Analysis of Electric-Thermal Field and Research on Temperature Rise Characteristics of High-Voltage Vacuum Interrupter Integrated with Main and Auxiliary Gaps in Series

The vacuum interrupter of transmission grade is an urgent industry-level problem to be solved, the requirements for insulation and current-flow capacity become more stringent under high voltage and high current conditions. The high-voltage vacuum interrupter integrated with main and auxiliary gaps in series is expected to become a new solution for achieving 252 kV and above voltage levels. By utilizing the auxiliary gap to assist the main gap insulation and arc extinguishing, it overcomes the insulation bottleneck of long vacuum gaps. However, its temperature rise characteristics under high current conditions remain to be studied. This paper establishes a model of vacuum interrupter integrated with main and auxiliary gaps in series. Based on heat transfer theory, a thermal network model of the vacuum interrupter integrated with main and auxiliary gaps in series is developed to analyze and calculate its heat dissipation process. According to the computational results, a structural optimization method is proposed—employing a heat-dissipating shield—to improve the temperature rise of the vacuum interrupter, followed by simulation validation. The study indicates that the new structure of the high-voltage VI integrated with main and auxiliary gaps in series can meet the insulation requirements for high-voltage-level VIs. With the heat-dissipating shield, the maximum temperature rise inside the VI is 68 K, representing a 17% reduction compared to the unoptimized structure, effectively improving thermal performance and enhancing current-flow capacity. This research provides a new structural approach for the development of high-voltage level vacuum interrupters.