Space charge characteristics in XLPE/BN nanocomposites at different temperatures

In order to explore the method of improving the space charge characteristic of crosslinked polyethylene for HVDC cable, a small amount of nano-BN (0.1 wt%, 0.5 wt%, 1 wt%) are added into the crosslinked polyethylene matrix using the melt blending method. Because electrical characteristics of crosslinked polyethylene (XLPE) often depend on temperature, it is important to study the space charge injection characteristics of XLPE and nanocomposites under various temperatures. In this paper, the space charge characteristics of XLPE and XLPE/BN nanocomposites at different temperatures are tested by pulsed electro-acoustic (PEA) measurement. The results show that the temperature and the addition of nano-BN both have a great effect on the space charge characteristics of XLPE/BN. At 20 o C, homocharge is observed adjacent to anode, while at higher temperatures (40 o C, 60 o C) the space charge distribution is basically dominated by negative charges with deeper injection. The average volume charge density of nanocomposite with concentration of 0.1 wt% is always lower than that of pure XLPE at each temperature. Therefore, moderate addition of nano-BN can suppress the injection of positive charges. It is suggested that the improved space charge characteristics mainly arise from the interaction area formed by nano-BN. Besides, the mean attenuation rate of space charge in XLPE/BN nanocomposites decreases with the increase of nano-BN and accelerates as the temperature increases.