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排序方式: 共有167条查询结果,搜索用时 15 毫秒
1.
This paper mainly focuses on the influence of three kinds of media: air, air-10%PA (Nylon) and air-10% POM (polyoxymethylene) on low-voltage circuit breaker arcs. A threedimensional (3-D) model of arc motioa under the effect of external magnetic field is built based on magnetohydrodynamics (MHD) equations. By adopting the commercial computational fluid dynamics (CFD) package based on the control-volume method, the above MHD equations are solved. For the media of air-10%PA and air-10%POM, the distributions of stationary temperature and electrical potential and the transient motion processes are compared with those of air arc. The research shows that both air-10%PA and air -10% POM can cool the arc plasma and the former is more effective. Both of them can increase the stationary voltage as well. Moreover, the presence of the two mixtures can accelerate the arc motion toward the quenching area and ensures the arc quenched in time. 相似文献
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Simulation Research of Magnetic Constriction Effect and Controlling by Axial Magnetic Field of Vacuum Arc 总被引:2,自引:0,他引:2
Based on magnetohydrodynamic (MHD) model of vacuum arc, the computer simulation of vacuum arc was carried out in this paper. In the MHD model, mass conservation equation, momentum conservation equations, energy conservation equations, generalized ohm‘s law and Maxwell equation were considered. MHD equations were calculated by numerical method, and the distribution of vacuum arc plasma parameters and current density were obtained. Simulation results showed that the magnetic constriction effect of vacuum arc is primarily caused by the Hall effect. In addition, the inhibition of axial magnetic field (AMF) on constriction of vacuum arc was calculated and analyzed. 相似文献
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Numerical Study on Arc Plasma Behavior During Arc Commutation Process in Direct Current Circuit Breaker 总被引:1,自引:0,他引:1
This paper focuses on the numerical investigation of arc plasma behavior during arc commutation process in a medium-voltage direct current circuit breaker(DCCB) contact system.A three-dimensional magneto-hydrodynamic(MHD) model of air arc plasma in the contact system of a DCCB is developed,based on commercial software FLUENT.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 root.The distributions of pressure,temperature,gas flow and current density of arc plasma in arc region are calculated.The simulation results indicate that the pressure distribution related to the contact system has a strong effect on the arc commutation process,arising from the change of electrical conductivity in the arc root region.In DCCB contact system,the pressure of arc root region will be concentrated and higher if the space above the moving contact is enclosed,which is not good for arc root commutation.However,when the region is opened,the pressure distribution would be lower and more evenly,which is favorable for the arc root commutation. 相似文献
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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. 相似文献
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高气压电弧的状态及其转换 总被引:1,自引:0,他引:1
阐明了高气压条件下(1个大气压及以上)电器分断电路过程中金属蒸气态电弧和气体态电弧及其转换这一物理事实;简要论证了电弧状态及其转换对电极材料侵蚀机理、电弧停滞时间和电弧移动特性等科学问题的重要性;较系统地分析了金属蒸气的形成原因和扩散机理。 相似文献
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基于振动信号小波包提取和短时能量分析的高压断路器合闸同期性的研究 总被引:12,自引:4,他引:12
该文提出了一种分析高压断路器合闸同期性的新方法将小波包提取算法和短时能量分析方法相结合,利用小波包分解与重构原理将断路器合闸振动信号分解到不同频段中,并对代表高频冲击信号的分解系数进行重构,然后运用短时能量分析方法对重构后的信号进行分析,辨识出合闸变位点。通过对三相合闸过程的分析,得出三相同期性。通过MATLAB仿真分析和实验结果验证了该方法的有效性。 相似文献
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真空电弧磁流体动力学模型与仿真研究 总被引:3,自引:11,他引:3
以离子与电子的双流体模型以及麦克斯韦方程为基础,推导得到了真空电弧的二维磁流体动力学(MHD)模型。MHD模型中包括质量方程、动量方程、能量方程、麦克斯韦方程和全欧姆定律,通过对这些方程的数值计算,得到了真空电弧等离子体参数与电流密度的分布,文中计算分析了电弧电流、电极间距以及不同分布的纵向磁场对真空电弧等离子体参数与电流密度的影响。 相似文献