GB278831A - Improvements in electric transformers - Google Patents

Abstract

278,831. Tinsley, H., and Gall, D. C. July 31, 1926. Systems depending on static transformers.-A transformer, particularly suitable for use in electric railway signalling systems, is provided with two primary windings and has associated with one winding means, such as a condenser, adapted to produce a time displacement between the primary currents, produced from a single phase supply, so that a decrease of impedance in the secondary circuit causes a decrease in the current or power output in that circuit. Fig. 3 shows the transformer applied to a railway signalling system in which a relay 6 is connected through the track rails 4, in sections separated by insulated joints 5, in series with the secondary winding of the transformer 7 having two primary windings connected in parallel with the supply mains 8, one winding having a condenser or phase changing device 3. When the track section is unoccupied the relay 6 is supplied with actuating current to maintain a signal, crontrolled by the relay, in a safety position. The presence of a train in the section decreases the impedance so that the current output in the secondary or track circuit is decreased due to the action of the transformer thus ensuring the deenergization of the relay and consequent operation of a danger signal. The device may be formed so that the phase changing device con. stitutes an integral part of the structure or by assembling and connecting a pair of transformers and a condenser or a condenser and transformer having a divided or tapped primary winding. The transformer may be used with two element or polyphase track relays.