运行多年的液体硅橡胶套管老化特征及修复效果评估  

Ageing Characteristics and Repairing Evaluation of Long-Term Operating LSR Bushings

作　　者：韦晓星 徐驰 卢文浩 陈灿[2] 刘婉莹 贾志东[2] WEI Xiaoxing;XU Chi;LU Wenhao;CHEN Can;LIU Wanying;JIA Zhidong(EHV Power Transmission Company Maintenance&Test Center,China Southern Power Grid,Guangzhou 510663,China;Graduate School of Tsinghua University,Shenzhen 518055,China)

机构地区：[1]南方电网超高压输电公司检修试验中心,广州510663 [2]清华大学深圳研究生院,深圳518055

出　　处：《电瓷避雷器》2020年第3期197-204,共8页Insulators and Surge Arresters

基　　金：国家自然科学基金资助项目(编号:51707021)。

摘　　要：1999年投运500 kV高压直流套管户外侧出现严重的粉化龟裂现象,该套管外绝缘护套采用液体硅橡胶(LSR),并于2015年采用RTV进行外绝缘修复。通过憎水性、憎水迁移性、拉伸强度和撕裂强度测试分析了复合套管伞裙的宏观老化特征;借助扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)等手段分析了套管伞裙老化的微观特征;同时对修复后的套管伞裙性能进行评估。研究发现,液体硅橡胶伞裙老化由外表面向内部逐渐发展,具有明显的粉化层和未粉化层,老化后伞裙的憎水性、憎水迁移性、拉伸强度和撕裂强度均有不同程度的下降。微观下老化伞裙出现不规则片状分层,表面粗糙不平,附着力大大降低;粉化层中聚二甲基硅氧烷(PDMS)侧链有机基团被氧化,交联形成更多Si-O-Si键,同时伴随着TiO2和白炭黑填料的析出;由于老化过程中硅橡胶材料从有机向无机转变,粉化层中C元素和Si元素含量降低,O元素含量升高。研究表明,通过喷涂RTV修复老化的液体硅橡胶伞裙能够改善憎水性和憎水迁移性,但仍需定期监测修复套管的外观及憎水性变化。A serious aging problem happened on the outer part of 500 kV DC wall bushings which have been operatingsince 1999.The bushings sheds were manufactured by liquid silicone rubber,and repaired by RTV in 2015.In this paper,the macroscopic aging characteristics of the aging sheds were investigated by hydrophobicity and hydrophobicity transfer test,tensile and tear strength test.Then the microscopic characteristics of the aging sheds were obtained by using Scanning Electron Microsope(SEM),Fourier Transform Infrared Spectroscopy(FTIR)and X-ray Photoelectron Spectroscopy(XPS).Meanwhile the status of the bushing after repairing was also evaluated in the end.It was found that the aging of the LSR shed developed from outer surface into the inside,and the layer structure including the chalking layer and the inner layer was obviously observed.The hydrophobicity,hydrophobicity transfer,tensile strength and tear strength of the aging sheds had different decrease.At microcosmic angle of view,the aging sheds appeared irregular shaped patches with a reduced surface roughness and adhesion;FTIR and XPS results indicated that the side chain groups of polydimethylsiloxane(PDMS)in the chalking layer were oxidized,and crosslinked with other polysiloxane chains,forming more Si-O-Si groups,accompanied by the precipitation of TiO2 and white carbon black fillers.Due to the change of silicone rubber material from organic to inorganic in the aging process,the content of C and Si elements in the powder layer decreased,and the content of O element increased.The research also shows that,the hydrophobicity and hydrophobicity transfer of the aging LSR sheds can be improved by RTV repairing,but the appearance and hydrophobic changes still needs to be regularly monitored in the operation.

关 键 词：液体硅橡胶 老化 粉化层 傅里叶变换红外光谱 X射线光电子能谱 

分 类 号：TM215[一般工业技术—材料科学与工程]