Abstract
THE population of Copenhagen and its suburbs is about 800,000 and they are served by a number of railways, the most important belonging to the State Railway. The problem of electrification presented special difficulties as Denmark is dependent on imported coal for its electric power supply. During recent years, an appreciable amount of electric power has been transmitted from Sweden by 25,000 volt cables which pass under the Sound. When the problem of supply was first investigated, the choice narrowed down to 3,000 volts or 1,500 volts direct current. The latter was chosen, as, although the cost of the overhead equipment was greater, the cost of equipping the cars was less. Hence, when in the future the number of cars is increased, the cost will be less. An account of the system is given by J. Kristensen in the Electrical Times of August 23. He says that all the lattice masts are galvanised, as although it is more expensive than painting it is far more durable. Electrically, the whole system is divided into sections connected through line disconnecting switches. To prevent the electrolysis of neighbouring pipes, extensive precautions are taken. The use of stone ballast keeps the resistance between rail and earth very high, and the resistance of the return system is made as small as possible by joints of heavy copper wire electrically welded to the rails. To prevent interference with telegraph and telephone wires, these have been effectively insulated and placed as far away from the rails as possible. The smallest train is called a ‘half-train’ and is made up of two motor coaches with a ‘trailer’ between. It has a seating capacity of 250, and standing room for 200 more. The line Frederiksborg-Klampenborg was opened in April, and the line Copenhagen-Hellerup in May.
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Electrification of the Suburban Railways of Copenhagen. Nature 134, 317 (1934). https://doi.org/10.1038/134317c0
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DOI: https://doi.org/10.1038/134317c0