摘要
为了深入理解温度变化对交联聚乙烯（XLPE）运行电缆中水树生长的影响,该文揭示了温度转换条件下（高温转低温或低温转高温）XLPE试样中水树出现加速生长的行为。在恒温和温度转换两种条件下对一组XLPE样本分别进行加速水树老化实验,通过显微镜对比观测了两种条件下的水树形态及尺寸。同时对另一组XLPE样本在0℃恒温和0℃转60℃条件下进行电压老化实验并检测此组样本的取向度。显微测试结果表明：0℃转至60℃条件老化样本中的水树尺寸显著高于0℃恒温条件老化样本中的水树尺寸。取向度检测结果表明,0℃转至60℃条件下进行电压老化样本中的水树区域存在取向。基于高聚物的取向理论,在0℃条件下进行水树老化时,水树及其前方一定区域的分子链段在电场力作用下发生取向。而当试样从0℃转至60℃时,在一定时间内水树及其前方区域的局部分子链段保持取向。在更为剧烈的分子热运动作用下,取向的分子链段之间更容易发生疲劳断裂,从而显著提高了水树的生长速率。这表明在许多温度交替变化的地区可能存在水树加速生长现象。
To understand the influence of temperature transformation on water tree propagation, the mechanism of temperature transformation on promoting water tree propagation was revealed in XLPE samples under the condition of temperature transformation（from high temperature to low temperature or from low temperature to high temperature）. One group of XLPE samples were subjected to an accelerated water tree aging experiment under two conditions（constant temperature and temperature transformation）, respectively. The morphologies and sizes of water trees under the two aging conditions were measured and compared. Meanwhile, the other group of XLPE samples was just subjected to a voltage aging experiment under constant temperature of 0℃, and temperature transformation from 0℃ to 60℃, respectively. Furthermore, the orientation degree of the samples in this group was measured by the IR（Infrared Spectroscopy） method. The microscopic test results show that the growth rate of water trees under the condition of temperature transformation from 0℃ to 60 ℃ is significantly higher than that of under constant temperature of 0℃. The results of orientation detection show that water tree region in samples subjected to voltage aging under temperature transformation from 0 ℃ to 60 ℃ is oriented. Based on the orientation theory of polymer, when XLPE samples are subjected to aging at 0℃, the molecular chain segments in and in front of the water tree region can be oriented under the effect of the electric field force. However, when the aging temperature increases to 60 ℃, partial molecular chain segments in and in front of the water tree region can keep oriented for a certain time. Under severer molecular thermal motion, the parts between oriented molecular chains can easily break which can greatly promote the growth rate of water trees. The result shows that there can be propagation acceleration phenomenon of water trees in many areas where the temperature frequently changes.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2018年第3期956-964,共9页
Proceedings of the CSEE
关键词
交联聚乙烯
水树
温度交替
取向
分子热运动
XLPE
water tree
temperature transformation
orientation
molecular thermal motion
