一起金属氧化物避雷器异常状态诊断与分析

Diagnosis and Analysis of a MOA Abnormality

MOA(金属氧化物避雷器)因具备良好的非线性伏安特性和通流能力而广泛应用于电力系统中,其长期运行可能会出现发热、绝缘性能下降等缺陷。综合运用阻性电流检测、HFCT(高频电流互感器)局部放电检测、红外精确测温等带电检测技术对某220 kV MOA进行诊断与分析,通过停电试验和解体检查验证了带电检测结论,发现异常原因是:避雷器内部未充N2或充N2不足造成内部构成负压,下端防爆装置承受向内应力,长期运行后防爆装置向内破裂,造成避雷器内部受潮,绝缘性能下降,最终导致异常发热。

MOA(metal oxide arrester)has good non-linear volt-ampere characteristics and through-flow capacity,and thus is widely used in power system.Heat and insulation performance decline may occur with its long-term operation.In this paper,live resistance current detection,HFCT(high frequency current transformer)PD detection and infrared thermal imaging are used to diagnose and analyze a 220 kV MOA.Living detection conclusion is verified by outage test and disassembling inspection.The reason of the MOA abnormality is that N2 vacancy or insufficient N2 leads to the internal negative pressure;explosion-proof equipment bears inward stress and breaks inwardly after long operation,which causes MOA internal damping,insulation performance decline and finally heat abnormality.