Abstract: A switching device for switching bipolar DC currents in a high-voltage system includes at least two electromechanical switching units and a semiconductor switching arrangement. The electromechanical switching units have a first switching status and a second switching status. In the first switching status, the DC current can be passed via at least one of the electromechanical switching units without in this case flowing via the semiconductor switching arrangement. In the second switching status of the electromechanical switching units, the DC current can be passed via the semiconductor switching arrangement and can be switched off.

Abstract: A switch for a high-voltage direct current transmission path includes a vacuum circuit breaker for disconnecting the transmission path and a gas-insulated circuit breaker for disconnecting the transmission path. The gas-insulated circuit breaker is connected in series with the vacuum circuit breaker. A device is provided for building up a counter-current against the current in the transmission path for the purpose of reducing the current across the vacuum circuit breaker. The elements of the switch are actuated by a control device in such a way that the switch is switched off at or close to the zero crossing of the current.

Abstract: A switching device for switching bipolar DC currents in a high-voltage system includes at least two electromechanical switching units and a semiconductor switching arrangement. The electromechanical switching units have a first switching status and a second switching status. In the first switching status, the DC current can be passed via at least one of the electromechanical switching units without in this case flowing via the semiconductor switching arrangement. In the second switching status of the electromechanical switching units, the DC current can be passed via the semiconductor switching arrangement and can be switched off.

Abstract: A switch for a high-voltage direct current transmission path includes a vacuum circuit breaker for disconnecting the transmission path and a gas-insulated circuit breaker for disconnecting the transmission path. The gas-insulated circuit breaker is connected in series with the vacuum circuit breaker. A device is provided for building up a counter-current against the current in the transmission path for the purpose of reducing the current across the vacuum circuit breaker. The elements of the switch are actuated by a control device in such a way that the switch is switched off at or close to the zero crossing of the current.

Abstract: An insulating component for use in high-voltage switching equipment, especially gas-insulated switching gear. A nozzle made of an insulating material is used in a power switch. Portions of the surface of the nozzle subject to high dielectric stresses in use are provided with increased surface roughness in the form of grooves. These grooves may be cut by a lathe.