Complex sentence: Mikhail Osipovich Dolivo-Dobrovolsky (in Gatchina near Saint Petersburg --), was a Russian engineer, electrician, inventor, developed the first three-phase generator and three-phase motor (1888) in the world, studied star and delta connections.
Split into simpler sentences: Mikhail Osipovich Dolivo-Dobrovolsky (in Gatchina near Saint Petersburg --), was a Russian engineer, electrician, and inventor. He developed the a three-phase generator and a three-phase motor (1888) and studied star and delta connections.