Mikhail Dolivo-Dobrovolsky

Mikhail Osipovich Dolivo-Dobrovolsky (Russian: Михаи́л О́сипович Доли́во-Доброво́льский; German: Michail von Dolivo-Dobrowolsky or Michail Ossipowitsch Doliwo-Dobrowolski; Polish: Michał Doliwo-Dobrowolski; January 2 [O.S. December 21, 1861] 1862 in Gatchina near Saint Petersburg – November 15 [O.S. November 3] 1919 in Heidelberg, Germany), was a Polish-Russian engineer, electrician, and inventor. Born in a mixed family between a Polish noble family originating from Mazowsze, and a Russian noble family. Emigrated to Germany due to political persecution of Poles after the assassination of Alexander II of Russia (1881). He studied at the Darmstadt University of Technology (TH Darmstadt) in Germany. From 1887 he worked for AEG.

One of the founders (the other two were Nikola Tesla and Galileo Ferraris) of three-phase electrical systems, he developed the three-phase electrical generator and a three-phase electrical motor (1888) and studied star and delta connections. The triumph of the three-phase system was displayed in Europe at the International Electro-Technical Exhibition of 1891, where Dolivo-Dobrovolsky used this system to transmit electric power at the distance of 176 km with 75% efficiency. In 1891 he also created a three-phase transformer and short-circuited (squirrel-cage) induction motor.