GB809432A - Improvements in or relating to electromagnetic relays - Google Patents

Abstract

809,432. Electromagnetic relays. STANDARD TELEPHONES & CABLES Ltd. Aug. 10, 1955, No. 23011/55. Class 38 (5). A relay comprises a pair of parallel cores 1, 2, one or both of which carry one or more windings (not shown), and connected by magnetic bars 3 situated centrally as shown or at one end of the cores. A pair of armatures 4, 5 hinged at the ends of the core 1 have cross-plates 6, 7 connected by bars 8, 9 operating contact spring sets 10, 11. In one method of operation the bars 3 are central and a winding is placed on each end of the core 2, energization of one or the other winding causing attraction of a corresponding armature. Thus, there must be always one winding energized. In another method of operation, the bars 3 comprise permanent magnets and are situated at one end of the cores and only a single winding on core 2 is necessary. On de-energization of the winding the attracted armature remains held by the permanent magnet flux. The polarity of the energizing current determines which armature is operated. In a further arrangement permanent magnet bars 3 having soft iron shunts are placed at one end of the cores 1, 2, the armature nearer to the bars 3 (e.g. armature 5) having a much greater reluctance than the armature 4 and being spring-biased to the released position. When the coil is not energized the armature 4 is held in the attracted position by the spring. Current in the coil of one polarity serves to reinforce the spring pressure whilst current of the opposite polarity causes attraction of the armature 5. An actual relay construction is described with reference to Figs. 2-6 (not shown), this construction being similar in a number of respects with the relay disclosed in Specification 809,431.