XZP/XZWP4-160直流绝缘子覆冰闪络电弧特性的研究

Study on flashover arc mechanism of XZP/XZWP4-160 DC insulator under icing condition

在人工气候室内对覆冰XZP/XZWP4-160绝缘子的闪络特性及放电发展过程进行了试验研究。根据试验结果进行分析得出:弧根周围空气的热电离导致了电弧的发展,静电场力对电弧的发展起到了加速作用,电击穿仅发生在闪络最终的跳跃阶段;通过测量闪络过程中的放电电压、泄漏电流、闪络时间、覆冰水电导率、电弧长度及电弧半径等参数,得到电弧的发展速度及临界电弧长度均随覆冰水电导率的增加而减小,弧根电流密度随着气压的降低而增大;与正极性电弧相比,负极性电弧的发展速度快且弧根半径大。进一步分析覆冰绝缘子的闪络过程可知:覆冰绝缘子存在2个不同的闪络路径,即沿冰层外部和内部,这是由于电弧热作用蒸发的Na原子进入弧柱的方式不同造成的。

The laboratory investigations of discharge processes and flashover performances were carried out on the XZP/XZWP4-160 DC iced insulators in the artificial climate chamber. According to the experimental results from this study and the subsequent theoretical analyses, it is pointed out that the thermal ionization of the air in front of an arc root resulted in arc movement; the electrostatic force had an auxiliary effect of impelling arc propagation; the electrical breakdown only occurred during the final jump period of the flashover; during flashover process, related parameters were recorded, which include the applied voltage, the leakage current, the freezing water conductive, the flashover time, the arc length and the arc root radius; arc developing speed and the critical arc length decreased with an increase in freezing water conductivity; current density at the arc root increased with a decrease in air pressure; compared to a positive arc, the developing speed and the arc root radius of a negative arc are greater. The analyses of arc propagation process show that an arc could propagate in two different ways： inside or outside the ice, which resulted from the different manner of Na atom entering the arc body.