GB411427A - Improvements in and relating to electric converting apparatus - Google Patents

Abstract

411,427. Converting. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Mittag, A. H. ; 139, Elmer Avenue, Schenectady, New York, U.S.A.) Oct. 1, 1932, No. 27308. Convention date, Oct. 1, 1931. [Class 38 (ii).] Apparatus for transmitting energy in either direction between D.C. and A.C. circuits under any desired power factor conditions comprises a pair of electric valves connected in series in every path between the circuits and a commutating condenser 21 connected between the common connections of adjacent pairs of valves. In the arrangement shown in Fig. 1, for converting between a D.C. circuit 10 and a single-phase A.C. circuit 11, one side of the D.C. circuit is connected to the mid-point of a winding 14 connected to the anodes of two-electrode valves 19, 20, the cathodes of which are connected to the anodes of three-electrode valves 17, 18 whose cathodes are connected to the other side of the D.C. circuit. The condenser 21 is connected between the two pairs of valves, and the grids of the valves 17, 18 are energized at the desired frequency and phase from a grid transformer 22, which may be energized from the A.C. circuit 11 through a phase-shifting transformer in cases where the A.C. circuit includes an independent source of E.M.F. In a polyphase arrangement, Fig. 2, the circuits are interconnected through a transformer having a primary winding 32 and a six-phase secondary winding 33 having a neutral point connected to one side of the D.C. circuit 10 through a smoothing reactor 16. The outer ends of the phase windings 33 are connected to the anodes of valves 40 .... 45, and the cathodes of alternate valves are connected to the anodes of valves 17, 18 shunted by the commutating condenser 21, the cathodes of the valves 17, 18 being connected to the other side of the D.C. circuit. The grids of the valves 40 .... 45 are excited from a phase-shifting transformer 47, and those of the valves 17, 18 are excited with a triple frequency by means of a rotary frequency changer 50 and phase-shifting transformer 51. In a modification, Fig. 3, the grids of the valves 40 .... 45 are excited from a pair of three-phase windings 62, 63, the neutral points of which are connected to the cathode circuits of the valves through windings 64, 65 of a second grid transformer 22 controlling the valves 17, 18. In another arrangement, Fig. 4 (not shown) the invention is applied to the full wave converting apparatus shown in Fig. 3 of Specification 411,145, an additional pair of valves being connected between the commutating condensers and their associated reactances. Specifications 219,026, [Class 38 (ii)], and 390,184 also are referred to.