This power breaker has at least one quenching chamber, which is filled with an insulating medium, is of cylindrical design, extends along a central axis (2) and has a power current path, having two stationary consumable contact arrangements (5, 6) which are arranged on the central axis (2), are at a distance from one another in the axial direction and are arranged in the power current path. In the connected state, the consumable contact arrangements (5, 6) are electrically conductively connected by means of a moving bridging contact. An arc zone (24) is provided between the consumable contact arrangements (5, 6). A rated current path is arranged in parallel with the power current path. The power breaker is provided with at least one source for a highly pressurized insulating medium. The medium passes from this source directly into the arc zone (24), through at least one injection channel (62, 63). This high-pressure injection considerably improves the breaking capacity of the power breaker.