Study on the effect of artificial radiation simulating terrestrial solar ultraviolet radiation on negative DC discharge performance of air gap

It is important to reveal the effect of terrestrial solar ultraviolet radiation (TSUVR) on discharge performance of external insulation for the design and operation of a power system in regions with strong TSUVR, especially in Tibet. However, no research was carried out in this field until now. In this study, an artificial UV lamp was used to imitate TSUVR in the relevant experiments to research on the effect of negative DC discharge. It was found that artificial radiation simulating terrestrial solar UV radiation (STSUVR) does not affect appreciably the negative DC corona characteristics and breakdown voltage of short rod-plane air gaps of several electrode materials. That is because the wavelength of the STSUVR is in the range of 290-400 nm, and its intensity is less than 200 W/m². Thus, air, Cu and Fe cannot be photoionised by STSUVR. There is also no effect of the STSUVR on arc propagation because of energy. Although a part of the photons in the TSUVR has higher energy than the work function of Al, it is very easy for the Al to be oxidised, and the oxide film (Al₂O₃) can prevent Al from being ionised by TSUVR. Therefore the TSUVR does not have an obvious effect on negative DC discharge performance of air gap.