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The installation of overhead lines may require reconstruction of bridges to provide safe electrical clearance. [20] Overhead lines, like most electrified systems, require a greater capital expenditure when building the system than an equivalent non-electric system. While a unelectrified railway line requires only the grade, ballast, ties and ...
A related but separate gauge is the loading gauge: a diagram or physical structure that defines the maximum height and width dimensions in railway vehicles and their loads. The difference between these two gauges is called the clearance .
Overhead lines or overhead wires are used to transmit electrical energy to trams, trolleybuses or trains. Overhead line is designed on the principle of one or more overhead wires situated over rail tracks. Feeder stations at regular intervals along the overhead line supply power from the high-voltage grid.
A catenary pole of the system. Catenary wires and contact wires are tensioned by individual tension balancers. The basic system unit is an elementary electrical section consisting of a segment of one or more parallel tracks, each with a contiguous contact (or catenary or trolley) wire for the locomotive pantograph and an electrically separate feed wire.
The overhead line (3) and feeder (5) are on opposite phases so the voltage between them is 50 kV, while the voltage between the overhead line (3) and the running rails (4) remains at 25 kV. Periodic autotransformers (9) divert the return current from the neutral rail, step it up, and send it along the feeder line.
Dual electrification is a system whereby a railway line is supplied power both via overhead catenary and a third rail. This is done to enable trains that use either system of power to share the same railway line, for example in the case of mainline and suburban trains (as used at Hamburg S-Bahn between 1940 and 1955). [1]
The minimum railway curve radius is the shortest allowable design radius for the centerline of railway tracks under a particular set of conditions. It has an important bearing on construction costs and operating costs and, in combination with superelevation (difference in elevation of the two rails) in the case of train tracks , determines the ...
The overhead wiring, generally having two separate overhead lines and the rail for the third phase, was more complicated, and the low frequency used required a separate generation or conversion and distribution system. Train speed was restricted to one to four speeds, with two or four speeds obtained by pole-changing or cascade operation or both.