GB641287A - Improvements in and relating to electromagnetic relays - Google Patents

Abstract

641,287. Electromagnetic switches. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 2, 1948, No. 3023. Convention date, July 25, 1942. [Class 38(v)] In a shock-proof relay the armature 13 is pivoted at its centre of gravity on a ridge 32, Fig. 4, formed on the bight portion of a U-shaped saddle 30. The saddle is fixed to the core 12 of the electromagnet and the armature held in place on the saddle by a bolt 31 passing through a shouldered washer 34 into the core. The arrangement provides sufficient space for the armature to pivot. In a modification, Fig. 7 (not shown), the bolt itself has a shouldered head and there is no separate washer. A spring 36 biasses the armature away from the R.H. leg of the magnetic frame 10, and in the form shown the armature carries two insulating bars 20 which carry strips 19 bearing contacts 18 at their ends each movable between a pair of fixed contacts 17. The spring 36 has a high frequency of vibration and the resonant frequency of the stationary parts is also high and different from that of the armature. For withstanding moisture the spool on. which the winding is wrapped is of a phenolic condensation product coated with cellulose acetate.