Analysis of shrinkage characteristics of GaInSn liquid metal in pre-arc process

Based on the self-shrinkage effect of liquid metal and its high electrical and thermal conductivity, liquid metal energy dissipator has a good application in the energy absorption branch of high-voltage DC system. However, the liquid metal energy dissipator is a closed device, and liquid metal vapor will be generated during its working process, which increases the pressure in the cavity, so the change characteristics of pressure in the cavity and its influencing factors also affect its energy consumption capacity and its service life. In this paper, the force and motion of liquid metal are analyzed, a mathematical model of shrinkage time before arc is constructed, the influence of short-circuit current and pore size on shrinkage time is explored, and the key factors affecting shrinkage time are clarified. Based on the theory of magnetohydrodynamics, the whole process of liquid metal from the beginning of contraction to the truncation of arc is simulated, so as to obtain the change characteristics of physical parameters such as pressure and Lorentz force in the cavity during the shrinkage process, and study the influence on the contraction time by adjusting the short-circuit current and aperture size. A GaInSn liquid metal energy dissipation test platform was built, and the pre-arc shrinkage characteristics of GaInSn liquid metal were studied, the variation of voltammetry characteristic curve during liquid metal energy dissipation was detected, and the accuracy of the simulation model was verified by experimental data. This study provides a theoretical reference for liquid metal energy dissipators applied to different grades of power systems.