余弦方波电压频率对电缆典型绝缘缺陷击穿时间的影响

Influence of Cosine SquareWave Voltage Frequency on Breakdown Time of Typical Cable Insulation Defects

为研究余弦方波电压频率对电缆典型绝缘缺陷击穿时间的影响,本研究制作了针板电极缺陷和水树缺陷模型,分别利用0.1、0.5、1.0 Hz的余弦方波电压进行击穿试验,统计了击穿时间的分布和击穿点的时刻,观测了击穿通道的微观形貌,并讨论余弦方波电压频率对电缆典型绝缘缺陷击穿时间影响的作用机制。结果表明:随着余弦方波电压频率的增大,电缆典型绝缘缺陷的击穿时间显著缩短,分散性下降。绝大多数击穿发生在电压的极性变换阶段也就是余弦方波的上升沿或下降沿位置。空间电荷注入导致的极性转换过程中合成场强增大和单位时间内极性转换次数的增加可能是引起上述现象的主要原因。

In order to study the influence of the cosine square wave voltage frequency on the breakdown time of typical cable insulation defects,we prepared the needle plate electrode flaws and water tree defect models.Breakdown tests were carried out with the cosine square wave voltages of 0.1 Hz,0.5 Hz,and 1.0 Hz,respectively.The distribution of breakdown time and the moment of breakdown point were counted,the microscopic morphology of the breakdown channel was observed,and the mechanism of the influence of the cosine square wave voltage frequency on the breakdown time of the typical insulation defect of the cable was discussed.The results show that with the increase of the frequency of the cosine square wave voltage,the breakdown time of the typical insulation defect of the cable is significantly reduced,and the dispersion is reduced.The vast majority of breakdowns occur during the voltage polarity change phase,which is the rising or falling edge of the cosine square wave.The increase of the synthetic field strength during the polarity conversion process caused by space charge injection and the increase in the number of polarity conversions per unit time may be the main reasons for the above phenomenon.