Noise measurement diagnostics for large electric machines

The paper describes a non-destructive diagnostic method primarily intended for large rotating machines and transformers. The method is based on the assumption that the emitted noise is characteristic of the mechanical condition of the machine concerned. On the theoretical side, subject to analysis have been the electric machine noise sources and their mathematical description. In practical situations, the noise signals are picked from sound field of the machine. A critical review of the strong points and weak spots of noise diagnostics is presented, as well as the prospects for practical utilization of the method based on noise measurement and analysis.