GB834142A - Improvements in or relating to polarised electromagnetic changeover relays - Google Patents

Abstract

834,142. Electromagnetic relays. SIEMENS & HALSKE A.G. Dec. 19, 1957 [Dec. 21, 1956], No. 39548/57. Class 38 (5). A polarized electromagnetic change-over relay has a deflectable magnetic contact arm 4 and two fixed magnetic contact arms 2, 3 in a sealed tube 1. A U-shaped permanent magnet 5 embraces the tube with its field perpendicular to the axis of the tube and passing across the gap between the contacts. Operating coils 6, 7 set up a magnetic field along the contact arms so as to deflect the arm 4 to engage one of the arms 2 or 3 dependent upon the direction of the current in the coils. The magnet 5 may be tilted so that its right-hand end is brought nearer to one of the arms 2 or 3 so as to bias the arm 4 in that direction (Fig. 3). The flexural stiffness of the arm 4 and the strength of the magnet 5 may be such that the arm 4 is bi-stable and is retained in the position which it occupied when last energized. An operating coil 10 (Fig. 4) may surround the tube 1 and magnet 9 which is then cylindrical or formed by bending so as to leave an axial slot (Fig. 6, not shown). A second cylindrical permanent magnet, axially polarized, may surround the end of the tube containing the arm 4 so as to bias it towards one of the fixed contacts (Fig. 7, not shown). Both cylindrical magnets may be rotatable about the axis of the tube to adjust for structural asymmetry in the relay.