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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on to afford the greater part of the protection. In somelocalities, a wire strung on the same pole line at a short distancefrom the power wires and grounded at very frequent intervals hasbeen found to reduce troubles due to lightning. The grounding of the neutral of tliree-wire secondary systemsforms a means of protection of such circuits against high potentialswhich might arise from accidental contact with the primaries, andis recommended in some cases. The grounding of the neutral ofhigh-tension systems reduces the potential between the lines andthe ground, but a single ground will cause a short-circuit on theline with any grounded system. Grounding, through a resistancewhich will limit the flow of current in such a short-circuit, has beenrecommended and is employed in some instances. Spark arrestersare installed at the ends of high-tension underground systems toprevent high voltages which might injure the insulation in case ofsudden changes in load, grounds, and short-circuits. 94
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ELECTRIC RAILWAYS PART I INTRODUCTION Before a student can appreciate the purposes of the differentparts of an electric railway system, he must know what the primarypurpose of such a system is, as the details of selection and operationof equipment must have a direct bearing upon this purpose. Letus start, therefore, with the following important statement, which weshall try to keep in mind throughout the course: The purpose of a railway system is to transport paying load betweenpoints at minimum total cost with maximum safety. Railways are termed in law common carriers, and as such theyenjoy privileges not common to other lines of business, such as the useof streets and roads, and are more or less of a monopoly in their terri-tory. For this reason they are subject to the control of the public toa greater extent and this fact affects the engineering problems and thedetails of equipment. For example, the state commissions whichcontrol railway operation and equipment—subject, of course,

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