STUDY ON THE DIFFERENCE OF DC BREAKDOWN STRENGTH BETWEEN XLPE AND LDPE

In order to study the difference of DC breakdown strength between cross-linked polyethylene (XLPE) and low-density polyethylene (LDPE). XLPE and LDPE from three kinds of cable insulating materials samples were selected to test the DC breakdown strength and thermally stimulated depolarization current (TSDC) and X-ray diffraction (XRD) experiments. The results showed that the increase of DC breakdown strength after crosslinking is the result of the synergistic effect of two factors. One factor is that the density of deep traps will increase after crosslinking, resulting in the increase of DC breakdown strength. The other factor is that the crystallinity will decrease after crosslinking, which will hinder the improvement of DC breakdown strength. The effect of deep trap density on DC breakdown strength is greater, so DC breakdown strength will increase after crosslinking. This work provides a reference for investigating the DC breakdown strength of XLPE and LDPE.