Acoustic noise caused by a.c. corona on conductors: Results of an experimental investigation in the anechoic chamber

The paper describes an experimental research performed in the anechoic chamber with the aim of investigating the qualitative and quantitative characteristics of the acoustic noise caused by a.c.corona on conductors. Conductors of different type and size, smooth and stranded, with and without surface treatment, were tested dry and wet within a large range of voltage gradients. On the basis of the results obtained, a number of conclusions is drawn concerning: the nature of the phenomenon, and in particular the characteristics of the frequency spectra; the laws related to noise variation with voltage gradient, conductor diameter and number of subconductors per phase; the physiological effects of the audible noise.