避雷器是整个电力系统绝缘配合的基础设备，必须依据避雷器性能，确定系统所有高压电器设备的耐压能力，所以其性能选择具有重大意义。
The arrester is the basic equipment for the insulation coordination of the whole power system. It is necessary to determine the withstand voltage capacity of all high-voltage electrical equipment in the system according to the arrester performance, so its performance selection is of great significance.
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。
The zinc oxide resistor of MOA bears the operating voltage for a long time, and the leakage current continuously flows through each series resistor of MOA. The magnitude of this current depends on the thermal stability of MOA and the aging degree of the resistor. If the MOA is degraded under the action load, the normal insulation level to the ground will be reduced, and the leakage current will gradually increase until the MOA is damaged by breakdown.
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, it is necessary to carry out preventive test and monitor the working condition of MOA regularly, and measure the leakage current of MOA as an important means to judge the operation condition of MOA.