GB838299A - Improvements in or relating to electromagnetic relays - Google Patents

Abstract

838,299. Electrically - released switches. REYROLLE & CO. Ltd., A. June 22, 1956, No. 19408/56. Class 38 (5). A relay magnetic circuit comprises a core A carrying windings B<SP>1</SP>, B<SP>2</SP> and a yoke C connected to the core through a fixed air gap formed by the flange D<SP>2</SP> of a non-magnetic bush D which surrounds the threaded core end A<SP>1</SP>. A permanent magnet K extends between the core and yoke and produces a flux in two paths as shown in Fig. 3; however, the flux in the left-hand path is insufficient to attract a pivoted armature F against its spring bias. Preferably, the reluctance of the left-hand path due to the air gap between the armature and core A is greater than the reluctance of the right-hand path due to the bush D. Energization of the series connected coils B<SP>1</SP>, B<SP>2</SP> with D.C. from a source L produces a counterclockwise flux in the circuit B, C, F and the armature is attracted so that an armature arm H operates spring contacts J. On de-energization of the coils the armature remains held by the permanent magnet flux, and the armature is released by energizing the coil B<SP>1</SP> with current of reverse polarity from a source M.