Effects of Channel Structure on Energy Dissipation for GaInSn Liquid Metal Arcing Process

In ultra-high voltage and high-voltage DC distribution networks, energy dissipation tributary of breaking current demands dissipation more than megajoules during a brief period when a short circuit fault occurs. However, existing energy dissipation equipment hardly fulfills demands. A novel device of GaInSn liquid metal arcing is expected to be used in energy dissipation branch of circuit breakers to dissipate energy in high-voltage DC system. In this paper, a liquid metal energy dissipation test platform is built, and self-shrinking trigger and arcing mechanism of gallium indium tin (GaInSn) liquid metal is studied in arc process. Key parameters affecting energy dissipation in liquid metals arcing process are discovered. Energy dissipation channels of cylindrical and conical hole structures are proposed, and their arcing process and energy dissipation characteristics are explored. Energy dissipation of liquid metal is separated to four phases: contraction phase, arc starting phase, liquid metal phase change of arc-burning phase, arcing extinction and liquid metal recover phase. Effects of channel structure and current amplitude on energy dissipation characteristics of GaInSn liquid metal are studied. A finite element simulation model of GaInSn liquid metal is constructed in arc process, and temperature distribution is analyzed in liquid metal arcing energy dissipation process. Peak values of temperature for cylindrical and conical through-holes structure are clarified. Finally, topology of hybrid DC circuit breaker based on composite energy dissipation of GaInSn liquid metal and Metal Oxide Varistor (MOV) is proposed, and simulation model of liquid metal and MOV composite energy dissipation is constructed. The energy dissipation ratio and distribution of liquid metal and MOV under different structures are explored. Results of study provide guidance for liquid metal energy dissipation module with other energy dissipation components.