The main reason for dampness is related to the production and transportation of products. The main reason is that there is no strict requirement for the environment in the production process (normal production environment has strict requirements for temperature and humidity, especially the gap. Once the temperature and humidity do not meet the requirement, explosion will easily occur, which is also the overvoltage protection in power system. One of the important reasons for protective device explosion.
受潮的途径有两个：一是密封不良使潮气或水分侵入，密封垫的质量和组装工艺是关键;二是产品元件受潮或装配车间不合格造成的。外部污秽可能引起过电压保护器表面电压分布不均匀，有可能使过电压保护器局部发热。这就要求过电压的相与相、相与地的距离满足系统的要求， 而且使用的绝缘材料（如过电压底盒、 硅胶套、硅胶电缆等）要求比较高。
There are two ways to get damp: one is that the bad sealing makes the moisture or water invade, the quality of the gasket and the assembly process are the key; the other is that the product components are damped or the assembly workshop is not qualified. External contamination may cause uneven voltage distribution on the surface of the overvoltage protector and may cause local heating of the overvoltage protector. This requires that the distance between phase and phase, phase and ground of overvoltage meet the requirements of the system, and the insulation materials used (such as overvoltage bottom box, silica gel sleeve, silica gel cable, etc.) are relatively high.