Low-voltage circuit breakers are used to switch on and off electrical current in circuit. During the interruption process, the contacts of the breaker are separated and an electric arc is established between contacts. Under the actions of Lorentz and aerodynamic forces, the arc has to move along the rail electrodes toward the quenching area. During the motion process, the stagnation and back commutation occur and worsen the performances of circuit breaker. According to the real interruption process, a three-dimensional (3-D) model of arc motion under the effect of external magnetic field is built based on magnetohydrodynamic (MHD), which can predict the restriking phenomena. With air vents opened to 60%, the restriking phenomena occur under 3 mT magnetic field; when the magnetic field is increased to 5 mT, the restriking phenomena disappears. Moreover, it shows that with air vents opened to 20%, 60% and 100%, the arc can arrive in the splitter plates successfully under 10 mT magnetic field without restriking.

Qian Yang;命哲 荣;翊 吴;Zhi Qiang Sun

Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering

2007-2-25

The influence of electrode separations on vacuum arc characteristics under different states in vacuum interrupters is simulated and analyzed. For low current diffused state vacuum arc, the diffused state of vacuum arc increases and ion temperature, electron temperature, plasma pressure all increase with the increase of electrode separations; For supersonic constrictive state vacuum arc, with the increase of electrode separations, constrictive state of vacuum arc increases and ion temperature, electron temperature, plasma pressure all increase, and the distributions of anode axial current density and heat flux density to anode become more nonuniform; For subsonic state (ion) high current vacuum arc, with the increase of electrode separations, the loss of interelectrode plasma increases. For above three kinds of vacuum arcs under different states, with the increase of electrode separations, arc voltage and heat flux density to anode both increase. Simultaneously, It is found that modeling and simulation is the effective method understanding microscopic process of vacuum arc.

Li Jun Wang;申利 贾;宗谦 史;Ling Zhang;命哲 荣

Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering

2008-3-5

This paper focuses on the numerical investigation of arc plasma behaviour in arc chamber of direct current (DC) circuit breaker. A 3-D simulation model of arc chamber including ferromagnetic splitter plates is built and calculated, which is based on magneto-hydrodynamics theory. Coupled electromagnetic and gas dynamic interactions are considered as usual, and a thin layer of nonlinear electrical resistance elements is used to represent the voltage drop of plasma sheath and the formation of new arc roots. Therefore, the arc-splitting process with ferromagnetic plates can be included. To reduce the time consuming, the arc simulation results of arc commutation process from contact to arc runner is taken as the calculation initial condition in the model. Arc motion is described in detail by the temperature distribution. Moreover, the simulation result is compared with experimental result, which shows good agreement.

命哲 荣;翊 吴;Fei Yang;Chunping Niu;Ruiguang Ma

2011

The electron energy distribution function (EEDF) of cold atmospheric plasmas (CAPs) is often assumed to be Maxwellian, but it is actually non-Maxwellian, as calculated from the Boltzmann equation. To determine the impact of the Maxwellian assumption, two global models with Maxwellian and non-Maxwellian EEDFs are developed for the He + air CAPs, and the resulting discharge characteristics and reactive species are compared. With the increasing air concentration from 100 to 50 000 ppm in He + air feeding gas, the simulation results of both global models display similar trends, and the orders of the densities of both global models are similar for the reactive species and each air concentration scenario. However, the Maxwellian assumption leads to lower electron temperature, weaker electronegativity, less power dissipation to Ion Joule heating, higher densities, and lagging peak points for most types of reactive species compared to using the non-Maxwellian EEDF. These findings indicate that the Maxwellian assumption is capable of capturing the main physicochemical features of He + air CAPs, but it can lead to large calculation errors at the quantitative level.

Bowen Sun;Dingxin Liu;Aijun Yang;命哲 荣;小华 王

Physics of Plasmas

2019-12-1

Based on a two-dimensional axisymmetric magneto-hydrodynamic (MHD) model, low current vacuum arc (LCVA) characteristics are studied. The influence of cathode process under different axial magnetic fields and different anode radii on LCVA characteristics is also simulated. The results show that the influence of both cathode process and anode radii on LCVA is significant. The sign of anode sheath potentials can change from negative to positive with the decrease of anode radii. The simulation results are in part verified by experimental results. Especially, as the effect of ion kinetic energy is considered, ion temperature is improved significantly; which is in agreement with experimental results.

Lijun Wang;申利 贾;宗谦 史;Ling Zhang;命哲 荣

Plasma Science and Technology

2007-12-1

This paper focuses on the simulation of the low-voltage arc with an opening contact. A controllable experiment setup with a rotating contact is designed to investigate the arc behaviour. Supported by the experiment, the phenomena of arc elongation and commutation in the case of rotating contact are simulated with the dynamic grid technique introduced. Under the given condition of the external magnetic field and the contact rotating velocity, the stagnation and rapid jump of two arc roots are observed by the calculated and experimental arc root displacement. The voltage of arc column can be divided into four phases and its sharp rising progress comes from the increase of the displacement difference between two arc roots in x direction.

翊 吴;命哲 荣;Zhiqiang Sun;小华 王;Jian Li;建洪 黄

Plasma Science and Technology

2007-12-1

The emerging demand on development of high-voltage direct current (HVdc) networks brings about an increasingly urgent need for a fast and reliable HVdc circuit breaker. This paper proposes a novel topology of HVdc circuit breaker combining a liquid metal load commutation switch and a two-stage commutation circuit, which offers an effective solution for isolating faults while preserving larger current breaking capability and lower overvoltage rate of rise. With the topology optimized in terms of circuit parameters for determining their optimum design values, the handling of short-circuit faults for the proposed circuit breaker in HVdc application is predicted theoretically. Finally, preliminary tests from a developed low-power prototype are presented together with a comparative simulation study provided to verify the performance of the proposed HVdc circuit breaker.

翊 吴;Yifei Wu;命哲 荣;Fei Yang

IEEE Transactions on Industrial Electronics

2019-8

This paper is concerned with the investigation of the motion of an air arc plasma in a quenching chamber, in particular with the effect of different chamber widths and outlet areas. A simplified arc chamber of a low-voltage switch device is used for the analysis. Based on a set of governing equations, a 3-D air arc plasma model is constructed and solved by a commercial code. It is found that increasing both the chamber width and the outlet area leads to an increase in the arc speed, but the strength of the dependence varies, depending on the values of the chamber width and the outlet areas. The tail of the arc column becomes shorter as the chamber width is reduced. This is shown due to the reduction in the backward flow by the squeezing of the two flow vortices that occurs.

翊 吴;命哲 荣;兴文 李;Anthony B. Murphy;小华 王;Fei Yang;Zhiqiang Sun

IEEE Transactions on Plasma Science

2008

Air DC switch has been widely used with the development of DC power system, while the limited speed of available DC switch mechanism has become the bottleneck of some key equipments and facilities development of industry. This paper focuses on the research of a new high-speed DC switch repulsion mechanism with experimental and simulation methods. Coupled with some key multi-physical equations, the numerical model was built. For the reason of accuracy, skin effect and the proximity effect caused by the current in the coil are also taken into account. According to the simulation results, which indicate several key parameters severely affecting the mechanism speed, a high-speed DC switch repulsion mechanism is developed. By the test of mechanism motion, its average speed can be up to 8.4m/s and its mechanism response time is 250us, which verifies the simulation results. Furthermore, during high speed motion the stress on the metal plate and moving contact is also discussed. It is noticed that the influence of the material deformation on the mechanical motion is very important.

Fei Yang;Hailong He;命哲 荣;Zhengyong Hu;翊 吴

2011

The present contribution is continuation of Part 1: Equilibrium composition and thermodynamic properties. This paper is devoted to the calculation of transport properties of mixtures of water and carbon at high temperature. The transport properties, including electron diffusion coefficient, viscosity, thermal conductivity, and electrical conductivity are obtained by using the Chapman-Enskog method expanded to the thirdorder approximation (second-order for viscosity), taking only elastic processes into account. The calculations, which assume local thermodynamic equilibrium, are performed for atmospheric pressure plasmas in the temperature range from 400 to 30,000 K for pressures of 0. 10, 1.0, 3.0, 5.0 and 10.0 atm. with the results obtained are compared to those of previously published studies, and the reasons for discrepancies are analyzed. The results provide reliable reference data for simulation of plasmas in mixtures of carbon and water.

Wei Zong Wang;J. D. Yan;命哲 荣;A. B. Murphy;J. W. Spencer

Plasma Chemistry and Plasma Processing

2012-6