. The street railway review . ELWELL PAKKICR IlKLTKl) I)VNAM(Used on the Blacl<)l Electric isii .ii OF ISSi).iperes, 201) volts the electric generator so firmly that the gradual abanflonment olother systeins. whether horse, cable, steam or air. has been merelythe natural outcome of the situation. The railway generator, starting with the fairly developed formsof 1880, has undergone a process of growth in which, until recently,the changes have been rather of detail than of principle. Theearly machines were not required to supply a large output, andthey were accordingly of smal
. The street railway review . ELWELL PAKKICR IlKLTKl) I)VNAM(Used on the Blacl<)l Electric isii .ii OF ISSi).iperes, 201) volts the electric generator so firmly that the gradual abanflonment olother systeins. whether horse, cable, steam or air. has been merelythe natural outcome of the situation. The railway generator, starting with the fairly developed formsof 1880, has undergone a process of growth in which, until recently,the changes have been rather of detail than of principle. Theearly machines were not required to supply a large output, andthey were accordingly of small diiucnsions. To attain the requisitevoltage with the old bipolar fields, two factors were essential:. SMALL LAWKKNl-F,, IAHIS .V sDouble hornetthoe field inaifnetH—I :OTT UYNAMO—INOi). The use of heavy armature windings and a high rale of reach this high rate of revolution without prohibitory peri-pheral speeds, the armature diameter was usually small, and hencethe armature windings were crowded. The necessity of high speeds led, with the engines then in use,to belt driving, which was continued as the standard method upto within the last decade. The former consideration (the neces- sary crowding of the armature windings) led to successive efifortsat armature ventilation, in spite of which liot and easily burned-outarmatures for many years constituted one of the larger difficultiesin central station work. These conditions also led to excessive iron and copper lossesand consequently to low efficiencies. A generator of 1885-86-87was considered good if it gave out in electric energy 50 per centof the mechanical input. But such efficiency was, under existingconditions, s
Size: 1552px × 1609px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
