造成金属氧化物避雷器泄漏电流和阻性电流异常通常有以下几个方面原因。 

Metal oxide surge arrester leakage current and resistance current abnormal usually has the following several reasons.   

　　（1）避雷器内部受潮。密封不良如运输过程中橡胶绝缘外套受损出现了一些细微的裂纹、密封胶圈永久性压缩变形等使潮气侵入阀片；由于环境温度冷热交替，避雷器内空气膨胀收缩的呼吸作用，使可能存在的微小漏孔逐步扩大，形成潮气进入通道。当氧化锌阀片受潮，运行中会造成泄漏电流增大，严重时可能出现沿阀片柱表面和绝缘套内壁表面的放电，甚至引起爆炸。 

(1) the arrester internal be affected with damp be affected with damp. Poor sealing rubber insulation coat as transit damaged some small crack, permanent compression deformation and so on make the o-ring seal moisture into the valve; Due to environment temperature alternating, lightning arrester expansion shrinkage of respiration of the air inside, make possible tiny hole leakage gradually expanded, forming the moisture into the channel. When zinc oxide valve piece be affected with damp be affected with damp, causes in the operation of the leakage current increases, serious when may occur along the valve plate column invest in surface and wall surface discharge, even explode.   

　　（2）阀片本身老化引起故障。由于氧化锌阀片直接接入电网电压，长期在工频或谐振过电压作用下避雷器绝缘性能会不断劣化，当泄漏电流流过阀片时其中有功分量将使阀片本身发热，造成其伏安特性变化，长期发热导致温升的后果是加速老化，陷入恶循环，直至发生热击穿。 

(2) the valve itself ageing cause failure. Due to zinc oxide valve directly connected to the electricity grid voltage, long-term in power frequency resonance overvoltage or under the action of lightning arrester insulation performance will continue to degradation, when leakage current flows through the valve of active component will make the valve itself fever, cause its volt-ampere characteristic change, long-term heat cause temperature rise is accelerated aging, into a bad cycle, until the thermal breakdown occurs.   

　　（3）环境污秽影响引起的避雷器损坏。当环境污秽及在高温环境下，极易造成避雷器电场分布不均，在避雷器上部靠近法兰处电流很大更易引起老化。根据以往运检记录可知，避雷器故障大多发生在夏季高温污秽地区。而且，当避雷器绝缘外套存在污秽在雨雪作用时，避雷器内外电位不同，使得阀片与绝缘外套间产生一个径向电位差，可能造成局部放电。 

(3) the filthy environment damage caused by lightning arrester. When the environment polluted and under the environment of high temperature, easy to cause lightning arrester electric field distribution, near the flange on the upper arrester current is much more likely to cause aging. Based on previous shipment inspection record, the lightning arrester failure occurs mostly in the summer heat impurity region. And, when the lightning arrester insulation coat is defiled in snow and rain, lightning arrester and potential, makes the valve plate, the potential difference between the insulation coat and to create a radial may cause partial discharge.   

　　（4）避雷器发生热击穿。当避雷器发热功率比散热功率大时，热量的积蓄可使阀片温度升高甚至使绝缘外套热击穿。发热功率由通过阀片电流的有功分量决定，因此监测总电流中有功部分可以知道发热功率的变化；而散热功率取决于环境温度、周围介质和避雷器结构尺寸等因素。 

(4) the arrester thermal breakdown occurs. When lightning arrester heating power is greater than the cooling power, heat savings can make the valve plate temperature even insulate coat thermal breakdown. Heating power is determined by the through valve current active component, so monitoring the active part of the total current can know the change of heating power; And heat dissipation power depends on environmental factors such as temperature, ambient medium and arrester structure size.   

　　该避雷器解剖后中上部氧化锌阀片表面存在的白色粉末状物质应是阀片进水受潮后发热产生的遗留物，受潮造成避雷器绝缘水平下降，使泄漏电流增大；当内部不能保持足够干燥时加速阀片老化，在中上部每节阀片的压接处，发现有金属锈蚀痕迹，而底部阀片节间仍保持光亮，说明避雷器中上部阀片发生一定程度氧化。

The lightning arrester dissection of the upper surface of zinc oxide valve plates after white powder material should be the valve water be affected with damp be affected with damp heat produced by the relic, be affected with damp be affected with damp cause the loss of lightning arrester insulation level, increased leakage current. When internal cannot maintain enough dry accelerated aging valve plates, and on the top of each section of the valve pressure it, signs of metal corrosion were found, and the bottom valve plates internode remains light, lightning arrester in the upper valve plates happened to a certain extent oxidation.