软件翻译不评分！！！

近期翻译的都是关于电缆的发展史，国内相关的资料比较少，在此分享给大家。

读英文吃力的朋友，可以等翻译出来后，再读！！

另外，大家翻译时，最好校验一下，便于朋友们理解。

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.

1.9中压电缆的发展

在美国，20世纪60年代中期，聚乙烯材料被应用于迅速发展的地下住宅输配电系统。它的防潮能力比丁基橡胶要优异，并可以被高速的挤出。聚乙烯被用于带有绕包带导体和绝缘屏蔽的电缆上。由于绕包带和绝缘屏蔽内有碳黑，可以起到半导电的作用。到1968年，事实上，所有的地下住宅输配电力系统都是用中压聚乙烯绝缘电力电缆。常用的聚乙烯是“高分子量聚乙烯”。分子量越高，电性能越好。可以稳定挤出的高分子量聚乙烯被广泛采用。在那时，很少使用护套结构。

在1965至1975年间，开发出了可以挤出的热塑性屏蔽料，这使得电缆工艺更加简单，电缆的质量更加稳定。

在1959年，XLPE做为一种含碳的混合物，第一次被申请专利。在1963年，弗兰克博士，申请了没有填充物的XLPE专利。但是由于地下输配电系统要维持和架空电缆近似的成本，XLPE并没有被广泛应用。交联剂的添加和连续硫化管道使用，造成了高昂的成本。与此同时，ERP进入了人们的视野。巨大的初装成本，延缓了XLPE的推广，直到1980年，才做为公共用途被接受。

XLPE和EPR，具有优异的运行电压 ，可以在高温下运行，这使得XLPE和EPR成为了在商业及工业中电力供应的首选。同时，这两种材料不像HMWPE那样，会产生熔体流动。

为了改善连接头和终端的剥离，在20世纪70年代，XLPE电缆和以前的HMWPE一样，带有了热塑性的绝缘屏蔽。为的提升变形抗力，要求电流有所下降。直到20世纪70年代末，可交联的绝缘屏蔽才被开发出来。

在过去，导体屏蔽和绝缘可以一起挤出，但是绝缘屏蔽需要单独挤出。半成品电缆先被收到电缆轴上，然后在另外一个挤出机，生产绝缘屏蔽。这就增加了电缆被污染的风险。当可以交联的绝缘屏蔽被开发出来，导体屏蔽，绝缘和绝缘屏蔽就可以实现同时生产国。我们利用的是三层共挤工艺。三层共挤很快流行开来，通过三层共挤，三个机头同时供应一个机头进行挤出。

在20世纪70年代中期，抗水树高分子量聚乙烯被 开发出来。但是这种新材料的发展受到了限制，并没有成为市场的主力。

到1976年，市场的结构是这样的:45%XLPE，30%HMWPE，20%TR-HMWPE，以及5%EPR..

在20世纪70年代末，一种可剥离的热固性的绝缘屏蔽料被开发了出来。这种材料被用于“高温”的XLPE，并且是可以剥离的。和过去相比，在做接头时，会很省力。

到1980年，护套的使用开始流行起来。在1972年到1973年，已经开始认识到，在强电压下，“水树”中导致电缆寿命降低的重要因素。护套可以降低水份的渗透。因此，水树可能通过护套来优化及延迟。到1980年，40%的在售电缆，都是有护套的。

在20世纪80年代，EPR开始流行起来。在20世纪70年代中期，EPR的挤出技术已经实现了突破，可以像XLPE一样生产。尽管EPR电缆具有新的特性，但是过高的成本，导致EPR电缆很难被推广。

在1981年，产生了另外一个突破性技术，“干法交联”。在此之前，交联工序是在高压蒸汽中进行。因此，为了延长电缆寿命，在加过程中避免水份的介入是非常重要的。此时，大家认识到，通过干法交联，不光可以增加生产速度 ，同时还可以把水汽排除在外。

另外一个转折点是发生 在1982年，开发出了防水树的交联聚乙烯。这种产品，到现在仍然大量供货。和普通的XLPE比较起来，TR-XLPE能够更好的抵抗水树的产生。到1983年，HMWPE和TR-HMWPE在市场上就彻底消失了。

到1984年，市场上大约:65%XLPE，25%TR-XLPE，及10%EPR。同时，有一半的电缆是有护套的。

在20世纪80年代的后半段，开发了另外一项重要的技术，导体的填充绞合。其实类似的技术在10年前就已经被一些大厂所了解，挤出“胶状”特在导体之间。这种材料能够阻止水份在导体之间流动，填充了导体之中的间隙。

在20世纪80年代末，在材料领域做了一次重要的优化，开发出了更加平滑，更加清洁的导体屏蔽料。在材料领域，大量的改进和优化，在20世纪80年代，中压电缆的寿命提高 到了30或40年，甚至达到60年。在1995年，市场大约是这样分布的:45%TR-XLPE，35XLPE，20EPR。