脱气时间对XLPE电树引发和生长特性的影响

Effect of Degassing Time on Initiation and Growth Characteristics of Electrical Tree in XLPE

为了探究脱气处理对XLPE绝缘性能的影响,研究了不同脱气时间对XLPE交流电树枝引发和生长特性的影响。首先,采用热压法制备厚度为5 mm的XLPE薄片样本,在70℃的真空干燥箱中分别脱气0、1、2、3、4和5 d。然后,对6组试样分别进行交流电树枝引发和生长实验以及介电性能测试。最后通过气相色谱–质谱测试,定量表征不同脱气时间的XLPE中交联副产物种类和含量的变化,以进一步分析它们对XLPE电树引发和生长特性的影响。结果表明:在所设置的实验条件下,脱气2 d试样的电树抑制性能最好。脱气过程中,XLPE内部气孔和副产物的含量共同影响材料的电树引发和生长特性;材料内气孔越多,气孔内易产生局部放电从而引发电树;而副产物中的苯乙酮作为电压稳定剂则会抑制电树引发与生长。因此,气孔和副产物含量随脱气时间的动态变化导致脱气2 d的XLPE试样电树引发电压最高,电树生长平均长度和宽度最小。

In order to explore the effect of degassing treatment on the insulation properties of XLPE,the effects of different degassing time on the AC tree initiation and growth characteristics of XLPE were studied in this paper.Firstly,XLPE sheet samples with a thickness of 5 mm were prepared by hot pressing and degassed in a vacuum drying oven at 70℃for 0 d,1 d,2 d,3 d,4 d and 5 d,respectively.Then,the AC tree initiation and growth experiments and dielectric properties of 6 groups of samples were tested,respectively.Finally,the changes of crosslinking by-products in XLPE with different degassing time were quantitatively characterized by gas chromatography-mass spectrometry,so as to further analyze their effects on the electrical tree initiation and growth characteristics of XLPE.The results show that,under the set experimental conditions,the electrical tree inhibition performance of degassed samples for 2 days is the best.In the process of degasing,the content of pores and byproducts in XLPE jointly will affect the electrical tree initiation and growth characteristics of the material.The more pores in the material will enable the partial discharge easy to occur in the pores,which leads to electrical tree.Acetophenone,as voltage stabilizer,can inhibit the initiation and growth of electrical tree.Therefore,the dynamic changes of content of pores and byproducts with degassing time lead to the highest electrical tree initiation voltage and the lowest average length and width of electrical tree in XLPE samples degassed for 2 days.