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Measurement of magnetostriction harmonics under stress is beneficial to clarify the raltionship between magnetostriction and transformer noise. In this study, a magntetostriction measuring system with small uncertainty is developed to measure the magnetostricion under stress of ± 20MPa. The magnetostriction under sinusoidal and nonsinusoidal flux densities can be measured by digital waveform control. The components of magnetostriction harmonics and specific power loss at different percentage of the 3rd harmonic in flux density and phase delay of the 3rd harmonic with respect to the fundamental harmonic are investigated.

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The van-der-Pauw (VDP) method and the traditional measurement method are used to measure the resistivity of the electrical steel plate and strip samples. According to the comparison of the two methods, the relative difference between them is 0.27% for sample of g-o-material and 0.06% for that of n-o-material. The uncertainty of the two methods both are 0.31%. It can be stated that the two methods, the VDP and the traditional method, applied to strip samples, show excellent agreement and should be introduced both in the new edition of the IEC 60404-13 standard.