Identifier: cyclopediaofappl05amer (find matches)
Title: Cyclopedia of applied electricity : a general reference work on direct-current generators and motors, storage batteries, electrochemistry, welding, electric wiring, meters, electric lighting, electric railways, power stations, switchboards, power transmission, alternating-current machinery, telegraphy, etc.
Year: 1916 (1910s)
Authors: American Technical Society
Subjects: Electric engineering
Publisher: Chicago : American Technical Society
Contributing Library: Northeastern University, Snell Library
Digitizing Sponsor: Northeastern University, Snell Library

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of these is shown in Fig. 208. Here the trolley wireis continuous and is fed into at different points. The long feederssupplying the more distant portion of the road are larger than thosesupplying the trolley near by, so as to maintain as nearly as is feasiblethe same voltage the entire length of the line. The plan shown resultsin a higher voltage near the power station than at distant points butthe distribution of voltage is better than if the heaviest feeders werefeeding into the trolley near the power house. In the other plan,shown in Fig. 209, the trolley wire is divided into sections and each 317 220 ELECTRIC RAILWAYS is fed through a separate feeder which is of such size as to maintainthe same voltage on all the sections with the ordinary load. Feeder Calculations. In estimating the proper sizes of wire fora feeder system, probable loads are assumed at certain points alongthe line. These will depend on the size and number of cars in opera-tion, grades, and many local conditions.
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Fig. 209. Feeder System Using Separate Trolley Sections For example, assume that three cars are placed, as shown in Fig.209, each at the end of a feeder section and that each is drawing 50amperes. The line voltage is 600 and the allowable drop in feeders,trolley, and return circuit w411 be placed at 10 per cent, or 60 volts.The track is single and laid with rails weighing 70 pounds to theyard. The trolley wire is No. 00. The lengths of the sections areas given in the figure. I As the sizes of trolley wire and rails are given, the drops inthese must be calculated first and the remainder of the allowabledrop will be that which may occur in the feeder. The current ineach trolley wire is 50 amperes and from wire tables a mile of No.00 wire will cause a drop of 20.5 volts with 50 amperes. The cur-rent in the two miles of track nearest the power house is 150 am-peres, in the next section 100 amperes, and in the last section, 50amperes. The corresponding voltage drops are calculated from the

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