Vibration analysis of small power transformer

Abstract

PurposeThe purpose of this paper is to present a methodology of identification and calculating vibrations of power transformers caused by magnetostriction.Design/methodology/approachAll 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.FindingsTensor 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/implicationsAssumption of magnetic isotropy of the transformer core is the main simplification during analysis.Practical implicationsIt 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/valueThis paper provides a step‐by‐step explanation of how to get core vibration starting from magnetic field distribution.

Experimental study of vibration characteristics of 110 kV oil-immersed transformer

“…With the deepening of research, scholars have found that the direct causes of transformer vibration and noise mainly include the following aspects: first, core vibration caused by magnetostriction of silicon steel sheet; second, core vibration caused by electromagnetic attraction; third, vibration caused by magnetic leakage; and fourth, DC bias has influence of on transformer noise. 6,7 Among them, the magnetostriction effect of silicon steel sheet is an important cause of transformer vibration. Scholars have carried out various researches on the vibration of silicon steel sheet due to the magnetostriction effect, including modeling, theoretical derivation, analysis and calculation, and experiments.…”

Magnetic forces applied to the tank walls of a large power transformer

“…Therefore, their acoustic parameters have become almost as important as the classic exploitation ones (Girgis et al , 2008). The noise coming from the load current usually dominates the no-load emission originated from the magnetostriction phenomena (Kubiak and Witczak, 2010) appearing in the transformer core. The contribution to the load noise created by windings alone is usually estimated by the empirical relationships (Lukic et al , 2012).…”

Design and Analyze the Optimum Operating Point between Magnetic Flux Density and Vibration Noise of Transformer Cores

“…Based on previous researches [8], the MS behavior of silicon steel materials follows piezomagnetic laws which is rewritten as:…”

“…Several papers have analyzed the vibration of cores due to magnetostrictive effect in 2D, some based the Principle of virtual work [3], and others based the equations of elasticity method in a similar way as thermal stresses [4][5][6]. The aim of this paper was to investigate a feasible way to determine the operating point of transformer cores within the vibration noise limit set by the government.…”

“…Because the vibration of laminated cores due to MS is not only in the plane of the sheets, but also out-of-plane [7,8], so a 3D numerical model including MS effects and magnetic anisotropy was developed, which was used to analyze the magnetic flux density and deformation of laminated cores. The acoustic field was also analyzed based on the total sound power emitted by the cores and windings.…”