GB470532A - Improvements in and relating to electrical contact making and breaking devices - Google Patents

Abstract

470,532. Electromagnetic switches and switch contacts. ELECTRICAL APPARATUS CO., Ltd., and BARBOUR, R. H. July 28, 1936, No. 20871. [Class 38 (v)] Electrical contact making and breaking devices such as contactors switches and circuit breakers, particularly those used on A.C. circuits of the type comprising a moving contact mounted on a carrier, limited relative movement of the contact and carrier being permitted under the control of a spring have an additional spring between the carrier and the movable contact which acts as a flexible limit to the relative movement of the moving contact and carrier in the contact-opening movement the strength of the additional spring or springs thus varying the speed of separation of the contacts. As applied to an electromagnetic contactor of the type described in Specification 456,125, the contact carrier, as shown in Fig. 2, comprises insulating members 23, 33 carried by the armature 13 and biassed from the fixed core 12 by springs 17 surrounding guide pins 15, Figs. 4 and 5. The movable contacts consist of bars 18 slidable on guide rocks 28, adapted to bridge pairs of fixed contacts 19. The contacts are normally held relatively to the carrier by springs 21 acting on plates 24 engaging shoulders 25 in the contact housing additional springs 22 acting on the underside of the bars 18 to. hold them against the plates 24. As the armature is attracted on energization of the coil 11, the bars 18 are first moved against the contacts 19 by downward movement of the carrier after which further movement of the carrier takes place independently of the contact bars 19. During this movement the springs 21 press the contacts firmly into engagement. In the contact-opening movement when the electromagnet is deenergized the carrier is retracted by the springs 17, the contacts however remaining in engagement by the pressure of springs 21'until the plates 24 are engaged by the shoulders 25. Further movement of the carrier then lifts the plates 24 clear of the bars 18 which are then moved away from the contacts by the additional springs 22. The contacts are thus separated at a speed which is not necessarily the same as that which the contact-carrier has attained at the moment of the contact, separation and different speeds of separation may be produced by substituting different strengths of springs 22. The amount of relative movement of contacts and carriers in the opening movement is limited by stops 26. The relatively-fixed contacts may be substituted by contacts, movably mounted in the manner described above, and the moving contact or contacts may alternatively be operated pivotally.