Electromagnetic noise in large induction motors

Abstract

An approach to prevent noises of large induction motors which are subjected to various forms of vibration caused by electromagnetic exciting forces is presented. From the results obtained in experimental investigations for many actual large motors, it has become clear that all the components of the noise and vibration paths from exciting point to radiational sound field must be taken into consideration for avoiding typical peak noise and vibration. A substructural system analysis is adopted to comprehend the vibrational behavior of all components by using FFT (fast Fourier transform) analysis and the transfer function method. The combined system simulation is done in a digital computer by using modal parameters to estimate the frequency response of the total structure. It means that the contributions of each component to the total noise and vibration are predicted without actual motors. Now, through this investigation, it is considered possible to predict quantitatively the effects of each component al least on vibration.