35kV盘形悬式瓷绝缘子串断裂事故分析

分析盘形悬式瓷绝缘子串在线路发生单相接地后出现断裂的事故原因。通过随机抽取两片可表征事故绝缘子电气性能的同批次同型号绝缘子进行电气试验,试验结果表明试品绝缘子陡波耐受性能不合格,其瓷片层间绝缘存在微观缺陷。综合考虑试品电气试验结果和事故特征可判定,事故绝缘子瓷片层间绝缘在间歇性电弧接地过电压的作用下发生内击穿是造成本次绝缘子串断裂事故的直接原因。为避免类似事故再次发生,应杜绝陡波耐受性能不合格的绝缘子入网运行。

Analysis of Fracture Accident of 35 kV Disc Type Suspension Porcelain Insulator

The fracture accident of disc type suspension porcelain insulator string which happened after the single-phase grounding of transmission line is analyzed. Two pieces of insulators in the same batch and same type which can represent the electrical performance of fault insulators are randomly selected to make the electrical test. Test result shows that the steep front impulse tests of insulator samples were not qualified because of micro defects of layer insulation between porcelain pieces. Comprehensively considering the electrical test results of samples and fault characteristics, it is judged that the direct reason of the fracture accident of insulator string is the internal breakdown of layer insulation between porcelain pieces under the action of intermittent electric arc grounding overvoltage. In order to avoid similar accidents, insulators with unqualified steep front impulse tolerance performance should he forbidden into operation in power grid.