A circuit breaker apparatus has a housing, electrical power inlet, electrical power outlet, a main circuit breaker, a grounding switch, and a mechanical linkage. The main circuit breaker and the grounding switch each have a pair of contactors therein. The mechanical linkage is movable between a pair of positions in which one of the positions causes the pair of contactors of the main circuit breaker to close and the pair of contactors of the grounding switch to open and another position in which the pair of contactors of the main circuit breaker are open and such that the pair of contactors of the grounding switch are closed. The housing has an interior that is filled with an isolating gas.

A switch includes: a first contact and a second contact placed on an operation axis and facing each other; an urging part that urges the second contact to a first contact side; and a second magnetic material part that engages with the second contact to restrict the second contact from moving to the first contact side. The switch also includes: a conductor part that passes current when an arc is formed between the first contact and the second contact; and a first magnetic material part that surrounds the conductor part. When current flows through the conductor part, the second magnetic material part is disengaged from the second contact.

A switch includes: a first contact and a second contact placed on an operation axis and facing each other; an urging part that urges the second contact to a first contact side; and a second magnetic material part that engages with the second contact to restrict the second contact from moving to the first contact side. The switch also includes: a conductor part that passes current when an arc is formed between the first contact and the second contact; and a first magnetic material part that surrounds the conductor part. When current flows through the conductor part, the second magnetic material part is disengaged from the second contact.

In a gas circuit breaker, arc-extinguishing gas is filled in a container. A movable portion housed in the container includes a movable arc contact. The movable portion includes a pressure accumulator that increases pressure of an arc-extinguishing gas. An opposing portion housed in the container includes an opposing arc contact, an exhaust pipe, and a shielding portion. The shielding portion includes a first shielding wall intersecting with an axial direction of the pipe and a second shielding wall having a cylindrical shape extending from the first shielding wall toward the movable portion along the axial direction of the pipe. The second shielding wall includes through-holes. Lengths of the respective through-holes along the axial direction are from 18 millimeter's to 55 millimeters inclusive. An arc-extinguishing gas whose pressure has been increased in the pressure accumulator flows into a space to extinguish arc discharge, and flows into the second shielding wall.

A switch includes a first contact and a second contact that are placed along an operating shaft and can reciprocate with respect to each other. An end of the second contact opposite to an end thereof on the side of the first contact is housed in a housing space of a housing box. The pressure in the housing space is increased due to an arc generated when the first contact approaches the second contact. The increased in the pressure causes the second contact to move toward the first contact.

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.

An interrupter unit for a circuit breaker has two electrically conductive arcing contact pieces, which can be moved relative to one another along a switching path. An insulating nozzle has a nozzle channel through which the switching path runs. A heating volume is connected to the nozzle channel. A separating housing divides the heating volume into a cold gas region and a hot gas region. A cold gas duct runs through a nozzle channel end section of the nozzle channel and is connected to the cold gas region. A hot gas duct runs through the nozzle channel end section and is connected to the hot gas region.

A switch includes a first contact and a second contact that are placed along an operating shaft and can reciprocate with respect to each other. An end of the second contact opposite to an end thereof on the side of the first contact is housed in a housing space of a housing box. The pressure in the housing space is increased due to an arc generated when the first contact approaches the second contact. The increased in the pressure causes the second contact to move toward the first contact.

In a gas circuit breaker, arc-extinguishing gas is filled in a container. A movable portion housed in the container includes a movable arc contact. The movable portion includes a pressure accumulator that increases pressure of an arc-extinguishing gas. An opposing portion housed in the container includes an opposing arc contact, an exhaust pipe, and a shielding portion. The shielding portion includes a first shielding wall intersecting with an axial direction of the pipe and a second shielding wall having a cylindrical shape extending from the first shielding wall toward the movable portion along the axial direction of the pipe. The second shielding wall includes through-holes. Lengths of the respective through-holes along the axial direction are from 18 millimeter's to 55 millimeters inclusive. An arc-extinguishing gas whose pressure has been increased in the pressure accumulator flows into a space to extinguish arc discharge, and flows into the second shielding wall.

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.