Research on the trigger process of surface flashover triggered vacuum switch

The key to promoting the development of triggered vacuum switch is an in-depth research on the physical process of its trigger phase. This paper mainly divides the trigger process into metal electrode melt evaporation, neutral metal vapor layer expansion, electron collision ionization multiplication, and charged particle migration. An approximate analytical formulation of the trigger delay time theory is presented based on a one-dimensional heat conduction model and an electron collision ionization multiplication process. The trigger delay time experimental platform is built with a removable vacuum chamber. The influence factors involved in the mathematical description proposed are studied experimentally. Theoretical analysis and experimental results show that both trigger current rise rate and main electrode operating voltage have an approximate inverse relationship with trigger delay time. The main electrode gap distance is directly proportional to the trigger delay time, but the effect will be weaker as the main electrode gap distance increases. Overall, the consistency of the experimental results and theoretical analysis on influence trends well support the theoretical model.