Study on the influence mechanism of anode spots on cathode splashing erosion in vacuum arcs

Abstract Vacuum switches are widely utilized in the medium-voltage switchgear field due to their rapid dielectric recovery characteristics and environmental friendliness. This study addresses the unclear mechanism by which anode spots affect cathode splashing erosion in vacuum arcs. Under fixed electrode distance conditions, we experimentally investigated the influence of anode spot jets on cathode splashing erosion and the relationship between cathode splashing erosion and post-arc anode temperature across various arc conditions. Two optical diagnostic methods were employed. The first method involved the visualization of metal droplets using high-power laser illumination combined with narrowband filters. The second method was a dual-wavelength approach to measure the temperature of the anode surface. The results indicate that the anode spot jet is a decisive factor in the formation of localized bright spots near the cathode, leading to significant cathode splashing erosion. In all arc conditions, cathode splashing erosion increased with the rise in peak post-arc anode temperatures and was closely related to the type of anode material. The study demonstrated that the energy density of evaporated atomic flux released from the anode is a key factor causing localized melting of the cathode and the generation of continuous metal droplets. Thus, we propose a hypothetical mechanism for the influence of anode spots on cathode splashing erosion: once anode spots form, evaporated atoms from the anode locally heat the cathode surface, resulting in localized melting, which interacts with cathode spots to produce continuous metal droplets.