Modelling of the pre-arcing period in HBC fuses including solid - liquid - vapour phase changes of the fuse element

In this paper, we present a model and a numerical method of the fuse element heating including solid-liquid-vapour phase transitions in order to evaluate the pre-arcing time in HBC fuses. The mathematical model is based on the enthalpy formulation of the heat equation with a source term representing the Joule effect coupled with the Laplace equation for the potential and the Ohm´s law. We obtain an approximation of the governing equations using a specific numerical scheme for time discretization and unstructured triangle or tetrahedral element grids are employed in spatial discretization using a standard piecewise linear finite element method. Numerical simulations of two fuse elements, used in industrial applications, are carried out and compared with experimental measurements obtained using a 100 kVA power station.