GB190427209A - An Improved System of Electrical Distribution for Railways and Method of Operating same. - Google Patents

Abstract

27,209. Hallberg, J. H. Dec. 13. Electric railways; electric locomotives and motor vehicles.-Relates to the polyphase working of electric railways, and comprises the distribution of the power by a high-potential, single-phase current, and its utilization in the motors in the form of a polyphase current of low potential, the transformation being effected in fixed substations on the low-potential urban sections of the road and in the cars themselves on the high-potential extra-urban sections. Fig. 2 is a diagram of the circuits &c. on one of the cars, including the transformer apparatus carried on the car. This apparatus, which is similar to that at each of the transformer substations, comprises a single-phase motor 0 fed from the high-potential line and coupled, as by a shaft 25, to a polyphase generator D, which, thus, although rotating mechanically with the motor C, is electrically independent thereof, and is wound and connected so as to be capable of supplying current of one or other of several frequencies without change in the speed of rotation. The shaft 25 is geared to a direct-current dynamo G, which at starting is fed from an accumulator I in order to bring the motor C into step with the main single-phase generator, and which thereafter serves to excite the rotors of the motor C and generator D. The polyphase traction motors F comprise stators 21, connected in multiple with the tri-phase bus-bars 59, 60, 61, and rotors 20 fixed direct on the car axles, brushes, commutators, &c. being thus dispensed with. On the country sections of the road, the single-phase, high-voltage current is supplied to the car across an overhead conductor and a rail &c. 10, and is transformed on the car as described above into polyphase current, which is led through the twopole switch 57 and reversing-switch 58 to leads 59, 60, 61 extending throughout the train. The speed of the motors F is controlled by means of resistance 43 in the coils of the exciter G. On urban sections, the transformer in the car is thrown out of action, and polyphase current from the substations is supplied by the conductors 10, 14, 15 passing, on its way to the switches 57, 58 and train-leads, through a regulating-device, which, preferably, is a reactance apparatus R, comprising fixed coils 44 through which the current passes and movable iron cores 45. On down-grades, the motors F act as generators and thus drive the transformer apparatus so as to supply energy to the line.