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.

The phenomenon of vacuum arc plasma reignition has a significant impact on the safe and stable operation of the power system. In order to reveal the mechanism of the reignition phenomenon, a vacuum arc plasma experimental platform based on a removable interrupter chamber is constructed. The evolution of the vacuum arc plasma morphology in the interrupter chamber is captured by a high-speed camera during the opening and closing process. The evolutionary behavior of plasma morphology under multiphysics fields in the diffusion–extinction phase of vacuum arc plasma is experimentally investigated, and the effects of electromagnetic field, temperature field, and metal vapor flow on vacuum arc plasma reignition are studied. Furthermore, the copper vapor diffusion–extinction multiphysics (CVDEM) model is developed. Specifically, the distributions of key parameters, such as temperature (electrons and ions), density (electrons and ions), pressure, velocity, current density, and magnetic flux density, during the plasma combustion process are calculated. Finally, the multiphysics field coupling mechanism is investigated. The results of the simulation are in good agreement with the experimental data. The results indicate that the evolution of the vacuum arc plasma morphology is effectively captured by the detachable interrupter experimental platform designed in this article. The maximum values of the plasma temperature field, current density field, and pressure field are concentrated at the cathode position. The maximum electron and ion density is located above the cathode. The maximum value of the magnetic induction is at the edge of the plasma column. As the current decreases, the interpolar temperature field and the current density field contract, leading to the dissipation of the interpolar plasma pressure. The temperature field decays at an accelerated rate during the diffusion phase, and the temperature field has the highest sensitivity to external influences. During the extinction phase, the overall temperature of the plasma is characterized by the ion temperature, and the rapid decay of the ion temperature field and current density field is the main cause of plasma extinction.