Every process and device on Earth is based on energy transformation of one kind or the other. Electrical generators have played and integral part in the progress of man through the last 100-odd years. Such has been their importance that today if there are no generators, there would be no electricity, and subsequently no device or piece of technology would be able to work.
At a very basic level, a generator is a machine which converts mechanical energy to electrical energy. Generators are available in different configurations for different kinds of applications and machines. They function exactly opposite to an electric motor. Let's take a closer look at generators and find out how they actually work.
What is an Electrical Generator?
An electrical generator supplies electricity by converting mechanical energy obtained from various sources. It uses an arrangement of magnets and rotors to derive electricity from mechanical motion. More on that later. Depending on the source from which the mechanical energy is derived, there are various types of electrical generators.
If you are wondering how does a diesel generator work, then the answer is same as that of an electrical generator. The only difference is that the mechanical energy for this type of generator is derived from chemical energy released through combustion. A dynamo and a car alternator are two other types of generators that supply electricity to automobiles. Every type of generator which includes the big ones that are operational in power stations and the small ones like the car alternator, have the same principle of working which you will read about in the next section. The only thing which differs is the way in which the mechanical energy is derived.
Working Principle of a Generator ― Electromagnetic Induction
To know the working of any machine, one must know the physical idea or principle on which it is based. Every machine built by man harnesses natural physical laws for its working.
Almost every single physical device and every single biochemical mechanism is driven by the electromagnetic force. In fact, it wouldn't be an understatement if I say that we live in an electromagnetic world. The working principle of an electrical generator is no exception to this. A generator works on the principle of electromagnetic induction. It states that a changing magnetic field creates a current through a conductor.
If you have a workshop around, gather some metal shavings and spread them on a sheet of paper. Now, get a small magnet and move it over that sheet. You will see that metal shavings cling on to the magnet and move in synchronization to the movement of the magnet. If you place the magnet on the paper, they arrange themselves in a specific pattern around it. That is magnetic induction at work! The changing magnetic field around the metal shavings influences the electrons in orbit around atoms in them. The magnetic field change pushes the electrons around, creating small electric currents in the metal shavings. Every magnetic field is created by an electric current. The magnetic field in magnets is the result of currents in the atoms of the material which makes magnets. In general, every electric current creates a magnetic field around it and every changing magnetic field creates an electric current.
Working of an Electric Generator
Every generator consists of two main components: stator (stationary part) and rotor (the moving part). In every generator, stator is a single or a set of magnets, while the rotor is a metal loop which rotates in it. When the metal loop of a rotor revolves between the magnets, the magnetic field associated with electrons in them changes and an electric current is generated in it. With every rotation, the changing magnetic field creates a current, which is then transported through a coil to an external electrical circuit. That is how electricity is supplied by the generator! The current that is produced depends on the strength of the magnetic field and the speed of rotation of the loop. The carbon brushes are used to absorb the electricity from the rotor and connect it with an electrical load, which in turn sends the energy to your homes through the power stations.
Generators may have an alternative arrangement, where the stator can be the metal loop, while rotor is the magnet, that is, a magnet rotates around a stationary metal loop, generating current in it. The mechanical force required to turn the rotor is provided by various methods. In a diesel generator, it is driven by a motor, which runs on diesel combustion. The generators in power stations have huge and more number of magnets in them and the rotors there are driven by various other sources like falling water (in a hydroelectric power station), steam generated by heat supplied through nuclear fission (nuclear power station), the movement of a crankshaft in a car (in an alternator), and more such mechanical sources of energy. There is an elaborate mechanism that supplies the electric power generated in power stations to our homes through electrical cables.
There is a lot more complexity involved in the working of a generator, which works at a power station. Every machine like a generator is an extension of an idea or principle. Once you understand the principle or the idea behind it, understanding the working based on it is a simple job.