Effect of thickness on space charge behavior in XLPE under different temperature

摘要

The space charge behavior in cross-linked polyethylene (XLPE) high voltage direct current (HVDC) cables may be affected by the thickness of the insulation, so an equivalence analysis of the space charge distributions in XLPE sheets with different thicknesses is of great significance. This paper presents space charge behavior in XLPE sheets with the thicknesses of 150, 300, 500 and 800 μm from room temperature to 80 °C under 5-40 kV/mm by pulsed electro-acoustic (PEA) method. The results show that, in samples with different thicknesses, the space charge distributions have strong equivalence at room temperature in the peak values of homocharge and the relative charge depth. However, at temperatures of 40 °C and 80 °C, in samples with different thicknesses, the space charge distributions are quite different and the charge mobility and the trap depth change with the sample thickness. It is probably due to the aggravated heat dissociation of impurities in thick samples which may introduce a new trap band with lower energy levels.