Vibration analysis of small power transformer

Purpose - The purpose of this paper is to present a methodology of identification and calculating vibrations of power transformers caused by magnetostriction. Design/methodology/approach - All calculations are based on finite element approach. Electromagnetic model uses 2D time stepping solution in nonlinear continuum of the core accompanied with equivalent representation of overlapping areas. Structural model is 3D with special representation for laminated core limbs. Theoretical results are compared with experimental ones obtained as operational deflection shapes from vibration measurements. Findings - Tensor representation of magnetostriction stress enables calculation of equivalent forces acting on arbitrary chosen parts of laminated core. These forces converted into amplitude and phase of Fourier spectrum and introduced into structural model make possible to get displacement field with reasonable accuracy. Research limitations/implications - Assumption of magnetic isotropy of the transformer core is the main simplification during analysis. Practical implications - It was proved that small deformation of the core structure originated from assembly technology may be the reason of substantial growth of the vibration level. Originality/value - This paper provides a step-by-step explanation of how to get core vibration starting from magnetic field distribution.