Power transformer sound pressure level spectra versus electrical current spectra: experimental findings

Abstract

All high-voltage installations are subject to a series of legislation and regulations to limit the permitted noise levels. Considering area, levels are divided into public areas, areas of increased sensitivity and occupational exposure areas. In addition, it is well known that there is a connection between load harmonics and noise in certain frequency spectrum. In order to investigate this phenomenon in more details, the in-situ field measurements of power harmonic and sound pressure levels are conducted in two high voltage substations The results showed that the noise values at all observed voltage levels are within the limits prescribed by the regulations. Moreover, dominant peaks in sound pressure level spectra typical for power transformers (fundamental, third, fifth and seventh harmonic) are visible in the corresponding current spectra. However, sound spectra peaks without obvious electrical counterpart have been detected as well, which will be subject of our future research.