GB775742A - Improvements in voltage regulator devices - Google Patents

Abstract

775,742. Transformers. FOSTER TRANSFORMERS, Ltd., JENNINGS, R. E., and STEWART, 1. R. MAXWELL-. April 13, 1955 [April 14, 1954], No. 11012/54. Class 38(2). A voltage regulating device incorporating an on-load transformer tap-changing system comprises coarse and fine switches mechanically coupled through a reduction gear, the coarse switch co-operating with tappings on the transformer and the fine switch supplied from a further transformer and arranged to inject a variable voltage into the output circuit. A coarse switch comprises two contacts 18, 19 moving together over studs 11 ... 17 con. nected to tappings on a transformer winding T. The fine switch comprises a movable brush 5 associated with secondary windings 3, 4 of a toroidally wound transformer, the primary winding 2 of which is energized from a further transformer winding 20. The secondary windings 3, 4 are connected to the moving contacts 18, 19 of the coarse switch and the maximum voltage from each secondary winding is made equal to half that which exists between the tappings, or studs, of the main transformer winding T. Assuming an initial zero voltage position with both moving contacts 18, 19 on stud 11, then as the brush 5 is rotated over a winding 3 or 4 the voltage of the output circuit O will be increased up to half an increment when the brush 5 has moved half a revolution. At this point the contact 19 will move to stud 12 but the voltage of the output circuit O will remain at half an increment because the Winding 3 or 4 opposes the voltage derived from the main winding. Further rotation of the brush 5 now decreases the opposing voltage until when the brush 5 has completed one revolution the opposing voltage is zero and the voltage of the output circuit O will be one increment. Continued rotation of the brush 5 will still further increase the voltage of the output circuit. Apparatus according to the invention may be associated with that of Specification 775,741. The toroidally wound transformer 2, 3, 4 is. of circular outer configuration and has a contact moving around it in direct contact with the turns thereof and associated with a further contact co-operating with a slip-ring. Each secondary winding may be in two parts wound alternately one beside the other and each connected to its associated circuit through current limiting resistors. Specifications 607,347, 619,474, [Group XXXVII], 675,615 also are referred to.