GB371734A - Improvements in and relating to electric power converting apparatus - Google Patents

Abstract

371,734. Converting. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Prince, D. C. ; 1424, Wendell Avenue, Schenectady, New York, U.S.A.) Sept. 1, 1931, No. 24558. Convention date, Sept. 2, 1930. [Class 38 (ii).] In an arrangement for supplying an A.C. load circuit 19 from a D.C. source 10 and comprising a pair of valves the anodes of which are connected to opposite ends of an inductive winding 17 between the mid-point of which and the cathodes of the valves the D.C. circuit is connected, the capacity necessary for effecting commutation comprises a pair of condensers 15, 16 normally connected in series between the anodes and associated with an automatic switch 25 responsive to load current whereby under heavy current conditions (as, for example, when a motor is being started) the condensers are connected in parallel thus effecting the increase in commutating capacity necessary under such conditions. The contacts of the switch may be so arranged that in an intermediate position of the switch, an intermediate value of capacity is provided by the short circuiting of one condenser. Grid control is effected in normal manner through a transformer 23 having a phase-advancing condenser 28 in its primary circuit and a biasing battery 20 and currentlimiting resistance 21 in its secondary circuit.