GB407714A - Improvements in and relating to electric converting apparatus - Google Patents

Abstract

407,714. Converting. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Sabbah, C. A. ; 1, Washington Avenue, Schenectady, New York, U.S.A.) Sept. 19, 1932, No. 26028. Convention date, Sept. 19, 1931. [Class 38 (ii).] In a rectifier or inverter system the D.C. circuit is bridged by two parallel paths, each path including a pair of valves 12, 13 and an inductive winding, the A.C. network being connected between centre-taps of the inductive windings. These inductive windings are coupled, but have a large leakage reactance so as to give protection against short circuit and back-ignition. Grid control renders the valves 12, 15 and 13, 14 alternatively conductive so that A.C. flows in the primary winding of the transformer 20. The windings 16, 17 are arranged on a core 18 having a third limb with an air-gap 19. During normal operation the currents flowing in the windings will produce fluxes in the core having the same direction so that the arrangement will act as a choke. If back-ignition occurs in one of the valves, the A.C. circuit will be short circuited, the short circuit current being limited by the leakage reactance of the arrangement since currents flow in the windings 16, 17 producing fluxes in opposition. In a modification two A.C. circuits are supplied. Reference has been directed by the Comptroller to Specifications 144,720, [Class 38 (ii)], and 374,012.