Arc Simulation And Experimental Study Of DC Air Circuit Breaker With Different Arc Driving Mode

Since the 21 st century,DC transmission and distribution technology has been unprecedented development and considerable application.The rapid development of highpower DC power supply,puts forward higher requirements for the corresponding electrical equipment.DC air circuit breaker,as the leading product of low-voltage switchgear,is mainly used in fault isolation,breaking the current under normal or abnormal conditions,and providing protection for load.Moulded case circuit breakers are widely used in low-voltage distribution systems to provide overload and short-circuit protection for load equipment.They are responsible for switching on,carrying and interrupting normal or abnormal condition currents.With the continuous improvement of voltage level,the existing air DC circuit breakers are limited by the key parameters such as interruption capacity.It is extremely difficult to extinguish arc quickly and reliably,which can no longer meet the current demand of large capacity,miniaturization and long life of circuit breakers in China's DC distribution systems and engineering applications.Therefore,it is of great practical significance to study and grasp the factors affecting arc regulation and find effective arc driving methods to guide and improve the development and design of DC air circuit breaker products.In this paper,a prototype of DC air circuit breaker is manufactured and an interruption experiment platform is set up.The interruption of a specific circuit is completed under the conditions of internal gas-producing material and applied magnetic field.The relevant data of arc and the dynamic arc images are collected and analyzed.Based on the theory of magnetohydrodynamics(MHD)and relevant assumptions,according to the prototype model and experimental conditions,a two-dimensional arc simulation model of DC air circuit breaker interrupter was established by COMSOL Multiphysics software.The moving mesh technique is used to simplify the motion of the moving contacts in the interrupter model as a uniform circular motion.The simulations of model interruption arc under different magnetic fields are completed,and the whole dynamic processes of arc variation are obtained.By comparing and analyzing the differences of physical field,Lorentz force,conductivity distribution and arc voltage and current characteristic curves in arc extinguishing chamber,the fundamental causes of arc dynamic evolution,"double arc root" and arc root transition are revealed,and compared with the experimental results under the same conditions,the correctness of the simulation model is demonstrated.By changing model parameters and entrance boundary conditions,the effects of air inflow with different pressure on arc extinguishing chamber arc of air circuit breaker are simulated and compared with arc dynamic characteristics under different applied magnetic fields.At the same time,the arc evolution process of the model when it interrupts large voltage circuit driven by magnetic field is investigated.It is proved that the simulation model has good extensibility and can guide the design and experiment of circuit breaker arc extinguishing chamber correctly by means of simulation.The simulation and experimental results show that the model can well reveal the whole dynamic process of arc development in the interrupter chamber of DC air circuit breaker and the influencing factors of arc dynamic change.The effective means of arc driving are explored from two aspects of air flow and magnetic field,which has certain guiding significance for designing and improving the structure of arc chamber in circuit breaker.