Dolivo-Dobrovolsky, Mikhail Iosifovich (2.01.1862–15.02.1919) was a Russian physicist and electrical engineer who laid the foundations of three-phase current engineering. Born in St Petersburg. He studied at the Riga Polytechnic Institute and was expelled from it for taking part in student political demonstrations, without the right to enter any higher educational institution in Russia. He graduated from the Higher Technical School in Darmstadt (1884) and worked at the factories of the Edison electrical company (Germany); in 1914–18 he lived in Switzerland.
He was the author of many discoveries and inventions. He proposed a system of three single-phase alternating currents shifted in phase by 120° (three-phase current) and built the first three-phase generator with a rotating magnetic field (1888). He designed a three-phase motor with a rotor of cast iron and an induction motor with a short-circuited rotor (1890), and invented three-phase transformers (1890), the phase meter (1894) and others. He worked out the “star” and “delta” connection schemes for generators and motors and built in 1891 the first three-phase transmission line, about 170 km long.