GB247131A - Method of and means for operating mechanically driven rectifiers in connection with electric transformers - Google Patents

Abstract

247,131. Lodge-Cottrell, Ltd., (Lurgi Apparatebau Ges.). Feb. 25, 1925. Commutator switching-arrangements.- Mechanically driven rectifiers are employed in conjunction with a tapped transformer for obtaining two or more direct currents of different voltages from a single source of alternating current. In the arrangement shown in Fig. 1, the transformer secondary winding is tapped at its centre to obtain a second series of rectified impulses of half the voltage of the transformer secondary. Lower voltage impulses of unequal magnitude may be obtained by arranging the tapping at a point other than the centre of the secondary winding. By tapping the transformer secondary winding at two points as shown in Fig. 5, lower voltage impulses of equal magnitude may be obtained. By adding to the arrangement shown in Fig. 5 a central tapping from the secondary winding of the transformer, rectified impulses of three different voltages may be obtained. Fig. 9 shows a further arrangement whereby rectified impulses of four different voltages are obtained between the leads I, II, III, IV and earth. In order that, when several rectifier discs are employed in conjunction with a single transformer, all the discs may be earthed simultaneously and at the same pole, a single rectifier disc from which no direct current is taken may be employed to effect the earthing of all the discs. The several discs may be mechanically coupled and driven by a singles synchronous motor or they may be independently driven by separate synchronous motors. In the latter case. means are provided to ensure that the discs are correctly positioned in relation to each other. The invention is also applicable to three-phase transformers, Fig. 13 showing an arrangement whereby rectified impulses of four different voltages may be obtained at the points a - - d. Specification 185,891 is referred to. Reference has been directed by the Comptroller to Specification 246,624.