Derivation of a plane vibration model for electrical machines on soft machine foundations

Abstract

The paper shows the derivation of a plane vibration model for natural vibration analysis of electrical machines mounted on soft machine foundations. The model represents a simplified single mass system, which can be used to calculate the natural vibrations, which occur in the transversal plane of a soft mounted electrical machine. After the mathematical description of the analytical vibration model and the necessary boundary conditions have been derived, an example of an electrical machine mounted on a steel frame foundation is shown. The natural frequencies are calculated and a comparison between the analytical vibration model and a finite-element vibration model is deduced, showing satisfying correlations. Additionally, it is shown in the example that the size of the contact area between machine feet and foundation may significantly influence the natural vibrations, by stiffening the foundation. On one hand, the aim of the paper is to derive a simplified plane vibration model to calculate the natural vibrations in the transversal plane of soft mounted electrical machines. On the other hand, the aim is to describe the derivation of the plane vibration model and to derive the necessarily boundary conditions for the calculation of the substitute foundation stiffness data.