Simple Method for Determination of Substation Spacing for AC and DC Electrification Systems

A simple method for the determination of traction power substation spacings is developed for ac railroad electrification systems. Single-end-feed, center-feed, and double-end-feed systems with or without booster transformers can be represented, being the most common supply configurations. The method is extended to include autotransformer systems and can also be used for calculation of substation spacings for dc light rail and heavy rail systems. The entire power system is represented, including the electric utility system, the traction substations, the catenary system or third rail, the return current system, and the trains. Multitrack systems can be approximated, and effects of currents at harmonic frequencies produced by the electrical locomotives are evaluated. The mathematical description results in a number of equations suitable for microcomputer solution. The use of the method is demonstrated a sample case, and a convenient way of presenting the substation spacings for a given set of conditions is illustrated by the use of nomographs.