一起氧化锌电阻片侧面绝缘釉层短路引起的避雷器故障分析OA

With the wide application of metal zinc oxide arresters in power systems,damage faults due to aging,moisture,environmental pollution and other reasons happen quite often.For a damage defect of abnormal heating of a 500 kV line zinc oxide resistors,through the analysis of live detection,power off detection and inspection under disassembled condition,the cause of the defect was found that there was no drainage hole at the lower flange of the arrester,which caused the explosion-proof plate rusted,re-duced its strength and damaged after long-term exposure to acidic rainwater.Moisture intrusion into the arrester cavity causes damping of the valve blocks,and the performance of the side insulating coating of valve blocks decreases and leads to short-circuit breakdown.Then,through drying the damp valve blocks and knocking out the side insulating coating of valve blocks,it was further verified that the leakage current increased due to the short circuit of the side insulating coating of valve blocks.After the short-circuit breakdown of the side insulating coating of the partial valve blocks,the charge rate of the normal valve blocks increases,which further accelerates the deterioration.Finally,the entire valve block column in the upper section breaks down along the side insulating coating.Corresponding preventive measures are put forward according to the cause of the fault.