The Effect of Nano-scale SiO2 on the Flashover Voltage of Epoxy/ SiO2 Nanocomposite

Epoxy insulator has been widely used in railway transmission line due to its excellent physical and chemical properties. On these transmission lines, corona could occur even on well designed hardware and insulators, which can inject the charge in the surface of insulators and damage the polymer insulators. When a composite insulator is moistened by fog or rain, charged water droplets are formed on the surface, which may affect the insulation performance. Recently a number of papers have reported enhanced electrical (aging and breakdown) performance of Epoxy/SiO₂ nanocomposite, but little attention has been focused on the performance of water droplets on a polymer nanocomposite surface with corona discharge. This research investigates the dynamic behavior of charged water droplets on the surface of Epoxy/SiO₂ nanocomposite. The samples were made by dispersing nano-scale SiO₂ powdered in epoxy with the weight ratios of 1, 3, 5, 7 wt%, and were put under needle electrodes for 5 minutes before the test. Then the experiment was carried out under a dc stress between two aluminum plate electrodes. The initial surface flashover voltage was recorded during the experiments. The results indicate the relationship between the quantity charge of the water droplet and the initial flashover voltage via the charged water droplet. We get the conclusion that the greater charge quantity, the higher flashover voltage.