Magnetomechanical vibrations of three-phase three-leg transformer with different amorphous-cored structures

This paper mainly studies the magnetomechanical effects of three-phase three-leg transformers with amorphous cores in different bending structures, where the magnetic properties of audible noises related to core vibrations are discussed. In general, a Fe-based amorphous SA1 core exhibits higher audible noise and magnetostriction than that of a silicon steel core. Audible noises and core vibrations of amorphous cores can be more easily induced especially after the lamination process. Experiments performed in this study use different core bending structures to determine torsion stresses between core leg and yoke. Three different core structures, including C-core with rectangular corner, C-core with arc corner, and torodial core, are investigated. Experimental results indicate that amorphous-cored transformer with a rectangular core has higher vibration intensities. This is likely due to the condensed distribution of magnetic flux lines in core corners that may induce higher magnetic inductions associated with higher magnetostriction. The effects of core vibrations and audible noises on amorphous-cored transformers due to magnetostriction variations are addressed. It is concluded that a three-phase three-leg amorphous transformer with a toroidal core should have lower core vibrations and audible noises than the counterparts of conventional C-core transformers.