Research On Air Arc Characteristics And Image Processing Based On Gas Components

With the development and improvement of low-voltage distribution network,higher breaking capacity requirements are put forward for gas dielectric circuit breakers in distribution network.The arc plasma produced when the gas dielectric circuit breaker breaks the fault current of short circuit is a mixture of gas dielectric and vapor.In air arc,the physical properties of air arc based on different gas components are different,the behavior of arc plasma changes accordingly,which affects the breaking ability of circuit breaker.In order to study and master the air arc characteristics of different gas components,a magnetohydrodynamic(MHD)arc model established in this thesis,and the temperature field,flow field and other macro characteristics of air arc of different gas components are discussed.The spatial distribution characteristics of air arc shape and temperature are obtained by image processing and comparative experiment.Firstly,the air arc of pure air and copper vapor mixture is taken as the research object,and the physical parameters of gas mixture based on different gas components are obtained.A magnetohydrodynamic model is established,and the distribution of temperature,velocity,pressure and potential of air arc with different gas components is simulated by finite method.The results show that the air arc with different gas compositions has a common character,that is,the arc is elliptical.The spatial distribution law of temperature,velocity,pressure and potential of the two gas components is the same,and the maximum value of them all appear at cathode region.The difference is that the maximum temperature,pressure and potential difference of the air arc mixed with copper vapor is smaller than that of the pure air arc,and the maximum velocity is larger than that of the pure air arc.Secondly,through the air arc pulling experiment,a high-speed camera is used to capture the continuously changing air arc image.The shape distribution,temperature and geometric characteristics of pure air arc and mixed copper vapor arc are studied based on using image processing technology,and the variation law of arc area and perimeter is revealed.The results show that from the beginning to the end of arc burning,the air arc of the two gas components changes from round to oval shape.The high temperature of the arc is diffused from the arc column region to the polar region.The temperature of the mixed copper vapor arc is smaller than that of the pure air arc.The arc area increases first and then decreases,and the arc circumference increases.The area of the mixed copper vapor arc is always smaller than that of the pure air arc,and the arc circumference is smaller than that of the pure air arc in most of the time.Finally,according to the temperature characteristics of air arc with different gas components,the results of simulation calculation and test of image processing technology are compared and analyzed.The characteristics of air arc morphology and temperature distribution tend to be consistent,and the difference of temperature extreme values is small,which verifies the accuracy of simulation results.It provides theoretical support for further understanding of air arc characteristics and finding an effective way to extinguish arc quickly.