GB409682A - Improvements in and relating to electric converting apparatus - Google Patents

Abstract

409,682. 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. 30, 1932, No. 27218. Convention date, Oct. 1, 1931. [Class 38 (ii).] Apparatus for transmitting energy in either direction between a D.C. and a polyphase A.C. circuit comprises a plurality of windings each provided with a neutral point, a plurality of electric valves interconnecting the circuits through these windings, and an interphase transformer interconnecting the neutral points and having a neutral point connected to one side of the D.C. circuit, the interphase transformer being associated with external capacity in such a manner as to produce a periodic potential adapted to commutate the current under any desired power factor conditions on the A.C. circuit. In one arrangement, Fig. 1, for transmitting energy between a D.C. circuit 10 and an A.C. circuit 11, the circuits are interconnected by a transformer having a winding 12 connected to the A.C. circuit and two starconnecting windings 13, 14 connected to one side of the D.C. circuit through valves 15-20, and to the other side through an interphase winding 21 shunted by a condenser 22. The conductivities of the valves are controlled by the secondary winding 23 of a grid transformer, the primary winding 24 of which may be energized from any source of A.C. of the frequency of the circuit 11. If the latter is connected to an independent source of E.M.F. for determining the frequency and phase relations of its voltages, the grid transformer may be energized from the A.C. circuit 11 through a phase-shifting transformer 26. Means, such as those described in Specification 390,184, should be provided for giving the grid potentials a peaked wave form. In another arrangement, Fig. 2, energy is transmitted by means of a transformer winding 12 connected to the A.C. circuit 11, and three single phase windings 30, 31 and 32, the outer terminals of which are connected to one side of the D.C. circuit through valves 33-38. The mid points of the windings 30-32 are interconnected by a star-connected polyphase network 39, the neutral point of which is connected to one side of the D.C. circuit, while condensers 40 are connected between each pair of adjacent terminals of the network for commutating the load current between the valves under any desired power factor conditions.