The contact system of the vacuum switch is a crucial factor affecting the breaking performance of the vacuum switch. The study of the arc characteristics has significant impacts in improving the breaking ability of the vacuum switch. It is difficult to fully grasp the characteristics of the vacuum arc by experimental methods. The vacuum arc simulation model can obtain the internal parameters spatial distribution and motion characteristics more effectively. A high-current vacuum arc magnetohydrodynamic model was established, which considered the influence of ion and electron viscosity and the combined effect of the transverse magnetic field (TMF) and the axial magnetic field (AMF). The simulation obtained the plasma parameters of the arc column region as well as the temperature distribution characteristics of the cathode and anode surfaces. In addition, the changes in plasma parameters during arc movement under the action of different TMF and AMF components between TMF contacts were discussed. The simulation results are relatively consistent with the experimental results and the existing research results, which provide theoretical support for the research on the mechanism of vacuum arc motion characteristics.
The severity of the contact surface ablation determines the breaking capacity of the vacuum circuit breaker, and the interaction between the arc root and the electrode is the main cause of the contact surface ablation. The characteristics of the arc root determine the magnitude of the electromagnetic force received by the arc during the movement stage as well as the shape and speed of the arc movement. It will eventually affect the temperature of the contact surface and the ablation situation. This paper studied the arc root characteristics of high-current constricted vacuum arcs between the iron-core cup-shaped transverse magnetic field contacts and put forward the idea of using the ratio of cathode and anode arc root areas to quantitatively analyze the concentration of vacuum arc. The research on the arc root characteristics of the vacuum arc can help to improve the arc characteristics and arcing mechanism, and the proposition of the ratio can provide a new method for the study of constricted arc. This can provide a basis for improving the arc extinction performance of the switch, reducing the ablation of the contact material, and improving the contact life.
The cup-shaped transverse magnetic field (TMF) contacts contain radial components and tangential components in the TMF generated when the current is interrupted. The tangential force generated by the radial magnetic field component drives the vacuum arc to rotate, and the tangential magnetic field component generates a radial force that causes the vacuum arc to move radially outward. In this paper, in order to study the influence of the arc force direction on the arc characteristics, the influence of the contact structure parameters such as the inclination of the inner wall on the arc force direction is simulated, and the breaking tests of different levels of current are carried out on the contact with different structure parameters. It is found that the direction of the Lorentz force has a significant effect on the breaking characteristics of the current, and the tangential and radial force components have varying degrees of influence on the motion characteristics of the arc during the start process and the metal droplet splashing.
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