The evolution law of the pantograph-catenary arc with the multi-stress coupled force analysis under the sub-atmospheric pressure strong-airflow condition

As the unique power entrance, the pantograph-catenary plays a vital role in providing traction power for high-speed railways. Along with the operational velocity of trains constantly increasing, the poor contact between the contact wire and the pantograph strip happens frequently due to the "rigid point" existing on the contact wire, forming the "off-line" phenomenon. The off-line phenomenon is normally accompanied by the pantograph-catenary arc occurring, which seriously threatens the safety of the power supply for the high-speed train. Nowadays, as some railways have been built in remote places at high altitude, the motion characteristics of the pantograph-catenary arc under the sub-atmospheric pressure with strong airflow are extremely different from the case under normal pressure. Herein, a pantograph-catenary arc experimental platform is built for observing the evolutionary process of the arc under the sub-atmospheric pressure strong-airflow condition. The impact brought from different air pressures and airflows on the arc is analyzed, as the experimental results show that the pantograph-catenary arc has different motion characteristics when the arcing process is at different stages. To further explore the reason resulting in the varying motion characteristics of the arc, a multi-stress coupled force analysis model is established, with the consideration of the influence of air pressure, wind load, thermal buoyancy, air resistance, arc self-magnetism, etc. From the perspective of force acting on the arc, the arc formation mechanism at the development evolutionary stages is investigated under sub-atmospheric pressure strong-airflow conditions, which lays a theoretical foundation for effectively restraining the pantograph-catenary arc.