Temperature Decay Dynamics of Anode Surface after Current Zero in Vacuum Interrupter

In vacuum interrupters, reignition caused by plasma between contacts during transient recovery voltage application is a concern. The supply of metal particles is predominantly through evaporation from the electrode surface, with particularly high temperatures and increased particle emission at the anode spot due to continuous heating. In this paper, multiple-image optical measurement was conducted on CuCr electrodes to observe the temperature decay of the anode surface after current zero. In the condition of long gaps, the temperature immediately after arc extinction was suppressed because of avoiding arc concentration, and the molten area expanded. The effect of electrode temperature and molten area was evaluated based on the supply amount of CuCr particles from anode surface, which was calculated from the surface temperature distribution. Subsequently, the density distribution of metal particles between contacts was simulated. This paper contributes to understanding the role of contact gap distance in insulation strength in axial magnetic field electrodes, aiming for the adaptation of vacuum interrupters to high voltage classes.