SF6 AUTO-EXPANSION CIRCUIT-BREAKER DESIGN - NUMERICAL AND EXPERIMENTAL INVESTIGATIONS OF ARC-GAS INTERACTIONS

This paper presents investigations of arc-gas interactions in a SF6 auto-expansion circuit breaker. On one hand, mass, momentum and energy conservation equations are solved using a "finite volume" method adapted to take into account unsteady motion, compressibility and real gas properties, Joule losses in the arc, radiative exchanges and energy transport by convection and conduction. On the other hand, specific measurements of local and global quantities are carried out (pressure rise, arc temperature and voltage, radiated power, ...). The good agreement between experimental results and the simulation permits to have reasonable confidence in the calculated results and to use the information given by the numerical model as a design aid.