Design and test of the trigger vacuum switch and its trigger source for high temperature environment

A surface-flashover trigger vacuum switch (TVS) was developed to satisfy the stability and high temperature (above 120 degrees) working environment requirements for the discharge switch. Compared with the self-breakdown gas switch, TVS can greatly improve the working life and stability of the whole device. In this paper, TVS was designed with multi-rod electrode system to improve the ability of current carrying and with suitable main electrode to improve the DC withstand voltage at the same time. Additionally, its electric field uniformity was optimized, developing suitable main electrode chamfer by theoretical calculation and simulation study. The TVS developed has an outer diameter of 68mm, a working voltage of up to 25kV, and a peak current capacity of 30 kA/100 μs. After 1000 cycles, the triggering characteristics and DC withstand voltage level of the TVS developed were still good, fully meeting the working requirements for the discharge switch in high temperature environment. What's more, aimed at the high temperature working environment of the TVS, the trigger circuit was devised. Because the common thyristor and diode working under high temperature is not reliable, this paper designed a trigger source without any semiconductor device, using a three electrode spark gap instead of the thyristor to control the trigger of the TVS. The trigger capacitance was designed to charge from the main circuit charge capacitance, which can simplify the circuit and has no potential isolation problem. The simulation and experimental test demonstrate that the trigger scheme is feasible.