The influence of holes number on wall pressure in the liquid metal arcing process

For DC transmission systems, under fault conditions such as short circuits, the energy dissipation branch of the DC circuit breaker must rapidly absorb and dissipate megajoule-level energy within a very short time interval. Leveraging the self-contraction behavior of liquid metals together with their high electrical and thermal conductivities, liquid metal energy dissipator (LMED) has recently received considerable attention as a promising candidate for use in the energy dissipation branch of high-voltage direct current (HVDC) systems. Owing to its hermetically sealed configuration, liquid metal vapor is inevitably generated during operation, leading to an increase in internal cavity pressure. As a result, the pressure distribution and its temporal evolution inside the cavity have a direct influence on the energy dissipation capability and the service life of the device. In this paper, the pressure distribution inside the cavity during LMED operation is analyzed, and the influence of cavity pressure on arcing process is studied. A simulation model for arc behavior incorporating a gallium-indium-tin liquid metal medium is formulated. The arc evolution in the liquid metal medium is numerically investigated to characterize the transient pressure behavior within the cavity during LMED operation. Furthermore, the effects of short-circuit current magnitude, number of holes, and series–parallel configurations on the internal pressure are systematically evaluated. A gallium-indium-tin LMED test platform is built. The arc behavior associated with gallium–indium–tin liquid metal is systematically examined. Furthermore, the transient development of the liquid metal pressure distribution throughout the energy dissipation process is investigated. The analysis of the cavity pressure distribution presented herein offers a theoretical foundation to support the design of novel liquid metal energy dissipators.