Vibration characteristics of transformer core components

Transformer core is a typical laminated structure consisting of plurality Si-Fe sheets. Its vibration is the major cause of the transformer noise and also related to transformer health. In this paper, components of a transformer core are investigated experimentally. Via examining the modal characteristics of the transverse and longitudinal wave types in bars made of laminated Si-Fe sheets with various boundary conditions, the equivalent orthotropic elastic modulus and loss factors are determined and presented by empirical expressions. These expressions are also evaluated as functions of the number of sheets in the lamination, clamping forces and their locations, boundary conditions and painting treatment on the outer surfaces of the lamination. The physical mechanisms behind these expressions are discussed qualitatively.