Dielectric and space charge characteristics of nano-modified liquid silicone rubber for high-voltage DC cable accessories

Abstract

In order to solve the problem of space charge accumulation in high-voltage DC cable accessories, nanometer titanium dioxide (TiO2) doping method is used to improve the space charge performance of liquid silicone rubber (LSR). Conductivity, dielectric spectrum and DC breakdown field strength, space charge distribution, and the trap level distribution of nano-TiO2/LSR composite samples were tested in this paper. With the increase of the doping concentration of nanoparticles, the DC conductivity increased, and the DC breakdown field strength decreased. The er of the TiO2/LSR composite sample increased with the increase in the doping concentration of nano-TiO2. As the frequency increased, tanδ decreased first in the low-frequency region and then increased in the high frequency. When the electric field strength increases from 10 to 20 kV/mm, the same polarity charges appear near the upper and lower electrodes of the sample, and the space charge accumulation doubled. After the addition of nano-TiO2, under the two electric field strengths, the space charge accumulation of 4 wt%-TiO2/LSR composite materials decreased by 24.55 nc and 81.03 nc, respectively. The trap energy level of the 4 wt% nano-TiO2 composites becomes smaller, and shallow traps are introduced, it was verified that the addition of 4 wt% nano-TiO2 particles reduced the space charge inside the composite sample and achieved the effect of suppressing space charge.