Dependence of electrical treeing behavior on cross-linking temperature of XLPE

In this paper, XLPE laminate was employed as test sample to investigate the effect of cross-linking temperature on characteristics of electrical treeing. The samples were cross-linked at the temperature ranged from 150°C to 220°C by adding dicumyl peroxide (DCP) as cross-linking agent into low density polyethylene (LDPE). A pair of needle-plate electrodes was employed to initiate the tree by applying ac voltage between the electrodes. The experiment was carried out at 30°C, 60°C and 90°C, respectively. A digital microscope was employed to observe the growth process of electrical trees. The profile of crystal grains were captured by using a polarizing microscope. Obtained results show the dependence of characteristics of both tree initiation and propagation upon cross-linking temperature of XLPE. It is suggested that the treeing behavior is influenced by both crystallinity and crystal grain morphology which are varied as a function of the cross-linking temperature.