脱气处理对交联聚乙烯中交联副产物及空间电荷特性的影响

Effects of Degassing Treatment on Crosslinking Byproducts and Space Charge Characteristics in Cross-linked Polyethylene

为研究脱气时间对电缆绝缘层中剩余交联副产物的影响,在65℃的烘房中对交联聚乙烯(XLPE)高压直流(HVDC)电缆进行了不同时间的脱气处理,并采用气相色谱-质谱法(GC-MS)检测了经过4、5、6周脱气处理后XLPE绝缘中残留的交联副产物的种类和含量,同时对不同脱气时间的试样切片进行空间电荷测试,分析不同脱气时间对试样空间电荷特性的影响。结果表明:XLPE中的交联副产物主要为α-甲基苯乙烯、苯乙酮和苯甲醇,且其含量随脱气时间延长而明显下降。不同交联副产物的脱出速率不同。同一种交联副产物其脱出速率在不同脱气阶段也有所不同。不同脱气时间的试样在短路过程中的平均体电荷密度及其衰减率明显不同,随着脱气时间的延长,相同短路时间的试样中平均体电荷密度有所下降,试样中的平均体电荷密度衰减率也有所下降。

In order to study the effects of degassing time of cable on the residual crosslinking byprod- ucts, the cross-linked polyethylene （XLPE） high voltage direct current （HVDC） cable was degassed in a drying room at 65℃ for different time. The kinds and concentrations of the crosslinking byproducts in samples after degassed for 4, 5, and 6 weeks were analyzed by the gas chromatography-mass spectrome- try. Besides, the space charge measurements were conducted on sliced samples with different degassing time to analyze the influences of degassing time on their space charge characteristics. The results show that the main crosslinking byproducts in XLPE are ^-methylstyrene, acetophenone and benzyl alcohol, their concentrations decrease with the increases of degassing time. The attenuation rates of different cross- linking byproducts are different. The attenuation rates of the same crosslinking byproduct are different at different degassing stages. The mean volume density of space charge and its attenuation rate of the sam- ples with different degassing time are different in the short circuit process. As the degassing time pro-longs, the mean volume density of space charges in samples with the same depolarization time decreases, the attenuation rates of mean volume density of space charge in samples also decreases.