Effect of insulating materials thermal aging on electric field distortion of typical defects in cable terminal joints
The cable terminal joint is an essential component of the power cable transmission system.To investigate the effect of insulating material aging on the electric field strength distribution around the internal defects of cable terminal joints,the domestic 10 kV cross-linked polyethylene(XLPE)cable and silicone rubber(SIR)cold-shrinkable cable terminal joint were selected.The XLPE and SIR in the cable terminal joint were firstly thermally aged at 150℃for 16 days,and their relative permittivity and conductivity were tested before and after the aging process.Additionally,a three-dimension simulation model of the 10 kV cable terminal joint was built using the COMSOL Multiphysics software,and the electrical parameters of XLPE and SIR were set based on the aforementioned test results.Three typical defects,such as misalignment of outer semiconductive layer,XLPE main insulation scratches,and sharp-pointed metal were embedded in the simulation model.The electric field strength distribution of the defects with various size and at different positions was analyzed in the aged insulating materials of cable terminal joint.The results show that the relative permittivity of XLPE and SIR increase from 2.5 and 2.85 to 4.4 and 3.21,respectively,after the thermal aging.Meanwhile,the electrical field distortion in the cable terminal joints increases with the aged insulating materials,and specifically,the electrical field distortion at the XLPE and SIR interface is significantly enhanced.Under the three typical defect conditions,the electric field distortion inside the cable terminal joints becomes more noticeable after the thermal aging process,with the maximum electric field strength at the sites of misalignment of outer semiconductive layer,XLPE main insulation scratches,and sharp-pointed metal reaches 5.26,3.5,16.91 kV/mm,respectively,which increases by 17.41%,6.38%,and 21.83%compared to the non-aged state.The study demonstrates that insulating aging exacerbates the electric field distortion at defect sites,further influences the safety and reliability of the cable,and increases the risk of the cable faults.
cable terminal jointcross-linked polyethylene cablesilicone rubberthermal agingtypical defectsimula-tion calculationelectric field strength distribution
万方数据
维普
