35kV电力电缆冷缩式中间接头典型缺陷电场计算及故障分析

Electric Field Calculation of Typical Defects in 35 kV Power Cable Joints and Fault Analysis

通过对含有气隙缺陷的冷缩式中间接头建立物理模型,采用等效电路法分析了气隙尺寸、压接管外绕包半导电层的电阻率对气隙场强的影响。结果表明:气隙尺寸与场强成反比关系,当半导电层的电阻率超过一定值时,气隙场强会显著提升,超过空气最大击穿场强。通过对两例实际接头故障情况的分析,得出与模型分析一致的结论,并提出预防措施,为今后35 k V中压电力电缆接头故障的预防及原因分析提供参考。

A physical model of cool shrinkable joint with air gap defect was established, and the influence of air gap size and resistivity of semi-conductive layer of pressure pipe on the electric field of air gap was analyzed by the equivalent circuit method. The results show that the air gap size is inversely proportional to the electric field. When the resistivity of semi-conductive layer exceeds a certain value, the electric field of air gap will increase significantly, which is over the maximum breakdown strength of air. Through the analysis of two actual joint fault cases, we obtain the consistent conclusion and present prevention measures, which can provide a reference for future fault prevention and reason anlysis of 35 kV medium voltage power cable joints.