不同温度下XLPE电缆中电树枝的生长特性  

Growth Characteristics of Electrical Tree in XLPE Cable Under Different Temperatures

作　　者：廖瑞金[1] 郑升讯[1] 杨丽君[1] 刘玲[2] 叶开颜[3] 

机构地区：[1]输配电装备及系统安全与新技术国家重点实验室,重庆大学,重庆400030 [2]广东电网公司广州供电局,广州510260 [3]重庆市电力公司沙坪坝供电局,重庆400030

出　　处：《高电压技术》2010年第10期2398-2404,共7页High Voltage Engineering

基　　金：国家自然科学基金(50807054)~~

摘　　要：为了研究温度对电树枝的引发和生长发展特性的影响,本文针对15kV交联聚乙烯(XLPE)电缆设计了一套采用金属针缺陷模拟集中电场应力的实验系统。通过在4个不同温度下对交联聚乙烯(XLPE)电缆进行电树枝生长实验,结果表明,温度对电树枝引发及生长影响显著。在潜伏期,一方面,电荷的注入及自由基的连锁反应因热的作用而加剧;另一方面,在高温下由于分子热运动和自由体积膨胀,聚集态发生了从玻璃态到高弹态的转变从而导致电树枝的引发时间的大大缩短。在生长发展期,XLPE电缆电树枝的分形维数随温度上升并不单调,而是与其聚集态紧密相关。在玻璃化转变温度(θg)以下,电树枝形态由枝状向丛状转变;在玻璃化转变温度(θg)以上,电树枝逐渐稀疏,分形维数减小;电树枝随温度升高有明显加速生长趋势。通过实验研究表明,在集中电场应力下,当XLPE电缆运行温度超过110°C时,即使是短时的电热作用,也会缩短其寿命。In order to study the initiation and the characteristics of growth and development of electrical tree of the XLPE cable influenced by temperature,an experiment system for 15kV XLPE cable which adopts metal needle defects to model a region of electrical stress is designed.Electrical treeing experimental was carried out on XLPE under four different temperatures,it has been shown that the initiation and the growth of electrical tree is influenced significantly by the temperature.In the incubation period,on the one hand,the injection of electrical charge and free radical chain reaction because of the role of heat was intensified;on the other hand,due to the thermal motion of molecules and the expansion of free volume under the high temperature,the congregation is changed from the glassy state to the high-elastic state and the initiation of electrical tree is obviously reduced.And during the growth and development period,fractal dimension of electrical tree of the XLPE with the temperature rising is not monotonous,but is tightly related to its congregation,The pattern of electric tree changes from the dendritic to the plexiform below the temperature of the glass transition temperature（θg）,And the electric tree gradually becomes spare and the fractal dimension decreases above the temperature of glass transition temperature（θg）.The growth trend of electrical tree becomes more fast with the temperature rising.Through the experimental study showed that under concentration of electrical stress,when the operating temperature exceeds 110°C,even in the very short-term the life of XLPE cable will also be shorten.

关 键 词：交联聚乙烯 电树枝 温度 分形 空间电荷 聚集态 

分 类 号：TM247[一般工业技术—材料科学与工程]