壁面滑移对两种聚合物熔体共挤出影响的数值研究

在壁面滑移的边界条件下，利用聚合物流体计算软件包POLYFLOW对两种熔体的二维等温共挤出进行了数值模拟，在两侧壁面滑移系数相同和两侧壁面滑移系数不同这两种情形下分别计算了共挤出流动的速度场、压力场、黏度场及剪切速率场，讨论了壁面滑移对共挤出流场、界面形状和挤出胀大的影响，模拟结果表明：当两侧壁面滑移情况相同时，滑移系数越大，界面偏移越大，熔体胀大率增大；当两侧壁面滑移情况不同时。滑移系数相差越大，界面偏移越大，滑移系数小的一侧熔体挤出胀大显著。     

影响两步法硅烷交联低压架空电缆绝缘热收缩性能的工艺研究

绝缘热收缩性能是交联聚乙烯绝缘电力电缆和架空绝缘电缆型式试验中的一项重要指标。针对交联聚乙烯绝缘电力电缆和架空绝缘电缆经常出现绝缘热收缩性能不能满足产品标准的试验要求,导致电缆产品出现不合格的现象,通过分析研究电缆绝缘材料、导体温度、挤塑温度、挤塑模具和冷却等各个环节对绝缘热收缩性能的影响,并对交联聚乙烯绝缘电缆的热收缩性能进行了多次试验验证,得出了有效减小绝缘热收缩率的方法及措施,使电缆的热收缩性能完全满足产品标准的型式试验要求。     

电力电缆敷设用润滑剂的性能分析与选择

随着电力电缆采用排管敷设越来越多,电缆敷设用润滑剂的应用显得越发重要,以IEEE 1210为基础对常用的电力电缆敷设用润滑剂的材料性能进行了对比试验,发现拉线润滑剂对电力电缆的绝缘屏蔽性能影响大。不仅进行了理论计算,同时也模拟了现场情况,分析相应的润滑效果。通过对比研究得出,良好的润滑剂非常适用于中高压电力电缆的牵引敷设,避免电缆受伤和性能劣化,从而保证电缆回路的长期稳定运行。     

电池用柔性隔热板的研究

研究了一种可瓷化的柔性隔热板,其特点是常温下为橡胶形态,非气孔性隔热材料,不影响被保护物质的运行导热功能,兼具柔韧性和抗压变性能;高温状态下陶瓷化并形成均匀的层状气孔,迅速起到隔热隔火作用;加工性能优异,适用于挤出、模压等工艺。研究了白炭黑用量及自制隔热粉对隔热板的力学性能及隔热性能的影响,并对其配方进行优化。通过热重分析及多路温度分析仪发现,加入自制隔热粉后,试样烧蚀残留率为77.9%,烧蚀残留率明显提高,同时隔热板上下表面温差可达130℃,可满足新能源电池在高、低温环境下热传导的要求。     

聚合物加工助剂在HDPE绝缘料中的应用研究

在 HDPE绝缘料中 ,添加 50 0 ppm聚合物加工助剂 PPA10 2 6 ,不影响 HDPE绝缘料原有的技术性能 ,加工性能显著改善 ,挤出压力降低 2 0 % ,挤出速度提高 30 % ,挤出表面光洁度达到进口HDPE绝缘料同等水平。     

超高压电力电缆树枝放电抑制机理的探讨

介绍高压和超高压电力电缆绝缘介质中电树放电、水树放电引发的理论,以及目前国内外对电力电缆中树枝化放电的抑制方法。对相关产品标准中有关抑制树枝化措施的规定进行了理论探讨。采用超净化电缆料进行超净化、超光滑挤出层工艺加工是抑制树枝化的有效方法。电缆料中添加稳压剂能有效抑制电树,水树的引发。严格执行相关标准是抑制树枝化技术的关键。     

高性能低卤低烟料在电缆和光缆中的应用

本文介绍一种新研制的低卤低烟聚氯乙烯电缆料 ,其燃烧时的发烟量较低 ,机械物理性能较高 ,有良好的工艺挤出性能 ,现已批量用于电力电缆和光缆     

聚合物加工助剂在HDPE绝缘料中的应用研究

在ＨＤＰＥ绝缘料中，添加５００ｐｐｍ聚合物加工助剂ＰＰＡ１０２６，不影响ＨＤＰＥ绝缘料原有的技术性能，加工性能显著改善，挤出压力降低２０％，挤出速度提高３０％，挤出表面光洁度达到进口ＨＤＰＥ绝级料同等水平。     

铁路10kV单芯电力电缆对信号电缆的影响

建立了铁路10 kV三相单芯电力电缆对邻近的信号电缆产生纵向感应电压的计算模型,结合仿真计算分析了电力电缆正常运行时对信号电缆的影响,得出结论：无论信号电缆采用何种接地方式,电力电缆正常工作电流在信号电缆芯线上产生的感应电压都在容许值60V范围内,但为减小这种影响,三相单芯电力电缆宜采用换位结线方式。     

大电感电力电缆设计

电容电流过大是电力电缆线路最重要的问题之一。为减小电力电缆线路的对地电容电流,对传统电力电缆进行了创新设计,在电力电缆线芯外添加了磁粉层而成为大电感电力电缆。介绍了大电感电力电缆电感和电容的计算方法。建立了大电感电力电缆和传统电力电缆的ANSYS有限元仿真模型,对它们的导体电阻、绝缘电阻、电感、电容、集肤效应和涡流损耗进行了对比分析;建立了2种电力电缆的基于MATLAB的对地电容电流仿真模型,并对它们的对地电容电流和接地故障时的暂态电容电流进行了对比分析。结果表明:大电感电力电缆能够满足传统电力电缆的基本技术要求;根据磁粉量的大小不同,大电感电力电缆的单位长度电感值可达传统电力电缆的2~10倍,电容电流比传统电力电缆减小10%~20%,涡流损耗比传统电力电缆减小1%;并且磁粉层越厚,电容值就越小。因此,增加磁粉层,不仅能减少电容,从源头上减少电力电缆的电容电流,而且能降低电力电缆的集肤效应和涡流损耗。     

Weld lines in power cable insulation

The quality of XLPE insulation of power cables has improved markedly in recent years, and insulation failures caused by contamination have diminished. As a result, focus has shifted on the effects of insulation morphology. There are concerns about the weld lines regarding the anisotropy and frozen-in mechanical stress. The weld line that is formed has different properties than the matrix and the region is considered to be a mechanically weak point. In a recent study, seams were observed in the XLPE insulation of power cable. Their type and intensity vary because of the melt temperature and homogeneity in the extrusion. The mass distribution also has a certain influence. Typically, the seams are quite harmless for the dielectric properties of the insulation. Occasionally, severe weld lines may be considered as possible weak regions in the insulation construction. By performing electrical needle tests on four cable samples, it was found that the weld line containing sector of the cable is measurably weaker than the insulation in general. The rotating mass distributor, or more specifically, the conical extrusion was able to modify, level out and reduce seam effect. While there is no guarantee that the extrusion will have high insulation quality, it is possible to reduce the seams. The traditional extrusion process, however, should be considered as a less robust solution than the rotating mass distributor with respect to the seams.     

Development of XLPE insulated DC cable

This paper describes the development of dc XLPE cable. Through a series of material investigations, an XLPE compound containing highly purified special filler was developed. To check the dc insulation performance of the cable insulated with this new material, a prototype cable with 9 mm insulation thickness was manufactured. It was confirmed that the performance of the prototype cable was excellent. Based on the study of the prototype cable, a 250-kV dc cable with 20 mm insulation thickness was designed and manufactured. Through a series of voltage tests, excellent dc insulation performance of the developed cable was verified.     

硅烷交联聚乙烯电缆修补试验

本文介绍硅烷交联聚乙烯电缆绝缘缺陷 ,在绝缘挤出之后与温水交联之间采用热压模方法修补 ,可达到预期效果 ,即绝缘电性能及热老化性能均能满足使用要求。     

电缆绝缘层老化对接头界面压力的影响研究

为研究老化电缆绝缘层弹性模量变化对界面压力的影响,本文实测三根不同运行年限电缆绝缘的击穿场强与介质损耗角正切表征其电性能,以及在不同温度下的弹性模量表征力学性能。基于超弹性材料本构理论,计算电缆接头与本体装配后的界面压力,并建立电缆接头的二维轴向仿真模型,计算轴向上的界面压力。仿真与理论计算结果的对比表明,运用二维轴向仿真模型计算电缆接头与本体之间的界面压力的误差不超过3.2%,仿真模型计算的准确度可为研究接头轴向上的界面压力分布提供可靠的数据,虽然不同运行年限电缆绝缘层电性能不同,且弹性模量最大差异为29%,但界面压力仅变化0.275%。因此,全新接头与已运行一定年限的电缆装配后,仍能保证足够的界面压力。     

Interfacial improvement of XLPE cable insulation at reducedthickness

An interfacial diffusion method was devised to reduce insulation thickness by improving the interfacial properties of XLPE cable insulation. This method is based on a proposed concept of the facilitation of oriented lamellar growth at the interface by addition of special ingredients to the semiconducting layer, which would diffuse into polyethylene in the three layer simultaneous extrusion process for cable manufacture. Diffusion of the ingredients would facilitate lamellae to grow perpendicularly to the semiconducting layers, as predicted theoretically from a free energy model. It was clarified experimentally that oriented lamellar growth would increase the breakdown strength of XLPE insulation. It is suggested the XLPE cables manufactured by this method could be reduced in thickness especially for extra-high voltage, or the cable could be upgraded from 65 to 154 kV as the insulation thickness remains 9 mm     

阻燃聚烯烃电缆绝缘及护套挤出工艺探讨

本文从电缆料品种 ,挤出设备、模具和工艺等几个方面 ,对阻燃聚烯烃电缆绝缘及护套挤出工艺进行了探讨 ,以获得圆整和光洁的绝缘及护套表面 ,提高产品的质量     

Automatic control system of extrusion of polymer cable insulation

In this paper, problems of automated control of the extrusion of polymer cable insulation and the choice of optimum operating process conditions were considered. The methods and algorithms for automated process control of applying plastic insulation used in the manufacture of cables ensuring the specified product quality were developed.     

Underground cable technical trends for the largest rural electricco-ops

This paper discusses the technical trends, purchasing requirements, and installation practices for medium-voltage (15-35 kV) underground residential distribution (URD) insulated power cables specified by rural electric co-ops. The data was obtained from survey replies by 50 of the largest electric cooperatives, selected on their number of underground miles installed. These utilities furnished key information about their specification preferences for URD power cables including the following: filled/solid conductors, insulation and conductor shield compounds, extrusion and curing methods, copper neutral type, jacket type and material, and cable acceptance tests. Utilities also provided information on the number of cable miles purchased each year, the voltage class and insulation thickness specified and the percentage of cable direct buried versus installed in duct. The results provide meaningful information that enables all rural electric co-ops to determine whether or not their own URD cable specifications are keeping pace with the industry     

导电杂质影响下35kV电缆终端绝缘特性研究

35 kV电缆终端在现场安装过程中,易混入导电颗粒、压铅微粒等导电杂质,严重影响其运行可靠性。为研究导电杂质影响下电缆终端绝缘性能的特征状况,首先利用有限元分析软件,通过在电缆终端绝缘与应控管交界处设置导电杂质,文中建立终端缺陷模型,模拟导电杂质影响,探究了电缆终端在运行电压下,其内部电场分布的情况。然后,根据仿真结果与实际情况,文中制作了含导电杂质的电缆终端样品,利用局部放电测试平台测试电缆终端样品的局部放电信息。研究结果表明,导电杂质的引入将增大电缆终端内部的电场畸变,严重影响终端的绝缘性能;同时也加强了电缆终端的放电活动,使得放电量明显加大,严重降低了35 kV电缆终端的电气绝缘性能。