Simulation on electric-thermal-stress field for installation defects of T-type cable joint in 10 kV ring main unit

During the installation of the T-type cable joint of the 10 kV ring main units, defects such as impurities left behind or scratches on the cross-linked polyethylene insulation may occur due to installation negligence or non-standardization, resulting in the increase of local electric field strength and the occurrence of abnormal temperature rise, which can trigger partial discharge and even lead to fire accidents. In this paper, the JB-10/630 T-type cable joint is taken as the research object, and the electric-thermal-stress field simulation calculation model is established. Simulation and analysis are conducted for metal or semi-conductive particle installation defects and scratch installation defects at the interface of silicone rubber insulation layer/cross-linked polyethylene insulation layer and stress cone/cross-linked polyethylene insulation layer. The results show that the three installation defect regions lead to large distortion of the electric field and stress field, but the influence on the temperature field is relatively small. In addition, the distortion of the electric field becomes more severe as the radius of the metal particles increases, posing a potential threat to the insulation of the joint. Applying silicon grease paste at the scratch defect can avoid the phenomenon of stress concentration and electric field distortion around the defect.