Abstract: A high-voltage power breaker includes two arcing contact pieces which are separated from one another when disconnected and between which an arc is struck in an arcing area. The arcing area is filled with a quenching gas, where the quenching gas has been heated by the arc flowing out from a constriction point of an insulating nozzle. The insulating nozzle surrounds the arcing area, through at least one outlet flow channel which has a number of areas which the quenching gas passes through successively. The first area which faces the constriction point of the nozzle has a specific flow resistance which is less than that of the constriction point. The first area in the outlet flow direction of the quenching gas is followed by at least one second area, one third area and one fourth area. The specific flow resistance of the second and fourth areas are each greater than the specific flow resistance of the immediately preceding area in the outlet flow direction.