| 摘要 |
A gas-blast circuit breaker includes within a contact chamber which is filled with a pressurized arc extinguishing gas a hollow shaft rotatable about its axis, a pair of normally open power switching contact structures located at opposite sides of the shaft and which are connectable temporarily in series during an opening operation of the breaker, and a normally closed supplementary switching means of the knife blade type arranged in a current path electrically in parallel with the power switching contact structures. Each of the power switching contact structures includes a movable contact carried by the rotatable shaft and a nozzle communicating with the interior of the shaft for carrying off the flow of arc extinguishing gas when the movable contact disengages from its associated stationary contact, and the supplementary switching means includes a movable contact blade carried by the rotatable shaft in association with a stationary contact. The operating sequence of the switches during a circuit breaking operation is that when the hollow shaft is rotated, the circuit through the power switching contact structures is completed before the circuit through the supplementary switching means is opened thereby enabling the contacts of the latter to open in an arc-free manner and transfer the load current to the circuit through the then in series connected power switching contact structures.
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