Control and auxiliary equipment for direct-current electric locomotives

The paper presents a review of problems and practice in the design and arrangement of control gear for the main motors, together with some notes on auxiliary machines and services, for modern directcurrent electric locomotives. Most of the locomotives now in service are equipped with rheostatic control, employing resistors in the power circuit between the supply line and the main motors, and the energy loss involved is one of the main reasons for the development of several interesting alternatives using rotating machines, e.g. boosters, motor-generators, metadynes. In view of the widespread use of rheostatic control, the paper is confined to this system. The subject is divided into the following functional groups covering the main features of the equipment: (1) power-circuitarrangements, (2) current collection, (3) power-circuit apparatus, (4) control circuits for main motors, (5) control-circuit apparatus, (6) protection, (7) auxiliary machines and control, and (8) layout of equipment. The important subject of electric braking will be discussed in another paper, and is not therefore included.