Inhibition of Electrical Tree Initiation inside High-Voltage Cross-Linked Polyethylene Cable with Nonlinear Shielding Layer

Electrical tree aging is one of the leading factors causing degradation and breakdown of insulation performance of high-voltage cross-linked polyethylene (XLPE) cable. A lot of attention has been paid to inhibiting electric tree initiation and propagation inside high-voltage cable. In this study, insulation composites with nonlinear electrical conductivity are prepared. Experimental results show that these composites are helpful for enhancing the apparent breakdown electric field strength of XLPE in the pole electrode system. A kind of high-voltage XLPE insulated cable with new structure is designed by using these composites as nonlinear shielding layer. Numerical simulation results indicate that nonlinear shielding layer can obviously improve the distribution of electrical field at the defect of insulation surface of high-voltage XLPE cable, and decrease the maximum electrical field strength at the defect. This new structure is potential for effectively inhibiting electrical tree initiation inside high-voltage XLPE insulation cable, thus increasing life span and operational reliability of the cable.