GB391674A - Improvements in and relating to electric distribution systems - Google Patents

Abstract

391,674. Electric supply systems. BRITISH THOMSONHOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Schmidt, A. ; 1147, Parkwood Boulevard, Schenectady, New York, U.S.A.) Sept. 19, 1932, No. 26030. Convention date, Sept. 19, 1931. [Classes 38 (ii) and 38 (iv).] In a direct-current transmission circuit comprising insulated conductors forming an arrangement such as a cable, having electrostatic capacity, inductive reactance is provided to limit the rate of electrostatic discharge, e.g. under short-circuit conditions, and a further means, such as high resistance in parallel therewith, is provided to limit the rise of voltage across the reactance. The Figure shows a system of direct current transmission between alternating current systems 1, 2, the rectification of the current from system 1 being effected by a pair of vapour discharge devices 7, 8 connected as shown to the secondary of a preferably step-up transformer 9 and the inversion into the system 2 being effected preferably by valves 10, 11 and a transformer 14, the whole constituting a parallel inverter similar to that described in Specification 219,026 in that the control electrodes 12, 13 are energized from the system 2 through a grid transformer 15 having in its primary circuit a phaseadvancing condenser 16 and a short-circuit resistance 17. The inductive reactance elements in the direct current transmission are shown at 18 and the shunt resistances therefor at 19.