共查询到20条相似文献,搜索用时 15 毫秒
1.
Katsumi Yoshino Tsuyoshi Demura Masaki Kawahigashi Yoshitsugu Miyashita Kiyoshi Kurahashi Yoshiji Matsuda 《Electrical Engineering in Japan》2004,146(1):18-26
Cross‐linked polyethylene (XLPE) has been widely adopted as insulating material for high‐voltage power cables up to 500 kV. Further improvement of electrical and thermal properties on insulating material is required in order to increase cable operation efficiency. Therefore, the development of novel insulating material possessing high thermal properties will be necessary. Recent progress of catalysis technology contributes to obtain new polymeric materials which may be applied to electrical insulation. The authors investigated the basic properties of newly developed stereoregular syndiotactic polypropylene (s‐PP) which is synthesized with homogeneous metallocene catalyst. Though recycling of cross‐linked polymers such as conventionally used XLPE may be difficult because of their poor heat deformation, the s‐PP which is not cross‐linked must be suitable for recycling. A series of experiments on its physical and electrical properties gave the following results.
- (1) s‐PP has sufficient flexibility compared with isotactic polypropylene (i‐PP ).
- (2) Both AC and lightning impulse breakdown strength of s‐PP in spite of no cross‐linking are superior to those of XLPE in the temperature range from 25 to 90 °C.
- (3) Degradation by copper of s‐PP is less than that of i‐PP.
- (4) s‐PP/VLDPE blend shows sufficient brittleness temperature for use.
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TAKASHI KURIHARA EIJI TSUTSUI EIJI NAKANISHI KIYOSHI MAKI KENICHI MURAKAWA KOJI MORIMOTO TOSHIHIRO TAKAHASHI TATSUKI OKAMOTO 《Electrical Engineering in Japan》2017,198(4):37-50
Dry‐cured and extruded three‐layer (E‐E type) 6.6‐kV cross‐linked polyethylene (XLPE) cables were introduced into electric power systems more than 30 years ago, but they do not experience failures because of water tree degradation. Also, the degradation index of water treeing for these cables has not been established. Therefore, investigating results of residual breakdown voltage and water tree degradation of these cables will help us plan for cable replacement and determine water tree degradation diagnosis scheduling, and will be fundamental data for cable lifetime evaluation. In this study, the authors measured the ac breakdown voltages of dry‐cured and E‐E type 6.6‐kV XLPE cables removed after 18 to 25 years of operation and observed the water trees in their XLPE insulation. As a result, it was observed that breakdown voltages were larger than the maximum operating voltage (6.9 kV) and the ac voltage for the dielectric withstanding test (10.3 kV). Water trees were mainly bow‐tie water trees and their maximum length was approximately 1 mm. Although the number of measured cables was limited, the lifetime of this type of cable was estimated to be approximately 40 years, even experiencing water immersion. 相似文献
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《Power Delivery, IEEE Transactions on》2004,19(4):1532-1537
This paper provides data on four commercial tree retardant crosslinked polyethylene (TR-XLPE) and one cross-linked polyethylene (XLPE) insulated 15 kV cables supplied by three manufacturers. The cables have "super-smooth" conductor shields and "extra-clean" insulation and insulation shields. AC and impulse voltage breakdown and selected other characterization data are presented for cables that were aged immersed in room temperature water (15-30/spl deg/C) up to 24 months of a planned 48 months aging program. The five cables have high ac voltage breakdown strength, three of the TR-XLPE cables, actually increased in breakdown strength during aging. The one TR-XLPE cable that had the lowest ac voltage breakdown had vented trees at the insulation shield and high dissipation factor, which the other cables did not have. The impulse voltage breakdown strength of all cables decreased during aging; the cable with the lowest ac voltage breakdown also has the lowest impulse voltage breakdown. The dissimilar performance of the TR-XLPE cables and the excellent performance of the XLPE cable indicates evaluations at longer times are required to differentiate between modern TR-XLPE and XLPE insulated cables. 相似文献
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Ombello F. Attolini G. Caracino P. Nassi M. Spreafico S. Montanari G.C. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2002,9(6):958-963
The realisation of the so-called "cold dielectric" cable, where the insulation is kept at a cryogenic temperature, entails the choice of an optimised insulation system, with properties that are the best compromise between physical-electrical characteristics and design requirements. To this purpose, a specific study was planned to qualify different materials. On the basis of literature results, mostly carried out at liquid helium temperature, polypropylene laminate (PPL), paper, high-density polyethylene (HDPE) fiber and ethylene-propylene rubber (EPR) were chosen as potential candidates for the final use in liquid nitrogen. Electrical properties of materials were evaluated and compared by means of different models. Flat and cylindrical models were used to characterise the intrinsic properties of materials and determine the impact of the technological processes, respectively. Short term and long term tests were carried out at liquid nitrogen temperature and at different absolute pressures for the evaluation of electrical endurance. As far as short term tests are concerned, AC and lightning impulse (LI) breakdown step tests were performed. Long term tests were carried out under AC field; furthermore, power factor and partial discharge measurements were made to evaluate the impregnation process. The results of the whole testing procedure indicate that PPL shows the best behaviour for the application at cryogenic temperature in a superconducting cable. 相似文献
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With the development of modern power systems, especially that of the global energy internet, high-voltage, direct current(HVDC) cable power transmission will play an important role in the future. The key problem of HVDC cable power transmission is the need for novel cable insulation materials that have high performance, recyclability, and higher working temperature to replace traditional crosslinked polyethylene. This paper investigates the thermal and electrical properties of polypropylene(PP)/Al2 O3 nanocomposites as a potential recyclable HVDC cable insulation material. The developed nanocomposites exhibit excellent thermal and electrical properties with the introduction of Al2 O3 nanoparticles. Particularly, the space charge accumulation is greatly suppressed. 相似文献
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Murata Y. Katakai S. Kanaoka M. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1996,3(3):361-365
This paper discusses tree inception and breakdown voltage characteristics of XLPE cable insulation subjected to impulse voltages superimposed on ac voltage. The tree initiation tests were performed on laboratory-molded specimens equipped with needle electrodes, whereas the breakdown tests were conducted on a full-sized cable. The impulse tree initiation stress was found to be dependent on the magnitude of the pre-applied ac stress and the relative polarities of the impulse and the ac peak at the instant of their superposition. Although the impulse polarity has an effect on the tree inception, the general behavior is that the tree inception stress always decreases with an increase of the pre-applied ac stress. This phenomenon is discussed in terms of the space charge effect and the influence of the impulse voltage application itself. The impulse strength of a full-sized cable insulation was found to be independent of the pre-applied ac stress as long as that stress did not exceed the operating stress of a 500 kV cable insulation. However, subjecting cable insulation to higher ac stresses before impulse application caused a reduction of its breakdown strength as compared with the insulation without ac prestressing 相似文献
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Don‐Chan Cho Ryousuke Ishii Keiichiro Shizu Hitoshi Semi Tatsuo Mori Teruyoshi Mizutani Mitsugu Ishioka 《Electrical Engineering in Japan》2002,139(4):17-25
We investigated the high‐field conduction, DC and impulse breakdown strength, space charge distribution, and tree inception voltage for three kinds of new low‐density polyethylene (LDPE) prepared using a metallocene catalyst (mLna, mLao, mLldao), linear LDPE prepared using a Ziegler catalyst (LLao), and LDPE prepared by a high‐pressure process (LDna). The dc and impulse breakdown strengths of LDPEs prepared using a metallocene catalyst were higher than those of LLao and LDna. The high‐field currents of LDPEs prepared using a metallocene catalyst were lower than those of LLao and LDna. A homo‐space charge was accumulated near the cathode in mLna. The tree inception voltage of mLna was higher than that of LDna. From these results, it is concluded that LDPE prepared using a metallocene catalyst has electrical insulating properties superior to the conventional LDPE and that the former has potential as a power cable insulator. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(4): 17–25, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.1164 相似文献
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500kV XLPE电缆绝缘中树枝化现象的述评 总被引:4,自引:0,他引:4
介绍日本开发 5 0 0 k V XL PE电力电缆时研究树枝化现象的形成 ,评述 XL PE电缆形成电树和水树与场强的相关性、树枝引发场强和长期寿命特性的研究结果 ,说明由此确定 5 0 0 k V XL PE电力电缆的绝缘设计。 相似文献
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Kenichi Ishimatsu Channarong Banmongkol Tatsuo Mori Teruyoshi Mizutani Mitugu Ishioka 《Electrical Engineering in Japan》2000,130(2):1-9
Now low‐density polyethylene (M‐LDPE) prepared using metallocene catalyst has narrower composition distribution and molecular weight distributions than linear low‐density polyethylene (LLDPE) using Ziegler catalyst. The authors compared the electrical insulating properties of M‐LDPE films and conventional LLDPE films. The high‐field current of M‐LDPE was found to be lower than that of LLDPE. The difference in current increased with the decrease of temperature. The high‐field current was much reduced in M‐LDPE with a low melting point. The impulse breakdown strength of M‐LDPE increased with the decrease of temperature. The insulating properties of M‐LDPE with a low melting point were improved at 30 °C. These results were explained by the fact that M‐LDPE with a low melting point includes more low‐molecular‐weight components. We also discuss the effects of antioxidant on the electrical properties of M‐LDPE. We compared the electrical conduction and breakdown strength of undoped M‐LDPE and antioxidant‐doped M‐LDPE. Differences in their electrical properties were minor. It was found that the excellent properties of M‐LDPE do not depend on the effects of antioxidant. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 1–9, 2000 相似文献
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聚丙烯作为一种复合绝缘材料目前已广泛应用于射频电容器及电力电缆等设备中。聚丙烯混合天然纳米黏土颗粒后可作为一种纳米复合绝缘材料应用于实际工程中。本文旨在通过实验及理论的研究获取该复合绝缘材料的电气性能,为其应用提供技术支持。首先搭建了一套用于测试材料电气击穿特性的综合实验平台,接着分别在2种不同的加压方式下测量得到了混合不同重量比例(0%、2%和6%)纳米黏土颗粒的聚丙烯绝缘薄膜的电流密度及击穿场强值。研究结果表明:1)混合纳米颗粒的聚丙烯其击穿场强要明显高于未经纳米黏土添加的试品;2)复合绝缘材料电流密度与电场强度之间呈现非线性的函数关系,并有饱和趋势。随着电场强度的增加,复合绝缘材料的相对介电常数也发生着变化。在本文的实验样品范围内,纳米黏土颗粒的添加比重为2%时对于材料电气性能的提升较为明显。本文的研究成果可为聚丙烯复合绝缘材料的应用提供参考。 相似文献
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The electrical characteristics and insulation design strength of liquid-nitrogen-impregnated synthetic insulation were considered. The impregnation of liquid nitrogen into insulation paper can be monitored by measuring the electrostatic capacitance of the cable. ∈ tan δ, an index of the dielectric loss, was 0.31% for cellulose paper and 0.18% for semisynthetic paper, polypropylene laminated semisynthetic paper, and biaxially oriented polypropylene laminated paper. It was found that the decline of the thickness dependence of the breakdown strength of the liquid-nitrogen-impregnated insulating cable was steeper than that of the oil-filled cables. It is possible to design the insulation strength of the 66 kV cable to be 10 kV/mm 相似文献
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《Electric Power Systems Research》2001,60(1):9-15
Cables as elements of power distribution system have great influence on its reliable service and overall planning requirements. During last years, crosslinked polyethylene (XLPE) cables have been more and more used in power systems. This paper presents the results of an investigation of changing of (XLPE) cables insulation breakdown stress (AC BDS) due to water absorption. The paper deals with AC BDS of the following kinds of XLPE cable insulations: steam and dry cured with water tree retardant crosslinked polyethylene (TR-XLPE) and non-tree retardant crosslinked polyethylene (XLPE). During tests, the tap water was injected into, (1) conductor with cable ends closed; (2) into cable conductor with ends opened; and (3) into metallic screen with cable ends opened. The presence of water in XLPE cables was subjected to electrical stress and heating. AC BDS tests were performed as a function of aging time and water content in the cable insulation at different aging temperatures. Also, in this investigation, tests with the changing of AC BDS in the radial direction of unaged and aged XLPE cable insulations were carried out. 相似文献
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Hvidsten S. Holmgren B. Adeen L. Wetterstrom J. 《Electrical Insulation Magazine, IEEE》2005,21(6):17-23
This paper reports the results from the condition assessment of 12- and 24-kV cross-linked polyethylene (XPLE) cables using a technique based on dielectric spectroscopy initially developed at KTH in Sweden. The work aims to examine whether the method could detect water tree degradation for the second generation medium voltage (MV) cables with long, but not bridging, water trees. While the overall cable condition was better than expected for second generation XPLE cables, water trees were found in most of the selected cables. The diagnostic method based on the measurement of the dielectric response could only detect water tree degradation in the examined second generation cables when the water trees bridged the insulation wall. Condition assessment above service stress may, in some cases, be required to detect bridging water trees. The results indicate that there is a correlation between the voltage level and the breakdown voltage of the cable. This can be used as a diagnostic criterion for this group of cables. 相似文献
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《IEEJ Transactions on Electrical and Electronic Engineering》2017,12(Z2):S10-S15
Inorganic fillers were added to epoxy resin for preparing micro and nano filler/epoxy composite, and then the breakdown strengths, depths of erosion caused by partial discharge, and electrical tree experiments of composites were investigated. It was found that the loading of micro fillers usually decreases the short‐time breakdown strength (breakdown under a continuously rising voltage) of the composites. On the contrary, it increases the ability to withstand long‐time electrical aging (erosion or breakdown caused by electrical tree under a discontinuously rising voltage or constant voltage) of the composites. The effect of inorganic fillers in suppressing the electrical tree or erosion channel propagation in the composite is different during the process of withstanding short‐time breakdown and long‐time electrical aging. Defects are introduced during the mixing of fillers and epoxy resin, which play a role to decrease the short‐time breakdown strength and accelerate long‐time electrical aging. It is concluded that micro and nano inorganic fillers can suppress the electrical tree channel propagation and erosion caused by partial discharge, whereas defects play the opposite role in composites. Two opposite effects of inorganic fillers and defects exist simultaneously during the process of electrical aging and breakdown; whereas inorganic fillers play a primary role in long‐time electrical aging, defects play a primary role in short‐time breakdown. 相似文献
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聚合物复合电介质材料在电工领域有着广泛的应用。在电力设备运行过程中,电介质材料在温度、电(磁)场、机械力以及环境的作用下会发生击穿现象,造成电力设备失效以及由此引起的损失。因此,提升复合电介质的击穿强度一直是电工领域的重要问题。纳米复合电介质代表未来电力设备绝缘的发展方向。该文首先简述聚合物电介质的基本击穿理论,并总结提升纳米复合电介质击穿强度的基本策略及原理。接着,聚焦纳米粒子对电荷产生、输运以及电场分布的作用,总结几种提高纳米复合电介质击穿强度的方法,包括纳米粒子的表面工程、调控纳米粒子的维度和排列、制备多层结构的复合电介质、制备核壳结构纳米粒子复合介质,以及利用金属纳米颗粒的纳米效应。最后,对提升纳米复合电介质击穿强度未来的研究方向进行展望。 相似文献