Study On The Arc Formation And Relevant Parameters In Circuit Breaker

The theories of arc play a very important role in the design and investigation of circuit breakers. Arc is a type of gas discharge, and the physical process from gas breakdown to arc is quite complicated. The studies of arc formation can provide a profounder understanding of the generation and extinguishment of arc, and have theoretical and practical significances for better design and improving the interruption performance of circuit breakers.Based on the theories of electric arc and gas discharge, research and exploration are carried out by taking the example of two typical electrode structures, flat-plate and pin-plate. The investigation and simulation on the breakdown of gap show that the discharge channel shape within the flat-plate electrode gap is the pattern of main and secondary discharge channels existing synchronously, while the discharge channel shape within the pin-plate electrode gap is the pattern of electrical trees.A dynamic evolution model of gas breakdown is proposed according to the characteristics of discharge channels. The varieties and relations of macroscopic and microcosmic parameters in the discharge channels with and without branches are described, and the simulation of dynamic evolution from gas discharge channel to arc is carried out. Moreover, the characteristics of discharge channel shapes in different electrode gap during each discharge stage are obtained. The similarities and differences of the development of the two pattern discharge channel are contrasted, and the influences of the relevant parameters including the distribution of electrical field, voltage , current and the integrated coefficient which is used to describe the microcosmic phenomena of ionization, recombination and diffusion during the process of the discharge channel development are analyzed.The dynamic evolution model is applied to the study of vacuum circuit breaker. The shapes and evolution roles of initial discharge channel formed in the breakdown of vacuum gap are obtained, and the variety roles of electron and the positive ion in the discharge channel are acquired. Moreover, the variety roles of the channel radiuses and the distributions of the electron temperature are also obtained. Through the investigation of discharge evolution under different applied current, the tendency that the shapes of vacuum arc change from diffused mode to constrictive mode with the increasing of the applied current is testified, establishing a foundation to the deep analysis of vacuum arc variety roles, and the correctness of the discharge model proposed in this thesis is proved.