Dielectric Properties and Creepage Discharge of Epoxy/Silica Nanocomposite in Mineral Oil

This paper deals with the effect of the nano filler loading in epoxy resin (EP) on creepage discharge properties of the epoxy/silica nanocomposite (EP/S-NC) in mineral oil under standard lightning impulse voltage application using needle-bar electrode arrangement. Experimental results allow to estimate discharge occurrence probability (P-d) at each voltage level. The relative permittivity epsilon'(r) and dielectric loss are measured at 50 Hz - 5 MHz for EP/S-NC with a good dispersion of nanoparticles in the base epoxy matrix. As a result, it is found that P-d decreases with increasing the filler loading up to 1 wt%, and then increases. Namely, the nano filler content of 1 wt% produces the best insulation performance in terms of P-d. The relative permittivity of the composite decreases with decreasing the filler loading below 1 wt%, while further increasing nano silica filler loading results in increased epsilon'(r) above 3 wt%.