GB262777A - Improvements in or relating to combined overload and reverse current switches - Google Patents

Abstract

262,777. Siemens - Schuckertwerke Ges.- Dec. 8,1925, [Convention date]. Electromagnetic switches; cut-out arrangements. - A discriminating reverse-current and overload switch for use at a, b, c, d, Fig. 2, to protect rotary converters g<1>, g<2>, rectifiers u<1>, u<2> &c. supplying the same bus-bar s in parallel has a switching period shorter with reverse current than with current of normal direction, the operating flux reaching the release point more quickly in the case of reverse current than with normal. The switch comprises a magnet structure with a coil g energized from a constant voltage, this coil alone being adequate to attract the armature h and break the main circuit at k<1>, k<2>. The magnet structure is provided also with a series coil f which with current in the normal direction opposes g. A heavy current in this direction is therefore necessary to overcome the action of the coil g and cause the operation of the switch, whereas at zero current or any reversal of current the switch opeates. The line element is furnished by the use of short-circuited bands on the core which retard the growth of the flux- Specification 240,453 is referred to.