Experimental study of the noise generated by urban high-voltage electrical substations

Abstract

This work describes the results of sound pressure measurements carried out in the vicinity of ten high voltage electrical substations operating in areas of considerable urban density in the State of Rio de Janeiro. The work was motivated as a strategy to guide the proposition of an acoustic attenuation solution to meet the imposition of the Public Prosecutor's office, which interposed a civil action in the name of dissatisfied residents of the neighbourhood of one of the substations studied. Based on the acoustic limits imposed by the applicable environmental legislation, the study evaluated the acoustic noise level at different points in the neighbourhood of ten urban substations in the city of Rio de Janeiro, studying in depth the acoustic noise in the internal and external environments of the substation subject to the civil action brought. Although it is not possible to eliminate the acoustic noise generated by high voltage transformers since it results from the natural phenomenon of magnetostriction, which is intrinsic to the operation of any high-power electrical transformer, there are alternatives to mitigate the sound pressure level. As part of the strategy, the work recommends, as a first action, eliminating any tonal component associated with the acoustic noise, as its presence in the frequency spectrum causes discomfort to the human ear and penalizes measured levels by +5 dB. The work also shows that it is not trivial to discuss the impact of acoustic noise generated by substations installed in urban communities, whose acoustic noise commonly exceeds regulated limits. In conclusion, the work confirms that most electrical substations operate on the boundary line of the permissible noise limits.