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軟件翻譯不評分�。�！
近期翻譯的都是關于電纜的發(fā)展史，國內相關的資料比較少，在此分享給大家。
讀英文吃力的朋友，可以等翻譯出來后，再讀��！
另外，大家翻譯時，最好校驗一下，便于朋友們理解。
1.6 UNDERGROUND RESIDENTIAL DISTRIBUTION SYSTEMS
The development of modern underground residential distribution (URD) systems may be viewed as the result of drastically lowering first costs through technology. Post-war URD systems were basically the same as the earlier systems except that there were two directions of feed (the loop system.) System voltages rose from 2,400/4,160 to 7,620/13,200 volts. The pre-1950 systems were very expensive because they utilized items such as paper insulated cables, vaults, switches, and submersible transformers. Those systems had an installation cost of $1,000 to $1,500. Expressed in terms of buying power at that time, you could buy a luxury car for the same price! Underground service was, therefore, limited to the most exclusive housing developments.
But for three developments in the 1960s, the underground distribution systems that exist today might not be in place. First, in 1958–1959, a large Midwestern utility inspired the development of the pad-mounted transformer; the vault was no longer necessary, nor was the submersible transformer. Second, the polyethylene cable with its bare concentric neutral did not require cable splicers, and the cable could be directly buried. While possibly not as revolutionary, the load-break elbow (separable connector) allowed the transformer to be built with a lower, more pleasing appearance.
The booming American economy and the environmental concerns of the nation made underground utility systems for new residential subdivisions the watchword of the Great Society. In a decade, URD had changed from a luxury to a necessity. The goal for the utility engineer was to design a URD system at about the same cost as the equivalent overhead system. There was little or no concern about costs over the system’s life because the polyethylene cable was expected to last 100 years!
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1.6地下住宅配電系統(tǒng)
通過技術開發(fā)，極大地降低了地下住宅配電系統(tǒng)（URD）的初裝成本，促進了地下住宅配電系統(tǒng)的發(fā)展。戰(zhàn)后，地下住宅配電系統(tǒng)和以前的系統(tǒng)沒有本質的區(qū)別，只從兩個方向供電（環(huán)形系統(tǒng)）不太一樣。系統(tǒng)電壓從2400/4160V升到7620/1320V。在1950年前的系統(tǒng)，由于 使用的紙絕緣，以及開關和深潛式變壓器都非常昂貴。這些系統(tǒng)的安裝成本達到$1000到$1500之間。用當時的話表示就是，用同樣的價格可以買一個昂貴的汽車。受到成本的影響，地下電纜不適用于住宅電力系統(tǒng)。
如果沒有20世紀60年代的三項重大發(fā)明，可能就不會有今天的地下配電系統(tǒng)。第一，在1958年至1959年，美國中西部的一個機構，發(fā)明了基座安裝式變壓器，因此就不再需要深潛式變壓器了，也就不在需要建立地下室了。第二，同心式的聚乙烯絕緣電纜，不再需要連接件了，并可以直埋地下。還有一項可能不算是革命性的發(fā)明，過載開關可以讓變壓器工作在更加友好的、低負荷的情況。
美國經(jīng)濟的爆發(fā)式發(fā)展和對環(huán)境的關注，使得地下住宅配電系統(tǒng)成為了偉大社會的新標志。地下配電系統(tǒng)從奢侈品變成了必需品。公共事業(yè)的工程師們，致力于設計出和架空電纜一樣成本的地下配電系統(tǒng)。由于取乙烯電纜被期望能夠使用100年以上，當時很少關注電纜的壽命問題。