GB361535A - Improvements in or relating to electro-magnetic relays - Google Patents

Abstract

361,535. Light current relays. COVENTRY AUTOMATIC TELEPHONES, Ltd. and MYERS, C., of General Electric Co., Stoke, Coventry. Oct. 20, 1930, No. 31373. [Class 38 (v).] In a relay having a plurality of coils with their associated flux paths and a permanent magnet, the flux paths are arranged so that although the armature may be attracted in one direction by any of the coils, variations of the flux through the coil included in the armature flux path caused by variations of current in that coil are not reproduced in the other flux paths. As shown in the Figure, an armature 1 pivoted at 4 to a yoke 3 is adapted to be attracted in the same direction by the energization of a coil 6 or of a coil 2. The latter is mounted on a polepiece of the yoke 3 adjacent the armature and the coil 6 on a cross-limb of the yoke. The two limbs of the yoke being bridged by a permanent magnet 5. Normally the greater part of the flux of the magnet 5 passes through the left-hand branch of the magnetic circuit, including the coil 6 and the polarity of the magnet is such that most of the flux of the coil 2, when energized, passes through the magnet 5. Thus if the coil 6 is shortcircuited and a current started or stopped in coil 2 no appreciable eddy-current effect is produced in the short-circuited coil and consequently no appreciable delay in the armature movement is produced by the short-circuited coil. The armature can be attracted by coil 6 if energized to produce a flux opposing that of the permanent magnet, the permanent magnet flux being this diverted through the path including the armature. Portions of the magnetic circuit may be made of nickel-iron alloy to assist in the reduction of eddy-current effects.