Noise Reduction Design of the Transformer and the Reactor

The purpose of this study is to solve the noise level caused by the transformer and reactor covered by the double covers, and to reduce the noise increased by the resonance of the wall. To research the phenomenon of the sound in the box, firstly, we simulated the vibration coupled noise analysis of a reactor, its double covers, and their air gaps by the finite element analysis. The simulation results shows that the noise of the air gap between the reactor and the wall to cover the reactor (cover 1), is increased by its resonant. For attenuation of this noise increase, we changed the size of the cover 1's height, and we attached the absorption materials inside of the cover 1's top. And we confirmed these noise attenuation effects. Secondly, we made a small scale model of the reactor with a shaker, and simulate the noise by experiments. This model was designed that the ratio of sound wave length of air gaps and the bending wave length of covers are same. The model measurement data of noise distribution was almost same as the simulation results. And we confirmed that noise attenuation effects for the absorption panel attachment inside of the cover 1's top. In addition to that inside attenuation of cover1, we had to increase the transmission loss of the top of cover1 for the resonant sound increase of the absorption panel back air layer. Both the attenuation levels of the double covers effect by this measure of the simulation and the small size model experiment, showed good agreements.