变压器典型工作环境对声功率测量结果的影响

变压器两侧常建有高大的防火墙,其从声学角度可视为刚性反射壁面,会改变变压器的辐射声场,进而影响变压器声功率测量结果。本文利用有限元、边界元等数值计算方法建立了变压器声辐射的仿真模型用以分析反射壁面对变压器声功率测量结果的影响,并通过实际测量验证了仿真计算所得结论。结果表明,反射壁面对变压器声功率测量结果的影响程度随反射壁面到变压器箱体距离增加而减弱,且当反射壁面距变压器箱体5 m以上时,其对变压器声功率基频及各谐波成份测量结果的影响均在2 dB以内。另外反射壁面对变压器噪声高频成份声功率测量结果的影响较大,而对100 Hz、200 Hz等低频成份测量结果影响较小,基本低于3 dB。

Effects of typical working environment on transformer sound power measurement

Transformers are usually separated by firewalls, which can be seen as rigid acoustic reflecting planes that could change the radiated sound field of transformers, and further affect the sound power measurement results of transformers. In this paper the finite and boundary element methods were used to build the simulation sound radiation model of transformers for analyzing the effects of reflecting planes on the sound power measurement results, and experiments were performed to verify the conclusions. The result shows that the effect of reflecting planes on the sound power measurement results become weaker as the reflecting planes become farther from transformers. When the distance between reflecting planes and the transformer was larger than 5 m, the variation on each frequency component of the sound power measurement results caused by the reflecting planes was less than 2 dB. Meanwhile, the reflecting planes have strong effects on the high frequency components of the sound power measurement results, but have weak effects on the 100 Hz and 200 Hz frequency components, which are within 3 dB.