GB150825A - Improvements in or relating to apparatus for converting alternating electric currents into direct currents and vice versa - Google Patents

Abstract

150,825. Calverley, J. E., and Highfield, W. E. June 10, 1919. Commutator switching-arrangements; phasechanging.-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, an additional exciting-winding or set of windings, connected to an alternating-current supply circuit, is provided on the transformer. In the arrangement shown, for converting direct current of one voltage to direct current of another voltage, separate commutators or sets of commutators are provided for the ordinary primary and secondary windings of the transformer. The low-voltage circuit II is connected through slip-rings H, J and a commutator E to windings Z on the three-phase transformers A, B, the windings Z being interconnected to one another and to the segments of the commutator to produce the succession of phase angles between successive segments indicated in the phase diagram, Fig. 2. The windings X, Y are similarly connected to commutators C, D which are in series with each other and connected by slip-rings F, G to the high-voltage circuit I. The exciting- windings L are supplied with current from the three-phase mains a, b, c which also supply current to a synchronous motor K<1> driving the shaft K on which the commutator brushes are mounted. An adjustable coupling K<3> may be provided between the low voltage and the high voltage commutators, or the segments of one commutator may be adjustable relatively to those of the other.