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With the development of the power industry and the increase in the capacity of power systems, vacuum switches have been developed rapidly. The distribution characteristics of the vacuum arc can reflect the working conditions of the vacuum switch. So, it is vital to understand the distribution characteristics in the vacuum arc burning process for understanding the interruption performance of vacuum switches. Based on the 3D magnetohydrodynamic model, we investigated the high-current vacuum arc burning process by modeling and numerical simulation. The research findings show a certain correspondence between the change in plasma parameters values and the change in arc current. The distribution of plasma parameters is uniform when the current is small. The distribution of plasma parameters in the first 1/4 cycle is more uniform than in the second 1/4 cycle. The evolution characteristics of the arc plasma parameters for interruption before the arc current maximum differ significantly from those for interruption after the arc current maximum and current maximum. The results of this study can provide a reference for the design and improvement of vacuum switches. [ABSTRACT FROM AUTHOR]

In the arc-burning process of a high-current vacuum arc (HCVA), the metal particles (MPs) splashed from the active anode will have a significant influence on the plasma characteristics of the arc column. In this paper, the influence of varying MPs on the characteristics of HCVA are studied by establishing a HCVA model containing single or multiple MPs. The simulation results show that when the MPs vaporized metal vapor (MV) enters the interelectrode region and once the arc column plasma cannot ionize all atoms immediately, the ionization layer and the neutral atom vapor area (NAVA) will be formed in the adjacent region of the MPs. When the MP diameter and temperature increase, the number of vaporized metal atoms increases, so that the influence range of MV increases, and the area of ionization layer and the NAVA increases. In addition, when the arc current increases or the MPs are closer to the cathode surface, the greater the ion number density and ion pressure around the MPs are, the stronger the compression on the MV will be, resulting in the decrease of the area of ionization layer and the neutral atom vapor, and the increase of the net ionization rate of the ion number density. When multiple MPs exist in the interelectrode region at the same time, the MV from the MPs will affect each other. In the central region of multiple MPs, the density of MV becomes the largest, while the net ionization rate of ion number density is distributed in the periphery region of the MP group. [ABSTRACT FROM AUTHOR]

In a switchgear, an external transverse magnetic field (ETMF) is generated by the U type loop consisting of the vacuum interrupter, external busbar and conductive rod connected to the vacuum interrupter. The ETMF will make the vacuum arc deflected and strengthen the contraction of the arc. This can increase the probability of breaking failure. To weaken the adverse effect of the ETMF, the real magnetic field data of the arc area with different structure parameters when the length of conductive rod, external busbar and phase distance is changed are obtained by establishing simulation model in this paper. Taking the real magnetic field data as the boundary condition, this paper obtains the typical parameters of the vacuum arc plasma with different structure parameters by using the established three-dimensional high-current vacuum arc magnetohydrodynamics model. The simulation results show that the ETMF makes the transverse magnetic field (TMF) of the arc area asymmetric, which leads to an arc deflection. Reducing the length of the conductive rod connected to the vacuum interrupter to 50 mm can effectively improve the asymmetry of the TMF caused by the EMTF, weaken the arc deflection phenomenon, make the distribution of the plasma parameters more uniform, and increases the utilization of the anode contact surface. Moreover, it can not only reduce the heat flux density into the anode as a whole, but also reduce the heat flux density in the high heat flux density area, so as to effectively reduce the degree of anode activity and improve the negative effects caused by the anode activity. The changes of other external structural parameters have less influence on the improvement of the vacuum arc deflection phenomenon. Increasing the phase spacing to 275 mm or reducing the length of the external bus bar to 100 mm can only slightly weaken the arc deflection. [ABSTRACT FROM AUTHOR]

Vacuum circuit breaker is a kind of power equipment widely used in the power system. It is developing toward the direction of high voltage and high current. How to design the contact to maximize the interrupting capacity of the contact system has been conducted by scholars. In this paper, the magnetic field simulation model of contact system is established, the magnetic field distribution characteristics of vacuum interrupters are studied, and the distribution characteristics of the magnetic field in the half cycle of the cup‐shaped axial magnetic field contact system are simulated and analyzed. On this basis, by changing the contact structure parameters, the effects of the number of slots in the cup, the slot angle, the center hole of the contacts, and the length of the slots on the distribution of the axial magnetic field were obtained. The results show that grooving the contact can reduce the eddy current, but it has a limited effect on reducing residual magnetic field. The increase of slot angle of contact cup can effectively reduce the residual axial magnetic field at the zero current moment and the axial magnetic field intensity at the peak current moment. Based on the above research results, a new embedded axial magnetic contact system with 12 slots embedded magnetic ring and reverse contact cup is designed. The embedded magnetic ring and reverse spiral slot increase the axial magnetic field at the peak current moment and reduce the residual axial magnetic field at the zero current moment. Finally, the characteristics of the magnetic field have been improved significantly compared with the magnetic field of traditional cup‐shaped axial magnetic field contact. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In the arcing process of high-current vacuum arc, the metal particles spattered from the active anode will have a significant influence on the plasma characteristics of the arc column when they entrance the interelectrode area. In this paper, the characteristics of a high-current vacuum arc with metal particle are studied by modeling and simulation. The results show that the vapor produced by metal particle will obviously cool the arc plasma and reduce the current density in the vicinity area of the metal particle. In addition, the metal particle will hinder the movement of the cathodic plasma and complicate the ion density distribution and movement process near the metal particle. Finally, an obvious ionization layer will be formed around the metal particle. When the metal vapor passes through the ionization layer, the vapor will be ionized rapidly, and an abundance of ions will be produced at the same time. The research results are of great significance for the deep understanding of arcing process of high-current vacuum arc. [ABSTRACT FROM AUTHOR]

With the advantages of environmental protection, small size, and light weight, the vacuum circuit breaker has been widely used in power systems. At present, it is developing toward the direction of high voltage and high current. In this paper, the magnetic field simulation model of a cup-shaped axial magnetic contact system is established, and the actual magnetic field data in the arc area are obtained as the boundary conditions, and then a three-dimensional steady-state magnetohydrodynamic model of the vacuum arc is established. The plasma parameter distribution characteristics in the vacuum arc area are studied by changing the number of slots in the contact plate, the angle of the contact cup chute, the length of the slot in the contact plate, and the central process hole. On this basis, a new type of embedded axial magnetic contact system including an embedded magnetic ring and a reverse contact cup is proposed, and the influence of changing the angle and number of inclined slots of the embedded contact cup on the arc distribution characteristics at the peak current and current zero is further studied. The simulation results show that the new structure contact is helpful to the breaking capacity of the vacuum switch and has a guiding significance for the design of the vacuum circuit breaker. By comparison, our simulation results have the same trend with the experimental results of other researchers. [ABSTRACT FROM AUTHOR]

Vacuum circuit breakers (VCBs) are widely used in power distribution systems. When the VCB in a switchgear interrupts the short circuit current, the U type loop, which consists of a vacuum interrupter, an external busbar and a conductive rod, generates an external transverse magnetic field (ETMF). This field deflects the vacuum arc and affects the interruption performance of the VCB. In this paper, the real magnetic field data of the arc region are obtained by establishing a simulation model of an electrode system, taking into account the real ETMF and real axial magnetic field (AMF). Furthermore, the three dimensional steady magnetohydrodynamic model of the vacuum arc is established by using real magnetic field data as the boundary condition. The vacuum arc characteristics under the combined effect of AMF and the asymmetric transverse magnetic field (TMF) are studied. The simulation results show that the ETMF considerably changes the Bx of the arc column, which demonstrates asymmetry in the positive and negative directions, whereas By demonstrates a weaker asymmetry. Moreover, the asymmetric TMF deflects the distributions of the vacuum arc plasma and increases the partial heat flux density and axial current density. With the increase in the severity of the short circuit, the TMF asymmetry of the arc region is enhanced and the deflection of the vacuum arc plasma is also enhanced. [ABSTRACT FROM AUTHOR]

When short current is interrupted in three-phase vacuum interrupter in switchgear, the “U”-type loop composed of external busbar, conductive rod, and vacuum interrupter, and its adjacent phases will generate external actual transverse magnetic field (EATMF) in the interrupter. The existence of EATMF will deflect the vacuum arc, which will affect the breaking performance of vacuum switch. In view of this situation, this article establishes two kinds of electrode system simulation models considering and not considering EATMF. The simulation results show that EATMF is not uniformly distributed in the interelectrode region, but is stronger in the contact cup edge area outside the “U”-type loop, weaker in the “U”-type loop, and mainly affects ${B} _{x}$. In different short-circuit cases, EATMF is also different due to the difference of phase distance and short current. In the case of three-phase short circuit, the magnetic field in the interelectrode region of the middle phase is most significantly affected by EATMF. EATMF is closely related to the structure size of vacuum switch. By changing the structure size of vacuum switch (e.g., phase spacing ${d}$ , conductive rod length ${h} _{1}$ , ${h} _{2}$), EATMF can be weakened to some extent. [ABSTRACT FROM AUTHOR]