A separating wall for dividing a heating volume of a power circuit into a first sub-volume and a second sub-volume. The separating wall is formed with at least one wall opening which allows a flow of gas between the sub-volumes. The wall opening has an aerodynamically active opening surface based on a pressure difference between a pressure in the first sub-volume and a pressure in the second sub-volume.

A gas circuit breaker includes a rod-shaped fixed arc contact, a cylindrical movable arc contact to contact or be separated from the fixed arc contact, a heat puffer chamber storing an arc-extinguishing gas to be blown to an arc generated between the fixed arc contact and the movable arc contact, and an insulator received within a receiving hole formed in a distal end part of the fixed arc contact. An end surface of the insulator on a side of the movable arc contact faces the side of the movable arc contact via an opening end of the housing hole, the end surface on the side of the movable arc contact is disposed closer to the inside of the housing hole than the opening end is, and the insulator is made of an ablation material that is vaporized by heat of the arc.

To provide a gas circuit breaker designed to achieve further improvement in interruption performance for a small to medium current. The gas circuit breaker according to the present invention includes: an operation mechanism 1; a heat puffer chamber 19; a machine puffer chamber 32; a release valve 34; a movable main contact 5 and movable arc contact 11; a stationary main contact 6 and stationary arc contact 12; a movable-side leading conductor 14; and a stationary-side leading conductor 15, and features: a separation cylinder 21 for radially partitioning the heat puffer chamber 19; an inner circumferential flow path 24 formed on an inner circumferential side of the separation cylinder 21; and a check valve 22 for opening or closing a communication hole 23.

The invention relates to an electric arc-blast nozzle for a circuit breaker comprising a middle portion forming a throat defining internally an axial passage for interrupting an electric arc, and two end portions extending on either side of the middle portion and being designed to receive respective arcing contacts and that are movable axially relative to each other.

The middle portion and the two end portions are made of a same dielectric material obtained from a composition consisting of a fluorocarbon polymer matrix and of at least one oxide, the oxide(s) being present in a proportion by weight lying in the range 11% to 50%, relative to the total weight of the composition.

The invention also relates to a circuit breaker including such a nozzle.