Theoretical Calculation Of The Self-extinguishing Type SF₆ Circuit Breaker

The self-extinguishing type SF6 circuit breaker, developed on the basis of the puffer type SF6 circuit breaker, has been implemented advanced interrupting principle and reduced the operating energy of circuit breaker largely, which made it successful to equip with low energy spring mechanism characterized by simple structure, good stability, high reliability, etc. Thus, the miniaturization, which stands for the developing direction of high voltage circuit breaker, has been realized. So, it is very important to study the theory and test of the self-extinguishing type SF6 circuit breaker.Integrated the requirement of developing the self-extinguishing type SF6 circuit breaker, this paper performed theoretical calculation and numerical analysis on the mechanic performance, electric and gas-flow fields distribution of the circuit breaker, and provided a theoretical basis for the development of The self-extinguishing type SF6 circuit breaker.At first, the electric field distribution in the chamber of the breaker was calculated with the help of ANSYS program, and then the inner structure and porcelain of the chamber was optimized according to the calculated results and verified through tests. During the calculation of gas-flow field, aimed at concrete structure model studied, a mathematical model for gas-flow field was worked out with FORTRAN language by the use of modified fiuid-in-cell method and movable mesh technique. With this program, calculated the gas flow properties in the chamber during the short-current interruption, analyzed the changing feature of gas pressure in the puffer chamber and expansion chamber, the feature that gas pressure, speed and density in gas-flow field distribute with time and space. And finally, the law of gas flow in chamber under small-current condition was got. The structure parameters were changed to analyze the influence of the change of structure parameters on gas flow feature under small-current condition.At last, the theoretical calculation was compared with the test results, the directive function and practical value was analyzed. The analysis and calculation aimed at the problems appearedin the tests were performed. Finally, the study and development on this product have been finished.Through the analysis and calculation mentioned above, this thesis realized the theoretical research on the self-extinguishing type SF6 circuit breaker, and provided a theoretical basis for the study and development of the self-extinguishing type SF6 circuit breaker.