Abstract：Liquid metal current limiter (LMCL) have unique advantages. It has a good application prospect in the current limiting of the power grid. In order to reduce the erosion of LMCL and improve the service life, a resistive wall liquid metal current limiter (RWLMCL) was designed in this paper. During the current limiting process, the resistive wall can be connected to the circuit. First, the reason for the RWLMCL reduced arc intensity was analyzed from the perspective of current distribution inside the cavity. When the wall is the resistive material, the arc resistance and the wall resistance share the short-circuit current. During the burning arc process, the arc resistance increases gradually with the enhancement of the arc, and the wall branch current gradually increases. Compared with the insulating wall LMCL, the current flowing through the arc branch of the RWLMCL is decreased, and the arc intensity is reduced, which can effectively reduce the erosion of the cavity. Further, in order to explore the mechanism of the liquid metal self-pinch effect in the RWLMCL, the liquid metal dynamic change under the action of current was analyzed by experiment and simulation. The liquid metal current density at both ends of the channel will suddenly change because of the RWLMCL channel structure. The liquid metal Lorentz force changes most at the four corners of the grooves and channel. Under the action of Lorentz force and air flow, the liquid metal at the four corners is first depressed. With the increase of the current, the liquid metal Lorentz force in the depressions further increases, so that the depressions continues to deepen and expand. The depressions reach the bottom end of the channel, and the liquid metal paths break. By replacing the insulating wall of the LMCL with a resistive wall, the liquid metal self-pinch effect is still effective. The simulations are in good agreement with the experiment results, which proves the rationality of the theoretical model. Finally, using LC oscillation circuit as power supply, experiments were carried out on three LMCLs, i.e. polymethyl methacrylate (PMMA), ZnO pulse power resistance (ZnO PPR) and Fe-Co-Ni walls. In this paper, PMMA was used as the insulating wall material to simulate the existing LMCL. The current limiting characteristics and arc erosion of the three LMCLs were compared in detail. Compared with the PMMA wall LMCL, the peak current, peak arc voltage, pre-arc time, and arcing time of the Fe-Co-Ni wall LMCL are reduced by 2.68%, 95.0%, 23.9%, and 68.8%, respectively. In this experiment, the Fe-Co-Ni wall LMCL has the best current limiting characteristics. Compared with the PMMA wall LMCL, the liquid metal erosion of the ZnO wall LMCL and the Fe-Co-Ni wall LMCL is significantly weakened. The degree of liquid metal erosion is related to the wall material. The greater the conductivity of the wall material, the smaller the current flowing through the arc branch and the lower the arc energy, resulting in less erosion. Therefore, the RWLMCL can reduce the erosion of the cavity and prolong the service life of the LMCL. Based on the research in this paper, the design idea of LMCL cavity is expanded. So that more new materials are applied to the field of current limiting.
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2023, Vol. 38 
