The invention and the first alternators

The first generator   as well as modern generators alternating current   generate electricity. Electricity is one of the main components of the energy cycle in nature. To convert any energy into an electric generator is designed alternating current, in translation from the Latin - the manufacturer. The device, generating electricity, converts the mechanical or energy of nature into electrical. Most often used mechanical motion   steam, gas turbine, hydraulic or diesel engines.

History of the invention of an electric generator

The history of the invention of the power generator shows that the foundations of the first generator were laid by the invention of the battery by the Italian Alessandro Volta, the generation of a magnetic field from an electric current by the Dane Hans Christian Oersted and the electromagnet by the British William Sturgen. Practically discovering and investigating electromagnetic induction by scrolling a copper disk between the poles of a magnet, Faraday generated electricity   in a changing magnetic field, thus making the prototype of the first electric generator. From this moment, the first generators were started.

In 1833, a Russian scientist of German origin, Emil Khristianovich Lentz, published an article on the law of reciprocity of magneto-electrical phenomena, that is, on the interchangeability of a device that generates electricity and an engine. The first generators invented in the 19th century rotated a heavy permanent magnet near the wire coils gradually improving and finding practical application. Gradually, the power and consumer properties of the devices were refined over time. Now without electricity and its manufacturer can not do. Where electric power can not be connected from the power plant, mobile diesel engines of the power station are offered by generator rental.
  What kind of energy producers do not exist at the present time, because the transformation from one type into another is the basis of life. Getting energy from the sun, wind, Earth, water movement, hydraulics, atomic, tidal, geothermal sources will surprise no one.

There are even generators receiving energy without fuel and external motion by means of the device by using the Earth's magnetic field.

Thus, the energy conversion generator is that small part of the eternal process of the energy cycle formed as a result of the Big Bang in the Universe, releasing energy and linking it in the process of its development.
  There is a theory based on the generation of free energy dependent on gravity and time, but the research data goes beyond materialistic physics and science in general.

The first elementary source of electric power was invented in 1663 by a German scientist Otto von Guericke. He created an electrostatic generator that extracted from a rubble ball cast from sulfur, which was rotated by hand, considerable sparks, the noses of which could even be painful. As a result, an electric charge was accumulating on the ball - "electric fluid" as at that time called this electrical phenomenon. Guericke managed to notice the weak glow of the electrified ball in the dark and, most importantly, for the first time to find that the fluffs attracted by the ball later repel from it - this phenomenon neither Gerike nor many of his contemporaries could explain for a long time. The ball power was less than 1W. It would seem - a trifle, but with its help were discovered many important phenomena and properties of electricity.

F. Hawkesbyin 1705 he created an electric generator, using a glass bowl instead of a sulfur ball. In 1744 a sliding contact was introduced into such a machine-a conductor-a metal tube suspended from silk threads, and later mounted on insulating supports. This contact served as a reservoir for collecting electric charges, and the machine was able to continuously spin electric power. After the invention of the Leyden jar (see below), these devices were also installed next to the machine.

In 1799 the Italian scientist   Alessandro Volta   invented a more perfect source of electric current than Muslenbrook (see below), and most importantly almost continuous (determined by the humidity of the gasket) first electrochemical generator, so-called. "Volt post". His source of electricity, he named in honor of the Italian anatomist Luigi Galvani galvanic cell. It was a source of electricity more powerful than the generator of Gerike.

Studying the experiments of Galvani, who discovered the contraction of the muscles of the prepared frog when they came into contact with two dissimilar metals, Volta disagreed that this phenomenon was caused by a special "animal" electricity inherent in living organisms. He claimed that the frog in Galvani's experiments "is a sensitive electrometer," and the source of electricity is the contact of two dissimilar metals.

However, numerous experiments have shown that simple contact of metals is not enough to obtain any appreciable current. A continuous electric current can arise only in a closed electrical circuit, composed of various conductors: metals (which he called the conductors of the first class) and liquids (named by them conductors of the second class).

Between small disks of copper and zinc (electrodes), Volta placed a porous pad impregnated with acid or alkali (electrolyte).

As a result of the chemical reaction that occurs between the electrodes and the electrolyte, an excess of electrons is formed on the zinc electrode, and it acquires a negative electric charge, and on the copper one, on the contrary, there is a lack of electrons, and it acquires a positive charge. In this case, between different electric charges of such a current source, electric field, electromotive force (abbreviated EMF) or voltage acts. As soon as the conductor is connected to the poles of the cell or battery, an electric field will appear in it, under which the electrons will move to where their deficiency, that is, from the negative pole through the conductor to the positive pole of the source of electrical energy. This is the ordered motion of electrons in the conductor-the electric current. The current flows through the conductor because the electromotive force acts in the resulting circuit (the positive pole of the element, the conductors, the negative pole of the cell, the electrolyte).

While the pad is wet, a chemical reaction occurs between the discs and the solution, creating a weak electric current in the conductor connecting the disks. Connecting pairs of disks in the battery, it was possible to receive already considerable electric current. Such batteries were called volt poles. They were the beginning of electrical engineering.

By accumulating a large number of such elements, Volta received an electrochemical source of electricity with a voltage of up to 2 kV. It was already it is enough to study electricity, to obtain an electric arc, an electric arc candle, to weld metals, and so on.

Batteries, which we now use in watches, receivers, etc. - are the same, but improved, volt bars - galvanic cells.

If a column is made of several pairs of various metals, for example zinc and silver (without gaskets), then each zinc plate charged with electricity of the same sign will be in contact with two identical silver plates charged with electricity of the opposite sign, and their common action will be mutually destroyed .

In order for the action of individual pairs to be summed up, it is necessary to ensure that each zinc plate touches only one silver one, that is, to eliminate the oncoming metal contact. This is done with the help of conductors of the second class (wet cloth circles); such circles separate metal pairs and at the same time do not interfere with the movement of electricity.

It is established that the electrons in the conductor move from the negative pole (where there is an excess of them) to the positive (where there is a defect in them), but even now, as in the last century, it is commonly assumed that the current flows from plus to minus, i.e. In the direction opposite to the motion of the electrons. The conditional direction of the current, in addition, is laid by scientists in the basis of a number of rules related to the determination of many electrical phenomena. At the same time, this convention does not create any special inconvenience if one firmly believes that the current in the conductors is opposite to the direction of the motion of the electrons. In the same cases, when the current is created by positive electric charges, for example, in electrolytes of chemical sources direct current, the current of "holes" in semiconductors, there are no such contradictions at all, because the direction of motion of positive charges coincides with the current direction. As long as the cell or battery is operating, the current flows in the same direction in the outer portion of the electrical circuit. Such a current is called permanent.

If the poles of the element are interchanged, only the direction of the electrons will change, but the current, in this case, will also be constant. And if the poles of the current source are interchanged very quickly and rhythmically? In this case, the electrons in the outer part of the chain will also alternately change their direction of motion. First they will flow in one direction, then when the poles are reversed - in the other, the reverse of the previous one, then again in the direct, again in the reverse, etc. In the chain, the leak will no longer be constant, but alternating current.

With alternating current, the electrons in the conductor seem to oscillate from side to side. Therefore, alternating current is also called electrical fluctuations. The alternating current advantageously differs from the constant in that it is easily convertible. So, for example, with the help of a transformer, you can increase the AC voltage or, conversely, lower it. Alternating current, in addition, can be rectified, that is, converted to direct current.

Within 2 - 3 years after the creation of the voltaic column a number of scientists developed several different modifications of batteries of galvanic cells. Among the various designs of the voltaic column, a galvanic battery built in 1802 deserves special attention. V.V. Petrov   (see below).

Numerous experiments with a volt pole, conducted by scientists from different countries, already within 2 to 3 years after the creation of the column led to the discovery of chemical, thermal, light and magnetic actions of electric current.

In 1824 Arago   described the phenomenon of " magnetism rotation", Satisfactorily to explain which neither he nor other physicists could. The essence of the phenomenon was as follows (Fig. 4.2) . The horseshoe magnet could rotate around the vertical axis, and above its poles was an aluminum disk, which also could rotate on an axis coinciding in direction with the axis of rotation of the magnet. At rest, no interactions between the disk and the magnet were observed. But when you started to rotate the magnet, as the disk rushed after him and vice versa. To exclude the possibility of entrainment of the disk by air streams, the magnet and disk were separated by glass.

The discovery of electromagnetic induction (1831) helped Faraday explain the Arago phenomenon and at the very beginning of the research wrote: "I was hoping to make a new source of electricity from Mr Arago's experience." Faraday first introduced the notion of magnetic lines of force, the totality of which constitutes a magnetic field, as a physical reality. He was shown that the current is induced only when the conductor is moving across magnetic lines of force. Hence the possibility of generating an electric current when moving a closed conductor in the field of a magnet resulted.

From disk Arago Faraday really made a new source of electricity. As a result of numerous experiments, Faraday built first electromagnetic generator, the so-called "Faraday disk", by means of which it was possible to obtain an electric current.

Forcing an aluminum or copper disk to rotate between the poles of the magnet, Faraday placed brushes on the disk axis and on its periphery. Thus, an electric machine (a DC generator) was designed, which later was called a unipolar generator (Figure 4.4).

Further investigations of electromagnetic induction led to the establishment of laws on the direction of the induced current. This law was formulated in 1832. Emilie Lenz and allowed him to formulate the most important for electrical engineering principle - reversibility of the generator and motor modes of electrical machines.

Electric generator   is a device in which non-electrical forms of energy (mechanical, chemical, thermal) are converted into electrical energy.

• 1. History
  • 1.1 The Dynamo Machine of Yedlik
  • 1.2 The Faraday Disc
  • 1.3 Dynamo
  • 1.4 Other electric generators using rotation
  • 1.5 MHD generator
• 2 Classification
• 3 Electromechanical induction generators
  • 3.1 Classification of electromechanical generators
• 4 See also
• 5 References

History

Yedlik Dynamo Machine

In 1827, Hungarian Anosh István Yedlik began experimenting with electromagnetic rotating devices, which he called electromagnetic self-rotating rotors. prototype of its unipolar electric motor (was completed between 1853 and 1856) and the stationary and rotating parts were electromagnetic. He formulated the concept of a dynamo at least six years before Siemens and Wheatstone, but did not patented the invention, because he thought he was not the first to do it. The essence of his idea was to use instead of permanent magnets two oppositely located electromagnets, which created a magnetic field around the rotor. The invention of Yedlik for decades ahead of his time.

The Faraday Disc

In 1831, Michael Faraday discovered the principle of the operation of electromagnetic generators. The principle, later called Faraday's law, was that the potential difference was formed between the ends of the conductor, which moved perpendicular to the magnetic field. He also built the first electromagnetic generator, called the Faraday Disk, which was a unipolar generator that used a copper disk rotating between the poles of a horseshoe magnet. He produced a small constant pressure   and strong current.

Another drawback was that the output voltage was very small, because only one coil was formed around the magnetic flux. Experiments have shown that using many turns of wire in a coil, one can often obtain the higher voltage required. Winding from wires became the main characteristic of all subsequent developments of generators.

However, recent advances (rare earth magnets) have made possible unipolar motors with a magnet on the rotor, and must make many improvements to the old designs.

Dynamo machine

Main article Dynamo machine

The dynamo became the first electric generator capable of generating power for industry. The work of the dynamo is based on the laws of electromagnetism for converting mechanical energy into pulsating direct current. The direct current was generated by using a mechanical commutator. The first dynamo was built by Hippolytus Pixie in 1832.

Having passed a number of less significant discoveries, the dynamo became the prototype, from which there were further inventions, such as DC motor, alternator, synchronous motor, rotary converter.

The dynamo machine consists of a stator that creates a constant magnetic field, and a set of windings rotating in this field. On small machines, a permanent magnetic field could be created with the help of permanent magnets; in large machines, a permanent magnetic field is created by one or more electromagnets, whose windings are usually called excitation windings.

Large, powerful dynamo machines can now rarely be seen, because of the greater universality of the use of alternating current on power supply networks and electronic solid-state converters of direct current to alternating current. However, before the alternating current was discovered, huge dynamo machines producing direct current were the only opportunity to generate electricity. Now dynamo cars are a rarity.

Reversibility of electrical machines

The Russian scientist EH Lenz, in 1833, pointed to the reversibility of electric machines: the same machine can operate as an electric motor if it is powered by current, and can serve as an electric current generator if its rotor is driven into rotation by some engine, such as a steam engine. 1838. Lenz, one of the members of the commission for testing the electric motor of Jacobi, in his experience proved the reversibility of an electric machine.

The first generator of electric current, based on the phenomenon of electromagnetic induction, was built in 1832 by the Parisian techniques of the Pixins brothers. This generator was difficult to use, since it was necessary to rotate a heavy permanent magnet, so that in two wire coils, fixed motionless near its poles, an alternating electric current appeared. The generator was equipped with a device for rectifying the current. In an effort to increase the power of electric machines, the inventors increased the number of magnets and coils. One of these machines, built in 1843, was the generator of Emil Shterer. This machine had three strong movable magnets and six coils rotating around the vertical axis. Thus, at the first stage of the development of electromagnetic current generators (until 1851) constant magnets were used to obtain a magnetic field. At the second stage (1851-1867) generators were created, in which magnets were replaced by magnets to increase the power. Their windings were fed by a current from an independent small current generator with permanent magnets. A similar machine was created by the Englishman Henry Wald in 1863.

During the operation of this machine, it turned out that generators, supplying with electricity to the consumer, can simultaneously feed themselves with their own magnets. It turned out that the cores of electromagnets retain residual magnetism after switching off the current. Due to this, the generator with self-excitation gives a current even when it is started from a state of rest. 1866-1867 years. a number of inventors received patents for machines with self-excitation.

In 1870 the Belgian Zenob Gramm, who worked in France, created a generator that was widely used in industry. his dynamo machine, he used the principle of self-excitation and improved the ring anchor invented back in 1860 by A. Pacinotti.

In one of the first Gramm machines, the annular anchor, mounted on a horizontal shaft, rotated between the pole pieces of two electromagnets. The anchor was rotated through a drive pulley, the windings of the electromagnets were connected in series with the armature winding. The Gram generator produced a direct current, which is removed by means of metal brushes that slid over the collector surface. At the Vienna International Exhibition in 1873, two identical Gramm machines were displayed, connected by 1 km long wires. One of the machines was driven by an internal combustion engine and served as a generator of electrical energy. The second machine received electrical energy through wires from the first and, working as an engine, propelled the pump. It was a spectacular demonstration of the reversibility of electric machines, discovered by Lenz, and a demonstration of the principle of energy transfer to a distance.

Before the connection between electricity and magnetism was discovered, electrostatic generators were used, which worked on the basis of the principles of electrostatics. They could produce a high voltage, but they had a small current. Their work was based on the use of electrified belts, plates and disks for the transfer of electrical charges from one electrode to another. Charges were developed using one of two mechanisms:

• Electrostatic induction
• Triboelectric effect, in which the electric charge was generated due to the mechanical contact of two dielectrics

Because of the low efficiency and complexity of isolating machines that generate high voltages, electrostatic generators have low power and have never been used to generate electricity in industry-wide scales. Examples of vehicles of this kind that have survived to this day are the Electroform Machine and the Van de Graaf Generator.

Other electric generators using rotation

Without a switch, the dynamo is an example of an alternator. With an electromechanical commutator, a dynamo machine is a classic direct current generator. The alternator must always have a constant rotor speed and be synchronized with other generators in the power distribution network. The DC generator can operate at any rotor frequency within its acceptable limits, but generates a constant current.

MHD generator

The magnetohydrodynamic generator directly generates electric power from the energy of a plasma moving through a magnetic field or other similar conductive medium (for example, a liquid electrolyte) without the use of rotating parts. The development of generators of this type began because at its output high-temperature combustion products are obtained which can be used to heat steam in combined-cycle power plants and thereby increase the overall efficiency. The MHD generator is a reversible device, that is, it can also be used as an engine.

Classification

• Electromechanical
  • Induction
  • Electroforming machine
• Thermoelectric
  • Thermocouples
  • Thermal emission converters
• Photocells
• Magnetohydro (gas) dynamic generators
• Chemical sources of current
  • Galvanic cells
  • Fuel Cells
• Biogenerators

Electromechanical induction generators

Electromechanical generator   is an electric machine in which mechanical work   is converted into electrical energy.

It establishes the relationship between the EMF and the rate of change in the magnetic flux of the generator winding.

Classification of electromechanical generators

• By type of primary motor:
  • The turbogenerator is an electric generator driven by a steam turbine or gas turbine engine;
  • Hydrogenerator is an electric generator driven by a hydraulic turbine;
  • Diesel generator - an electric generator driven by a diesel engine;
  • The wind generator is an electrical generator that converts the kinetic energy of the wind into electricity;
• By type of output electric current
  • Three-phase generator
    • With the inclusion of windings star
    • With the inclusion of windings in a triangle
• By the method of excitation
  • With excitation by permanent magnets
  • With external stimulation
  • With self-excitation
    • With sequential excitation
    • With parallel excitation
    • With mixed excitement

see also

• Tachogenerator
• Unipolar Generator

References

• Unipolar generator, Computerra
• Construction of electrical machines

Electric Generator

Electric generator Information Video

An electric generator is what, An electric generator is one, An electric generator is an explanation