Influence Mechanism of Kinematic Properties on Drastic Arc Length Variation During Secondary Arc Motion Near Power Transmission Line Insulator String

Secondary arc is generated by the electromagnetic coupling between the faulted and sound phases after removing the ground fault, severely threatening the stable operation of the power system. To study the secondary arc’s spatiotemporal evolution characteristics near power transmission line insulator string, this article obtains the arc motion images and voltage-current waveforms through experiment. Then the 3-D data are obtained based on binocular stereo vision. Finally, the variation law of arc length and diameter over time is obtained. The results show that the arc length increases gradually over time under wind loads, thermal buoyancy, and electromagnetic forces. Whereas, the short circuit phenomenon between the arc columns, between the arc columns and the arc root, as well as the arc-root jumping phenomenon during the arc motion cause the arc length to change abruptly. The magnitude of secondary arc current shows a positive correlation with the probability of short circuit between arc columns. Conversely, the probability of short circuit between arc columns decreases as the insulator strings length increases. The above kinematic properties do not occur occasionally but throughout the arc ignition process. The study of the arc motion laws could provide reference for comprehending the physical properties of secondary arc near the insulator string.