摘要
为研究交联聚乙烯(XLPE)绝缘内部水树自恢复后的微观形貌变化与其粘弹性对水树自恢复的影响机制,室温下(20℃)对2组XLPE样本分别施加有效电压老化时间均为21天的持续性老化与周期性老化。实验结果发现:相较于持续性老化样本,周期性老化样本中水树产生了自恢复现象,其水树样本尺寸较短,而扫描电镜(SEM)观察到其水树区域的微孔却尺寸相对较大,分布也较为密集。通过动态热机械分析(DMA)测试和电场仿真,表明交变电场下XLPE内部弹性能量的不断累积与形变的逐渐增大,直至超过其弹性极限时将导致水树生长。周期性电压老化下的水树样本在撤去电压后,水分逐渐渗出水树区域,储存在水树通道和微孔内部的弹性能量逐渐消失,从而导致其水树尺寸明显小于持续电压老化下的水树样本。此外,老化过程中,水分多次重复进出已有的水树区域,对周围的XLPE基体造成机械疲劳损伤,是导致周期性老化样本水树区域微孔尺寸较大,分布密集的原因。
To investigate the microstructure changes of water tree in cross-linked polyethylene(XLPE)after self-recovery and influence mechanism of viscoelasticity of XLPE on the self-recovery of water tree,we performed the continuous water tree aging and periodic water tree aging experiments,respectively,on the two groups of XLPE samples at 20℃,in which both effective aging times were 21 days.According to experimental results,self-recovery phenomenon of water tree can be found in periodic samples,and the sizes of water tree under periodic aging of water tree is relatively shorter than the sample under continuous aging,but voids in the water tree region observed by scanning electron microscope(SEM)is relatively larger and denser.Based on the dynamic thermal mechanical analysis(DMA)test and electric field simulation,it is shown that the continuous accumulation of elastic energy will gradually increase the deformation inside XLPE under alternating electric field.When the deformation exceeds the elastic limit of the material,the water tree is incepted.When voltages are removed,water will permeate out of the water tree region and the elastic energy stored in water tree channels and water tree voids will gradually be released,which results in the shorter water tree length in the periodic aging samples.Moreover,water will permeate into and out of the existing water tree region repetitively,causing mechanical fatigue on the surrounding XLPE matrix,which results in larger and denser voids in the water tree regions of periodic aging samples.
作者
陈泽龙
周凯
李天华
尹游
朱光亚
CHEN Zelong;ZHOU Kai;LI Tianhua;YIN You;ZHU Guangya(College of Electrical Engineering,Sichuan University,Chengdu 610065,China)
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2019年第11期3579-3586,共8页
High Voltage Engineering
基金
国家自然科学基金(51477106)~~
关键词
交联聚乙烯
水树
自恢复
微观结构
粘弹性
XLPE
water tree
self-recovery
microstructure
viscoelasticity
