From the history of electrical engineering. "The Tale of Electricity." Centuries and people. Tesla or Ferraris? Mikhail Osipovich Dolivo-Dobrovolsky.

We begin our story with the words of Tesla himself, who wrote, shortly before his death, a remarkable essay on the history of electrical engineering, "The Tale of Electricity": "Who really wants to mash all the greatness of our time, he must get acquainted with the history of the science of electricity. Fairytales "Thousand and One Nights".

For the first time phenomena, now called electrical, were seen in ancient China, India, and later in ancient Greece. The preserved legends say that the ancient Greek philosopher Thales of Miletus (640-550 BC) already knew the property of amber, rubbed with fur or wool, to attract scraps of paper, fluff and other light bodies. From the Greek name for amber - "electron" - this phenomenon later received the name of electrification.

About amber in Tesla's "Tale" we find the following poetic lines: "The story begins long before the beginning of our era, in those times when Thales, Theophrastus and Pliny talked about the miraculous properties of the" electron "(amber), this amazing substance arising from tears Geliad, the sisters of the unfortunate young man Phaethon, who was trying to get hold of Phoebus's chariot and almost burned the whole earth. "However, having created poetic legends about amber, the Greeks did not continue to study its properties. The Romans did not add anything to the knowledge of the ancient Greeks, and in the Middle Ages, they also forgot what they knew about amber in the ancient world. Only at the end of the XVI century the court physician of the English Queen Elizabeth William Hilbert studied everything that was known about the properties of amber to the ancient peoples, and himself conducted many experiments with amber and magnets. In 1600 he published a great work "On the magnet, magnetic bodies and the largest magnet - the Earth" - a true body of knowledge of that time about electricity and magnetism.

Hilbert first discovered that the properties of electrification are inherent not only in amber, but also in diamonds, sulfur, and pitch. He also noticed that some bodies, such as metals, stones, bone, do not electrify, and divided all the bodies found in nature into electrified and non-electrizable ones. Paying special attention to the first, he carried out experiments on the study of their properties. In the middle of the 17th century a well-known German scientist, Mayor of Burgas, the inventor of the air pump Otto von Guericke, built a special "electric car", representing a ball of sulfur the size of a child's head, mounted on an axis. If, during the rotation of the ball, he was rubbed with the palms of his hands, he soon acquired the property of attracting and repelling light bodies. Over the course of several centuries, the Englishman Hoxby, German scientists Bose, Winkler and others have significantly improved the machine. Experiments with these machines led to a number of important discoveries: in 1707 the French physicist du Fei discovered the difference between electricity obtained from friction of a glass ball (or circle) and obtained from friction of a steep wood tar. In 1729, the Englishmen Gray and Wheeler discovered the ability of some bodies to conduct electricity and for the first time pointed out that all bodies can be divided into conductors and non-conductors of electricity.

But a much more important discovery was described in 1729 by Moushenbrek, a professor of mathematics and philosophy in the city of Leiden. He found that a glass jar, glued on both sides with tin foil (sheet of staniol), is capable of accumulating electricity. Charged to a certain potential (the concept of which appeared much later), this device could be discharged with a significant effect - a large spark that produced a strong crack, similar to the lightning, and had physiological effects when the hands touched the lining of the can. From the name of the city where the experiments were made, the device created by Moushenbreck was named the Leiden bank. Investigations of its properties were made in various countries and caused the emergence of many theories that tried to explain the observed phenomenon of charge condensation.

One of the theories of this phenomenon was given, by the eminent American scientist and public figure Veniamin Franklin, who pointed to the existence of positive and negative electricity. From the point of view of this theory, Franklin explained the process of charge and discharge of the Leyden jar and proved that its plates can be arbitrarily electrified by electric charges of different sign.

Franklin, like the Russian scientists MV Lomonosov and G. Rikhman, paid much attention to the study of atmospheric electricity, a lightning discharge (lightning). As is known, Richman died, producing experience in the study of lightning.

The works of the Russian academicians Epinus, Kraft and others revealed a number of very important properties of electric charge, but they all studied electricity in a state of motionless or instantaneous times, that is, the properties of static electricity. Its movement manifested itself only in the form of a discharge. The electric current, that is, the continuous movement of electricity, still nothing was known.

The practical significance of the knowledge about electricity accumulated over two centuries was relatively small. This is explained by the fact that the requirements of practice and industry did not put forward to science the requirements of cognition of electricity and the study of the possibility of its use. "We learned something about electricity only from the time when its technical applicability was discovered," Engels wrote in a letter to G. Starkenburg on January 25, 1894.

The largest discovery in this area in the 18th century was the discovery in 1791 by the Italian anatomist Luigi Galvani of the appearance of electricity when two dissimilar metals came into contact with the body of a prepared frog. Galvani himself mistakenly believed that this phenomenon is caused by the presence of a special animal electricity.

But soon another Italian scientist, Alessandro Volta, gave a different explanation for these experiments. He experimentally proved that the electrical phenomena observed by Galvani are explained only by the fact that a certain pair of dissimilar metals, separated by a layer of a special electrically conducting liquid, serves as a source of electric current flowing through closed conductors of the external circuit.

This theory, developed by A. Volta in 1794, made it possible to create the world's first source of electric current in the form of the so-called Volta pole. The latter represented a set of circles of two metals (copper and zinc), separated by linings made of felt dipped in brine or alkali. Description of this device, manufactured in late 1799, is given in A.Volta's letter to the president of the London Royal Society Bankusu dated March 20, 1800. It should be noted that Galvani was not far from the truth: as it was established later, in any organism life processes are accompanied by the emergence of electricity, which can with good reason be called an animal that does not, however, have anything in common with the electricity discovered by Galvani himself.

One of the first to study the properties of electric current in 1801-1802 was the Petersburg Academician VV Petrov. The work of this outstanding scientist, who built the world's largest battery of 4200 copper and zinc circles, established the possibility of practical use of electric current for heating conductors. In addition, Petrov observed the phenomenon of electric discharge between the ends of slightly diluted coals both in air and in other gases and a vacuum, which was called the electric arc. VV Petrov not only described the phenomenon discovered by him, but also pointed out the possibility of using it for lighting or melting metals and thus for the first time expressed the idea of ​​the practical application of electric current. From that moment, the history of electrical engineering as an independent branch of technology should begin.

Experiments with an electric current attracted the attention of many scientists from different countries. In 1802 the Italian scientist Romagnosi discovered the deviation of the magnetic needle under the influence of an electric current flowing along a conductor located near it. At the end of 1819, this phenomenon was again observed by the Danish physicist Oersted, who in March 1820 published a pamphlet entitled "Experiments Concerning the Action of Electric Conflict on the Magnetic Arrow" in Latin. In this work, the "electric conflict" was named electric current.

A small, only five-page, Oersted book was published in the same year in Copenhagen in six languages. His experiments were repeated in the autumn of 1820 by the Swiss naturalist de la Reeve at the Congress of Naturalists in Geneva. This congress was attended by a member of the Paris Academy of Sciences Arago, who on his return showed in the meeting of the Academy the experience of Oersted. Even before the end of 1820, Arago conducted a number of studies, of which the most important was the discovery in 1824 of the phenomenon of dragging a copper disk by a magnet rotating near it. This phenomenon, called the "magnetism of rotation", for a long time remained only an effective physical experience. But later it was precisely this that served as the basis for many practical inventions and, in particular, for the AC electric motor.

Of great importance were also the discovery by Bio and Savard of the laws of the action of the current on the magnetic needle. Particular mention should be made of the activities of the remarkable scientist Andre Marie Ampere, who initiated the study of the dynamic actions of electric current and established a whole series of laws of electrodynamics.

As soon as Arago demonstrated at the meeting of the Paris Academy of Sciences the experience of Oersted, as Ampere, repeating it, on September 18, 1820, exactly a week later, he reported to the academy about his research. At the next meeting, on September 25, Amper finished reading the report, in which he outlined the laws of interaction of two currents flowing along parallel conductors. From that moment the academy listened to Ampere's new reports weekly about his experiments, which completed the discovery and formulation of the basic laws of electrodynamics.

One of Ampere's most important services was that he first combined the two previously disconnected phenomena - electricity and magnetism - with one theory of electromagnetism and suggested that they be viewed as the result of a single process of nature. This theory, met by Ampere's contemporaries with great distrust, was very progressive and played a huge role in the correct understanding of later discovered phenomena.

Five years after Ampere's first works, the first electromagnet was built, and a deep study of the laws of electromagnetism began. In 1827, the German scientist Georg Ohm discovered one of the fundamental laws of electricity, which establishes the basic relationships between the strength of the current, the voltage and the resistance of the circuit through which an electric current flows; In 1847 Kirchhoff formulated the laws for the deployment of currents in complex chains.

The discoveries of Oersted, Arago, and Ampere interested the ingenious English physicist Michael Faraday and prompted him to tackle the whole range of questions about the conversion of electrical and magnetic energy into mechanical energy. In 1821, he found another solution to the problem of converting electrical and magnetic energy into a mechanical one and demonstrated his instrument, in which he received the phenomenon of continuous electromagnetic rotation. On the same day, Faraday recorded in his working diary the reverse task: "Turn magnetism into electricity." More than ten years it took to solve it and find a way to get electricity from the magnetic and mechanical. It was not until the end of 1831 that Faraday announced the discovery of a phenomenon called electromagnetic induction, which is the basis of the whole modern electric power industry.

Faraday's study and the work of the Russian academician E. X. Lenz, who formulated the law by which it was possible to determine the direction of the electric current produced as a result of electromagnetic induction, made it possible to create the first electromagnetic generators and electric motors.

Initially, electric generators and electric motors developed independently of each other, as two completely different machines. The first inventor of the electric generator, based on the principle of electromagnetic induction, wished to remain anonymous. It happened so. Soon after the publication of Faraday's report in the Royal Society, in which the discovery of electromagnetic induction was described, the scientist found in his mail box a letter signed with the initials of RMOhno contained a description of the world's first synchronous generator and the drawing attached to it. Faraday, having carefully studied this project, sent a letter to RM and the drawing in the same magazine in which his report was placed, hoping that the unknown inventor, following the magazine, would see published not only his project, but also Accompanying his letter to Faraday, highly appreciated the invention of RM

Indeed, after almost half a year, RM sent additional explanations and a description of the electric generator proposed by him to the editorial office, but this time he also wished to remain anonymous. The name of the true creator of the first electromagnetic generator remained hidden under the initials, and mankind still remains ignorant, despite the careful search of the historians of electrical engineering, to whom it owes one of the most important inventions. The RM machine did not have a device for rectifying the current and was the first alternator. But this current, it seemed, could not be used for arc illumination, electrolysis, telegraph, already firmly established. It was necessary, according to the designers of that time, to create a machine in which it would be possible to obtain a current constant in direction and magnitude.

Almost simultaneously with the RM, the construction of generators was carried out by the Pixey brothers and professor of physics at the University of London and a member of the Royal Society of W. Ricci. The machines they created had a special device for rectifying an alternating current into a constant one-the so-called collector. Further development of the DC generator designs went at an unusually fast pace. In less than forty years the dynamo machine has almost completely acquired the shape of a modern DC generator. True, the winding of these dynamo machines was distributed unevenly around the circumference, which worsened the work of such generators-the tension in them increased or decreased, causing unpleasant jolts.

In 1870, Zenobey Gram offered a special, so-called annular winding of the dynamo armature. Uniform distribution of the armature winding made it possible to obtain an absolutely uniform voltage in the generator and the same rotation of the engine, which greatly improved the properties of electric machines. In essence, the invention repeats what was already created and described in 1860 by the Italian physicist Pacinotti, but went unnoticed and remained unknown 3. Gramm. Machines with a ring anchor were especially popular after the reversibility of Gram's electric machines was discovered at the Vienna World Exhibition in 1873: the same machine, when the anchor was rotated, produced an electric current, when the current flowed through the armature it was rotating and could be used as Electric motor.

From this time, the rapid growth of the use of electric motors and the ever increasing consumption of electricity begins, which was greatly facilitated by PN Yablochkov's invention of the method of lighting with the help of the so-called "Yablochkov candle" - an arc lamp with a parallel arrangement of coals.

The simplicity and convenience of the "Yablochkov candles", which replaced expensive, complex and cumbersome arc lamps with regulators for the continuous approach of burning coals, caused their widespread distribution, and soon "light Yablochkov", "Russian" or "northern" light, illuminated the boulevards of Paris, embankments Thames, avenues of the capital of Russia and even the ancient cities of Cambodia. This was an authentic triumph of the Russian inventor.

But to power these candles with electricity, it was necessary to create special electric generators, giving not a constant but an alternating current, that is, a current, even if not often, but continuously changing its magnitude and direction. This was necessary because the coals connected to different poles of the DC generator burned unevenly - the anode connected to the positive one burned twice as fast as the cathode. The alternating current alternately turned the anode into a cathode and thereby ensured uniform combustion of the coals. Especially for the supply of "candles Yablochkov" and was created by PN Yablochkov, and then perfected by the French engineers Lonten and Gramm alternator. However, there was still no thought about the AC motor.

At the same time, for the separate supply of separate candles from the alternator, the inventor created a special device - an induction coil (transformer), which made it possible to change the voltage of the current in any branch of the circuit in accordance with the number of connected candles. Soon the growing demand for electricity and the possibility of obtaining it in large quantities came into conflict with the limited possibilities of transferring it to a distance. The low voltage (100-120 volts) of direct current applied at that time and its transmission over wires of a relatively small cross section caused huge losses in the transmission lines. Since the late 70s of the last century, the main problem, from the successful solution of which depended all future electrical engineering, was the problem of electricity transmission over significant distances without large losses.

The first theoretical justification for the possibility of transferring any quantity of electric power to any distances over wires of a relatively small diameter without significant losses by increasing the voltage was given by DA Lachinov, a professor of physics at the Petersburg Forest Institute in July 1880. Following this, the French physicist and electrical engineer Marcel Depre in 1882 at the Munich Electrical Exhibition carried out the transmission of electric power to several horsepower at a distance of 57 kilometers with an efficiency of 38 percent.

Later, DePre made a number of experiments, carrying out the transmission of electricity for a distance of a hundred kilometers and bringing the transmission power to several hundred kilowatts. Further increase in the distance required a significant increase in voltage. Depres brought it up to 6 thousand volts and made sure that the insulation of the plates in the collector of generators and DC motors does not allow reaching a higher voltage.

Despite all these difficulties, in the early 1980s, the development of industry and concentration of production increasingly demanded the creation of a new engine, more perfect than the widespread steam engine. It was already clear that it was advantageous to build power stations near coal deposits or on rivers with a large drop in water, while factories were built closer to sources of raw materials. This often required the transfer of huge amounts of electricity to the objects of its consumption over considerable distances. Such a transfer would be expedient only when tens of thousands of volts are applied. But it was impossible to obtain such a voltage in DC generators. To help the alternating current came and the transformer: using them, began to produce an alternating low-voltage current, then raise it to any desired value, transmit it at a high voltage, and again reduce it to the required one and use it in current collectors. But ... again there was a "but" ...

There were no AC motors yet. After all, in the early 80's, electricity was consumed mainly for power needs. DC motors for driving a wide variety of machines have been used more and more often. To create an electric motor that could work on alternating current was the main task of electrical engineering. In search of new ways, it is always necessary to look back. Was there anything in the history of electrical engineering that could suggest a way to create an alternating current electric motor? Searches in the past have been crowned with success. They remembered: back in 1824 Arago demonstrated experience, which initiated a lot of fruitful research. It's about demonstrating the "magnetism of rotation". Copper (not magnetic) disc was fond of a rotating magnet.

There was an idea, whether it is impossible, whether having replaced a disk coils of a winding, and a rotating magnet a rotating magnetic field, to create the electric motor of an alternating current? Probably, it is possible, but how to get the rotation of the magnetic field?

In these years, many different ways of applying alternating current have been proposed. A conscientious historian of electrical engineering will have to name the names of various physicists and engineers who tried to create AC electric motors in the mid-1980s. He will not forget to recall the experiments of Bailey (1879), Marcel Desprey (1883), Bradley (1887), the works of Wenstrom, Hazelwander and many others. The proposals were undoubtedly very interesting, but none of them could satisfy the industry: their electric motors were either cumbersome and uneconomical, or complex and unreliable. The principle of building simple economical and reliable AC motors was not found yet.

It was in this period that Nikola Tesla began, as we already know, the search for a solution to this problem. He went his own way, by reflecting on the essence of Arago's experience, and proposed a radical solution to the problem that arose immediately, which was acceptable for practical purposes. Back in Budapest in the spring of 1882, Tesla clearly realized that if in some way to supply the winding of the magnetic poles of the electric motor with two different alternating currents, differing from each other only by a phase shift, the alternation of these currents would cause alternating formation of the north and south poles or rotation Magnetic field. The rotating magnetic field must also entrain the winding of the rotor of the machine.

Having built a special source of two-phase current (two-phase generator) and the same two-phase electric motor, Tesla realized his idea. And although constructively his machines were very imperfect, the principle of rotating magnetic field, applied in the first models of Tesla, proved to be correct.

After considering all possible cases of phase shift, Tesla stopped at a 90 ° shift, that is, on a two-phase current. It was quite logical - before creating electric motors with a large number of phases, it was necessary to start with a two-phase current. But another phase shift could be applied: 120 ° (three-phase current). Without analyzing theoretically and not comprehending all possible cases, he focused his attention on the two-phase current, creating two-phase generators and electric motors and only briefly mentioned in his patent applications for multiphase currents and the possibility of their application.

But Tesla was not the only scientist who remembered Arago's experience and found a solution to an important problem. In the same years, Italian physicist Galileo Ferraris, representative of Italy at many international congresses of electricians (1881 and 1882 in Paris, 1883 in Vienna and others) was engaged in research on alternating currents. Preparing lectures on optics, he came to the idea of ​​the possibility of setting up an experiment that demonstrates the properties of light waves. To do this, Ferraris strengthened a copper cylinder on a thin thread, on which two magnetic fields, shifted at an angle of 90 °, acted. When the current is turned on in the coils, alternately creating magnetic fields, in one or the other of them, the cylinder under the action of these fields turned and twisted the thread, as a result of which it rose a certain amount upward. The device perfectly modeled this phenomenon, known as the polarization of light.

Ferraris did not intend to use his model for any electrical purposes. It was just a lecture device, the wit of which consisted in the skillful application of the electrodynamic phenomenon for demonstrations in the field of optics.

Ferraris is not limited to this model. In the second, more perfect model, he managed to achieve the rotation of the cylinder at speeds of up to 900 rpm. But beyond certain limits, no matter how the current strength that created the magnetic fields increased (in other words, no matter how much power expended), it was not possible to achieve an increase in the number of revolutions. Calculations showed that the power of the second model did not exceed 3 watts.

Undoubtedly, Ferraris, being not only an optician, but also an electrician, could not fail to understand the value of his experiments. However, according to his own admission, it never occurred to him to apply this principle to the creation of an electric motor of alternating current. The biggest thing he expected was to use it to measure the amperage, and even began to design such an instrument.

March 18, 1888 in the Turin Academy of Sciences Ferraris made a report "Electrodynamic rotation, produced with the help of alternating currents." In it, he told about his experiments and tried to prove that obtaining in such an instrument a coefficient of efficiency above 50 percent is impossible. Ferraris was sincerely convinced that by proving the inexpediency of using alternating magnetic fields for practical purposes, he is doing a great service to science. The report of Ferraris outstripped the message of Nikola Tesla at the American Institute of Electrical Engineers. But the application, filed for a patent in October 1887, testifies to Tesla's undoubted priority before Ferraris. As for the publication, the article Ferraris, accessible to all electricians in the world, was published only in June 1888, that is, after Tesla's widely known report.

For Ferraris's assertion that work on studying the rotating magnetic field was started by him in 1885, Tesla had every reason to argue that he was dealing with this problem even in Graz, its solution was found in 1882, and in 1884 in Strasbourg showed the operating model of his engine . But, of course, it's not just a matter of priority. Undoubtedly, both scientists made the same discovery independently of each other: Ferraris could not have known about Tesla's patent application, just as the latter could not have known about the works of the Italian physicist.

Much more important is that G. Ferraris, having discovered the phenomenon of a rotating magnetic field and built his model with a capacity of 3 watts, and did not think about their practical use. Moreover: if the erroneous conclusion of Ferraris about inexpediency of application of variable multiphase currents was accepted, then mankind would be directed for a few more years along the wrong path and deprived of the possibility of widespread use of electric power in the most diverse branches of production and life. The merit of Nikola Tesla is that despite the many obstacles and skeptical attitude to the alternating current, he practically proved the expediency of using multiphase current. The first two-phase motors created by him, although they had a number of shortcomings, attracted the attention of electrical engineers from all over the world and aroused interest in his proposals.

However, the article by Galileo Ferraris in the magazine Atti di Turino played a huge role in the development of electrical engineering. It was reprinted by one major English magazine, and the number with this article fell into the hands of another scientist, now deservedly recognized as the creator of modern electrical engineering of a three-phase current.

On one of the July days of 1888 the article of Ferraris was read enthusiastically by a young Russian, just four years before, graduating from the Darmstadt Higher Technical School, Russian engineer Mikhail Osipovich Dolivo-Dobrovolsky.

Mikhail Osipovich was born in Russia, in Gatchina - one of the picturesque suburbs of St. Petersburg, in the family of an official. For ten years he moved with his parents to Odessa, where his father, having retired, began publishing the progressive newspaper Pravda. To participate in this newspaper, he drew many leading figures of Russian and world literature, and soon this newspaper for an impermissible way of thinking was closed.

During this period, the Dolivo-Dobrovolsky family developed a critical attitude toward the tsarist system, and young Dobrovolsky differed from his contemporaries with advanced views.

In 1880, Mikhail Osipovich graduated from the Odessa Real School and in the fall of the same year entered the chemistry department of the Riga Polytechnic Institute. But he did not have long to be a student of this educational institution: in the spring of 1881, after the assassination of Tsar Alexander II, many revolutionary students of Russian universities and other higher educational institutions were dismissed without the right to continue teaching in Russia. In the number of them was Mikhail Osipovich.

At the end of 1881 Dolivo-Dobrovolsky entered the chemistry department of the Darmstadt Higher Technical School, but immediately more than chemistry was carried away by the then new subject - electrical engineering. In Darmstadt, the course of electrical engineering was taught by Professor Kitler, an excellent teacher who had rich practical experience, who managed not only to enthrall M. Dolivo-Dobrovolsky, but also to give him a decent supply of knowledge.

Having completed the course of the Darmstadt Higher Technical School, Dolivo-Dobrovolsky was invited to the German Edison Company and in 1884 started work at one of its factories. Deep and thoughtful engineer, he was well aware of all the shortcomings of direct current and more than once pondered the possibility of creating electric motors of alternating current.

Mikhail Osipovich thought a lot about this problem, more than once tried to turn the direct-current electric motor Gram into an alternating current machine - we remember that about this time Nikola Tesla was also involved in the same problem.

The article of Ferraris produced an exceptional impression on M.O. Dolivo-Dobrovolsky, and even at the time of reading he pictured the principle of the action of an electric motor based on the phenomenon of a rotating magnetic field. The error of Ferraris in calculating the efficiency was also found instantly, and for Mikhail Osipovich there was no doubt about the possibility of a rapid solution to the problem of the application of alternating current. M.O. Dolivo-Dobrovolsky has all advantages of a three-phase current in front of a two-phase current and has begun to design electric motors of a three-phase alternating current.