2400-Volt railway electrification

Abstract

The requirements of a railway load are of such a character that electricity can in many instances be profitably sold at a price, delivered to the substations, of less than one cent per kw-hr. It is only as a consequence of the enormous growth of the electricity supply business during recent years and the attendant advance in respect to the decreased cost and increased efficiency (brought about by progress in the art and scientific administration) that such low prices have become profitable. A situation has thus developed which renders it no longer of interest to railways to concern themselves with the large capital outlays associated with the manufacture and transmission of electricity. Their concern is merely with the price at which they can contract for the electricity to be delivered on their property; with the relatively small outlay which they will incur for substations and for the distribution system; and with the relatively large capital outlay for electric locomotives and for the electric equipment of motor-car trains. The predominating item in the capital outlay is that for rolling stock and against this outlay a credit can equitably be allowed since the replaced steam equipment can be used up on non-electrified divisions. In other words, in making up its budget for new rolling stock, a railway engaged in electrifying its system by divisions, will in each successive year devote a greater sum to the purchase of electrically-equipped rolling stock and a lesser sum to the purchase of equipment for steam operation. Consequently in investigations undertaken with a view to comparing the cost of electric operation with the cost of steam locomotive methods, the chief items involved relate to operating expenses and to the annual charges associated with the capital outlay for substations, distributing system and rolling stock. Before this situation had materialized, a considerable handicap to undertaking the electrification of divisions of railways consisted in the enormous capital outlays which the railways would have been obliged to incur in putting down plant for manufacturing their own electricity and in the low efficiency of such a plant when employed for the sole purpose of providing a widely fluctuating load. Under these conditions the true economic field for railway electrification was of a restricted character. Under the altered conditions, however, it can often be conclusively demonstrated that electric operation is economically superior to steam locomotive operation, even for divisions where the traffic consists of an irregular and sparse service of freight and express passenger trains.