Experimental verification of the potential of superhydrophobic surfaces in reducing audible noise on HVAC overhead line conductors

Abstract

Overhead line conductors can generate audible noise across a wide frequency spectrum as a result of elevated electric fields at the conductor surface. Such fields are enhanced by the presence of surface defects, insects, water drops and pollution. Within this paper, the impact of a superhydrophobic coating on the audible noise produced by an overhead line conductor is examined. Noise levels from a conductor coated with a superhydrophobic coating were compared to those from a bare conductor in a semi-anechoic chamber. The conductors were energised at voltages to provide surface electric fields ranging from 6 kV/cm to 21 kV/cm (rms). With a continuous water spray system depositing droplets on the conductor surface, the frequency domain sound pressure level, overall sound pressure levels and corona discharge magnitude were measured. It is demonstrated that the use of a superhydrophobic coating reduced audible noise levels and corona discharge magnitude, especially at electric fields above 14 kV/cm. The image analysis suggests that the water drop size distribution and the position of surface droplets on the conductor circumference play an important role in the magnitude of audible noise.