| 摘要 |
On opening of a circuit breaker, an end portion of a pivotable contact arm disengages from fixed contacts such that an arc is drawn therebetween radially across the pole face of a field coil, the end portion of the contact arm moving transversely to the field coil axis. The arc then transfers from the fixed contacts to a tubular electrode thereby bringing the field coil into circuit so that a magnetic field is generated which causes the arc to rotate and become extinguished. In the fully-open position of the circuit breaker, the end portion of the contact arm lies along the field coil axis. The whole assembly is disposed in a housing which contains the highly insulating gas sulphur hexafluoride. A single field coil and electrode can be shared between two such constructions. In addition, the initial arc can be drawn directly between the contact arm and the tubular electrode, rather than being transferred to the electrode from the fixed contacts.
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