GB375029A - Improvements in and relating to the conversion of polyphase currents into single phase currents - Google Patents

Abstract

375,029. Frequency changing ; phase changing. LÍBL, 0., 2, Neue-Bismarokstrasse, Hermsdorf, Berlin. May 8, 1931, No. 13656. [Class 38 (ii).] Polyphase current is converted into single phase current of lower frequency by transformers and rectifiers so arranged that succeeding phases of the polyphase current al, b1, cl, &c. have different amplitudes and the anodes of the rectifiers are rendered conductive in such order that a single phase current wave is built up in the load circuit as indicated by Fig. 1. Fig. 2 shows one arrangement in which a three phase network R, S, T supplies current to a pair of phase multiplying transformers P1, P2, wound so as to produce secondary phases of graded amplitudes. The secondary phases are associated with the anodes of a pair of rectifiers g1, g2 the circuits of which are completed at appropriate intervals by contacts on a switch drum h rotated synchronously with the supply current. The single phase load t is connected between the cathodes r1, r2 and the star points of the transformers so that one half cycle of the load current is derived from successively conducting anodes of rectifier gl, and the other half cycle from successively conducting anodes of rectifier g2. Other arrangements are described in whfch (1) the anode control switches are arranged between the secondaries of the transformers and the star points, Fig. 6 (not shown), (2) a single rectifier vessel is used with its cathode connected to the centre point of the primary of an output transformer, Fig. 5 (not shown), (3) the anode circuits are controlled by grids or ignition coils associated with separate rectifier vessels, Figs. 3 and 4 (not shown).