带电清洗剂对绝缘子用硅橡胶的溶胀效应及其影响研究

复合支柱绝缘绝缘子由于具有优异的防污性能,在直流换流站得到了广泛应用,但其在空间电荷和静电效应下积污严重而存在大面积污闪风险。为了评估复合支柱绝缘子带电绝缘清洗的可行性,对硅橡胶在新型绝缘清洗下的溶胀特性及其对硅橡胶的电气性能、力学性能以及憎水性的影响开展了试验分析。研究结果表明:硅橡胶溶胀随着溶胀时间的增加溶胀指数和直径增长率持续增大,浸泡时间20 min时圆形硅橡胶试样的直径增长率为4.7%、溶胀指数为6.8%。硅橡胶的复介电常数、复电容、介质损耗因素随着频率、溶胀指数增大而减小;在10-2~103Hz频域范围内硅橡胶溶胀不会造成介电性能下降。硅橡胶溶胀对憎水性和憎水迁移性无明显影响,干燥洁净硅橡胶溶胀前后接触角θ平均值在92°~98°范围内浮动,人工积污并经过憎水迁移后θ平均值在119°~128°范围内浮动。硅橡胶在发生溶胀后其力学性能小幅度下降,溶胀20 min的其断裂拉伸强度下降2%。试验结果表明硅橡胶在清洗剂中溶胀度受浸润时间影响较大,溶胀效应对憎水性、电气和力学性能影响较小,可通过采用易挥发配方或强对流措施控制清洗剂残留对硅橡胶的影响。

Study on Swelling Effect of Electrified Cleaning Agent on Silicone Rubber Used for Insulator and Its Influence

The pollution of Composite Pillar insulators in DC converter station is serious,which leads to the acceleration of corrosion and aging of umbrella skirt materials,and even pollution flashover accidents.Electrified cleaning of composite insulators is an important means to restore insulation performance and operation reliability.Composite insulator umbrella skirt is made of silicone rubber,and the detergent will swell the silicone rubber.In order to study the relationship between the swelling index of silicone rubber for composite post insulators in substations and their electrical and mechanical properties,the frequency domain dielectric spectroscopy and mechanical tests are carried out.The results show that the diameter growth rate of silicone rubber is 4.7%and the swelling index is 6.8%after20 minutes of swelling.The swelling index and the diameter growth rate continue to increase after further swelling,which indicates that the long time of live cleaning will lead to great changes in the shape and structure of composite insulators.The effect of frequency and swelling index on dielectric spectrum is consistent.The complex dielectric constant,complex capacitance and dielectric loss of silicone rubber decrease with the increase of frequency and swelling index.The molecular structure of silicone rubber will change greatly after swelling.The swelling of silicone rubber in the frequency range of 10-2~103 Hz will not cause the decrease of dielectric properties.The swelling of silicone rubber has no obvious effect on hydrophobicity and hydrophobicity migration.The average value of contact angle a of dry and clean silicone rubber before and after swelling fluctuates in the range of 92°~98°and the average value of 0 fluctuates in the range of 119°~28°after artificial fouling and hydrophobic migration.The mechanical properties of silicone rubber are weakened slightly by swelling.The breaking tensile strength of silicone rubber decreased by 2%after swelling for 20 minutes.The test results show that the swelling degree of silicone rubber in the cleaning agent is greatly affected by the impregnating time,and the swelling effect has little effect on hydrophobicity,electrical and mechanical properties,the influence of detergent residue on silicone rubber can be controlled by using volatile formula or strong convection measure.