# Effects of Controlled Oxygen Partial Pressure on Arc Dynamics and Material Erosion in a Pantograph–Catenary System

## TL;DR

This study examines how varying oxygen levels affect arc behavior and material erosion in a pantograph-catenary system, revealing a non-monotonic impact on stability and wear.

## Contribution

The study introduces a controlled experimental method to analyze the effects of oxygen partial pressure on arc dynamics and erosion in pantograph-catenary systems.

## Key findings

- 14 vol% oxygen showed the poorest arc stability with a 20.306% fluctuation coefficient.
- 17 vol% oxygen had the lowest current-carrying efficiency (56.070%) and most severe erosion.
- Erosion morphology evolved with increasing oxygen, transitioning from ablation to oxidative wear.

## Abstract

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.