The gas-circuit-breaker includes a container, opposing part, movable-part, and nozzle. An arc-extinguishing gas fills the container. The opposing-part is housed in the container and includes an opposing-arc-contact and an exhaust stack. The movable-part is housed in the container and includes a movable-arc-contact coming in contact with the opposing-arc-contact in a connected-state and separating from the opposing-arc-contact in an open-state; and a pressure-accumulation-part where an arc-extinguishing gas pressure increases. The nozzle is housed in the container and includes a space where arc-discharge occurs between the movable-arc-contact and the opposing-arc-contact. The nozzle includes a middle-part where the opposing-arc-contact is inserted and one or more jet-holes that eject, toward the space, partial arc-extinguishing gas flowing in from a flow-passage between the pressure-accumulation-part and the middle-part. The arc-extinguishing gas whose pressure increases in the pressure-accumulation-part flows into the space via the flow-passage and the jet-holes to extinguish the arc-discharge.

To improve an interruption process, a switching chamber for a gas-insulated circuit breaker comprises a thermal channel having a bend part delimited by an outer surface of an auxiliary insulating nozzle including a first bend section on a thermal volume side, a third bend section on an arcing region side, and a second bend section connecting the first bend section to the third bend section, and by an inner surface of a main insulating nozzle including a fourth bend section on a thermal volume side, a sixth bend section on an arcing region side, and a fifth bend section connecting the fourth bend section to the sixth bend section, such that in axial section view, the first to sixth bend sections form 30 degrees arcs of circles having respective radii R1, R2, R3, R4, R5 and R6 such that R1>R2>R3 and R4>R5>R6.

A gas-insulated high or medium voltage circuit breaker includes: a first arcing contact and a second arcing contact, whereby at least one is axially movable along a switching axis, thereby forming an arc between the first arcing contact and the second arcing contact in an arcing region, a buffer cylinder including a channel directed to the arcing region and/or a nozzle for blowing during the breaking operation an arc-extinguishing gas to the arcing region; a first enclosure associated to first arcing contact substantially sur-rounding the buffer cylinder and arranged slidable in respect to the buffer cylinder and/or a second enclosure substantially surrounding the nozzle and arranged slidable in respect to the nozzle; and a labyrinth structure provided in the first enclosure and/or in the buffer cylinder between the first enclosure and the buffer cylinder and/or in the second enclosure and/or in the nozzle between the second enclosure and the nozzle.

Disclosed is a DC circuit breaker capable of interrupting fault currents flowing in both forward and backward directions. The DC circuit breaker includes: a first mechanical switch for interrupting a current in a DC transmission line; a first diode connected in parallel with the first mechanical switch; a second mechanical switch, connected in series with the first mechanical switch, for interrupting a current in the DC transmission line; a second diode connected in parallel with the second mechanical switch; an LC circuit connected in parallel with the first and second mechanical switches and including a capacitor and a reactor connected in series to induce LC resonance; a first unidirectional switching device connected in parallel with the LC circuit and switching a current to induce LC resonance; and a bidirectional switching device connected in series with the LC circuit and switching currents flowing in both forward and backward directions.

A gas circuit breaker including a pair of main contacts is openable inside an insulating tank. A pair of arc contacts is arranged on the inner side of the main contacts, and a puffer cylinder has the main contacts and the arc contacts at an end. A puffer chamber is formed inside the puffer cylinder, and a puffer piston is provided on the inner periphery of the puffer cylinder. An insulating nozzle part is mounted on an end of the puffer cylinder to surround the arc contact. The insulating nozzle part includes a split nozzle base part and a split nozzle end part, and the split nozzle base part has a throat part.

A circuit breaker for a HV Circuit-breaker includes a pair of permanent contacts, at least one of them being movable along an axis; an insulating nozzle having a central cylindrical wall defining a longitudinal cylindrical hole, along the axis; a pair of arcing contacts, at least one of them being movable along the axis, a lateral wall of one of the arcing contacts being at a distance from the central cylindrical wall thereby defining a cylindrical volume between the arcing contact and the central cylindrical wall, the arcing contact further comprising at least one inner central channel extending along the axis and along part of the arcing contact, and at least one lateral conduit between the at least one inner channel and at least one lateral hole.