Generators play a very important role in the production of electrical energy, which is among the indispensable parts of our lives. In this article, we discussed the basic structure and working principle of generators.
History of the Generator:
Michael Faraday produced a small generator called the "Faraday disk" that could generate electricity in 1831, but his invention did not cause major technological breakthroughs in those years. In the 1850s, dynamos, which started to be produced in series, were used for the first time for lighting purposes.
When Thomas Edison and Joseph Swarm invented the light bulb in 1880, there was a great need for generators and power supplies. In 1882, the Edison company established DC generating centers in New York, London, and Milan to use electrical energy for lighting.
Shortly after this, discussions began about the use of DC and AC currents. As a result of the developments in transformers and generator systems until the beginning of 1890, American Nikola Tesla proved the advantages of using alternating current in electrical power transmission. The first major hydroelectric power station to use AC generators was opened in 1895 at Niagara Falls.
Today, generators have become one of indispensable elements of our lives. Recently, nanogenerators have been developed for robots and machines.
Structure and Working Principle of Generator:
Machines that convert mechanical energy into electrical energy are called "generators" or "alternators". The use of alternating current in the generation, transmission and distribution of electrical energy provides great convenience. Since generators are used to produce alternating current, synchronous generators (alternators) are of great importance. Today, there are various mechanical forces that we use to obtain electrical energy. These forces are; with water in hydroelectric power plants, with the steam obtained as a result of burning coal in thermal power plants, with the wind in wind power plants, with the steam produced with the help of the energy released from core splitting in nuclear power plants, etc. provided with figures. Generators consist of two main parts; armature (stator) and inductor (rotor).
The stator is the part where the alternating voltage is obtained in the alternators. They are made of packing of siliceous sheets, each surface of which is insulated. According to the stator structure, it is divided into two parts as standing stator and rotating stator. The rotor of the rotating stator alternator is fixed. The rotor of the stationary stator alternator is movable. Whether the alternator has a rotating stator or a stationary stator, there are always windings on the stator where alternating voltage is produced. There are always pole (direct current) windings on the rotor. In general, the stator is located in the rotating part in small power alternators. In large powerful alternators, it is in the stationary part.
Rotary stator alternators cannot be made for large powers. In machines with rotating stator, current and voltages are taken into the external circuit with the help of rings and brushes. However, this process will create many problems in strong currents and high voltages.
Rotating Armature Synchronous Generators:
In this type of synchronous generator, "a voltage is induced in conductors rotated in fixed poles according to Faraday's Law." They work with the principle of and the induced voltage is taken as alternating current with the help of bracelets and brushes.
Standing Armature Synchronous Generators:
This type of synchronous generators; They work with the principle of "a voltage is induced in conductors around poles rotated by mechanical energy, according to Faraday's Law". Generally, large powerful synchronous generators are manufactured in this type.
The principle of alternator with rotating rotor (Poles) and standing stator (Arduine)
The excitation coils at the poles of the synchronous machine are supplied with direct current. These direct current coils create a magnetic field. As a result of the synchronous generator being driven with synchronous speed (ns), the armature (rotor) rotates with this synchronous speed. This rotating field, which is rotated by external drive, will induce voltage in different phases in the stator winding. The voltage induced in the stator is directly switched to the external circuit without the need for a ring and brush.
Excitation of Alternators:
The loads of the alternators feeding the networks are not the same at all times of the day. However, while there are decreases in the terminal voltages of the alternators in the loaded operating conditions (especially in the inductive load), there are increases in the terminal voltage of the alternator whose load is removed (empty running). However, in electrical networks, a constant voltage is desired, not a variable voltage according to the load. This is achieved by adjusting the terminal voltages of the alternators according to different load conditions. As it is known, voltage in alternators;
►The number of revolutions,
►Depends on variables such as magnetic flux in poles.
Since the change in the number of revolutions will also change the frequency (F=P.n/120), the magnet on the poles for voltage adjustment
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