Effects of adding nanofiller on DC tracking failure of epoxy/MgO nano-composites under contaminated conditions

Nano-MgO particles were mixed into neat epoxy to obtain epoxy/MgO nanocomposites with percentages weight ratios of the nanofiller to the base epoxy of 1, 3, 5, 7 wt%. Tracking experiments were carried out by using positive dc voltage. The tracking process and discharge current were measured and the relation with the adding rate and applied voltage was investigated. Obtained results indicated that with increasing adding rate from 0 to 5 wt%, number of drops needed in tracking failure increased, weight loss of nanocomposites and area of tracking pattern decreased. The opposite varying tendency was obtained with increasing the adding rate from 5 to 7 wt%. Additionally, recurrence plot technique was employed to reveal nonlinear characteristics of discharge currents, which could reflect the effects of nano particles on discharge in tracking process. Fractal dimension method was applied to quantitatively reveal nonlinear characteristics of both scintillation discharge distribution and tracking pattern to investigate the effects of nano-MgO on the occurrence of tracking pattern. Finally, experimental results suggested that tracking resistance of epoxy could be improved by adding nano-MgO particles and the best improvement was obtained at 5 wt% adding rate.