Voltage endurance of low density polyethylene with surface treated inorganic filler

The effect of surface-treated inorganic filler on the voltage-endurance of Low-Density Polyethylene has been investigated. The inorganic filler used for the test is clay which was treated by adding silane and high speed stirring at 60 to approximately 70 °C. Both LDPE with treated filler (filled LDPE) and LDPE without filler (untilled LDPE) were used for voltage endurance, electrical breakdown and dielectric loss experiment. The experimental results show that the life index of filled-LDPE is higher than that of untilled LDPE. As the aging time prolongs, the residual electrical breakdown strength of filled-LDPE increases and the dielectric loss factor (tanδ) of filled-LDPE decreases at 70 °C, respectively. On the base of experimental results, a deep electronic trap mechanism for the effect of inorganic filler treated with coupling agent is put forward. It is considered that the surface-treated filler with silane may supply deep electronic traps reducing the carrier mobility and carrier density in filled-LDPE to suppress electrical tree propagation. Thermal stimulated current (TSC) and electrical treeing experiments have been performed. The experimental results are consistent with theoretical analyses.