The effect and dynamic behavior of particles in high-current vacuum arc interruptions

Abstract

Microparticles produced by high current vacuum arcs significantly reduce the insulation performance of vacuum interrupters. The objective of this paper is to observe the generation and dynamics of microparticles during the arcing and post-arcing period, and to further reveal the possible effects of particles during interruption of a high current vacuum arc. A plasma diagnosis system based on a laser-shadow technique was used to measure the particles in a demountable vacuum chamber. The results show that contact materials affect particle generation patterns. For a CuCr contact with a higher proportion of chromium, the formation of a melting pool is much more difficult and the flow of liquid metal on the surface can be suppressed, which also impedes the formation of particles. Moreover, reignition after arc extinction was found to be triggered by some incandescent particles. These hot particles have two effects on breakdown events during the post-arcing phase: they trigger a micro-discharge between a particle and the electrode, and new weak points are left on the surface that enhance the local field. More crucially, the lifetime of spontaneous particles spans up to hundreds of milliseconds after current zero, which indicates that long-delayed breakdown is correlated with the existence of particles. In addition, some particles could remain suspended near the electrode or oscillate between the contacts. The dynamic behavior of these particles can significantly lower the breakdown threshold and increase the possibility of breakdown.

Thermal Plasma of Electric Arc Discharge Between Cu-Cr Composite Electrodes

“…It is well-known that heterogeneous compound materials of two or more components with different melting and boiling points, such as Cu-Cr, are mostly manufactured by sintering and/or infiltration techniques. The compositions between 75/25% and 50/50% by weight of Cu-Cr contact material has proved optimum behavior in many respects for circuit-breakers [1][2][3]. Namely, high breaking capacity, gettering effect, smooth surface after arcing with subsequent high electrical strength, moderate chopping current of such composition are just those properties which are required in this kind apparats [1].…”

“…There are some investigations of plasma produced by high current vacuum arcs between Cu-Cr contacts in literature. Namely, in paper [3] was shown, that microparticles can be produced during interruption of a high current vacuum arc between such contacts. It is the reason, which causes the reduce of the insulation performance of vacuum interrupters.…”

Numerical investigation on the influence of metal particles on the characteristics of a high-current vacuum arc

“…On the other hand, in the HCVA, the energy flow is injected into the anode by the contracted arc plasma, the temperature distribution of the anode surface will also have a radial distribution due to the radial distribution of the energy flow [23][24][25].…”

COMPOSITE Cu-Cr MATERIALS UNDER THERMAL ACTION OF ELECTRIC ARC DISCHARGE PLASMA

“…For example, it was found in work [10], that Cu-45 %Cr material provides comparably the lowest cathode wear, while Cu-50 %Cr provides lowest anode wear. Moreover, it was concluded in [11] that it is much more difficultto form a melting pool on a Cu-Cr contact surface with a higher proportion of chromium. On the other hand, an increasing of Cr content leads to decreasing of interruption rate [12].…”