共查询到20条相似文献,搜索用时 15 毫秒
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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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Fukawa M. Kawai T. Okano Y. Sakuma S. Asai S. Kanaoka M. Yamanouchi H. 《Power Delivery, IEEE Transactions on》1996,11(2):627-634
500-kV XLPE-insulated cable with an insulation thickness of 27 mm has been developed for long-distance transmission lines. Basic studies on 500-kV XLPE cable have shown that contaminants in the insulation may be the factor determining electrical performance. This hypothesis is justified by the good correlation obtained between statistical estimations of the size of the largest contaminant in the insulation and the electrical characteristics of full-sized cables. Voltage-withstand and long-term tests have confirmed the design values for minimum breakdown stress, for AC and impulse voltage, and for the degradation coefficients 相似文献
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Ishibashi A. Kawai T. Nakagawa S. Muto H. Katakai S. Hirotsu K. Nakatsuka T. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1998,5(5):695-706
This review summarizes research on treeing phenomena, i.e. the formation of electrical trees and water trees, that has been undertaken in Japan for the development of 500 kV XLPE cable. Section 1 presents the results of factors affecting XLPE cable insulation breakdown under commercial ac and lightning impulse voltages. Section 2 verifies the phenomena of electrical tree formation in XLPE cable insulation using block samples and model cables, and gives the results of studies to determine the level electrical field stress initiation for such trees. Section 3 summarizes the results of studies on long-term aging characteristics, which is a particular problem under commercial ac voltages, while Section 4 explains how this research influenced the design of 500 kV XLPE cable insulation. All authors were members of `The investigation committee of fundamental process of treeing degradation' under IEEJ 相似文献
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Shigemitsu Okabe Takahiro Ohno Eiichi Zaima Akio Kishi Kazuaki Aono Noboru Hosokawa 《Electrical Engineering in Japan》1996,116(4):49-63
To evaluate an appropriate level of ac test voltage for 1000-kV transformers, it is necessary to make an accurate estimation of ac V-t characteristics. For the level of impulse test voltage, V-N characteristics are important to evaluate effects of impulse stress repetition. Since both of the characteristics are dependent on insulation structures and manufacturing processes of transformers, it is important to make accurate simulations on transformer insulation for reliable insulation data. To obtain some of the basic data for 1000-kV transformer test levels, long-time ac V-t tests and impulse V-N tests of up to 1000 times voltage application were carried out on an insulation model simulating fundamental structure of shell-form transformers. The model is composed of a parallel electrodes system with a compound structure of pressboard barrier and oil gap. The tests showed the following characteristics: ac V-t characteristics of up to several ten days could be described by two lines, each representing short-time and long-time characteristics. V-N characteristics of lightning and switching impulse were expressed by relatively flat lines, which showed a decrease in breakdown voltage by less than 10 percent after 1000 times impulse application. 相似文献
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Osuke Miura Naotaka Ichiyanagi Hirokazu Misawa Naomi Hashimoto 《Electrical Engineering in Japan》1997,121(3):20-26
A composite insulation system of laminated tape and high vacuum is newly proposed for a superconducting bus-line cable operated at relatively low voltage. Its breakdown characteristics were investigated using model cable specimens with different kinds of laminated tapes such as semisynthetic paper, polypropylene film, and kraft paper of insulation thickness less than 1 mm. First, ±dc, ac, and —Imp breakdown stresses of the semisynthetic papers were investigated. +dc breakdown stress was 21.7 kV/mm for a specimen of insulation thickness 1 mm and −dc breakdown stress was 41.5 kB/mm, so that the remarkable polar effect was observed. ac breakdown stress was 18 kV/mm. Also, the ratio of −Imp breakdown stress was about 3. Furthermore, ac breakdown stresses of other tapes were investigated, but remarkable differences among their stresses were not observed. Most of the specimens were broken from the “butt gap” between tapes. To understand this cause, measurements of the partial discharge were carried out. It was found that the inception stress of partial discharge of butt gap located just on the conductor was about 20 kV/mm, not dependent on the kind of tape. This value is much lower than the breakdown stress of the same length of vacuum gap. Therefore, it is considered that the trigger of the breakdown of this insulation system is the surface discharge along the edge of the butt gap. © 1998 Scripta Technica, Inc. Electr Eng Jpn, 121(3): 20–26, 1997 相似文献
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Kenji Kaminaga Masaki Ichihara Mitsuo Jinno Teruyoshi Tanabe Sadao Fukunaga Mamoru Kanaoka Hajime Takehana 《Electrical Engineering in Japan》1997,118(1):28-40
A 500-kV XLPE insulated cable with an insulation thickness of 27 mm has been developed for long-distance transmission lines. Basic studies on the 500-kV XLPE cable have shown that contaminants in the insulation may determine electrical performance. This hypothesis is justified by the good correlation obtained between statistical estimations of the size of the largest contaminant in the insulation and electrical characteristics of full-size cables. Voltage-withstand and long-term tests have confirmed design values for minimum breakdown stress, ac and impulse voltage, and degradation coefficients. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (1): 28–40, 1997 相似文献
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Huuva R. Englund V. Gubanski S.M. Hjertberg T. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2009,16(1):171-178
Electrical treeing in high voltage cable insulation has been studied widely as it is one of the major breakdown mechanisms for solid dielectrics subjected to high electrical stresses. The most frequently experimental set-up used to study electrical treeing is utilizing needles to achieve a high divergent field to promote the initiation of electrical trees. In this paper a new type of electrode configuration is described, which will be beneficial when examining electrical treeing in terms of both the capability to follow the course of events in real time and the small amount of insulation material is needed. This new electrode configuration makes use of a thin tungsten wire as electrode to obtain the high divergent electrical stress needed to initiate electrical trees. Multiple electrical trees are at times formed at different points along the wire during the testing, this indicates that the field are homogenous along the wire. This allows for determining the tree initiation field and the rate of tree growth. It is also shown that this electrode configuration is able to distinguish the increased electrical tree inception obtained by the addition of voltage stabilizers. 相似文献
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Hasegawa T. Hatano M. Yamaji K. Kouan T. Hosokawa N. 《Power Delivery, IEEE Transactions on》1997,12(4):1526-1531
Among special insulation tests for DC power converter transformers, polarity reversal tests can be substituted by applied AC voltage tests from a stress similarity in oil ducts. In order to investigate equivalent levels of other insulation tests to polarity reversal tests, the dielectric strength of a transformer at polarity reversals was examined by use of a model of typical oil/paper composite insulation. From the comparison of polarity reversal and other insulation tests, it was found that dielectric strength of transformer insulation at polarity reversals is phenomenally similar to that under switching impulse stresses. Equivalent AC test voltage to polarity reversal test was also estimated from the experimental results. The breakdown characteristics of polarity reversal tests showed that partial discharges at polarity reversals impose less harmful stress on insulation barriers than those at usual AC or impulse tests 相似文献
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Laboratory tests were performed to investigate the effects of lightning and thumping impulses on the performance of various 15 kV cable designs. The cable designs were aged in the laboratory using an accelerated water treeing test. Some samples were subjected to lightning impulses, some were subjected to thumping impulses, and some were aged without impulses applied. The impulse effects were evaluated using time to failure data, AC breakdown data, and impulse breakdown data. The results show that lightning or thumping impulses do not affect cable AC or impulse breakdown strength. There is also no visual difference between wafers taken from impulsed and control samples. However, there is a strong indication that lightning impulses can reduce cable life. Almost all the aging failures occurred while the cables were warm. No failures occurred during the impulse application. It is also shown that increased cable wall thickness extends cable life for the tree-resistant high-molecular-weight insulation material tested, but not for the crosslinked polyethylene insulation material tested 相似文献
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Suzuki H. Takahashi T. Okamoto T. Akita S. Ozawa Y. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2002,9(6):952-957
For the optimization of electrical insulation design for high temperature superconducting (HTS) cable, evaluation of electrical insulation characteristics especially for butt gap of LN/sub 2/ impregnated cold dielectric (CD) which consists of the wrapped tape insulation impregnated with LN/sub 2/ plays an important role. This paper presents partial discharge (PD) inception and breakdown characteristics in LN/sub 2/ impregnated butt gap model which modeled a weak point of the wrapped tape insulation impregnated with LN/sub 2/ and cable model with short length with polypropylene laminated paper (PPLP/sup /spl reg//), Nomex/sup /spl reg// paper and cellulose paper. PD current pulse was found to have a steep rise time of /spl sim/ ns and amplitude of /spl sim/ tens /spl mu/A at PD inception voltage region. Little dependency of breakdown stress on the insulating material is found. PD inception stress is almost independent of insulation thickness of 1 to 3 mm. The requirement insulation thickness for 66 kV class HTS cable is estimated to be /spl sim/ 5 mm under PD-free condition from viewpoint of long-term reliability. 相似文献
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Kazuhiro Mizuno Takeshi Sakamoto Kaoru Endo Hiroyuki Fujita Kiyoto Hiraishi 《Electrical Engineering in Japan》1996,116(5):97-106
A perfluorocarbon (PFC)-immersed 275-kV transformer with compressed SF6, gas has been developed. This paper describes the basic cooling and insulation characteristics of PFC, the ac partial discharge voltage, and the aging of PFC-immersed insulation. The results demonstrate that a prototype 275-kV 100-MVA three-phase transformer can be operated without any difficulties for an extended period of overvoltage. This prototype has an ac partial discharge initiation strength which is 1.5 times that of the ac test voltage and a lightning impulse breakdown strength which is 1.5 times that of the test voltage. A 275-kV 250-MVA three-phase transformer was built and is being operated at the Abe substation of Chubu Electric Power Co., Inc. The transformer has been operating satisfactorily. 相似文献
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Frayssines P.E. Lesaint O. Bonifaci N. Denat A. Devaux F. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2003,10(6):970-976
This paper presents a study of breakdown and prebreakdown phenomena (streamers) in liquid nitrogen and mineral oil under quasi uniform electric field, under ac and impulse voltage. Streamers preceding breakdown are studied up to 0.5 MPa by high-speed visualization and recording of emitted light. In these conditions, breakdown in LN/sub 2/ is mainly due to negative streamers, initiated at lower voltage than the corresponding positive voltage. Hydrostatic pressure has a limited effect on breakdown voltage, such as in mineral oil. It is shown that the ratio of impulse to ac breakdown voltage in LN/sub 2/ is surprisingly low (close to 1), whereas in the same conditions ac breakdown voltage in mineral oil is lower than impulse breakdown voltage. Practical consequences for the design of HV insulation in superconducting systems are discussed. 相似文献
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Mosinski F. Wodzinski J. Sikorski L. Ziencikiewicz J. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1994,1(4):615-623
The results of a composite voltage, ac with lightning impulse (LI) tests of a paper-oil insulation model are presented. It was demonstrated that the presence of the background ac voltage leads to a decrease in LI breakdown voltage. This is particularly conspicuous at opposite polarities. The dispersion of LI breakdown voltages decreases save for the case when the LI is superimposed on the opposite polarities. The dispersion of LI breakdown voltages decreases save for the case, when the LI is superimposed on the opposite polarity peak value of the ac sinusoid. In this critical case the combined breakdown voltage (ac+LI) may be even lower than the ac one 相似文献
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Hiraishi K. Uwano Y. Shirakura K. Gotanda Y. Higaki M. Endoo K. Horikoshi M. Mizuno K. Hora H. 《Power Delivery, IEEE Transactions on》1995,10(2):880-888
A perfluorocarbon (PFC) immersed 275 kV power transformer with compressed SF6 gas insulation has been under development. This paper clarifies the AC partial discharge inception voltage and time characteristics of PFC immersed insulation and also clarifies that a prototype 275 kV 100 MVA three-phase transformer could be operated without any trouble during long-term overvoltage tests. This prototype proved that it had AC partial discharge inception strength of higher than 1.5 times the AC test voltage and lightning impulse breakdown strength of 1.5 times the test voltage. A 275 kV, 250 MVA three-phase power transformer was developed and operated at the outdoor substation of the Chubu Electric Power Co., Japan. This transformer has been successfully operated to date and a detailed internal inspection of the transformer was carried out after one year and 9 months of successful practical operation. No significant abnormal condition was recognized 相似文献
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Mazzanti G. Montanari G.C. Motori A. Anelli P. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1995,2(6):1095-1099
The results of electrical endurance tests performed on ribbons cut from full-sized EPR cables are compared with those obtained by tests performed on cable models, having the same insulation as the full-sized cable. It is shown that the voltage endurance coefficient estimated on the basis of the short-term life test data has approximately the same value for cable models and ribbons, according to both inverse-power and exponential models. However, the surface roughness resulting from cutting the specimens can affect the result at high stresses 相似文献
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热老化对交联聚乙烯电缆绝缘中水树的影响研究 总被引:3,自引:2,他引:1
热老化过程不但会影响交联聚乙烯电缆绝缘的电磁学和物理化学性能,还对绝缘内水树的产生与生长有着一定的影响。通过研究热老化过程对XLPE电缆绝缘中的水树现象的影响,以及在几个有可能的影响因素当中,哪个因素对水树现象的影响最大。实验结果表明,在与XLPE电缆绝缘的热老化有关的各种因素对水树现象的影响中,热氧化对XLPE电缆绝缘表层水树的产生和生长的影响最大。尽管热氧化所引起的缺陷有可能就是XLPE电缆绝缘中水树生长过程中的起始点,但是它在一定程度上抑制着水树的成长,甚至有着"水树延迟效果"的美称。 相似文献
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Extruded polyethylene is used as the bulk insulation for ac HV cables because of its high electric resistivity and breakdown strength. Although the material at present has limited use in dc power cables, it is used extensively in submarine optical communication cable systems. This paper reports on the study of the short-term characteristics and long-term performance of low-density polyethylene (LDPE) insulation under dc electric stress. The results are presented in which controlled defects as found in practical systems (voids, metallic and non-metallic particles) were introduced into well-characterized polymer material so that their influence on electrical strength and breakdown mechanisms could be determined. Samples were compression-molded under laboratory conditions and subjected to ramp-to-failure and electrical aging tests at various stresses. Weibull statistics are used to analyze the results. Examination of electrically aged samples indicates an oxidation degradation around the defects due to stress enhancement. From the failed samples a value of n in the inverse power model was estimated. The residual life of aged samples was also examined 相似文献