10 kV电缆中间接头典型施工缺陷的电场及局放特性研究

电力电缆故障多发生于中间接头位置,而施工缺陷是引发中间接头故障最主要的原因。为评估电缆中间接头典型施工缺陷的危害性,文中建立电缆中间接头三维有限元模型,分析电缆中间接头存在硅脂涂抹不均匀、主绝缘划伤和接头受潮3种施工缺陷时的电场分布规律,探究不同缺陷位置与场强之间的关系,并搭建工频交流电压局放试验平台对试样进行局放试验。结果表明:硅脂涂抹不均匀时,空气间隙在应力锥周围造成的电场畸变程度最严重;远离应力锥时,场强逐渐减小。主绝缘划伤时,电场畸变最为严重,空气间隙在外半导切断处场强最大。接头受潮后,当水膜位于应力锥附近时,电场畸变程度最为剧烈。相同加压条件下,接头受潮、硅脂涂抹不均匀、主绝缘划伤3种缺陷造成局部放电的次数依次增加。

Electric field and local discharge characteristics of typical construction defects of 10 kV cable intermediate joint

Cable faults mostly occur in the middle joint of the cable, and construction defects are the most important cause of middle joint faults.To assess the dangers of typical cable intermediate joint construction defects, this paper establish cable intermediate joint 3 d finite element model, analysis of the cable intermediate joint silicone daub is uneven, be affected with damp be affected with damp three main insulation scratches and joint construction defects at the time of the electric field distribution, to explore the different defect position and the relationship between the field intensity, discharge test platform and building construction frequency ac voltage discharge test was carried out on the sample.The results show that the electric field distortion is the most serious when the air gap is around the stress cone, and the field intensity decreases gradually when it is far from the stress cone.When the main insulation is cut, the electric field distortion is the most serious, and the field intensity is the biggest at the air gap cut off.When the water film is near the stress cone, the electric field distortion is the worst.Under the same pressure condition, the number of partial discharges caused by three defects, namely, wet joint, non-uniform silicone grease coating and main insulation scratch, increased successively.