金属氧化物避雷器氧化锌电阻片长期承受运行电压，并有泄漏电流不断流过金属氧化物避雷器各个串联电阻片，这个电流的大小取决于金属氧化物避雷器热稳定和电阻片的老化程度。如果金属氧化物避雷器在动作负载下发生劣化，将会使正常对地绝缘水平降低，泄漏电流将逐渐增大，直至击穿损坏金属氧化物避雷器。
Zinc oxide resistors of metal oxide arresters withstand operating voltage for a long time, and leakage current continuously flows through the series resistors of metal oxide arresters. The magnitude of this current depends on the thermal stability of metal oxide arresters and the aging degree of resistors. If the MOA deteriorates under the action load, the normal insulation level to the ground will be reduced, and the leakage current will gradually increase until breakdown damages the MOA.
所以定期进行预防性试验和监测运行中金属氧化物避雷器的工作情况，把测量金属氧化物避雷器的泄漏电流作为判断金属氧化物避雷器运行状况的一种重要手段。
Therefore, preventive tests and monitoring of the operation of metal oxide arresters are carried out regularly. Measuring the leakage current of metal oxide arresters is an important means to judge the operation status of metal oxide arresters.