The features of positive dc corona discharge on the surface of the conductor with different contaminations

HVDC transmission lines operating in polluted areas may absorb a large amount of contamination, which seriously affects the corona discharge and its associated audible noise, electric field, ion current density from the transmission lines. To fully study the effects of conductor surface condition on photon count and dc electric field, conductors coated with different kinds of contamination were investigated and compared with a clean one. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis and SPIP were employed to characterize the surface morphology of the conductor samples. To fully study the effects of conductor surface condition on photon count and dc electric field, conductors coated with different kinds of contamination were investigated and compared with a clean one. Kaolin, salt and carbon were used as the coating contamination during the experiment. Experimental results illustrated by both ultraviolet photographs and measurement data reveal the dielectric coating resists corona discharge and enhances the onset voltage when the contamination is uniform enough, while electrical conductive contaminations have less impact when the coating is uniform enough.