Mikhail Osipovich Dolivo-Dobrovolsky (; or Michail Ossipowitsch Doliwo-Dobrowolski; – ) was a Russian Empire-born engineer, electrician, and inventor of Polish-Russian origins, active in the German Empire and also in Switzerland. After studying in Germany and while working in Berlin for Allgemeine Elektricitäts-Gesellschaft (AEG), he became one of the founders (the others were Nikola Tesla, Galileo Ferraris and Jonas Wenström) of polyphase electrical systems, developing the three-phase electrical generator and a three-phase electrical motor (1888) and studying 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. He designed the world's first three-phase hydroelectric power plant in 1891. Life Mikhail Dolivo-Dobrovolsky was born as the son of the Russian civil servant and landowner of Polish descent Josif Florovich Dolivo-Dobrovolsky and Olga Mikhailovna Jewreinova from an old Russian noble family in Gatchina near Saint Petersburg. He spent his school days in Odesa, where his father was transferred in 1872. After secondary school he went at the age of 16 to the Riga Polytechnic, a college founded by Baltic Germans, teaching in German language. At the end of the 1870s, after a series of assassination attempts and finally the murder of Tsar Alexander II in 1881, a wave of repression broke out, with which all progressively oriented students were expelled from their university, which was equivalent to a study ban in all of Russia. Among them was Dolivo-Dobrovolsky. After his forced exmatriculation in Riga in 1881, he left his homeland in 1883 and went to Germany. He studied at the first chair of electrical engineering worldwide, at the Technische Hochschule Darmstadt in the German Empire Grand Duchy of Hesse from 1883 to 1884. From 1885 to 1887, he became one of :de:Erasmus Kittler's first assistants. There he published several smaller publications and was in close contact with Carl Hering, a mechanical engineer from the USA and Kittler's first assistant. After the inventions, Dolivo-Dobrovolsky continued his research in the field of heavy current technology, inventing the phase meter in 1892 and the ferrodynamic wattmeter in 1909. He published papers and gave numerous lectures. From 1903 to 1907 he devoted himself to scientific work in Lausanne, where he acquired Swiss citizenship with his