DC generators
- Separately excited DC generator
- Self-excited DC generators
Permanent Magnet DC Generator
- A permanent magnet DC generator is the one that generates flux inside a primary coil using permanent magnets.
- It is composed of an armature and one or more permanent magnet positions around that. This type of DC generator does not produce a huge amount of energy.
Separately Excited DC Generator
- The field magnets are energised by external sources such as batteries in this generator.
Self-Excited DC Generators
This type of generator usually uses magnets that are charged using a current induced by the generator itself. Field coils are mechanically connected to the armature in these systems.
- Self-excited generators are used in modern technologies like portable generators.
Self-excited dc generators are classified into three types based on their position in the field, i.e. the coil.
- Series Wound Generators
- Shunt Wound Generators
- Compound Wound Generators
Series Wound Generators
In this type of generator, field windings will be linked in a series with armature connectors.
Shunt Wound DC Generators
Field windings are parallelly connected with the armature conductors in shunt-wound DC generators.
Compound Wound DC Generator
In this type of generator, there is a field winding and a shunt field winding. There will be one wound connected in a series form along with the armature, and on the other, they will be in a parallel series. They also have subtypes:
Short Shunt Compound Wound DC Generator
Short shunt uses one shunt field with only one attachment parallel to the armature winding.
Long Compound Wound DC Generator
The long compound uses a parallelly interconnected shunt to the series field and armature winding.
Conclusion
Therefore, DC generators are used to carry out one of the major functions, which is converting mechanical energy into electricity. A DC generator works based on electromagnetic induction. The structure of a DC generator consists of three major parts: magnetic field system, armature, commutator, and brush gear.
