Effect of relationship between magnetic moment energy variation and knee point squareness ratio on transformer noise

Abstract

This paper presents the effects of the magnetostriction of core loss and noise (sound level) on power transformers between 15 and 120 MVA and the results of an analysis relative to the parameters of the squareness ratio (SR). Three types of soft magnetic silicon steel were used in this study: 30ZH105, 27ZH100, and 27PH100. The hysteresis loop and magnetostriction were measured for various magnetic parameters of sound level and core loss. Moreover, finite element analysis was performed to indicate the flux density and the parameter of ΔBr variation dependent on transformer loss and noise. The design values for transformers with several capacities, with respect to sound level and core loss performance were compared. Studies have indicated that transformer noise includes hysteresis and the volume of ferromagnetic materials. The sound level performance displayed a lower noise result because of the core with a higher SR. Besides, it can be observed that the material has innate magnetic anisotropy and the greater the magnetic moment flip energy then induced higher the noise. Additionally, it was observed that a higher SR. of 27ZH100 for core loss was not significant. When the SR. with respect to the sound level was high, the experimental and design values were very similar by using fast Fourier transform to observe the noise operated at a different frequency spectrum between 50 Hz and 10 kHz. The design values for transformers with varying capacities, with respect to the sound level and core loss performance were analyzed and compared with the experimental values.