| 摘要 |
1,132,521. Automatic circuit-breakers; vacuum switches. S. SHIMADA. 28 Jan., 1966 [2 Feb., 1965; 5 Feb., 1965; 1 June, 1965; 26 Nov., 1965; 2 Dec., 1965; 22 Dec., 1965; 28 Dec., 1965], No. 3945/66. Heading H1N. An armature 19, Fig. 3, carrying one contact 14b of an automatic circuit-breaker and normally attracted to a permanent magnet 17 is surrounded by a coiled conductor 16 in series with the contacts so that under overload the armature 19 is heated by the coil 16 reducing the attraction by magnet 17 and allowing the contacts to be opened by springs 11. The magnet 17 is attached to a second magnet 45 which is magnetically coupled to a further magnet 49 movable by a handle 50 so that the contacts can be manually operated between open and closed positions. The magnets 17, 45 and armature 19 are slidable on a pin 44 mounted in a sealed evacuated envelope 37. In an alternative embodiment (Fig. 2, not shown) the magnet 17 is directly attached to a push-button (6<SP>1</SP>) and is held in the closed position by a fixed magnet (34). In a third embodiment (Fig. 1) the armature 19 is maintained in the closed position by the weight of attached magnet 17 but, under overload, the magnet separates from the armature and spring 11 draws the armature upwards to separate the contacts. The armature is located in the closed position by a ball catch 8-10. Under overload, the coil 16 heats the armature to reduce the magnetic attraction, thus releasing the contacts after a time delay but under shortcircuit conditions the magnetic effect of the coil reduces the attraction instantaneously providing a current limiting action. |
