Improvements in methods of, and means for, obtaining alternating currents of any periodicity from existing threephase systems of different periodicitiy

摘要

158,008. Taylor, A. M. June 25, 1919. Addition to 151,294. Systems depending on the use of static transformers; systems depending on the use of two or more machines.-Three feeders of a threephase electric supply system are employed to transmit an additional three-phase current, the frequency of which differs from that of the main supply. In a modification, an additional two-phase current and a single-phase current are transmitted: and in a further modification, an additional two-phase current is transmitted. The additional currents are fed to the system through the neutral points of the main generators, or the neutral points of transformers or static balancers and means are providedto stabilize the neutral points of the transformers or balancers when these are employed. The external magnetic field is reduced by connecting the lead or copper sheathing, broken into short lengths, to resistances buried in cast-iron boxes, or the sections may be earthed at their middle points. The main generators MG, Fig. 1, are connected to a sub-station SS through transformers SUT, feeders 3 PC, and transformers 3 PIP. The neutral points of the secondary windings of the transformers SUT are connected to an auxiliary generator AG. The neutral points of primary windings of the transformers 3 PIP are connected and their secondary windings are connected in mesh to a circuit supplied with the additional three-phase current. To stabilize the neutral point of the transformer, an additional short-circuited deltawinding is employed, Fig. 1a; or an interconnected star-winding may be employed. In the modification shown in Fig. 6, a twophase alternator AA is connected to the neutral points of the transformers SUT of a three-phase system, and a Scott-connection is employed at the sub-station to convert this cur. rent to a three-phase current. In the modification shown in Fig. 8, a two-phase current from the alternator AA and a single-phase current from the alternator A is superposed upon the feeders of the three-phase system. The various transformer winding arrangements which may be em. ployed are shown in Fig. 9. Specification 8853/11. [Class 38 (ii), Electric currents, Converting &c.], is referred to.