GB150824A - Improvements in or relating to apparatus for converting alternating electric currents into direct currents and vice versa - Google Patents

Abstract

150,824. Calverley, J. E., and Highfield, W. E. June 10, 1919. Commutator switching-arrangements; phase, changing.-In converting apparatus of the type in which a set of transformer windings are interconnected to form a closed circuit and connected to commutating-gear in substantially the same manner as that in which the winding of a Grammering armature is connected to its commutator, such as is described in Specification 140,853, two or more commutators are connected in series with one another through their 'brushes. In the arrangement shown in Fig. 1 for converting three-phase current to direct current, or vice versa, the closed circuit is divided into two sections A<2>, B<2>, each of which comprises a series of similar windings on the three-phase transformer cores A, B, and the sections are respectively connected to the segments C', D' of the commutators C, D. The transformer cores also carry windings A<1>, B<1> connected to three-phase mains X, Y, Z as shown in Fig. 2, in such a manner as to produce at successive commutator segments the relations shown in the phase diagram on the right of Fig. 2. The commutator brushes are mounted on a shaft E driven by a synchronous motor, which may be provided with means for adjusting its field strength or the angular position of the stator. The two commutators may be connected by an adjustable coupling K<3>, or the segments on one commutator may be adjusted angularly with respect to those on the other. The direct current output or supply is connected to slip-rings F, G. In cases where it is desirable to run the shaft at a reduced speed, the sections of the closed circuit may be connected to the commutator segments in such a manner as to give more than one possible brush position for each pair of brushes in substantially the manner adopted for multipolar direct-current machines. The number of commutators may be increased, each section of the closed winding being connected to two or more commutators in parallel, the sets of commutators being then connected in series.