Mechanism of eddy current-induced electromagnetic force and vibration noise of large-capacity transformer oil tanks

Heavy eddy currents exist in oil tanks during the normal operation of high-voltage and large-capacity transformers. Therefore, considerable vibration and noise are produced. Electromagnetic interference was studied in detail. The calculation of electromagnetic force in oil tanks due to the eddy current and related vibration noise was studied. A 334-MVA single-phase oil-immersed transformer was considered, and the leakage magnetic field, eddy current, and the electromagnetic force of the oil tank were calculated using the finite element method. The distribution characteristics of electromagnetic force were analyzed. The corresponding three-dimensional finite element model of vibration was established based on the stiffness characteristics of the transformer. The frequency characteristics of oil tank vibration caused by the electromagnetic force were analyzed using harmonic response analysis. The simulation model of noise caused by the vibration of oil tank was established. The fundamental frequency noise and high-frequency noise were calculated. The spectral characteristics of noise were obtained. The influence of load change on the electromagnetic force, vibration, and noise caused by the oil tank was investigated. The mathematical relationship between vibration noise and load was analyzed. The above study can provide reference and design basis for the safety design and noise prediction of large-capacity power transformers.