Study On Gap Breakdown Of SF₆ Circuit Breaker Based On Microscopic Theory

The study of the arc theoretical has an important guiding role, in the high-voltage electrical equipment. The arc is also very important on the breaking of circuit breaker or the electrical insulation problem. However, the formation and development of the arc is a very complex process, its impact parameter and the randomness of discharge development are so much that our researchers have raised the challenge. But only we have more in-depth study on the nature of process of generation, development and formation of arc, can we simulate more accurately on the breaking performance in the circuit breaker. And it also has an important guiding role on the design of the circuit breaker.Firstly, based on the theory of the arc and gas discharge, in view of non-uniform distribution level of the SF6 circuit breaker contactor, this paper take use of a pin-to plate to simulate its cutting-edge discharge and make the model. Through the analysis of SF6 itself on the unique negative electrical and thermal conductivity, meshing between the plates, the electric field calculation and assignment of boundary conditions provide strong supports for the development of arc.Secondly, according to theories of fractal and probability development, it simulate discharge process about the generation of discharge channel, dendrite development, channel formation and contraction to the center of the arc. It mainly research the electronics, process of collision ionization and adsorption between the plate is analyzed. At same time, the force analysis to the electrons is carried out under the effect of electric field and spontaneous magnetic field and explore its the potential law of motion.Finally, a novel dynamic evolution model is proposed, according to the analysis of the various parameters which effected arc generation, such as role of electric force, the role of spontaneous magnetic field and temperature generate on the thermal diffusion of electrons. From the simulation we can get that the initial generation and development of arc model is different, in the different electric field distribution. In the two kinds of different gas medium like SF6 and vacuum, the diversification of the electron density, electron velocity, the collision coefficient, temperature and thermal conductivity and the development law of current in arc are analyzed comparatively.