Insulation state analysis and upgrading feasibility study of existing AC 10kV XLPE distribution cables in Jiangsu grid of China

Based on the technical principles provided by CIGRE SC B1 brochures, this paper assesses the insulation state of existing AC 10kV XLPE distribution cables in Jiangsu province and analyzes the feasibility of 10kV grid to be upgraded to 20kV. Score system is established mainly based on the breakdown voltages of sample existing cables, also on dielectric loss angle tangent and aging factor. This system is then used to assess and grade the insulation state of existing 10kV XLPE cables in Jiangsu area. By voltage endurance coefficient and breakdown field strength measurement, remaining life expectancies of 10kV cables are checked before they are upgraded to 20kV. Besides, new and old 10kV cables are tested by 20kV voltage class criteria. At present, several 10kV power circuits have put into test run under 20kV.