In practical terms, the year 1866 can be considered as the year of birth of the electric machine, as it was on this date that the German scientist Werner Siemens invented the first self-induced direct current generator. https://www.mrosupply.com/generators/electrical-generators/standby-generators/5792832_7043_generac/ However, we must mention that this electric machine, which revolutionized the world in a few years, was the last stage of a process of studies, researches and inventions of many other scientists, for almost three centuries. Dobrowolsky developed, in 1891, the first series production of asynchronous motors, in the powers of 0.4 to 7.5kW.
It was the electrical engineer Dobrowolsky, of the AEG firm of Berlin, that persevering in the research of the AC motor entered, in 1889, with the patent application of a three-phase motor with cage rotor. The engine featured had a power of 80 watts, an approximate efficiency of 80% in relation to the power consumed and a great starting torque. The advantages of the squirrel cage rotor motor over the direct current were striking: it had simpler construction, quieter, less maintenance and high operating safety.