Variation of Noise and Magnetostriction Associated with Joint Types of Transformer Core

In order to study the acoustic noise generated by transformer cores, the impacts of types of core joint and the number of laminations per layer on noise levels were investigated. In addition, localized magnetostrictions on transformer cores were measured with strain gages, and the differences caused by types of core joint were investigated. The followings were obtained as the results. The step-lap configuration reduced noise levels in comparison with conventional lap. The increase of the number of laminations per layer raised the noise levels. The differences occurred on the higher harmonic components than the fundamental component. There was a certain connection between localized magnetostriction and noise with respect to types of core joint. The magnetostriction measured on a single sheet sample with sinusoidal excitation had less correlation with the localized magnetostriction measured on the core.