A STUDY ON THE VIBRO-ACOUSTIC ANALYSIS TECHNOLOGY ABOUT THE TRANSFORMER LOAD-NOISE

Recently, the importance of low-noise design on transformers has been growing. This is due to increasing requirements from customers whose substations are being installed nearby downtowns. Increasingly stringent noise emission limits are therefore being placed on transformers by both regulators and utility operators. However, the absence of adequate modelling tools to predict noise levels of transformers during the design phase is leading to difficulties in consistently meeting the acoustic specifications for the manufacturers. This paper presents a numerical methodology to identify the vibration characteristics and predict the sound pressure levels from the load-noise of large power transformers. The methodology involves development of the vibro-acoustic finite element model of a transformer including the excitations of the forces present in a transformer's active part. Additionally, the application of the vibro-acoustic modelling methodology with regard to the computer-aided design of transformers has been presented through a sensitivity analysis. The validation of the vibro-acoustic modelling scheme detailed in this paper has been conducted with appropriate experimental measurements. The measurements were conducted on several manufactured transformers. Specifically, it has been shown that experimentally determined modal tests and sound pressure levels are in good agreement with numerical results. Through this process, the analysis technology suggested in this paper was validated.