File:Bell telephone magazine (1922) (14752978211).jpg

Identifier: belltelephonemag4344amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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al alternatingcurrent (AC) system. But DC has notbeen practical up to now because therewas no way to obtain the required highvoltage. However, recent developmentsby Swedish engineers now make it pos-sible to construct converter stationswhich may be used at each end of a lineto convert high voltage AC to DC andback to AC again. On systems of severalhundred miles or more, the cost of con-verters will be more than offset by thesavings in transmission line cost. A fewDC systems are already in operation inforeign countries and several are nowplanned for the United States. ^ All these technical developments—high capacity generating units andmore efficient methods of transmission—point to the need for new methods oforganization and operaton in the in-dustry. For example, individual powercompanies that cannot justify construct-ing one of the giant new high-efficiencygenerating units by themselves can oftenpool their resources to build one. Thus,they can all gain the advantages of lower 18
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Pictorial block diagram of themany kinds of communicationsneeded to control the operationsof a typical power company. POWER PLANT first cost and cheaper operation. Andwith the new EHV transmission lines,companies can interconnect their sys-tems to make use of these large generat-ing miits as well as to gain many otherbenefits in the nature of reduced standbyrequirements, exchange of power to carefor demand peaks, etc. One tangible and very large projectthat exemplifies the benefits to be gainedthrough interconnection is the PacificNorthwest-Southwest Intertie. This gi-gantic transmission system will compriseessentially four large transmission lines(opposite page) connecting the vast hy- dro-electric generating resources of thePacific Northwest with the growingpower-using centers of the Southwest.Two of these lines will operate at 500,000volts AC, and two will operate at 750,000volts, using the new DC technique. To-gether, the lines will be able to transmitover four million kilowatts o

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