500 kV葛双一回复合绝缘子芯棒裂断原因分析

通过对一起复合绝缘子芯棒断事故特征分析和同期运行在500kV输电线路上的复合绝缘子抽样试验,初步判断复合绝缘子芯棒断裂原因属酸蚀脆断,并据此提出防止类似事故发生的措施,即厂商应改进金具接头界面的密封工艺并注意复合绝缘子芯棒的抗蚀性能,而设计者应改进复合绝缘子的技术参数。     

高压直线型复合绝缘子防脆断掉线措施的分析

分析了500kV盘北线路的两起直线型复合绝缘子芯棒脆断掉线事故，芯棒脆断的特征，脆断的原因。介绍并分析了所采取的防脆断措施：“全部更换发生事故的同型号复合绝缘子；直线型复合绝缘子串改为并联双串，以增加安全系数。”并介绍了国内外双串并联绝缘子的应用情况。     

一起220kV复合绝缘子芯棒断裂事故分析

复合绝缘子芯棒断裂事故会对输电线路的安全稳定运行构成严重的威胁。结合某220 kV线路复合绝缘子芯棒断裂事故,对断裂绝缘子及同批次产品进行了外观检查、性能试验、解剖检查、材料试验,分析了绝缘子芯棒断裂的原因及机理。结果表明:该绝缘子端部结构存在缺陷及密封性能不良的问题,导致芯棒玻璃纤维受到酸液侵蚀,逐渐产生应力腐蚀过程,在弱酸腐蚀及应力的共同作用下机械性能不断降低,最终整支芯棒发生断裂。针对芯棒脆断现象和长期机械性能不佳的问题,建议将复合绝缘子端部金具楔式结构逐批更换为压接式结构,并加强端部金具及护套的密封,以及采用无硼纤维耐酸芯棒。     

220 kV复合绝缘子芯棒脆断故障分析

针对一起220 kV复合绝缘子芯棒断裂故障,通过对绝缘子解体检查和芯棒性能试验分析,认为该绝缘子芯棒断裂的原因为绝缘子端部存在密封不良,引起潮气入侵,腐蚀芯棒,造成芯棒机械性能迅速下降而引发的脆断,提出防止类似事故发生的防范措施和建议。     

光纤布拉格光栅复合绝缘子的应力分布分析

为了最大程度地预防复合绝缘子芯棒脆断等掉串事故,采用在复合绝缘子芯棒中植入光纤布拉格光栅,实现对复合绝缘子芯棒应力的监测,从而判断复合绝缘子的运行状况.绝缘子芯棒在金具压接区部位的结构复杂,所受的应力分布不均匀,故不能直接用光纤光栅的自身应变来表征芯棒内部应变,因此先假设绝缘子芯棒和光纤光栅有相同的应变,对复合绝缘子芯...     

压接式复合绝缘子疲劳破坏的机理分析

以压接式复合绝缘子为研究对象,针对压接复合绝缘子在承受交变载荷的架空线路上易发生疲劳破坏的问题,分别从压接式复合绝缘子的芯棒基体材料、结构工艺、疲劳断口三个方面,分析压接式复合绝缘子疲劳破坏的机理,得出复合绝缘子抗拉不抗压的特性以及在金具与芯棒连接处产生应力集中原因;研究结果表明疲劳破坏首先发生在接触区出口处外表面并向内部扩展。研究结果为线路复合绝缘子断裂事故原因的分析及抗疲劳的新型结构设计提供参考。     

复合绝缘子芯棒在表面微电流作用下的水解

近年来,我国出现了若干起复合绝缘子不明原因异常断裂事故,对超、特高压输电线路的安全稳定运行提出了严峻挑战。为此,从芯棒水解导致复合绝缘子异常断裂的假设出发,进行复合绝缘子芯棒材料在表面微电流作用下的水解试验,对复合绝缘子的这种异常断裂进行了实验室模拟。试验结果表明,模拟试验中的芯棒满足这种断裂现象的4个特征:1)芯棒质地变酥,颜色发生变化,形如朽木,玻璃纤维和树脂破碎;2)在高电压作用下,芯棒机械强度发生大幅下降;3)芯棒机械强度下降过程中,表面出现放电和温升现象;4)芯棒的机械强度下降是在没有外加机械载荷的条件下发生的。经分析,将复合绝缘子芯棒的酥朽断裂起始和发展过程分为水解潜伏期、水解发生期、水解发展期、放电发展期和失效发生期共5个阶段。复合绝缘子芯棒在表面电流作用下会加速水解:流过绝缘子芯棒表面的电流及芯棒表面的放电强度从水解发生期开始逐渐增大;到失效发生期,复合绝缘子芯棒表面形成明显的碳化通道,电流急剧增大,机械强度大幅下降。     

超声法检测绝缘子用玻璃钢芯棒脆断裂纹的研究

脆断是高电压复合绝缘子在很低的日常载荷下发生的恶性断裂事故，国内外研究认为应力腐蚀造成了绝缘子芯棒脆断的发生。文中根据芯棒脆断的特点，提出以超声纵波斜入射检测芯棒脆断横截面上的裂纹，同时据此研制了一种用于芯棒脆断裂纹检测的超声探头，并对芯棒脆断时裂纹的扩展过程进行了检测，得到了芯棒脆断裂纹发展过程中超声脉冲回波幅值的变化并对其进行了讨论分析，这对于进一步了解复合绝缘子的脆断机理有重要意义。     

复合绝缘子芯棒断裂研究现状

在电力系统中复合绝缘子芯棒承担全部机械负荷,故一旦发生芯棒断裂事故就会产生严重的后果。根据当前国内外对复合绝缘子芯棒断裂的研究情况,可将复合绝缘子断裂类型分为3类:普通形式断裂、脆性断裂和酥朽断裂;本文重点阐述了国内外对芯棒脆性断裂、酥朽断裂的研究过程、发生机理以及防护措施。同时根据研究现状提出一些亟待解决的问题,为今后的研究提供参考。     

220kV坪核线复合绝缘子芯棒脆断原因分析及对策

通过对220 kV坪核线复合绝缘子芯棒脆断造成相问短路事故的原因分析,指出其主要原因是耐张绝缘子使用单串且没有安装均压环连接方式的设计不合理,以及早期生产的复合绝缘子存在产品制造缺陷,芯棒不耐酸等原因所致.提出采用新工艺及材料制造的复合绝缘子,采用双串带均压环设计,预防芯棒脆断及造成掉线相间短路事故.     

500kV罗北甲线合成绝缘子芯棒脆断原因分析

文章分析了合成绝缘子芯棒脆断的原因，芯棒脆断是由端部密封不良造成酸蚀引起的，脆断一般发生在合成绝缘子的高压端。为防止脆断事故的发生，厂家在选用良好耐酸蚀芯棒的同时，应改进端部密封结构和均压环的设计，以防止密封失效。运行单位应对运行中的合成绝缘子加强检测，以便及早发现有隐患的合成绝缘子。     

合成绝缘子芯棒脆断性能及试验方法的研究

国内合成绝缘子的使用量越来越大，随着运行时间的增加，发生的故障也越来越多。其中由于合成绝缘子芯棒的脆断而导致的事故已经发生了多起，这个问题在国内引起了广泛的关注。文章在实验室采用两种加载方式对脆断过程进行模拟。一种是恒定应力法，用来检查芯棒的耐应力腐蚀性能；另外一种是递减应力法，用来模拟出和实际运行复合绝缘子中出现的尽可能类似的脆断断口。在实验室成功的模拟出和运行中几乎相同的芯棒脆断断口，对芯棒的脆断性能有所了解。试验时的一些因素会显著影响脆断的发展过程，而这些因素在国外试验草案中都未得到充分的讨论和说明。通过对试验条件的研究，给出了合成绝缘子芯棒耐应力腐蚀试验方法。     

500kV复合绝缘子断裂机理及检测方法

复合绝缘子断裂对输电线路的安全稳定运行构成了严重威胁。结合500 kV复合绝缘子断裂故障,分析了复合绝缘子断裂机理及原因,探讨了红外热像检测及紫外电晕检测技术在复合绝缘子检测中的应用效果。结果表明:在局部强电场和弱酸腐蚀综合作用下,芯棒机械性能降低是复合绝缘子断裂的重要原因;红外热像检测、紫外电晕检测等带电检测手段能有效发现复合绝缘子的缺陷,具有距离远、不接触、准确、实时、快速等优点;为避免复合绝缘子断裂事故,有必要优化复合绝缘子均压环的结构,选择最佳的均压环直径、管径及安装位置,改善复合绝缘子沿面场强及电压分布的不均匀性,抑制复合绝缘子局部区域的电晕放电现象。     

Failure analyses of nonceramic insulators. Part 1: Brittle fracture characteristics

Nonceramic insulators, also referred to as composite, polymer or polymeric insulators, are used in overhead transmission lines with line voltages in the range of 69 to 735 kV. Despite the many benefits that nonceramic insulators offer in comparison with their porcelain counterparts, they can fail mechanically in service by rod fracture. One of the mechanical failure modes of the insulators is a failure process called brittle fracture, which is caused by the stress corrosion cracking (SCC) of the GRP rods. The process is catastrophic and unpredictable, leading to the drop of energized transmission lines. The most important characteristics of the brittle fracture process, which can occasionally affect high voltage nonceramic transmission line insulators, leading to their catastrophic in-service failures, have been presented in this article. In addition, several experimental techniques were suggested for the simulation of brittle fracture under laboratory conditions. Only the most important aspects of brittle fracture process have been discussed here.     

Can water cause brittle fracture failures of composite non-ceramic insulators in the absence of electric fields?

It was postulated by J. Montesinos et al. (see ibid., vol.9, p.236-43, 2002), based on experimental evidence, that brittle fracture failures of composite (non-ceramic) HV insulators could be caused by water and mechanical stresses. It was also claimed therein that the brittle fracture process was more likely to happen with water than acids. This postulation could be of major importance as its ramifications might affect the entire composite insulator technology and, in particular, the usage of glass fiber polymer matrix composites in HV applications. Such an important statement should not be left without an independent verification. Therefore, attempts have been made in this research to initiate this process in unidirectional E-glass/modified polyester and E-glass/vinyl ester composites, used in non-ceramic insulators, by subjecting them to water under four-point bending conditions. This was done to independently verify the main conclusion of J. Montesinos et al. that water may be more damaging to unidirectional E-glass/polymer composites than acids. It has been clearly shown in this work that water, in the absence of electrical field, cannot cause stress corrosion cracking of unidirectional E-glass/polymer composites and thus brittle fracture of composite non-ceramic insulators. Thus the main results of J. Montesinos et al. could not be independently reproduced.     

FRP rods for brittle fracture resistant composite insulators

Brittle fracture of fibreglass reinforced polymer (FRP) rods can lead to mechanical failures of composite insulators even at low mechanical loads during operational service. Although this fact has been known for 20 years, it may still be a problem in some designs of composite insulators at the present time. In order to find countermeasures against brittle fracture, a study was carried out in the early eighties. It turned out that brittle fracture is a problem of FRP material and that material compositions exist, resistant to brittle fracture. A brittle fracture resistant FRP rod introduced in 1983 in one particular design of composite insulators resulted in a 15 year excellent service performance. This study deals with details of brittle fracture of FRP rods. Test setups were established to induce brittle fracture artificially. It was realized that brittle fracture is some kind of stress corrosion related to the composition of the FRP material. A broad variety of FRP materials was evaluated, showing the influence of the components of FRP material on the brittle fracture behavior of FRP rods as well as the effects of different manufacturing processes. The compositions of brittle fracture resistant FRP rods are disclosed. The results from artificial testing are compared with brittle fracture of FRP rods that occurred in composite insulators in operational service. Although no quantitative correlation could be established, the trend concerning the material behavior of FRP rods is similar     

500kV进口合成绝缘子芯棒脆断原因分析及对策

通过对一起合成绝缘子芯棒脆断事故的分析以及同批次运行的500 kv进口合成绝缘子的抽样试验,分析了合成绝缘子芯棒脆断的原因,发现该绝缘子芯棒脆断主要是由于端部密封不良及界面结构设计不合理,造成酸蚀并最终导致芯棒机械性能下降而发生脆断,同时,对该类运行中合成绝缘子的使用提出了相应的对策,以保证电网的安全可靠运行.     

FTIR analysis of non-ceramic composite insulators

The chemical environment responsible for the brittle fracture failure of composite (non-ceramic) insulators is determined. Also previously reported observations by the authors are verified. Five non-ceramic composite suspension insulators and one composite guide were subjected to FTIR analysis. Out of the six field failed units, five insulators showed significant levels of nitrate on their brittle fracture surfaces with small traces of nitrate also found on the fracture surfaces of the composite guide. The results strongly indicate that the most probable cause of brittle fracture failure of composite RV insulators in-service is the formation of nitrate and thus nitric acid. This is consistent with the observations and conclusions previously reported by the authors.     

复合绝缘子端部密封结构及其密封性能分析

分析了复合绝缘子机械连接型和压接型端部密封结构的密封性能，密封，推荐采用压接式高温硫化硅橡胶密封结构。