Auxiliaries for high-voltage D-C. multiple unit cars

The selection and application of auxiliary electrical devices on a high-voltage multiple unit car is of almost as much importance as the application of the main traction apparatus and requires careful consideration. This paper contains a description of the engineering features as worked out for electrified suburban lines operating on 1500-volt and 3000-volt systems. The control circuits have become very generally standardized at 32-volts, which is also well adapted for interior illumination and headlights. A motor driven generator supplies 3- to 5-kw. power per unit for control lights and battery charging. Such devices as heaters and motor-generator sets, requiring a considerable amount of electrical power, are necessarily constructed to operate at trolley potential. On the 1500-volt system, the compressor can be operated directly from the line potential while on the 3000-volt systems, a double commutator motor driving the generator supplies a 1500-volt source of power for the compressor.