GB612191A - Improvements relating to apparatus for operating devices having a negative resistance characteristic from an alternating electric current supply circuit - Google Patents

Abstract

612,191. Phase-changing; supply systems for lighting or welding arcs. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd., and WALKER, A. H. B. May 17, 1946, No. 14960. [Classes 38 (ii) and 38 (iv)] A load having a negative resistance characteristic, such as an arc lamp or welding device is fed from a single phase A.C. supply through a phase converter and rectifier, with the stabilizing ballast impedance connected to the supply side of the phase converter. The ballast impedance comprises an inductor 8 variable by tappings 10, and a condenser 7 of the kind described in Specification 473,368, connected across supply terminals 9. The 1-3 phase converter is combined with a transformer 1 having delta connected primary windings 2, 3, 4, of which 3 is connected across condenser 7, and 2 and 4 have an inductor 12 and a condenser 13 connected across them respectively. Three phase-displaced E.M.F's. are thus induced in the star-connected secondaries which supply arc lamp 16 through rectifiers 15. The current supplied may be varied by operating switches 17 to connect one or more auxiliary condensers 11, across reactance 8 or across condenser 7 and reactance 8 in series. Modifications are described in which the primary transformer windings are not connected to each other, the windings 2, 4 forming closed circuits with inductance 12 and condenser 13, Fig. 2 (not shown) and in which inductance 12 is replaced by an air-gap in the core limb carrying winding 2, Fig. 3 (not shown). In the latter case, winding 2 may be omitted, Fig. 4 (not shown). The advantages of supply through a phase converter and rectifiers are described in Specification 518,632.