Abstract: A medium-voltage substation includes at least two insulative material chambers each provided with at least one opening for the gas-tight passage of a set of three-phase busbars. Each chamber contains a three-position three-phase switch for connecting the busbars to first gas-tight electrical feed-throughs and for connecting the first feed-throughs to second gas-tight feed-throughs connected to ground. The first feed-throughs of at least one chamber are each electrically connected to a single-phase cable. The first feed-throughs of each chamber are electrically connected either to a fuse or to a pole of a circuit-breaker disposed in an insulative material compartment.

Abstract: A medium or high tension circuit breaker comprising a shell filled with a dielectric gas under pressure and containing: a fixed main contact, a moving main contact, a fixed arcing contact, and a moving arcing contact between which an arc is established during contact separation. The arc within the circuit breaker is split up into a large number of elementary arcs, with each elementary arc being established between two metal plates.