In response to the instability fluctuations and erosion characteristic changes in pantograph-catenary system (PCS) arcs induced by humidity variations in an open environment, a single-variable controlled experimental approach based on multi-source data fusion is proposed. This study innovatively establishes a humidity-controlled reciprocating current-carrying arc initiation test platform, integrating digital image processing with the dynamic analysis of multi-physics sensor signals (current, voltage, temperature). The study quantitatively evaluates the arc motion characteristics and the erosion effects on the frictional contact pair under different relative humidity levels (30%, 50%, 70%, and 90%) with a DC power supply (120 V/25 A). The experimental data and analysis reveal that increasing humidity results in higher contact resistance and accumulated arc energy, with arc stability first improving and then decreasing. At low humidity, arc behavior is more intense, and the erosion rate is faster. As humidity increases, the electrode wear transitions from adhesive wear to electrochemical wear, accompanied by copper transfer. The results suggest that the arc stability is optimal at moderate humidity (50% RH), with a peak current-carrying efficiency of 66% and a minimum loss rate of 14.5%. This threshold offers a vital theoretical framework for the optimization and risk assessments of PCS design.

Motivated by altitude-induced fluctuations in oxygen partial pressure (pO₂) and their impacts on PCS off-line arc motion and erosion response, this study proposes a comparative experimental approach featuring single-variable control under constant total pressure and coordinated multi-source electrical-signal observation. A reciprocating current-carrying arc-generation rig was established, in which pO₂ was equivalently regulated via a constant-pressure gas substitution and mixing approach. High-speed imaging–based quantitative vision analysis was integrated with synchronized voltage–current measurements to evaluate the net effects of five O₂ volumetric fraction levels (6, 11, 14, 17, and 21 vol%) under a DC supply of 120 V/25 A on arc dynamics, electrochemical processes, and contact pair erosion. Based on repeated-test results, the 14 vol% case exhibited the poorest stability (maximum fluctuation coefficient 20.306%), whereas the 17 vol% case showed the lowest current-carrying efficiency (minimum 56.070%) together with the most severe erosion damage. Moreover, with increasing pO₂, the erosion morphology evolved in a staged manner, transitioning from localized central ablation accompanied by melt-related traces to adhesive wear-induced delamination, and ultimately to electrochemical oxidative wear. Overall, pO₂ imposes a pronounced non-monotonic “window effect” on arc stability and erosion, providing key evidence for PCS structural optimization and risk assessment in open operating environments.

To mitigate localized erosion of pantograph–catenary system (PCS) contacts caused by random migration of arcs during contact loss, a periodic transverse magnetic field generated by a rotating permanent magnet was proposed to regulate arc motion. A synchronized high-speed imaging and electrical-signal acquisition platform was established to compare arc dynamics, current-collection characteristics, and carbon-electrode erosion under no field, a static field, and periodic fields of 5, 10, and 30 Hz at 120 V DC and 25 A, while SEM/EDS characterized surface morphology and elemental composition. The static field shortened the arcing duration and continuously stretched the arc column toward one side, but produced directional surface grooves. Under periodic fields, the arc column alternately deflected and contracted. Among rotating-field cases, 10 Hz yielded a normalized RMS current ratio of 72.923% and the lowest current fluctuation coefficient of 13.509%, whereas 30 Hz showed no further improvement in electrical or erosion performance. These results indicate that erosion mitigation is associated with both arcing energy and arc-root attachment-site renewal, and that the half-cycle at 10 Hz provides a favorable balance among arc migration, current-collection stability, and thermal-load dispersion, providing experimental guidance for selecting magnetic-drive parameters for PCS arcs.