Investigation on the Action of Eddy Current on Tank Vibration Characteristics in Dry-Type Transformer

This paper investigates the action of eddy current on tank vibration. Sound pressure level (SPL) is measured in situations where the winding is covered with an empty tank and exposed to air to verify the action of eddy current on tank vibration. The results show that tank vibration increases the average SPL by about 23 dB. Through experimental modal analysis, natural frequencies of the winding are away from the 100 Hz excitation but the natural frequency 99.787 Hz of tank is quite close to 100 Hz, which also explains the increase in the SPL. To make simulations on tank vibration caused by eddy current, a 3-D finite-element model is used for analyzing eddy current, electromagnetic (EM) force, as well as tank response in frequency domain. The computation shows a good agreement with the theoretical analysis that the phase angle of the EM force on tank shows a 90° shift compared with that of the winding. Also, the computation simulates the tank vibration caused by eddy current successfully.