Abstract: A rotor in an asynchronous electrical machine used in high speed applications, comprises an electrically conductive conductor surrounding a rotor shaft and located substantially adjacent to a stator of the asynchronous electrical machine, a coating layer made of a ferromagnetic particulate material having an electric conductivity substantially lower than that of the conductor, the coating layer being placed between the rotor shaft and the conductor and a metallic intermediate layer between the coating layer and rotor shaft, the metallic intermediate layer having yield point lower than that of the coating layer and the rotor shaft.

Abstract: The invention relates to an asynchronous electric machine, wherein a rotor rotating relative to a stator is provided with an electrically conductible coating. An air gap (.delta.) between the rotor and the stator is designed according to the following formula ##EQU1## in which D.sub.r =outer rotor diameter (mm),D.sub.s =inner stator diameter (mm),u=peripheral speed (m/s),.delta.=air gap (mm),A=a constant, whose magnitude .gtoreq.0.3, preferably 0.7-1.5, suitably 1,B=a constant, whose magnitude .ltoreq.150, preferably 50-100, suitably 70,C=a constant whose magnitude .ltoreq.1200, preferably 300-600, suitably 400; quality m/s/.sub.mmThe peripheral speed of the rotor is more than 100 m/s. Furthermore, the rotor is provided on its shaft body with an electrically conductible coating, which is designed to be continuous and to extend over the entire operative surface area of the rotor.