GB553329A - Improvements in electromagnetic relays - Google Patents

Abstract

553,329. Electromagnetic switches; contacts. WESTERN ELECTRIC CO., Inc. July 11, 1942, No. 9673. Convention date, July 17, 1941. [Class 38 (v)] In electromagnetic relays having contacts such as 8, 9, 13 carrying films of conducting liquid such as mercury, two or more of the contacts are of appreciable area so that on separation of the two contacts, the film between them is drawn, out and the actual moment of break retarded. Fig. 1 shows a form having two flattened fixed contacts 8, 9 between which moves a flattened contact 13 carried by a cylindrical armature 10 floating in mercury in a fixed guide tube 4 connected to an electrode 5. The members 4, 10 are of materials wettable by mercury and the contact 13 is formed from a doubled length of wire flattened at 13. Mercury is carried by capillary attraction up to the part 13 and thence to the contacts 8, 9. The armature is adapted to be attracted upwards to the pole pieces 2, 3 upon energization of the relay and additional delayed action is provided by means of a small hole 11 in the bottom wall of the armature. The contacts 8, 9 may be sufficiently close together that contact is made between 13 and 8 before the mercury film between 13 and 9 has broken. In modifications, one of the contacts 8, 9 is an unflattened wire so as to provide a quick "break" between it and the contact 13. Specifications 543,008, and 543,935 are referred to.