Förstudie till järnvägslinje in under en av Europas storstäder : Hjälpkraft, Traktionsspänning och Vagabonderande strömmar i returledning för likströmsbanor

Sammanfattning: The purpose with this pre-study of an underground railway track with d.c. traction was to examine alternatives to the auxiliary power, traction power and tracks/ return circuits. This with the problem of stray currents in mind as well with technical, safety and economy. The method used was primarily a literature study of theoretical, standards, other scientific studies, and calculations. The results and conclusions suggested to use a 1kV system for the auxiliary power system, a contact rail for the traction voltage and a slab track for rail and return circuit. This to keep drop voltage within limits, to keep system height down and limit the risk for stray currents. Furthermore, contact rail and slab track raise the comfort and safety, as well as lower the maintenance. The thesis stresses the importance of prevention of stray currents in initial stages of the planning and the fact that there are many ways to do this.