File:Pacific service magazine (1924) (14801653313).jpg

Identifier: pacificservicema1627paci (find matches)
Title: Pacific service magazine
Year: 1912 (1910s)
Authors: Pacific Gas and Electric Company
Subjects: Pacific Gas and Electric Company Electric utilities Electrical engineering Public utilities
Publisher: San Francisco : Pacific Gas and Electric Company
Contributing Library: San Francisco Public Library
Digitizing Sponsor: San Francisco Public Library

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imately2000 ft. away. The SanJoaquin River is crossedby using three high towersbetween the two anchorstructures, the middletower being located on anisland in the river. As thespans are shorter (3175ft. and 2250 ft. respective-ly) these towers are 269ft., 359 ft., and 314 ft.,in height. The 459-foottower on the south bank of the SacramentoRiver is believed to be the highest struc-ture used for supporting a transmission line.Before starting final designs on the longspans crossing the San Joaquin and Sacra-mento Rivers preliminary studies weremade of various schemes in order to deter-mine the most economical type of construc-tion. It was first necessary to decidewhether the river crossing spans would betaken care of by suspending the special high-strength conductor between the high towerslocated on each bank, designing these tow-ers to take the dead end pull of all theconductors, or whether greater economywould result if the high towers merelyacted as supports for the cables, the tension
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Looking across Sherman Island toward the 459-foot tower. being taken care of by low anchor towerslocated some distance back from the hightowers. An investigation showed the lat-ter plan to be the better from the stand-points of cost, construction and mainte-nance, and it was therefore adopted. With this general plan in mind, esti-mates were made which give considerationto several different types of cable or con-ductor, each requiring different heights andstrengths of towers. As a result of thisstudy a cable consisting of 19 wires of dif-ferent sizes was adopted. Thirteen of theseare of copperweld or copper-clad steel, giv-ing to the cable its strength, and the re-maining six are copper which, in additionto the copper coating of the other strands,give the necessary§% conductivity. Af-ter choosing thedesign it was nextnecessary to maketests of the cableto determine itsstrength and itselastic and ther-mal properties. Stud ies hadmeanwhile beenmade on the typeof insulation tobe used on b

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