金属氧化物避雷器的非线性电阻阀片主要成分是氧化锌，氧化锌的电阻片具有极为优越的非线性特性。正常工作电压下其电阻值很高，实际上相当于一个绝缘体，而在过电压作用下，电阻片的电阻很小，残压很低。但正常工作电压下，由于阀片长期承受工频电压作用而产生劣化，引起电阻特性的变化，导致流过阀片的泄漏电流的增加。电流中的阻性分量急剧增加，会使阀片上温度上升而发生热崩溃，严重时，甚至引起避雷器的爆炸事故。依照《金属氧化物避雷器通用技术规范》规定，金属氧化物避雷器的检测项目共6项，分别为（1）绝缘电阻；（2）直流U1mA及0.75U1mA下的泄漏电流；（3）运行电压下的交流泄漏电流；（4）工频参考电流下的工频参考电压；（5）底座绝缘电阻；（6）检查放电计数器动作情况。
The main component of non-linear resistance valve of MOA is zinc oxide, which has excellent nonlinear characteristics. Under normal working voltage, its resistance value is very high, which is equivalent to an insulator. Under the action of over-voltage, the resistance of resistor is very small and the residual voltage is very low. However, under normal working voltage, the valve plate is deteriorated due to long-term power frequency voltage, which leads to the change of resistance characteristics and the increase of leakage current flowing through the valve plate. The rapid increase of the resistive component in the current will cause the temperature on the valve plate to rise and cause thermal collapse, and even lead to the explosion of lightning arrester. According to the general technical specification for metal oxide surge arresters, there are 6 items to be tested for MOA, which are: (1) insulation resistance; (2) leakage current under DC U1mA and 0.75u1ma; (3) AC leakage current under operating voltage; (4) power frequency reference voltage under power frequency reference current; (5) insulation resistance of base; and (6) inspection of discharge counter Working conditions.