Railroad Electrification Energy Conversion and Transmission Costs

Railroad electrification is now being considered in several sections of the United States. Questions regarding choice of power supply, design and cost have prompted an analysis of these problems on a two-track railroad of moderate traffic density. The scope covers features from utility supply to locomotive pantograph, including conversion apparatus, substations, and transmission, Locomotives are not included. A 330-mile section of railroad is used with trackage and traffic density closely resembling an acutal case. A-c and d-c power systems are analyzed and compared. The a-c system is single-phase 25-cycle, with 24-kv trolley and 72-kv feeder-to-trolley voltages. Rotating frequency changer sets are used for conversion, supplying loads resulting from motive power equipped with single-phase motors, with or without power-factor corrective equipment, or with motor generators. The cost of conversion apparatus is considered separately, as it might be financed either by the railroad or utility. The d-c system uses 6-kv trolley voltage, with supplementary feeders. Metal-tank mercury-arc rectifiers are provided for conversion. Wood poles support all electrical circuits in both cases. Traffic densities are considered for 1940 and 1944 levels, the latter 57 per cent greater than the former. Cost estimates are based on 1939 price levels. The results show: 1. Traffic density is one of the controlling factors of cost of railroad electrification, but reasonable cost per annual thousand gross ton-miles can be obtained for a railroad handling moderate traffic. 2.