Abstract: A self-blowout circuit breaker is disclosed which includes contacts for connecting or disconnecting a circuit, a heating volume, a compression volume and an exhaust volume. The compression volume can be connected to the heating volume by at least one first valve, which heating volume is in turn connected to an arc zone. Upon the disconnection of the circuit, while a first arcing contact is being disconnected from an associated second arcing contact, an arc is produced between the two arcing contacts in the arc zone. The compression volume is separated from the exhaust volume by a combined filling and overpressure valve which is formed as at least one plate, and has at least one tab which is formed in the plate.

Abstract: A relief valve for discharging a dielectric gas between two volumes (V1, V2) of a high-voltage or medium-voltage interrupting chamber. There is used as a closure member a flexible metal blade secured to the body, the closure member therefore being opened by deformation of the flexible blade from a closed position (FIG. 1) in which it is pressed against a closure member seat formed in the body to a fully open position in which it fits closely against a stop member secured to the valve body while remaining within its elastic limit, the open passage for the gas being open in this fully open position (FIG. 1A) and the return of the blade from its fully open position to its closed position being possible because of its flexibility.

Abstract: In a switchgear, by using a spring with a varying spring constant from closing to electrode opening as a loading spring, spring load in the opened electrode state is made smaller than a spring load in the closed electrode state to decrease the energy required from electrode closing up to electrode opening. Moreover, by using a spring in which a load in the opposite direction to a load in the closed electrode state works in the opened electrode state, the opened electrode state can be held securely.