SF6 auto-expansion circuit breaker design: numerical and experimental investigations of arc-gas interactions

Investigations of arc-gas interactions in a SF₆ auto-expansion circuit breaker are presented. Mass, momentum, and energy conservation equations are solved using a finite volume method adapted to take into account unsteady motion, compressibility, real gas properties, joule losses in the arc, radiative exchanges, and energy transport by convection and conduction. In addition, specific measurements of local and global quantities are carried out, including pressure rise, arc temperature and voltage, and radiated power. Good agreement between experimental results and simulation gives reasonable confidence in the calculated results and makes it possible to use the information given by the numerical model as a design aid