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

Based on the self-shrinkage effect of liquid metal, liquid-metal energy dissipators (LMEDs) have good applications in the energy absorption branch of a high-voltage DC system. However, LMEDs instantaneously produce large amounts of liquid-metal vapor during operation; therefore, the varying characteristics of the pressure in the cavity affect their energy consumption capacity and service life. In this study, the force and motion of liquid metal were analyzed, a mathematical model of shrinkage time before the arc was constructed, the influence of short-circuit current and pore size on shrinkage time was explored, and the key factors affecting shrinkage time were clarified. Based on the theory of magnetohydrodynamics, the entire process of liquid metal from the beginning of contraction to the truncation of the arc was simulated to obtain the change characteristics of physical parameters, such as pressure and Lorentz force, in the cavity during the shrinkage process and to study the influence on contraction time by adjusting the short-circuit current and aperture size. A GaInSn liquid-metal energy dissipation test platform was built. The pre-arc shrinkage characteristics of the GaInSn liquid metal were studied, the variation in the voltammetry characteristic curve during liquid-metal energy dissipation was detected, and the accuracy of the simulation model was verified using experimental data. This study provides a theoretical reference for the application of LMEDs to power systems of different grades.