From sparks to wear: Understanding arc erosion and tribological mechanisms in pantograph-catenary systems under irregular wire conditions

The pantograph-catenary system bears the crucial task of supplying electrical energy to high-speed trains. However, as train speeds continue to increase, irregularities in the contact wire exacerbate vibrations within the pantograph-catenary system, frequently triggering pantograph arcs. To delve deeper into the characteristics and erosion mechanisms of these arcs, this study employed high-speed cameras and photodiodes to precisely capture the evolution of the arc morphology and fluctuations in the arc intensity triggered by contact pair irregularities. By adjusting the current intensity, we further analyzed the impact of arc discharge on the friction and wear performance of the carbon strips, as well as their current-carrying efficiency. The study revealed that when the current is sufficiently high, the arc column of the old arc, which forms when the contact pair separates, connects with the arc root of the new arc that is yet to make contact, leading to the formation of a continuous arc. Additionally, under the same current conditions, the arc intensity prior to contact between tribo-pairs is notably weaker than that at the moment of separation. Furthermore, parameters such as the arc ignition rate, wear volume, and temperature are positively correlated with the current intensity. Severe arc discharge not only deteriorates the electrical performance of the system, causing current distortion, but also exacerbates the instability of system operation. Abrupt changes in the friction coefficient can serve as harbors of intense arcs between the contact pair. Arc erosion causes severe damage to current-carrying tribo-pairs, with ablation pits eliminating thermal cracks and pores and leaving behind numerous molten copper particles, significantly increasing the wear volume. This study provides strong support for understanding the arc erosion process caused by contact wire irregularities and the mechanisms underlying the abnormal wear of carbon strips.