GB750019A - Improvements relating to electromagnetic relays and to circuits incorporating such relays - Google Patents

Abstract

750,019. Electromagnetic relays; protective cut-out systems. ENGLISH ELECTRIC CO., Ltd. Aug. 27, 1954 [Aug. 28, 1953], No. 23817/53. Class 38(5) A relay comprises three similar magnetically-separate cores 15, 13, 16, arranged side-by-side, the outer cores 15, 16 being energized by series-connected current coils 17, 18, and the centre core 13 being energized from a separate source by a voltage coil 14. The cores respectively co-operate with three magnetically-separate armatures 24, 25, 26 mounted on a carrier 27 pivoted at 28. A steel catch 34 pivoted on the carrier 27 in alignment with the armature 25 is biased clockwise by a spring 36 and by engaging an abutment plate 37 prevents pick-up of the relay by energization of the coils 17, 18. The relay is picked up by momentary energization of the coil 14 which also retracts the catch 34 so that it enters a slot 38, a contact 30 on an insulating arm 29 carried by the carrier 27 bridging a pair of contacts 31. The relay is retained closed against the .bias of a spring 33 by energization of the coils 17, 18. Protective cut-out systems. The contacts 31 are in the opening circuit of a breaker 53 controlling a series traction motor 50 supplied from an overhead line 51. An auxiliary shunt motor 55, controlled by a breaker 54 is connected in parallel with the motor 50, the combined load currents of the two motors returning to earth through the coils 17, 18. Thus, should the power supply fail or the load current fall below a predetermined value the relay releases and the breaker 53 'opens. In another arrangement (Fig. 6, not shown), employing two relays having their closing coils 14 connected in parallel and their tripping contacts 31 connected in series, the coils 17, 18 of one of the relays carry only the load current of the motor 50.