单一极性直流电压下交联聚乙烯电力电缆水树生长特性  

Propagation Characteristics of Water Trees in XLPE Power Cables Under Single Polarity DC Voltage

作　　者：周凯[1] 杨明亮[1] 陶文彪[1] 杨滴[1] 黄明[1] 

机构地区：[1]四川大学电气信息学院,成都610065

出　　处：《高电压技术》2015年第4期1075-1083,共9页High Voltage Engineering

基　　金：国家自然科学基金(51477106)~~

摘　　要：为研究直流电压极性对交联聚乙烯(XLPE)电力电缆水树生长特性的影响,对4种不同极性整流电压下的XLPE材料水树生长特性进行了对比分析。采用水针电极老化法,分别在正弦电压和4种整流电压下对XLPE薄片样本进行了加速水树老化。经过22 d时间的老化后,对样本进行了切片染色并观察了水树形态,对水树尺寸进行了测量统计。观测结果表明:不同极性整流电压作用下的水树尺寸和形态均存在明显差异;正极性下的水树宽度大于负极性下,水树长度却小于负极性下;正极性下的水树枝干分明,较为稀疏,水树区颜色较浅;负极性下的水树密集,枝干较粗,水树区颜色较深。基于以上观察,提出了整流电压下水树生长的离子扩散模型,认为水合离子在材料中的扩散对于水树老化过程起着重要作用。不同极性整流电压下,离子在聚合物中的扩散通量不同,通过水合带入的水分子数量不同,从而导致水树尺寸存在差异。In order to understand the influence of DC voltage polarity on the propagation of water trees in cross-linked polyethylene（XLPE） power cables, we tested and compared the propagation of water trees in XLPE material under four kinds of rectified voltages. Based on the water-needle aging method, samples of XLPE chips were aged under sinusoidal voltage and four rectified voltages, respectively. After 22 days of aging, samples were sliced and dyed. Moreover, we observed the water trees using optical microscope, and measured the sizes of the water trees. The experimental results show that the morphologies and sizes of water trees are dependent on the voltage polarity. Compared with water tress induced by negative voltages, those induced by positive voltages are significantly wider and shorter while having sparser and thinner branches. According to the observation, we put forward an ion diffusion model of the water tree propagation under rectified voltages, which indicates the important role that the diffusion of hydrated ions in the material plays in water tree aging process. Fluxes of ions vary due to the different polarities of voltage and hence induce different amount of water molecules into polymer, which eventually results in water trees of different morphologies.

关 键 词：交联聚乙烯 电力电缆 水树 直流电压 极性 离子扩散 

分 类 号：TM247[一般工业技术—材料科学与工程]