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軟件翻譯不評(píng)分�。�！
近期翻譯的都是關(guān)于電纜的發(fā)展史，國內(nèi)相關(guān)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(shí)，最好校驗(yàn)一下，便于朋友們理解。
1.9 MEDIUM VOLTAGE CABLEDEVELOPMENT
In the mid-1960s,conventional polyethylene became the material of choice for the rapidlyexpanding URD systems in the United States [6]. It was known to be superior tobutyl rubber for moisture resistance, and could be readily extruded. It wasused with cloth taped conductor and insulation shields, which achieved theirsemiconducting properties because of carbon black. By 1968, virtually all ofthe URD installations con-sisted of polyethylene-insulated medium voltagecables. The polyethylene was referred to as “high molecular weight” (HMWPE);this simply meant that the insulation used had a high “average” molecularweight. The higher the molecular weight, the better the electrical properties.The highest molecular weight polyethylene that could be readily extruded wasadopted. Jacketed construction was seldom employed at that time.
Extruded thermoplastic shields were introduced between 1965 and1975, leading to both easier processing and better reliability of the cable.
XLPE was first patented in 1959 for a carbon filled compound andin 1963 as unfilled by Dr. Frank Percopio. It was not widely used because ofthe tremendous pressure to keep the cost of URD down near the cost of anoverhead system. This higher cost was caused by the need for additives(cross-linking agents) and the cost of manufacturing based on the need formassive, continuous vulcanizing (CV) tubes. EPR was introduced at about thesame time. The significantly higher initial cost of these cables slowed theiracceptance for utility purposes until the 1980s.
The superior operating and allowable emergency temperatures ofXLPE and EPR made them the choice for feeder cables in commercial andindustrial applications. These materials did not melt and flow as did the HMWPEmaterial.
In order to facilitate removal for splicing and terminating, thoseearly 1970-era XLPE cables were manufactured with thermoplastic insulationshields as had been used over the HMWPE cables. A reduction in ampacity wasrequired until deforma-tion resistant and then cross-linkable insulationshields became available during the later part of the 1970s.
A two-pass extrusion process was also used where the conductorshield and the insulation were extruded in one pass. The unfinished cable wastaken up on a reel and then sent through another extruder to install theinsulation shield layer. This resulted in possible contamination in a verycritical zone. When cross-linked insula-tion shield materials became available,cables could be made in one pass utilizing “triple” extrusion of those threelayers. “True triple” soon followed, where all layers were extruded in a singlehead fed by three extruders.
In the mid-1970s, a grade of tree-retardant polyethylene(TR-HMWPE) was intro-duced. This had limited commercial application and neverbecame a major factor in the market.
Around 1976, another option became available—suppliers provided agrade of “deformation resistant” thermoplastic insulation shield material. Thiswas an attempt to provide a material with “thermoset properties” and thuselevate the allowable tem-perature rating of the cable. This approach wasabandoned when a true thermoset-ting shield material became available.
By1976, the market consisted of approximately 45% XLPE, 30% HMWPE, 20% TR-HMWPE,and 5% EPR.
In the late 1970s, a strippable thermosetting insulation shieldmaterial was intro-duced. This allowed the user to install a “high temperature”XLPE that could be stripped for splicing with less effort than the earlier,inconsistent materials.
Jackets became increasingly popular by 1980. Since 1972–1973,there had been increasing recognition of the fact that water presence undervoltage stress was caus-ing premature loss of cable life due to “watertreeing.” Having a jacket reduced the amount of water penetration. This led tothe understanding that water treeing could be “finessed” or delayed byutilizing a jacket. By 1980, 40% of the cables sold had a jacket.
EPR cables became more popular in the 1980s. A breakthrough hadoccurred in the mid-1970s with the introduction of a grade of EPR that could beextruded on the same type of equipment as XLPE insulation. The higher cost ofEPR cables, when compared with XLPE, was a deterrent to early acceptance evenwith this new capability.
In 1981, another significant change took place: the introductionof “dry cure” cables. Until this time, the curing, or cross-linking, processwas performed by using high-pressure steam. Because water was a problem forlong cable life, the ability to virtually eliminate water became imperative. Itwas eventually recognized that the “dry cure” process enabled faster processingas well as elimination of the steam process for XLPE production.
Anothermajor turning point occurred in 1982 with the introduction of tree-resis-tantcross-linked polyethylene (TR-XLPE). This product, which has supplanted con-ventionalXLPE in market volume today, shows superior water tree resistance when comparedwith conventional XLPE. HMWPE and TR-HMWPE were virtually off the market by1983.
By 1984, the market was approximately 65% XLPE, 25% TR-XLPE, and10% EPR. Half the cables, sold had a jacket by that time.
During the second half of the 1980s, a major change in the use offilled strands took place. Although the process had been known for about 10years, the control of the extruded “jelly-like” material was better understoodby a large group of man-ufacturers. This material prevents water movementbetween the strands along the cable length and eliminates most of theconductor’s air space, which can be a water reservoir.
In the late 1980s, another significant improvement in thematerials used in these cables resulted in smoother and cleaner conductorshields. Vast improvements in the materials and processing of extruded, mediumvoltage power cables in the 1980s have led to cables that can be expected tofunction for 30, 40, or perhaps even 60 years when all of the proper choicesare utilized. In 1995, the market was approxi-mately 45% TR-XLPE, 35% XLPE, and20% EPR.
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1.9中壓電纜的發(fā)展
在美國，20世紀(jì)60年代中期，聚乙烯材料被應(yīng)用于迅速發(fā)展的地下住宅輸配電系統(tǒng)。它的防潮能力比丁基橡膠要優(yōu)異，并可以被高速的擠出。聚乙烯被用于帶有繞包帶導(dǎo)體和絕緣屏蔽的電纜上。由于繞包帶和絕緣屏蔽內(nèi)有碳黑，可以起到半導(dǎo)電的作用。到1968年，事實(shí)上，所有的地下住宅輸配電力系統(tǒng)都是用中壓聚乙烯絕緣電力電纜。常用的聚乙烯是“高分子量聚乙烯”。分子量越高，電性能越好�？梢苑�(wěn)定擠出的高分子量聚乙烯被廣泛采用。在那時(shí)，很少使用護(hù)套結(jié)構(gòu)。
在1965至1975年間，開發(fā)出了可以擠出的熱塑性屏蔽料，這使得電纜工藝更加簡單，電纜的質(zhì)量更加穩(wěn)定。
在1959年，XLPE做為一種含碳的混合物，第一次被申請專利。在1963年，弗蘭克博士，申請了沒有填充物的XLPE專利。但是由于地下輸配電系統(tǒng)要維持和架空電纜近似的成本，XLPE并沒有被廣泛應(yīng)用。交聯(lián)劑的添加和連續(xù)硫化管道使用，造成了高昂的成本。與此同時(shí)，ERP進(jìn)入了人們的視野。巨大的初裝成本，延緩了XLPE的推廣，直到1980年，才做為公共用途被接受。
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XLPE和EPR，具有優(yōu)異的運(yùn)行電壓 ，可以在高溫下運(yùn)行，這使得XLPE和EPR成為了在商業(yè)及工業(yè)中電力供應(yīng)的首選。同時(shí)，這兩種材料不像HMWPE那樣，會(huì)產(chǎn)生熔體流動(dòng)。
為了改善連接頭和終端的剝離，在20世紀(jì)70年代，XLPE電纜和以前的HMWPE一樣，帶有了熱塑性的絕緣屏蔽。為的提升變形抗力，要求電流有所下降。直到20世紀(jì)70年代末，可交聯(lián)的絕緣屏蔽才被開發(fā)出來。
在過去，導(dǎo)體屏蔽和絕緣可以一起擠出，但是絕緣屏蔽需要單獨(dú)擠出。半成品電纜先被收到電纜軸上，然后在另外一個(gè)擠出機(jī)，生產(chǎn)絕緣屏蔽。這就增加了電纜被污染的風(fēng)險(xiǎn)。當(dāng)可以交聯(lián)的絕緣屏蔽被開發(fā)出來，導(dǎo)體屏蔽，絕緣和絕緣屏蔽就可以實(shí)現(xiàn)同時(shí)生產(chǎn)國。我們利用的是三層共擠工藝。三層共擠很快流行開來，通過三層共擠，三個(gè)機(jī)頭同時(shí)供應(yīng)一個(gè)機(jī)頭進(jìn)行擠出。
在20世紀(jì)70年代中期，抗水樹高分子量聚乙烯被 開發(fā)出來。但是這種新材料的發(fā)展受到了限制，并沒有成為市場的主力。
到1976年，市場的結(jié)構(gòu)是這樣的:45%XLPE，30%HMWPE，20%TR-HMWPE，以及5%EPR..
在20世紀(jì)70年代末，一種可剝離的熱固性的絕緣屏蔽料被開發(fā)了出來。這種材料被用于“高溫”的XLPE，并且是可以剝離的。和過去相比，在做接頭時(shí)，會(huì)很省力。
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到1980年，護(hù)套的使用開始流行起來。在1972年到1973年，已經(jīng)開始認(rèn)識(shí)到，在強(qiáng)電壓下，“水樹”中導(dǎo)致電纜壽命降低的重要因素。護(hù)套可以降低水份的滲透。因此，水樹可能通過護(hù)套來優(yōu)化及延遲。到1980年，40%的在售電纜，都是有護(hù)套的。
在20世紀(jì)80年代，EPR開始流行起來。在20世紀(jì)70年代中期，EPR的擠出技術(shù)已經(jīng)實(shí)現(xiàn)了突破，可以像XLPE一樣生產(chǎn)。盡管EPR電纜具有新的特性，但是過高的成本，導(dǎo)致EPR電纜很難被推廣。
在1981年，產(chǎn)生了另外一個(gè)突破性技術(shù)，“干法交聯(lián)”。在此之前，交聯(lián)工序是在高壓蒸汽中進(jìn)行。因此，為了延長電纜壽命，在加過程中避免水份的介入是非常重要的。此時(shí)，大家認(rèn)識(shí)到，通過干法交聯(lián)，不光可以增加生產(chǎn)速度 ，同時(shí)還可以把水汽排除在外。
另外一個(gè)轉(zhuǎn)折點(diǎn)是發(fā)生 在1982年，開發(fā)出了防水樹的交聯(lián)聚乙烯。這種產(chǎn)品，到現(xiàn)在仍然大量供貨。和普通的XLPE比較起來，TR-XLPE能夠更好的抵抗水樹的產(chǎn)生。到1983年，HMWPE和TR-HMWPE在市場上就徹底消失了。
到1984年，市場上大約:65%XLPE，25%TR-XLPE，及10%EPR。同時(shí)，有一半的電纜是有護(hù)套的。
在20世紀(jì)80年代的后半段，開發(fā)了另外一項(xiàng)重要的技術(shù)，導(dǎo)體的填充絞合。其實(shí)類似的技術(shù)在10年前就已經(jīng)被一些大廠所了解，擠出“膠狀”特在導(dǎo)體之間。這種材料能夠阻止水份在導(dǎo)體之間流動(dòng)，填充了導(dǎo)體之中的間隙。
在20世紀(jì)80年代末，在材料領(lǐng)域做了一次重要的優(yōu)化，開發(fā)出了更加平滑，更加清潔的導(dǎo)體屏蔽料。在材料領(lǐng)域，大量的改進(jìn)和優(yōu)化，在20世紀(jì)80年代，中壓電纜的壽命提高 到了30或40年，甚至達(dá)到60年。在1995年，市場大約是這樣分布的:45%TR-XLPE，35XLPE，20EPR。