Mykhaylo Osypovych Dolyvo-Dobrovolsky (21.12.1861, St. Petersburg, RI - 15/11/1919, Heidelberg, Germany) - electrical engineer, creator of the three-phase current technology.
Mykhaylo Dolyvo-Dobrovolsky was born on December 21, 1861 (2 January 1862) in St. Petersburg. In 1878 he entered the Riga Polytechnic Institute, but was expelled for participating in students’political speeches. In 1884 he graduated from Higher Technical School in Darmstadt in Germany and began to work as a designer at factories of electrical company of Thomas Alv Edison (later the firm AEG; from 1909 Dolyvo-Dobrovolsky was a director of the company).
Mykhaylo Osypovych improved electromagnetic ampermeters and voltmeters to measure direct and alternating current (1887 - 1888 years.). He for different kinds of measuring devices applied the principle of engine with the rotating magnetic field (1892). Also he created instruments for elimination of interference from electricity networks of strong currents (1892), invented the method voltage distribution of direct current based on the use of fixed inductors, which he called voltage divider (1893).
In 1888 Dolyvo-Dobrovolsky constructed the first three-phase alternator with a rotating magnetic field with power 2.2 kW, proposed three-phase AC induction motor with rotor from cast iron with planted hollow copper cylinder. Soon induction motor design has been greatly improved by using rotor of "squirrel wheel" type (1889). At the same time the scientist has developed all elements of the three-phase AC circuits, three-phase current transformers (1890), starting resistors, gauges (e.g, phase meter, 1894), the circuit of switching of generators and motors in the form of star and triangle and so on.
August 25, 1891 M. O. Dolyvo-Dobrovolsky demonstrated the world's first three-phase power transmission system at a distance of about 170 km. at the World electrotechnical exhibition in Frankfurt. Mykhaylo Osypovych was first who proposed a widely used method of extinguishing the arc in the switch apparatuses (1910 - 14). In 1919, he put forward the position that the transmission of electric power alternating current over long distances (hundreds to thousands km) prove unsustainable because of significant losses in the line.
Mykhaylo Osypovych Dolyvo-Dobrovolsky died on November 15, 1919, in Heidelberg, Germany.