GB191026390A - Improvements in Methods of and Means for Obtaining Alternating Currents from Continuous Current Circuits and vice versa. - Google Patents

Abstract

26,390. Taylor, A. M. Nov. 14. [Addition to 20,867/09.] No Patent granted (Sealing fee not paid). Commutator switching-arrangements; phase, changing; transformers.-In a system for converting direct currents into alternating currents, and vice versa, of the kind described in the parent Specification, wherein means are provided for altering the wave form of the alternating current, the transformer P is provided with an exciting-coil E supplied from a small synchronous alternator N driven from the motor M, which drives the commutators A, B, for the purpose of magnetically saturating the core and the transformer at certain periods. A small auxiliary transformer Z is also employed having an unsaturated core, its primary coil C being in series with the exciting winding of the main transformer, and its secondary coil L being in series with the secondary winding S of the main transformer. This effects the requisite deformations of the wave of electromotive force applied to the exciting-coil E, and at the same time adds a component to the alternating electromotive force delivered by the secondary winding S of the main transformer, so that a sine wave of electromotive force is transmitted to the mains D. The exciting-coil E may be connected to the mains D by means of a switch O, when the system is being used for rectifying alternating currents. The secondary coil S of the transformer P has two tappings, and a switch Q enables a part thereof to be cut out to compensate for the pressure drop in the transformer when reversed. The exciting-coil E may also have an additional number of turns adapted to be thrown into circuit by a switch R, the transformer P being then worked in an unsaturated condition with improved efficiency. In this case, the alternator N is designed to give the special wave shape which the primary winding of the transformer has to deliver for commutation purposes. The auxiliary transformer Z in this case is fed with a special wave from an auxiliary winding on the alternator N so as to deliver a compensating wave of electromotive force in the circuit of the coil S. The Figure shows the connexions for one phase only, the general arrangement for three-phase circuits being as set forth in the parent Specification.