Abstract: An automatically resetting safety valve for a generator circuit breaker is to open rapidly and wide, even if the pressure applied to a valve-closing body (1) does not increase substantially over a valve stroke (a) or even falls. In order to ensure this, a valve-closing-body joint (10) of the valve-closing body (1) via a first closing-body lever (H1) and via a first sliding joint (3), is connected in an articulated manner to a first support lever (H2), which is rotatably mounted in a first support lever joint (4) fastened to a lever wall (5). The first sliding joint (3), via a first compression spring (8), is in compressive connection with a spring wall joint (7) fastened to a spring wall (6). The valve-closing body (1) is movable along a plain-bearing axis (A). First and second closing-body levers (H1, H1′) and first and second support levers (H2, H2′), which are arranged in mirror image relative to the plain-bearing axis (A) of the valve-closing body (1), may be provided.