| 摘要 |
The device for switching electrical current contains a compressed gas-blast circuit-breaker, at least one vacuum circuit-breaker (14) and two current connections (2, 3). In this switching device, a first erosion contact (10) of the compressed gas-blast circuit-breaker is electrically conductively connected to a stationary electrode (15) of the vacuum circuitbreaker (14), a second erosion contact (7) of the compressed gas-blast circuit-breaker is electrically conductively connected to a first current connection (2) of the two current connections (2, 3) and a movable electrode (16) of the vacuum circuit-breaker (14) is electrically conductively connected to a second current connection (3) of the two current connections (2, 3), thereby forming an extinction current path. The two electrodes (15, 16) of the vacuum circuit-breaker (14) can be separated from one another without using the drive (5) and receive a contact pressure force which prevents the separation of the electrodes (15, 16) below a limit value of the current to be disconnected. During switching off, the current to be disconnected is commutated from a rated current path, which contains two rated current contacts (8, 11) of the compressed gas-blast circuit-breaker, into the extinction current path running in parallel therewith. The vacuum circuit-breaker (14) which is now situated in the extinction current path is only opened when the current to be disconnected exceeds the abovementioned limit value. Since the vacuum circuit-breaker (14) carries no rated current and, in contrast to the compressed gas-blast circuit-breaker, participates only in a few disconnection operations, it can be dimensioned for considerably lighter duty than a vacuum circuit-breaker which carries rated current and is actuated during every switching operation.
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