Optimization of arc extinguishing performance of switching-type SPDs

• The MHD model of follow-up arc in switching-type SPD is established. • The arc observation experiments are done by high-speed camera through manufacturing a transparent cover plate of switching-type SPD. • The optimization of aerodynamic distribution and background magnetic field is analyzed to enhance the arc-extinguishing capability. Switching-type surge protective devices (SPDs) possess a superior surge current discharge capability compared to voltage-limiting SPDs and avoid aging caused by leakage current. These advantages make switching-type SPDs widely applicable. The switching-type SPDs utilize a spark gap to release surge currents. However, due to suboptimal arc extinguishing structures, they often fail to cut the follow-up arc immediately, leading to SPD aging or even ignition. Therefore, this paper focuses on the dynamic characteristics of arc and optimization of arc extinguishing performance in switching-type SPD. The arc model is established based on Magneto Hydro Dynamic (MHD) theory. The accuracy of the MHD model is verified through arc observation experiments. Analysis of simulation and experimental results reveals that the initial model exhibits poor arc extinguishing capability, as the root of the arc fails to enter the arc extinguishing chamber immediately. To address this issue, optimization design is analyzed based on MHD theory, including improvements in aerodynamic distribution and enhancement of the background magnetic field. The simulation results show a great improvement on the arc extinguishing capability after optimization. These findings provide a valuable theoretical reference for the development of switching-type SPDs.