Abstract: A medium-, high-, or very high-voltage circuit breaker (10), comprising at least one arc-control chamber (12) and an outer casing (14) in which the arc-control chamber (12) is arranged. In the invention, the circuit breaker includes sealing ring (52) for sealing an opening (50) in a discharge cap (40) of the arc-control chamber (12), the ring (52) being movable between a sealing position and a retracted position in which they allow the gas to pass, the circuit breaker being configured in such a manner that in the closed position, the sealing ring (52) are in their retracted position, and in such a manner that passage from the retracted position to the sealing position takes place during an operation of opening the circuit breaker.

Abstract: A medium-, high-, or very high-voltage circuit breaker (10), comprising at least one arc-control chamber (12) and an outer casing (14) in which the arc-control chamber (12) is arranged. In the invention, the circuit breaker includes sealing ring (52) for sealing an opening (50) in a discharge cap (40) of the arc-control chamber (12), the ring (52) being movable between a sealing position and a retracted position in which they allow the gas to pass, the circuit breaker being configured in such a manner that in the closed position, the sealing ring (52) are in their retracted position, and in such a manner that passage from the retracted position to the sealing position takes place during an operation of opening the circuit breaker.

Abstract: A movable permanent contact (4) is made up of two portions (8, 11) separated by a dielectric spacer (12) and in communication with the electrical terminal (6) by means of respective rings of contacts (9, 10). The current flows mainly in the front ring (10) and the end of the portion (8) in normal operation. When the circuit breaker opens, the connection ceases, the current passes via the arcing contacts (2, 5), and the switching arc that appears briefly between contact portions (8 and 10) is confined in a step (14) and advantageously by a dielectric cap, thereby sparing the most sensitive portions of the volume between terminals, where the electrical field is the most intense.