Calculation for Arc Transition Moment of Sliding Electric Contact Pair Based on Coupled FE-BE Simulation

Sliding electrical contact is a common phenomenon in electrical equipment and affects performance. In this paper, the mechanism of sliding electric contact pair transition and the moment when transition occurs are investigated using the railgun as an example. Transition is the phenomenon where the contact between the armature and rails changes from solid-solid contact to solid-arc-solid contact. In this paper, the finite element-boundary element coupling method (FE-BE method) is used to simulate the process of armature movement. Then, the force, thermal, and electrical parameters on the armature/rail contact surface are analyzed to explore the development of contact separation. Finally, the occurrence of the transition is judged based on the Townsend discharge model (improved by Rogowski). A Small-caliber railgun firing test was carried out to validate the methodology presented in this paper. Results show that the drop edge of the current will result in the armature/rail not being able to make full contact, and the contact gap may break down, leading to a sharp increase in contact resistance and deterioration of railgun performance. Judging the occurrence of transition based on the evolution of the contact gap and the Townsend discharge model is reliable. The research provides new ideas for studying railgun transition and sliding electric contact failure.