GB189931A - Means for improving the current carrying capacity of existing three-phase alternating current cable systems - Google Patents

Abstract

189,931. Taylor, A. M. Oct. 12, 1921. Distributing mains, arrangements of; polyphase systems; systems depending on the use of two or more machines. - In a polyphase transmission system employing two or three-core cables, one six-core cable, or two six-core cables, generators and transformers with separated windings are employed and the connections to the cable cores are so arranged that the current carrying capacities of the cables are increased without straining the margin of insulation. The open delta secondary windings of a stepup transformer SUT, Fig. 1, are earthed at their mid points E and the terminals of these windings are connected to the cores of three-core cables in the manner shown and one core of each cable is connected directly to the bus-bars. In the modification shown in Fig. 4, two cables only are employed and the open delta windings are arranged on two limbs of the transformer and to improve the regulation, a second winding is placed on one limb or an additional single-phase transformer is employed at the receiving end. In a further modification an auto-transformer arrangement is provided at the receiving end. In the arrangement shown in Fig. 2, the main open delta generator MG is connected directly to the cores of three cables 3 P.C. and to an auto step-up transformer SUAT the ends of the windings of which are also connected to the cores of thei cables. A private consumer is connected at a point intermediate the generating station and the substation through an open delta transformer PCT. An independently wound generator SSMG, Fig. 3, is connected to the cable cores through auxiliary bus-bars ABB and a stepup auto-transformer SUAT and the main bus-bars MBB are connected direct to, the, cable cores. A modification of this arrangement is shown in Fig. 12 in which two separate generators MG, two auto-transformers SUAT and a six-core cable 6PC are employed. The generators are caused to run on half a revolution out of phase by means of a transformer PT. In a modification two separated: star-connected main generators are connected with their corresponding windings in series and the generators are caused to run one half a revolution out of phase Six phase and twelve-phase systems similarly arranged are described.