Abstract: An electric circuit-breaker in which the arc extinction chamber is filled with liquefield SF6 under pressure.The moving contact of the circuit-breaker cooperates with a blast-piston which, during opening of the breaker and after the moving contact has reached its ultimate open position, continues its travel in order to produce an intensive and protracted circulation of liquid dielectric from the arc extinction chamber in the region where the arc strikes across the contacts.Applications to ultra-high-speed breaking of high-tension, high-intensity alternating currents.

Abstract: The invention relates to hydraulic jack operating systems. The end-of-stroke damping of the jack is produced by an element of the shape of a truncated cone, integral with the stem of the jack, which penetrates into a floating ring and which defines, in this ring, a damping chamber isolated from the remainder of the capacity of the jack. When the stem of the jack makes its return movement, the chamber is re-supplied with oil through passages which were previously obturated by the displacement of the ring at the instant of the damping. The invention is applicable to high speed hydraulic controls for circuit breakers with ultra-rapid operation.

Abstract: A current-interrupting chamber containing stationary and moving contacts is filled with a dielectric consisting of SF.sub.6 gas maintained in the liquefied state under a pressure of considerably higher value than the critical pressure. An arc-quenching cylinder placed within the chamber in communication therewith contains a piston which is actuated conjointly with the moving contact so as to discharge a jet of liquid dielectric which is directed between the contacts in the radial centripetal direction and extinguishes the arc formed when the contacts are separated.

Abstract: A hydro-pneumatic accumulator of the type in which a piston slidable within a cylinder separates a liquid and a gas under pressure, is provided with an end closure of a non-magnetic material within which closure is provided a magnetically actuated switch. Movement of the piston causes a permanent magnet to be moved relative to the switch whereby movement of the magnet into the actuating range of the switch causes the switch to be actuated and an indication of the level of the liquid in the accumulator to be provided.

Abstract: A filter for liquids capable of containing a gas including a chamber for through-passage of a gas-charged liquid and which is subdivided into an upstream compartment and a downstream compartment by a filtering element, preferably in the form of a cylindrical strainer with a solid bottom, a liquid-supply pipeline opening into said upstream compartment, a liquid-outlet pipeline issuing from said downstream compartment, and an auxiliary conduit for exhaustion of gas directly communicating between said liquid-outlet pipeline and the upper part of said downstream compartment.

Abstract: The invention relates to drain devices in hydraulic control circuits, particularly for hydraulic ultrarapid release control of a circuit breaker. In order to enable rapid decompression and draining of high pressure fluid in an hydraulic jack which controls the circuit breaker, a plurality of drain valves are mounted directly on the jack in a cascade arrangement. The valves are hydraulically controlled by oil pressure on pilot jacks and are of progressively increasing cross-sectional areas. All the valves in cascade are physically coupled to one another and the setting to drain of the valve with the smallest cross-section is controlled by an electrovalve.