Gas circuit breaker having independent main and arcing circuits

Claim 1

Circuit-breaker with an arc-extinguishing device mounted in a tubular housing filled with an insulating gas of high dielectric strength such as sulfur hexafluoride and including: a main circuit having stationary and movable main contacts, an independent arcing circuit comprising stationary and movable arcing contacts forming an auxiliary circuit bypassing said main circuit, said movable arcing contact being axially movable in said housing and independent from said main movable contact, an operating mechanism coupled to said movable contacts so as to open said main contacts before the separation of said arcing contacts, said main and arcing contacts being surrounded by said insulating gas, a pair of input and output terminals extending through the wall of said housing and being longitudinally spaced in said housing, said main and arcing circuits being electrically connected in parallel to said input and output terminals and forming two independent current paths inside said housing, said main circuit extending rectilinear along the axial direction of said housing between said input and output terminals inside said housing, and said arcing circuit being laterally spaced from said main circuit, so that the electrical paths comprising loops formed by the main and arcing circuits have substantially the same reactance, said arcing circuit being formed such that a majority of the current of said breaker flows through the main circuit in the closed position of the circuit breaker until the separation of the main contacts, said arcing circuit including a connecting member which can move relative to said arcing circuits arranged between the movable arcing contact and one of a pair of current-supplying terminals so that the magnitude of current in said member as compared to the magnitude of current in said main circuit is low.