湿热环境下复合绝缘子HTV硅橡胶伞裙的吸湿特性研究

Study on Hygroscopic Characteristics of HTV Silicone Rubber Sheds of Composite Insulators Under Humid and Hot Environment

由于长期运行在湿热的气候环境下,近年来我国南方地区复合绝缘子异常发热、击穿断裂等故障时有发生,严重威胁了电网的安全稳定运行。为了描述湿热环境下复合绝缘子高温硫化(high temperature vulcanization,HTV)硅橡胶伞裙的吸湿行为,首先对复合绝缘子HTV硅橡胶伞裙开展湿热老化实验,然后利用扫描电子显微镜(scanning electron microscopy,SEM)分析样品的微观形貌,基于称重法得到不同温度下硅橡胶的吸湿率随时间变化规律,利用Fick扩散模型对实验数据进行拟合,并与运行老化伞裙进行对比,分析HTV硅橡胶的吸湿特性。结果表明:HTV硅橡胶的吸湿过程符合基于随机热运动的Fick扩散模型。随着湿热老化时间的增加,HTV硅橡胶表面微观形貌逐渐劣化,出现孔洞等缺陷,并进一步提升了材料的吸湿率与扩散系数。环境温度的提升能够促进HTV硅橡胶的吸湿进程,在硅橡胶的生产、储存和运输过程中可适当降低环境温度,抑制材料的吸湿,提高复合绝缘子的质量。

Due to long-term operation in hot and humid climate,in recent years,abnormal heating and breakdown of composite insulators have occurred frequently in southern China,which seriously threatens the safe and stable operation of power grid. In order to describe the hygroscopic behavior of high temperature vulcanization( HTV) silicone rubber umbrella skirt of composite insulator under humid and hot environment,the hygrothermal aging experiment of HTV silicone rubber sheds of composite insulator was carried out firstly,and then the micro-morphology of the sample was analyzed by scanning electron microscopy( SEM). The hygroscopicity of silicone rubber at different temperatures was obtained by weighing method. Fick diffusion model was used to fit the experimental data,and the moisture absorption characteristics of HTV silicone rubber were analyzed by comparing with the aging umbrella skirt. The results show that the moisture absorption process of HTV silicone rubber conforms to Fick diffusion model based on stochastic thermal motion. With the increase of wet-thermal aging time,the surface morphology of HTV silicone rubber deteriorates gradually,resulting in defects such as voids,and further improves the moisture absorption and diffusion coefficient of the material. The increase of ambient temperature can promote the moisture absorption process of HTV silicone rubber. Therefore,in the process of production,storage and transportation of silicone rubber,the moisture absorption of materials canbe inhibited by reducing the ambient temperature appropriately,and thus improve the quality of composite insulators.