GB291008A - Improvements in and relating to control and protective systems - Google Patents

Abstract

291,008. British Thomson-Houston Co., Ltd., (Assignees of Junken, L. H., and Blake, D. K.). May 23, 1927, [Convention date]. Void [Published under Sect. 91 of the Acts]. Switching systems.- Distribution networks comprising generators 2, 3 supplying bus-bars 8, 9 which in turn supply a work circuit through switches 6, 7, interconnecting circuits 4, 5, transformers 13, 14 and circuit-breakers 15, 16 have a highfrequency superimposed upon them to control and protect the system. The high-frequency (or other frequency separable from that of the power supply) is furnished by the devices 17, 18 to the bus-bars through condensers and serves to operate through the condensers 23, 24 responsive devices 21, 22 which derive energy from the low-tension sides of the transformers through leads 25, 26. In the closed position of the responsive devices, current flows through the circuits 27, 28 and through the maintaining coils of the circuit-breakers. If, however, the switch ti or 7 is opened, or if the supply lead 4 or 5 becomes open-circuited or short-circuited, the high-frequency supply no longer operates the corresponding responsive device which assumes the off position. In the case where apparatus having a high impedance to high-frequency currents is located in the connector 4 or 5 (for example, a voltage regulator) the high-frequency circuit is connected on the far side of this apparatus and the actuating circuit of the high-frequency generator is interlocked with the switch 6 or 7 through auxiliary contacts on the switch. In three-phase star-connected systems, direct current may be superimposed on the system for protection and control, instead of high-frequency currents. This direct current is inserted at the neutral of the generating stations and transmitted through the switches 6, 7 to the neutral of the transformers 13, 14 and there supplied to D.C. responsive means 21, 22.