What is Electric Generator, Definition, Types, Working Principle, & Applications

Hello friends, I hope all of you are having fun in your life. In today’s tutorial, we are gonna have a look at What is Electric Generator. There are numerous machines like motor, and transformers, are operating in our power system. The motor is an electrical machine that converts electrical energy into mechanical power. The transformer is used to step up and step down the voltage level in system. A motor is a machine used to transform electrical energy into mechanical energy. There are 2 main types of motors first the is ac motor and the second one is the dc motor. The sub types of dc motors are dc series motor, dc wound motor, dc shunt motor, and compound motor. Like dc motors, there are numerous types of ac motors like an induction motor, synchronous motor phase induction motors, and three phase induction motor.

Like these motors, there is a most important machine used in an electrical system that is a generator. Alike to motors there are numerous types of a generator such as induction generators, synchronous generators, dc generators, etc. ac generator like synchronous generator is used in generation station. In today’s post we will have a detailed look at working, construction, applications, types and some other related parameters of the generator. So let’s get started with what is Generator.

What is Electric Generator

• A generator is an electrical machine that transforms mechanical energy provided by the prime mover into electrical energy. The prime mover can be steam, water, gas turbine, wind turbine, etc.

• The first electrical generator was invented by Faraday in 1831, who was a scientist of the United Kingdom. Faraday’s generator name was Faraday Disk. This generator was to deliver power to the grid station.
• With the invention of the generator faraday also gave its operating principle in 1831 its rule is also known as Faraday’s law.
• Faraday’s law states that if some conductive material is placed in a magnetic field then emf will be induced in that conductive material.

Emf=dø/dt

• The construction of the Faraday disk generator was very simple for it he used a simple copper disk and rotated in a field of horseshoe-shaped magnet. The output of the Faraday generator was dc voltage.
• Both motor and generators have almost similar construction some can also drive as generators.
• Either a generator is dc or ac is playing very important rules in our generation system to industries and our homes providing power to our appliances and machines.

Working Principle of Generator

• The operation of an electrical generator depends on the Faraday law of electromagnetic induction.
• That says if conductor is put into the field then the voltage is induced in that conductor. In the case of the generator, the conductor is rotor of a generator and the field is provided by the stator of the generator.
• We can use the Fleming rule to find the direction of the voltage induced by that conductor. That explains that if we arrange our right-hand first finger, second finger, and thumb in such a way that these are at 90⁰ to each other, and we suppose that motion of the conductor is along the thumb, first finger is in the direction of field then the second finger will show the direction of voltage induces in the conductor.
• The working principle both ac and dc generators is similar but the difference is that at in dc generators commutators are used to provide a dc output.

Construction of Generator

• There are numerous parts of the generator are used in the construction of a generator but the most important parts are rotor and stator. Let’s discuss all these parts with the detail.

Yoke

• The outer structure of a generator is known as a yoke, it provides safety to the generator from the external environment. It is constructed with steel or cast iron.
• With providing strength to internal structure it also holds the stator windings that provide flux to a machine.

Windings

• There are two types of main windings are used in any generator either dc or ac first one is armature winding that is wound on the rotor of the motor and the second one is stator winding wound on the stator of the generator.

Rotor

• The rotor is of a generator that is rotating part over which armature windings are wound. In some dc generators instead of windings on rotor permanent magnet rotor is used.
• In ac machines there are two main types of the rotor is used first one is the wound rotor and the second one is squirrel rotor.

Equivalent circuit of Generator

• In the given figure, you can see the equivalent circuitry of the generator linked with the load. In the given figure you can see some parameters that are described here.
  • V_G is the open circuit voltages of a generator.
  • R_G is the interior resistance of the circuit.
  • V_L value of voltage when load connected.
  • R_L is the value of resistance offered by the load.

DC Generator

• Dc generator is a type of electrical generator that produces a dc voltage at its output terminals. Its construction is similar to the DC motor and we can use the dc motor as a generator also.
• There are some sub-types of dc generators like shunt generators, series generators, compound generator, etc.

• For an understanding of the workings of this generator, we take an example of a loop rotating in a magnetic field and compare with the practical generator.
• If we rotate a loop in a magnetic field of a permanent magnet then the voltage will induce in the loop.
• This is also according to the Faraday law that says that if we rotate any conductor in a field than voltage will be induced in that conductor due to flux variation in the conductor.
• If we compare a loop rotation in a field with the practical dc generator then we will come to know that the rotating part is the rotor of the generator and field is provided by the magnet at the stator or windings of the stator.

Advantages of DC generator

• These are some advantages of a dc generator.
• Its construction is very easy and can be repaired without any difficulty.
• Its working principle is very simple.
• This machine provides higher reliability.
• Its speed can be controlled very easily.
• Its output voltages value is constant.

AC Generator

• Ac generator is a type of electric machine that transforms mechanical energy into ac electric energy. Nowadays mostly ac generator is used in our commercial and industrial applications.
• There are 2 main types of ac generator first one is a synchronous generator and the second one is an induction generator that is also known asynchronous generator.
• In local and some commercial uses induction generator is used while in a generation and in a wind turbine synchronous generator is used.
• With the type of rotor design, the ac generator is further divided into types first one is the wound rotor and the second one is the squirrel rotor generator.

Induction Generator

• An induction generator is a type of ac generator it also known as an asynchronous generator. It works on the principle of electromagnetic induction.
• Its construction is similar to the induction motor so an induction motor can also be used as an induction generator with some modifications.
• It is mostly used in wind turbines, mini hydel generation plants, etc.

Synchronous Generator

• The synchronous generator is a type of ac generator that operates on the synchronous speed. Synchronous speed is the rotation speed of the field at the stator provided by the input supply.
• It is also called an alternator and used to transform mechanical energy into electricity.
• In our generation stations, mostly synchronous generator is used.
• They are available in ratings of fifteen hundred megawatts.

Difference between AC and DC Generator

• These are some differences between the ac and dc generator that is explained with the detailed.

AC Generator	DC Generator
The main difference is that the ac generator converts mechanical power provided by the prime mover into the ac power.	Dc generator converts mechanical input into the dc output.
Its output voltage varies its polarity after a certain interval of time.	Its output voltage flows with a similar polarity means are dc.
There is no need of commutators in the construction of this generator.	In this generator, commutators are used.
In an ac generator, slip rings are used.	In this generator, split rings are used for the conversion of ac into DC at the output terminals.
In ac, the generator armature is always exists at the rotor.	In dc generator, the armature part can be either rotor or a stator.
Its efficiency is larger due to less power losses.	Its efficiency is less due to large power losses.
Its output current can be induced at the stator or the rotor.	Output current is produced at the rotor.
Its output voltage are high and varies in amplitude normally frequency of output voltage is fifty or sixty harts’	Its output voltage are in less value and frequency is zero.
Its repair is very simple and its reliability is also good.	Its reliably is less due to continuous repairing.
Its types are induction, synchronous, single phase,  three-phase, wound rotor, etc.	There are only two types of dc generators. First one is self-excited and separately excited.
It is more expensive than the dc generator.	Its price is less