An electronic circuit breaker comprises an arc interruption mechanism that would enhance arc attraction to arc plates and would reduce the possibilities of an arc escaping from the arc plates. The arc interruption mechanism includes an enhanced arc extinguishing chamber. The arc extinguishing chamber includes a plurality of arc plates having first and second sides. The circuit breaker further comprises a stationary contact plate that includes a first arc runner disposed near the first side of the plurality of arc plates. The circuit breaker further comprises a load terminal that includes a second arc runner disposed near the second side of the plurality of arc plates. As an arc is attracted by the plurality of arc plates and the arc enters the plurality of arc plates, a length of a current path associated with the arc is reduced through the first arc runner and the second arc runner by reducing a resistance of the current path for the arc or by reducing a voltage across the circuit breaker.

According to an embodiment, a gas-blast circuit breaker comprises a heat removal unit in a flow path of arc extinguishing gas. The heat removal unit each includes: plate-shaped heat removal members contacting the arc extinguishing gas flowing in the flow path; and a holding portion holding the plate-shaped heat removal members to stack the heat removal members at intervals in a thickness direction. Each of the heat removal members includes: an upstream side end portion; a downstream side end portion; and a thickest portion with a largest thickness which is provided between the upstream side end portion and the downstream side end portion. Thickness of the heat removal member continuously changes between the upstream side end portion and the downstream side end portion via the thickest portion.

According to an embodiment, a gas-blast circuit breaker comprises a heat removal unit in a flow path of arc extinguishing gas. The heat removal unit each includes: plate-shaped heat removal members contacting the arc extinguishing gas flowing in the flow path; and a holding portion holding the plate-shaped heat removal members to stack the heat removal members at intervals in a thickness direction. Each of the heat removal members includes: an upstream side end portion; a downstream side end portion; and a thickest portion with a largest thickness which is provided between the upstream side end portion and the downstream side end portion. Thickness of the heat removal member continuously changes between the upstream side end portion and the downstream side end portion via the thickest portion.

A gas circuit breaker includes: a fixed arc contact extending along an operating axis; a moving arc contact allowed to move to a position where the moving arc contact contacts the fixed arc contact and a position where the moving arc contact is separated from the fixed arc contact; a frame forming a puffer chamber around the moving arc contact; a nozzle having a cylindrical shape centered on the operating axis, the nozzle being fixed to the frame and projecting in a direction toward the fixed arc contact from the moving arc contact; and an arc extinction assisting portion provided on an inner surface of the nozzle and made of an ablation material. The nozzle and the arc extinction assisting portion are provided with a fall-off preventing portion to prevent the arc extinction assisting portion from falling off the nozzle.

According to an embodiment, a gas-blast circuit breaker comprises a heat removal unit in a flow path of arc extinguishing gas. The heat removal unit each includes: plate-shaped heat removal members contacting the arc extinguishing gas flowing in the flow path; and a holding portion holding the plate-shaped heat removal members to stack the heat removal members at intervals in a thickness direction. Each of the heat removal members includes: an upstream side end portion; a downstream side end portion; and a thickest portion with a largest thickness which is provided between the upstream side end portion and the downstream side end portion. Thickness of the heat removal member continuously changes between the upstream side end portion and the downstream side end portion via the thickest portion.

According to an embodiment, a gas-blast circuit breaker comprises a heat removal unit in a flow path of arc extinguishing gas. The heat removal unit each includes: plate-shaped heat removal members contacting the arc extinguishing gas flowing in the flow path; and a holding portion holding the plate-shaped heat removal members to stack the heat removal members at intervals in a thickness direction. Each of the heat removal members includes: an upstream side end portion; a downstream side end portion; and a thickest portion with a largest thickness which is provided between the upstream side end portion and the downstream side end portion. Thickness of the heat removal member continuously changes between the upstream side end portion and the downstream side end portion via the thickest portion.

An apparatus switches a direct current in a high-voltage line. The apparatus contains a multiplicity of switching units, which are arranged so as to form a series circuit in the high-voltage line. Each switching unit in this case contains a switching element and a surge arrester arranged in a parallel circuit with the switching element, the threshold voltage of the surge arrester being higher than a rated voltage of the switching element. A sum of the rated voltages of the switching elements corresponds at least to an operating voltage of the high-voltage line. The switching elements are mechanical switches, and each mechanical switch contains a contact arrangement having two disconnectable contact pieces and is configured to build up an arcing voltage on disconnection of the contact pieces with a magnitude which is higher than the rated voltage of the mechanical switch.

An apparatus switches a direct current in a high-voltage line. The apparatus contains a multiplicity of switching units, which are arranged so as to form a series circuit in the high-voltage line. Each switching unit in this case contains a switching element and a surge arrester arranged in a parallel circuit with the switching element, the threshold voltage of the surge arrester being higher than a rated voltage of the switching element. A sum of the rated voltages of the switching elements corresponds at least to an operating voltage of the high-voltage line. The switching elements are mechanical switches, and each mechanical switch contains a contact arrangement having two disconnectable contact pieces and is configured to build up an arcing voltage on disconnection of the contact pieces with a magnitude which is higher than the rated voltage of the mechanical switch.

A switchgear includes an interrupter unit. The interrupter unit is provided with first and second switching contact pieces that are movable relative to one another. A switching-gas duct that runs through the interrupter unit originates at an arc gap in which an electric arc can burn. The duct connects the arc gap to the surroundings of the interrupter unit. At least some sections of the switching-gas duct are delimited by mutually encompassing elements similar to an annular duct. One of the elements is a first member which is braced at the end similar to a pipe joint and which has a free end that projects in the direction of the arc gap.

A switchgear includes an interrupter unit. The interrupter unit is provided with first and second switching contact pieces that are movable relative to one another. A switching-gas duct that runs through the interrupter unit originates at an arc gap in which an electric arc can burn. The duct connects the arc gap to the surroundings of the interrupter unit. At least some sections of the switching-gas duct are delimited by mutually encompassing elements similar to an annular duct. One of the elements is a first member which is braced at the end similar to a pipe joint and which has a free end that projects in the direction of the arc gap.