Mikhail Ossipowitsch Doliwo-Dobrowolski

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Michail Ossipowitsch Doliwo-Dobrowolski (around 1908)

Mikhail Dolivo-Dobrovolsky (better known as Mikhail of Dolivo-Dobrowolsky ; Russian Михаил Осипович Доливо-Добровольский / Mikhail Dolivo-Dobrovolsky , Polish Michał Doliwo-Dobrowolski ; * December 21, 1861 . Jul / 2. January  1862 greg. In Gatchina near Saint Petersburg ; † November 15, 1919 in Heidelberg ) was a Polish - Russian electrical engineer .

After emigrating from Russia due to political persecution of the Poles after the assassination of Tsar Alexander II of Russia (1881), he studied electrical engineering at the Technical University of Darmstadt . As a long-time chief designer at AEG , he invented the asynchronous motor and thus helped three-phase alternating current , also known as three-phase current, to be used in practice and the company to gain international recognition. He also carried out the first three-phase transmission from Lauffen to Frankfurt and thus initiated today's power supply networks .

Time in russia

Mikhail Ossipowitsch Doliwo-Dobrowolski at the age of 22

Michail von Dolivo-Dobrowolsky was born as the son of the Russian civil servant and landowner of Polish descent Josif Florowitsch Doliwo-Dobrowolski and Olga Michailowna Jewreinowa from an old Russian noble family in Gatchina. He spent his school days in Odessa , where his father was transferred in 1872. After secondary school he went to the Riga Polytechnic at the age of 16 . At the end of the 1870s, after the assassination of Tsar Alexander II, a wave of repression broke out, with all progressive students being expelled from their university, which amounted to a study ban in all of Russia. Among them was von Dolivo-Dobrowolsky. After his forced exmatriculation in Riga in 1881, he left his home country in 1883 and went to the German Empire .

Time in Darmstadt

The next station was Darmstadt , where the Technical University established the world's first chair and the world's first faculty for electrical engineering in 1882 , to which Erasmus Kittler (1852–1929) was appointed in the same year. In the electrical engineering course established by Kittler in 1883, Michail von Dolivo-Dobrowolsky studied from 1883 to 1884 and was one of Kittler's first assistants from 1885 to 1887 . There were already a few smaller publications and close contact with Carl Hering , a mechanical engineer from the USA and Kittler's first assistant. He finished his studies without a degree (engineering diploma). In 1887, Emil Rathenau, General Director of AEG , offered him a position, whereupon von Dolivo-Dobrowolsky remained associated with the company until the end of his life.

Situation of electrical engineering after 1880

The numerous low-voltage experiments in the 19th century found their practical application in high- voltage engineering from around 1880 , although numerous applications already existed. Arc lamps could be fed with electricity , powerful and reliable electric motors could be operated, heat could be generated, and even the electrochemical energy storage in batteries worked without any problems. Only one thing caused the greatest problems: remote transmission. For example, if you wanted to illuminate a hall, with the mains voltages possible at the time, the generator could not be more than a few hundred meters away, otherwise the transmission losses would be so immense that there was no longer enough energy available to the consumer. In the USA and Great Britain attempts were made to remedy this with three-wire direct current networks , which later became the single-phase three-wire network that is still common today in the low-voltage range in the USA . The company Siemens & Halske experimented without notable success with five-wire networks.

Invention of the three-phase system

Michail Dolivo-Dobrowolsky with colleagues at AEG in Berlin

At AEG, von Dolivo-Dobrowolsky initially tried to improve direct current technology. After all, the origins of AEG lay in an Edison subsidiary, and Thomas Alva Edison - like Siemens - relied entirely on direct current . At this time, the alternating current was gradually gaining attention among technicians; In 1885 , engineers from Ganz & Co. in Budapest designed the first transformer as it is today. For alternating current technology, however, further equipment was required, in particular reliably working and self-starting motors; the alternating current theory was also still underdeveloped. Before Dolivo-Dobrowolsky, the Italian Galileo Ferraris drew attention to alternating current. Ferraris experimented with two alternating currents shifted by 90 °, with which he operated specially designed motors. But he believed that the maximum efficiency would be 50%. Separately, Nikola Tesla constructed a synchronous motor for two- phase alternating current in 1887 , which was to introduce the two-phase alternating current network in the USA. Nikola Tesla dealt with the subject as early as 1882 and quickly developed a system that was protected by extensive patents . It included both motors and generators with multiphase, preferably two-phase alternating currents.

Independent of these events, AEG came up with a pioneering solution in 1888: Von Dolivo-Dobrowolsky worked with concatenated three-phase alternating current and introduced the term three-phase current for it. The associated asynchronous motor , which he invented , was the first functional solution. The asynchronous motor with squirrel cage rotor , however, had the problem of only delivering a low torque at low speeds such as when starting up . The solution was the slip ring motor , a variant of the asynchronous motor in which the short circuit of the rotor is opened and passed to the outside via slip rings . By connecting various external resistors, Dolivo-Dobrowolsky was able to present an asynchronous motor with high starting torque in 1891.

AEG's first three-phase AC motors were running at the beginning of 1889, and in the following year they were already producing 2 to 3  hp . Von Dolivo-Dobrowolsky paid attention to well-distributed windings, a low scattering of the lines of force and a force field that was as uniform as possible and achieved a satisfactory result. To this end, he also developed the first three-phase transformer in 1891 .

First remote transmission of electrical energy

Generator of the power plant in Lauffen am Neckar (contemporary wood engraving)

At AEG and its Swiss cooperation partner Maschinenfabrik Oerlikon (MFO), all components for a three-phase network were available, but so far they have only been running in trial operation. At this point in time, Oskar von Miller made the very daring suggestion that Dolivo-Dobrowolsky and his chief electrician partner Charles EL Brown realized at the MFO, at the International Electrotechnical Exhibition planned for 1891 in Frankfurt am Main, to present the three-phase transmission between Lauffen and Frankfurt : It should a 300 HP three-phase generator from MFO can be driven by the water turbine of the cement works in Lauffen am Neckar , generating a voltage of around 50 V and 40  Hz, stepping it up to 15  kV (later 25 kV) and then via 175 km overhead line to Frankfurt and then stepped down again to supply a 100 HP asynchronous motor and several three-phase small motors as well as around 1000 light bulbs . The performance of the engines that had previously been in trial operation was still just 2 to 3 hp. Nevertheless, the plant was able to be put into operation on the evening of August 24, 1891, and an examination committee determined that 75% of the energy generated in Lauffen reached Frankfurt. This proved that, on the one hand, alternating current is profitable for a large-scale public electricity supply and, on the other hand, that the three-phase components were meanwhile of the same quality as those used in direct current technology. The image-enhancing effect of the demonstration at the exhibition ultimately led to the breakthrough of three-phase current technology. At Siemens and Edison, however, AC technology only caught on slowly, which enabled AEG to become a global company.

Further activity and end of life

After this success, von Dolivo-Dobrowolsky continued his research in the field of power engineering; he invented the phase meter in 1892 and the ferrodynamic wattmeter in 1909 . He published publications and gave numerous lectures. From 1903 to 1907 he devoted himself to scientific work in Lausanne , where in 1906 he and the whole family obtained Swiss citizenship . After returning to Berlin, he continued his work at AEG and became technical director of the apparatus factory in 1909. On October 24, 1911, he received an honorary doctorate from the Technical University of Darmstadt, whose Dolivo building now bears his name.

In 1919 Dolivo-Dobrowolski died of a serious heart condition in the Heidelberg Academic Hospital. He was buried in the Waldfriedhof Darmstadt , where his grave site (grave site: R 6a 7) - located very close to the memorial of his teacher, Professor Erasmus Kittler - can still be visited today. In 1969 a street in downtown Darmstadt was named after him, Dolivostraße .

literature

Web links

Commons : Michail Ossipowitsch Doliwo-Dobrowolski  - collection of pictures, videos and audio files

Remarks

  1. ^ Gerhard Neidhöfer: Michael von Dolivo-Dobrowolsky and the three-phase current . 2nd Edition. tape 19 . VDE Verlag, 2008, ISBN 978-3-8007-3115-2 .
  2. ↑ VDE website
  3. ^ Gerhard Neidhöfer: Michael von Dolivo-Dobrowolsky and the three-phase current. Beginnings of modern drive technology and power supply. (= History of Electrical Engineering , Volume 9) 2nd edition. VDE-Verlag, Berlin / Offenbach o. J., ISBN 978-3-8007-3115-2 .
  4. ↑ WEKA Media Lexicon ( Memento from July 23, 2012 in the web archive archive.today )
  5. ↑ Gerhard Neidhöfer: Beginnings of three-phase technology and the connections with Switzerland . Lecture ETH Zurich, May 14, 2008 (with map of the pipeline on p. 10)
  6. ↑ Information board at the main entrance of the Waldfriedhof Darmstadt
  7. ↑ Street naming of the city of Darmstadt ( Memento from May 28, 2016 in the Internet Archive ) (PDF, 302 KB)
personal data
SURNAME Doliwo-Dobrowolski, Mikhail Ossipowitsch
ALTERNATIVE NAMES Михаил Осипович Доливо-Добровольский; Dolivo-Dobrowolsky, Michail von
BRIEF DESCRIPTION Polish-Russian electrical engineer
DATE OF BIRTH January 2, 1862
PLACE OF BIRTH St. Petersburg
DATE OF DEATH November 15, 1919
Place of death Heidelberg