110 kV复合外套金属氧化锌避雷器爆炸故障分析

Analysis on an Explosive Failure of 110 kV Polymer-Housed MOA

针对上海电网一起电缆出线无间隙110 kV复合外套金属氧化锌避雷器发生爆炸故障进行了分析。对该型号避雷器进行了外观检查、电气试验和解体拆卸,结合故障时刻天气及电网运行工况等因素,判断该避雷器故障由内部放电引发。内部放电原因推测可能是该避雷器成型过程中工艺质量控制不良,环氧玻璃纤维缠绕电阻片柱或硅橡胶伞裙外套浇注时内部存在气泡、杂质或水分,运行电压下电场分布不均生产局部放电现象,逐步扩大至绝缘击穿形成贯穿性放电通道,致使避雷器在短路接地电流下发生爆炸故障;也有可能是避雷器使用的环氧玻璃纤维引拔棒有制造缺陷,运行电压下与穿心电阻片组内表面发生沿面放电,最终发展成沿环氧玻璃纤维引拔棒及电阻片组内表面的贯穿性沿面闪络。最后,根据目前现行规程和技术手段,提出了结合定期巡视、带电检测和停电例行试验,对避雷器的运行状态做出评估,进而避免类似故障的发生。

Fault analysis is done for the explosion of a cable outlet 110 kV polymer-housed metal ox- ide arrester （MOA） with no gap occurred in Shanghai Power Grid. Considering the results of inspection, electrical tests and the disassembly to the MOA, combined with the weather, the power grid operating conditions and other factors, the failure caused by its internal discharge （ID） of the MOA is deduced. The ID reason of the MOA may be the poor control of the forming process in quality control process, which is the bubbles, impurities or water existing in the epoxy glass fiber winding valve or pouring a sili- con rubber bushing. The partial discharge produced by uneven distribution of electric field under operat- ing voltage, and it gradually expand the insulation breakdown to form the impenetrated discharge chan- nel, which causes the MOA occur the exploding fault under short circuited grounding current. But the manufacturing defects of the epoxy glass fiber rod may also produce the surface discharge through the in- ner surface of valves, eventually develop into the surface flashover between the surface of the epoxy glass fiber rod and valves to case the explosion fault of MOA too. At last, according to current regulations and technical measures, the method with combination of time inspection, live detection and electrical tests is Drooosed to evaluate ooerational status of the MOA to avoid the occurrence of similar failures.