THE EFFECT OF RADIATION ENVIRONMENT ON ELECTRICAL INSULATION MATERIALS

Ultra Violet radiation (UV) is the major factor that has serious effects on degradation of electrical insulators. Radiation sources of UV are mainly Sun’s rays, corona partial discharge formation and dry band arc discharge on the surface of the insulation that cause tracking and erosion phenomena. The effect of Ultra violet emission on the insulator surface flashover in presence of contamination has been presented. As UV sources, a special setup to simulate the UV rays of corona and dry band arcing and a Xenon-arc-lamps light to simulate the sunlight have been used. Artificial weathering has been made under controlled temperature and humidity. A light source less than 400 nm wavelength, producing more than 90% of the daylight spectrum has been used. Results show that the flashover voltages and the hydrophobicity of aged insulators decrease as the UV exposure time increases for different levels of moisture and pollution. The other characteristic that is important for monitoring the condition of insulators is the Leakage Current (LC). The harmonic of the LC for three distinct cases has been evaluated. The cases are: without arc (nominal voltage), the second is in presence of dry band arcing and corona discharge and the third is continuous arc.