Research On Influence Of Load Type On Arc Characteristics Of DC Air Circuit Breaker

In recent years,with the large-scale construction and planning of distributed energy storage,rail transit and HVDC transmission system,the HVDC transmission and distribution system has ushered in a golden period of rapid development.DC air circuit breaker is a commonly used switchgear in the field of low-voltage distribution.The rapid development of high-power DC power supply has put forward higher requirements for its breaking performance.Relative to the AC arc,DC arc has no natural current zero.Effective means must be taken to improve the arc voltage in short time,which makes the DC arc extinguishing is much more difficult than AC arc extinguishing,therefore,studying and mastering the dynamic characteristic of DC arc air under different load types,seeking effective measures to improve the arc voltage,to guide and improve DC air circuit breaker research and development design,has a certain practical significance.Based on the theory of magnetohydrodynamic(MHD),the mathematical model of the DC arc plasma air was established,mobile grid technology was adopted to realize the uniform circular motion of moving contact in arc quenching chamber,the condition in the arc plasma sheath was assumed,and the open circuit loop on both ends of the electrodes was coupled.By the coupling of external circuit module and DC discharge module the whole evolution process of arc of DC air circuit breaker was simulated at the function of different breaking load(resistance capacitance load and resistance inductive load).By comparing the arcing physical parameters in arc chamber,the movement of arc under different load conditions was analyzed to explore the mechanism behind the influence of load change on arc evolution.To test and verify the correctness of the simulation results,the experimental platform was set up,and the experimental prototype was designed.High-speed camera was used to take the arc image in DC arc quenching of air circuit breaker under the condition of capacitive and inductive loads and the dynamic behavior of breaking arc was also recorded.Comparing the experimental and the corresponding simulation results show that they are identical.The work of this paper has certain guiding significance for the research of DC air arc extinguishing theory and the improvement of DC air circuit breaker structure under different loads.