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

Abstract

The pantograph-catenary system bears the crucial task of supplying electrical energy to high-speed trains. However, as train speeds continue to climb, 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 arc morphology and fluctuations in 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 carbon strips, as well as their current-carrying efficiency. The study found 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 the tribo-pair is notably weaker than that at the moment of separation. Furthermore, parameters such as arc ignition rate, wear volume, and temperature all positively correlate with 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 a harbinger of intense arcs between the contact pair. Arc erosion causes severe damage to the current-carrying tribo-pairs, with ablation pits riddled with 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 abnormal wear of carbon strips.