File:Electric railways; a treatise on the modern development of electric traction, including practical instruction in the latest approved methods of electric equipment and operation (1908) (14781080013).jpg

Identifier: electricrailways00amer (find matches)
Title: Electric railways; a treatise on the modern development of electric traction, including practical instruction in the latest approved methods of electric equipment and operation
Year: 1908 (1900s)
Authors: American School (Chicago, Ill.) Cravath, James R Trow, Harris C
Subjects: Electric railroads
Publisher: Chicago : American School of Correspondence
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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d, how-ever, that with all the above mentionedadvantages, the single-phase system hasno disadvantages, as such is not thecase. The car etjuipment, due to thetransformers and the nature of themotors, is considerablv heavier. Themotors themselves are more expensiveon account of their special construc-tion. The equipment is not alwaysadapted for operation on existing lines.There is a slight increased apparentresistance of the trolley line and a con-siderable increased apparent resist-ance oi the rails, due to reactancecaused bv the alternatiiii!; nature of the current. There is also anactive electro-motive force between the field coils, which is objection-able, and there is a possibility of interference with neighboring tele-phone lines. Furthermore, there is slight loss in power in thetransformers on the car, while the power-factor of the motors is lessthan unity. Summing the matter up as a whole, liowcver, the advantagesseem to overbalaiice the disadvantages, at least for many kinds of
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MasttT <oiilroller Used in Comiec- lioii with the MiiMiple-rnit System as AppHed to Single-Phase Work. 144 THE SINGLE-PHASE ELECTRIC RAILWAY work, and it is safe to predict that this new system of operation willhave a very wide and inereasin<i; application in the near future. As to the operation of the system in general, the current maybe developed by single-phase, two-phase, or three-phase generators,and supplied to the transformer substations just as it was formerlysupplied to the rotary converter substations. Only a single phaseis used on any section of the trolley line. The voltage on this trans-mission line will depend upon the existing conditions, and can befigured out like any other problem in power transmission. Three-phase generators would ordinarily be used, as less copperis recjuired to suj)ply a given amount of ))ower. The common fre-quency is 25 cycles per second. At the transformer stations, the

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