Impulse and DC surface flashover of LDPE/TiO2 nanocomposites in Vacuum

This paper focuses on the impulse and DC surface flashover performance of LDPE/TiO2 nanocomposites, which is beneficial to the improvement of electric discharge in power equipment. The results point out that both impulse and DC surface flashover voltages initially increase and then decrease with the increase of nanoparticle loading (DC flashover voltage is higher than that of impulse). Samples with slight nanoparticles present higher flashovervoltages. Moreover, the permittivity exhibits an opposite variation with respect to surface flashover voltage. Slight nanoparticles reduce the relative permittivity, which is responsible for the high flashover voltage by suppressing the electric field distortion near cathode-sample-vacuum triple point. In addition, the surface conductivity significantly decreases in 0.5 wt% and 1 wt% sample, which is beneficial for the reduction of surface charge, causing a high flashover voltage. DC surface flashoverprobably depends on the surface layer characteristics (polarization and trapping/detrapping), while impulse surface flashover is mainly dominated by the secondary electron emission characteristics.