It seems, that pragmatic Europeans actually always have been romantic. Even in the XIX century, which is sometimes called "the age of steam and electricity", they tried in every way to decorate their life. No wonder even at trade shows, where the general public could learn about the latest advances in science and technology, most of its attention was attracted by the exhibits, which in varying degrees, simulate the nature. The first surprise is of the skill of imitation, and only then - a way that achieves the desired effect. It is not surprising that among the visitors of the Frankfurt International Electrical Exhibition in 1891 it was caused a real stir by a huge artificial waterfall. Pump that worked from a powerful electric motor, poured water on the whole 10 meters up, and from there it under cheers of the crowd with the crystal sprays dropped in the channel, decorated with stones and water lilies.
However, experts, many of whom were at the show a lot more were looking attentively not at the waterfall, but at the water pump. Two things caught their attention: firstly, it was not anywhere near power station, which supplied the engine of the pump, and secondly, the performance and reliability of the engine. And when visitors learned that the electricity supplied through the wires from the power station, located on the banks of the Neckar River in the town of Laufen, whose distance from Frankfurt Airport is 175 kilometers, interest and admiration become limitless.
So 120 years ago at an exhibition in Germany for the first time it have been amply demonstrated the possibility of a three-phase induction motor and the advantages of three-phase AC systems to others, especially in terms of power transmission over long distances.
It should be noted that attempts to transmit power over long distances were performed earlier. The most successful one can consider the experience of the transfer of electric current on a telegraph line Crail - Paris length of 56 kilometers, prepared and conducted by the famous physicist Marcel Deprez in 1885. French experimenter worked with constant current with highest that only he was able to achieve voltage of 6000 V. However, although this experience was considered generally successful, the efficiency of the transmission does not exceed 50%. Some electrical engineers began to argue that such efficiency is the maximum possible. Additionally, it was inconvenient to use the constant current, especially because of the impossibility of its transformation. There was a contradiction: to reduce transmission losses one should increase as much as possible the voltage, but the consumer could not use such energy without previous transformation. It was often very uncomfortable. One had to move to the alternating current.
The inventor of "electric candle" famous Russian physicist Pavel Yablochkov began to use the alternating current for practical purposes in the 70s of the XIX century. However, beyond the power of lighting it, he did not go. The outstanding electrical engineer Serbian Nikola Tesla made detailed studies of AC. He experimented with a variety of multi-phase circuits and electrical machines, but thought the two-phase scheme the most appropriated. It is for this scheme there has been constructed at the time the powerful hydroelectric plant at Niagara in the US and a few stations in Europe. However, shortly after it was proved that a more suitable for industrial and other needs is a three-phase current, they were converted. More contributed to this research, discovery and developments of outstanding engineer Mikhail Dolivo-Dobrovolsky.
In the Soviet and modern Russian literature M. Dolivo-Dobrovolsky often is called Russian electrician. This is not entirely correct. He really was born near St. Petersburg in the town of Gatchina in 1862, but was still more Russian-German engineer. The fact that because of his participation in students riots, Mikhail Dolivo-Dobrovolsky was denied the right to receive higher technical education, and was forced to go abroad. In Germany, he graduated from Darmstadt Higher Technical School and was left there for teaching. In 1887 he was invited to work at the Berlin firm "AEG" (Allgemeine Elektricitats-Geselschaft), which developed rapidly. He has worked all his life there - first as chief electrician, then - Technical Director. In 1889 M.Dolivo-Dobrovolsky has filed a patent application for a three-phase asynchronous electric motor with squirrel cage, by which quickly became known by electricians around the world. Then one by one he received patents for three-phase transformers, generators and motors. His scheme transformation phase voltage is used today without any major additions, as well as the asynchronous motors. Thus, it is M.Dolivo-Dobrovolsky is the author of theoretical development and practical implementation of the principles of all the main components of the three-phase AC system.
Returning to the Frankfurt Trade Fair in 1891 and its exhibits presented by the engineer M.Dolivo-Dobrovolsky, we note that he spent two series of experiments with the transmission of electricity from the power station on the river Neckar. He increased the voltage from 14600V to 28300 V. In Frankfurt via transformers the voltage was decreased up to 65V and this current, in addition to the mentioned above pump waterfall, was supplied to light the lamps. The efficiency of a normal operation with the voltage at 8500 V was 75%, and with increased voltage has reached 79%. Nothing could conclusively prove the advantages of the three-phase electric power transmission scheme over all the others! Therefore, many historians believe that it was from an exhibition in 1891 in Frankfurt should start counting years wide electrification.
... After the triumph in Frankfurt Mikhail Dolivo-Dobrovolsky continued to work with electrical engineering. Extraordinary interest was aroused by his report "The modern development of the art three-phase" at the First All-Russian Electrotechnical Congress in January 1900. He even was offered to take the post of dean of the electromechanical department of the newly opened St. Petersburg Polytechnic Institute. However, contractual obligations that Dolivo-Dobrovolsky has been associated with the firm "AEG", did not allow him to accept the offer. Soon there was aggravated a heart disease, which he had suffered since childhood, and for six years he was removed from the active technical creativity. Returned to the company in 1909, and in 1914 after the First World War he moved from Germany to Switzerland. Only in 1918, he returned to Berlin, where he intended to return to work at the firm "AEG", but the old disease aggravated, and in November 1919 he died. It should be noted that Mikhail Dolivo-Dobrovolsky has not taken German citizenship...
Dmitry Stefanovic