Experimental characterization of evaporation processes of copper and polyamide 6.6 caused by fault arcs

Abstract The increasing demand for gas-insulated switchgear raises the risk imposed by fault arcs, even though the probability of their occurrence is relatively low. Thermal and mechanical stresses caused by fault arcs pose safety risks for both humans and systems and, thus, are fundamental to consider during switchgear development. Magnetohydrodynamic models offer an opportunity to perform in-depth arc investigations to decrease the risks of over- and under-dimensioning switchgear concerning fault arcs, de-risking designs prior to performing expensive hardware tests. The current literature lacks studies focusing on superimposed ablation and erosion processes during fault arcs. To fill this gap, an extensive experimental study is conducted within a steel vessel that emulates typical designs of encapsulated, hermetically sealed compartments in gas-insulated switchgear. Systematic investigations of single phase-to-ground faults are performed under variable boundary conditions, such as geometric, electric, and fluid dynamic parameters. All parameters investigated influence ablation, erosion, and pressure rise rates. Erosion and ablation rates have been derived in the range of 0.5 to 7 mg C −1 and 1 to 10 μg/J, respectively. Measured erosion rates are a multiple of known published rates, whereby ablation rates are in line with the literature. These results can be used to further develop, validate, and verify magnetohydrodynamic fault arc models and to enhance the understanding of fault arcs.