余弦方波电压作用下不同水树长度缺陷XLPE材料的击穿特性

Breakdown Characteristics of Defective XLPE Materials with Different Water Tree Length Under Cosine Square Wave Voltage

为研究余弦方波电压作用下不同水树长度缺陷交联聚乙烯(XLPE)材料的击穿特性,采用高频高压电源对XLPE试样进行加速水树老化,制备了水树长度占比分别为30%、60%、90%的XLPE试样。测量了试样在0.1 Hz余弦方波电压下的击穿特性,并对击穿试验的结果进行了理论分析。结果表明:在3U0等效场强的作用下,0.1 Hz的余弦方波电压可以导致水树长度占比为90%的XLPE试样在15 min内击穿,但即使将加压时间延长至10 h,水树长度占比为30%、60%的XLPE试样也未发生击穿;水树缺陷的击穿存在临界场强,当施加电压的等效场强低于临界场强时,延长电压作用时间至10 h,水树缺陷也不会发生击穿,水树的形态也未出现显著改变;0.1 Hz余弦方波耐压试验可以发现电缆中水树长度占比为90%的缺陷,不能发现水树长度占比为30%、60%的缺陷,也不会导致这两种水树缺陷的恶化。

In order to study the breakdown characteristics of defective cross-linked polyethylene(XLPE)materials with different water tree length ratio under cosine square wave voltage,we used high-frequency and high-voltage power supply to accelerate water tree ageing of XLPE samples,and prepared the defective XLPE samples with 30%,60%,and 90%of water tree length ratio,respectively.The breakdown characteristics of the samples were measured under 0.1 Hz cosine square wave voltage,and the breakdown test results were analyzed theoretically.The results show that under the equivalent field strength of 3U0,the 0.1 Hz cosine square wave voltage can cause the XLPE sample with 90%of water tree length ratio to breakdown within 15 minutes,but even if extending the voltage applying time to 10 h,the XLPE samples with 30%and 60%of water tree length ratio will not breakdown.The breakdown of water tree defect has a critical field strength,when the equivalent field strength of applied voltage is lower than the critical field strength, extending the voltage applying time to 10 h, the water tree defect will notbreakdown, and the morphology of water tree do not change significantly. The 0.1 Hz cosine squarewave voltage-withstand test can find the defect with 90% of water tree length proportion in cable, andcannot find the defects with 30% and 60% of water tree length ratio and will not deteriorate these twowater tree defects.