GB512906A - Improvements in or relating to electric current converters - Google Patents

Abstract

512,906. Converting. SIEMENS-SCHUCKERTWERKE AKT.-GES. March 18, 1938, No. 8457. Convention date, March 18, 1937. [Class 38 (ii)] Comprises a rectifying arrangement in which the ripple frequency in the D.C. output circuit is increased by providing n three-phase " Graetz " connected rectifier systems which are supplied from a common transformer winding and are connected to the D.C. circuit through interphase transformers, the phase displacement between the system being 2#/6n. In the form shown in Fig. 1 two three-phase systems 3, 3<1> connected to the D.C. circuit through, interphase transformers 4, 4<1> are supplied from a transformer having a branched secondary winding providing two three-phase groups 30 degrees phase displaced. The rectifiers 3, 3<1> may be of the moving contact type. In a modification, an unsymmetrical polygon winding is used to give the phase displaced three-phase groups. In a further modification three three-phase groups are used the connection to the D.C. circuit being through two three-winding interphase transformers. Fig. 4 shows a 12-phase arrangement comprising two-phase displaced six-phase groups, the phase displacement being obtained by means of phase shifting transformers 6, 6<1>. The Specification as open to inspection under Sect. 91 comprises also arrangements in which two supply transformers are used and connected to the D.C. circuit through a single interphase transformer. In a modification of this, the rectifier groups are connected in series on the D.C. side. This subject-matter does not appear in the Specification as accepted.