Abstract
Low-voltage circuit breakers provide essential protection for industrial and residential power installations, by taking advantage of the voltage drop at the electrode–plasma interface to force current zero. This is accomplished by using the magnetic force and unbalanced pressure on the arc as the contacts open to push the arc toward a stack of steel plates that break the arc into subarcs and thereby multiply the number of voltage drops. As the fault current can be high, substantial energy can be dissipated, which results in interactions among the arc and solid counterparts in terms of wall ablation and metal evaporation. In this study, ablation experiments are conducted to demonstrate its great influence on the arc voltage and on the pressure field. Significant progress has been accomplished in the computation of arc dynamics through the coupling of fluid motion with electromagnetics, although an important mechanism in arc breaking simulation, the effect of Stefan flow caused by species generation, has not been considered. We report out a numerical approach for taking into account the effect of Stefan flow, particularly for the breakers with high gasifying wall materials. This approach accounts for the diffusion induced convection due to added-in species from the evaporation surfaces, which will largely influence the flow field and the properties of the plasma mixture. Apart from the voltage drop, this mechanism plays an important role in simulating arc interruption. The ability of conducting Stefan flow computation further enhances the understanding of arc behaviors and improves the design of practically oriented low-voltage circuit breakers.
Highlights
The function of a low-voltage circuit breaker (LVCB) in the power distribution system is to protect the electrical installations and to control and isolate the power supply in the electricity networks
Significant progress has been accomplished in the computation of arc dynamics through the coupling of fluid motion with electromagnetics, an important mechanism in arc breaking simulation, the effect of Stefan flow caused by species generation, has not been considered
Jeanvoine and Muecklich18 used the finite element method to simulate the heat transfer and metal erosion, and presented the estimation of temperature distribution in the arc spot. This work proposed another approach to estimate the evaporation rate at the arc spot with Langmuir free evaporation theory;18,19 his calculation was confined within a solid scitation.org/journal/jap domain. When it comes to wall ablation in LVCBs, Ruchti and Niemeyer6 investigated the ablation controlled arcs in cylindrical tubes theoretically and experimentally, concluding that ablation plays a critical role in controlling pressure, and the ablation rate can be scaled by factors such as current, geometry, and materials
Summary
The function of a low-voltage circuit breaker (LVCB) in the power distribution system is to protect the electrical installations and to control and isolate the power supply in the electricity networks. If the housing of the LVCB is partly made up of polymers that are gasified in high temperature environment, large volume of polymer vapor generation will tremendously increase the local pressure and alter the flow field which, accelerate the arc motion and expedite arc extinction.. If the housing of the LVCB is partly made up of polymers that are gasified in high temperature environment, large volume of polymer vapor generation will tremendously increase the local pressure and alter the flow field which, accelerate the arc motion and expedite arc extinction.5,6,25 This technique is expected to speed up the arc splitting and shorten the duration of arcing.
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