Abstract: A single- or multi-pole power circuit-breaker, comprises main contacts, overload- and/or short-circuit current-actuated tripping means, an actuating mechanism for the main contacts, an arc chute and a pressure trip unit having a return element and an actuating element responsive to an overpressure in the arc chute. The tripping of the power circuit-breaker by a trip mechanism is executable both by the tripping means and the pressure trip unit. The pressure trip unit is arranged immediately adjacently to both the arc chute and a main busbar. A tripping lug mechanically engages with the trip mechanism such that an overpressure in the arc chute is transmitted virtually instantaneously to the pressure chamber. The actuating element is configured to switch over directly from a home position to a tripping position, against the force of the return element, in a case of overshoot of a pressure threshold value set by the return element.

Abstract: A single- or multi-pole power circuit-breaker, comprises main contacts, overload- and/or short-circuit current-actuated tripping means, an actuating mechanism for the main contacts, an arc chute and a pressure trip unit having a return element and an actuating element responsive to an overpressure in the arc chute. The tripping of the power circuit-breaker by a trip mechanism is executable both by the tripping means and the pressure trip unit. The pressure trip unit is arranged immediately adjacently to both the arc chute and a main busbar. A tripping lug mechanically engages with the trip mechanism such that an overpressure in the arc chute is transmitted virtually instantaneously to the pressure chamber. The actuating element is configured to switch over directly from a home position to a tripping position, against the force of the return element, in a case of overshoot of a pressure threshold value set by the return element.