Study on Vibration Distribution Characteristics of a Three-Phase Three-Limb Transformer Core

Transformer vibration mainly comes from the iron core vibration caused by the magnetostriction. Affect by the core structure, fastening conditions and the degree of insulation, etc., the core body vibration is very complicated. A vibration testing platform based on laser Doppler vibrometer was set up to get the vibration characteristics and surface distribution of a three-phase three-limb transformer core under different excitation voltages. The results show that the vibration of the core body mainly comes from magnetostriction, which includes 100 Hz fundamental frequency and higher order harmonic. The fundamental frequency of vibration and the square of the excitation voltage is approximately linear, and the high frequency vibration near the rated excitation voltage increases significantly. Uneven distribution of core vibration is proved, the maximum vibration is founded at the joints along the iron core. The core limbs together with the upper and lower yoke vibration show U-shaped distribution, and the trends can be more obvious as the voltage rises. The results of this paper provide a reference to the transformer core vibration reduction and vibration-based core fault diagnosis.