The vibration signal based on the core proper can more accurately reflect condition of the core. In view of the typical core structure of power transformers

the vibration and distribution characteristics of a three-phase threecolumn core model are studied by using a vibrometer and an acoustic imaging system. The experimental results show that the fundamental frequency of the transformer core vibration is 100 Hz and contains integer multiples of higher-order frequency components. The vibration difference of the core in different directions and positions is big

and the plane normal vibration of the silicon steel sheet is stronger than that in the plane. The vibration of column B of the core is larger than that of columns A and C. The maximum vibration is located at the joint of core column and upper and lower yokes. The vibration along the core column and upper as well as lower yoke shows U-shaped distribution.The higher the voltage is

the more obvious the trend is. Both radiation sound field cloud image and sound image of the core show that the radiation noise contribution at the joint of the column B and the upper as well the lower yoke is much bigger than in other positions

which is in agreement with the surface vibration test results. It is of great significance to the core fault diagnosis method based on vibration signal and the vibration and noise reduction technology.