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Showing papers in "IEEE Electrical Insulation Magazine in 2006"


Journal ArticleDOI
T.A. Prevost, T.V. Oommen1
TL;DR: A brief discussion on the development of electrical grade paper/pressboard for transformer use from the raw materials, improvements made, and particularly the use of thermal upgrading agents to extend the useful life of transformers is presented in this article.
Abstract: This paper presents a brief discussion on the development of electrical grade paper/pressboard for transformer use from the raw materials, improvements made, and particularly the use of thermal upgrading agents to extend the useful life of transformers

232 citations


Journal ArticleDOI
T.V. Oommen1, T.A. Prevost
TL;DR: In this paper, the practical aspects of the usage of cellulose insulation in transformers with regard to maintaining the integrity over long periods of time and preserving and extending insulation life are examined and life plots are discussed in more detail.
Abstract: This paper examines the practical aspects of the usage of cellulose insulation in transformers with regard to maintaining the integrity over long periods of time and preserving and extending insulation life. The factors that relate to loss of life are examined and life plots are discussed in more detail.

191 citations


Journal ArticleDOI
T.W. Dakin1
TL;DR: In this article, the authors discuss the theoretically deduced mechanisms for the magnitude and the trends of conduction and polarization in electrical insulation (dielectrics) with molecular and physical structure, frequency, and temperature.
Abstract: This article discusses the theoretically deduced mechanisms for the magnitude and the trends of conduction and polarization in electrical insulation (dielectrics) with molecular and physical structure, frequency, and temperature. The discussion intends to explain the atomic, electronic, molecular, and ionic basis for these electrical properties, so that the reader can better understand why dielectrics behave the way they do. Application of these principles should also guide the reader to make estimates or rough predictions of conductivity and dielectric constant levels, and their variations, from an examination of the molecular/atomic composition of a material. Most of the discussion is more directly applicable to the condensed phases, solids and liquids. Gases, in principle, behave the same, but they have important differences because of their very much lower density and lack of restraint to molecular rotation and translation. An overriding factor in the magnitude of conduction and polarization is the number density of the participating species: electrons, ions, or dipolar molecules

142 citations


Journal ArticleDOI
TL;DR: In this paper, the authors focus on a range of elements critical to the degassing process, which form the fundamental chemistry, through computational and measurement techniques to the solutions that are in use today.
Abstract: This article focuses on a range of elements critical to this process; form the fundamental chemistry, through computational and measurement techniques to the solutions that are in use today. Degassing contributes greatly to the quality of power cables by improving the certainty in electrical testing and improving the dielectric properties. To ensure that the degassing process delivers the expected benefits, it is important to measure and model the process by which the crosslinking byproducts are desorbed from the cable polymers. Weight loss and HPLC have shown themselves to be the most effective and practical measurement techniques

123 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe typical cable defects uncovered while testing over 9,000 km of medium voltage XLPE insulated cables. And they discuss the "conversion" of water trees (WT) to electrical trees (ET) which are associated with partial discharge (PD) activity in the context of laboratory research.
Abstract: This paper describes typical cable defects uncovered while testing over 9,000 km of medium voltage XLPE insulated cables. After a brief review of the testing method, the procedure that led to the identification, localization, and characterization of typical defects found in operating cables is described. The paper also discusses the "conversion" of water trees (WT) to electrical trees (ET) which are associated with partial discharge (PD) activity in the context of laboratory research. Based on actual service performance of cables, several cases in which ETs associated with WTs did not lead to cable failure even after several years of service in very harsh operating environments are cited

82 citations


Journal ArticleDOI
TL;DR: In this paper, a comparison of the two main insulators used in extruded HV cables, EPR and XLPE, is made, and each material has some properties that are better than those of the other material.
Abstract: This article reviews the different components, conductors, semiconductive shields, insulation, sheaths, and jackets, that make up extruded, high-voltage cables. The different types of conductors are described as are the different insulation systems that are available for medium and HV cables. There is a comparison of the two main insulators used in extruded HV cables, EPR, and XLPE. Each material has some properties that are better than those of the other material.

67 citations


Journal ArticleDOI
TL;DR: This article showed that the mechanical and thermal properties of EPR cable dielectrics are very stable with temperature and showed that EPR polymer is essentially amorphous and does not suffer from the very large thermal expansion of TRXLPE as its crystallites melt.
Abstract: This paper shows that the mechanical and thermal properties of EPR cable dielectrics are very stable with temperature. Commercially available EPR and TRXLPE cable dielectrics typically have about the same thermal conductivity, although the thermal conductivity of TRXLPE above the melting point of the crystallites drops below that of the EPR dielectrics. The mechanical properties of EPR cable dielectrics are much more stable with temperature than those of the TRXLPE, as EPR polymer is essentially amorphous so that EPR cable dielectrics do not suffer from the very large thermal expansion of TRXLPE as its crystallites melt.

62 citations


Journal ArticleDOI
TL;DR: In this article, the authors describe the application of an innovative partial discharge detection and analysis approach to the diagnosis of HV polymeric cable systems and present the results of PD measurements performed off-line on cable systems, rated from 220 to 400 kV.
Abstract: This paper describes the application of an innovative partial discharge (PD) detection and analysis approach to the diagnosis of HV polymeric cable systems. The results of PD measurements performed off-line on cable systems, rated from 220 to 400 kV just after laying or after some time in operation, are presented. PD generating defect identification and location are discussed, also in relation to forensic observations

60 citations


Journal ArticleDOI
I. Hohlein1
TL;DR: In this article, the authors present some unusual cases of gassing in transformers in service without an actual fault and reveal that hydrogen production caused by stray gassing may be due to strongly hydro-treated oils, but is also very strongly influenced by transformer materials.
Abstract: This paper presents some unusual cases of gassing in transformers in service without an actual fault. These cases reveal that hydrogen production caused by stray gassing may be due to strongly hydro-treated oils, but is also very strongly influenced by transformer materials. Stray gassing with overproduction of saturated hydrocarbons with no production of hydrogen and no increased rates of hydrogen, ethylene, and other fault gases has probably always existed and is possibly related to oxidation. The overproportional development of methane and especially ethane proceeds in the first years of service and reaches a plateau after considerable consumption of oxygen. Possibly, this process is also catalytically triggered by transformer materials. Catalytic phenomena and stray gassing can be distinguished from a transformer fault through regular checks not only of the absolute DGA values but also the rates of gas increases

34 citations


Journal ArticleDOI
TL;DR: In this article, the authors present Paschen characteristic formulae with appropriate constants for most of the common gases used in high voltage technology, which enables the two physical-engineering constants B and C in formula to be determined.
Abstract: The aim of this article is to present Paschen characteristic formulae with appropriate constants for most of the common gases used in high voltage technology. This aim is achieved by choosing two appropriate well-separated values on the Paschen characteristic, and this enables the two physical-engineering constants B and C in formula to be determined.

33 citations


Journal ArticleDOI
TL;DR: In this paper, the theoretical considerations that have to be taken into account when using statistical failure analyses of service-aged components are discussed and two case studies in which statistical failure analysis is used to predict future failures and to see in what way strategies can influence this prediction are included.
Abstract: In this article, the theoretical considerations that have to be taken into account when using statistical failure analyses of service-aged components are discussed. Furthermore, two case studies in which statistical failure analysis is used to predict future failures and to see in what way strategies can influence this prediction are included. Then, conclusions are drawn based on the analysis of the two case studies

Journal ArticleDOI
TL;DR: In this article, the authors show that electrical tree propagation is the main electrical degradation mechanism that leads to breakdown of the main wall insulation and that poor impregnation of the insulation and type of taping can reduce time to breakdown significantly.
Abstract: Due to an increasing demand for new, or the refurbishment of power stations, high-voltage rotating machines continue to play a significant role in generating electrical energy. An important component of these machines is their electrical insulation. Although much research has been done to improve the material, about a quarter of all failures still are related to insulation problems. Research to improve winding insulation is very complex because a large number of factors influence insulation life, among them the raw materials, size of the mica tapes, geometrical characteristics of the bar and taping- or manufacturing techniques. The results show that electrical tree propagation is the main electrical degradation mechanism that leads to breakdown of the main wall insulation and that poor impregnation of the insulation and type of taping can reduce time to breakdown significantly.

Journal ArticleDOI
TL;DR: In this article, three on-site partial discharge measurements for cables are described to illustrate how the techniques achieve cost-effective insulation diagnosis to protect the main assets. But these measurements are not suitable for outdoor applications.
Abstract: On-line partial discharge (PD) measurements are an efficient method for detecting certain insulation defects of cables. These include defects in cable joints and terminations, and defects due to mechanical impact. Noninvasive, efficient, and widely applicable, portable on-line PD measurement techniques are strongly favored by the electricity industry. Three on-site PD measurements for cables are described in this article to illustrate how the techniques achieve cost-effective insulation diagnosis to protect the main assets.

Journal ArticleDOI
TL;DR: In this paper, the authors focus on some of the many issues that need to be faced when the remove option is selected, including separation of metals, reuse of materials that are no longer approved, and disposal of insulation materials.
Abstract: Underground cables form an efficient and environmentally attractive means by which to supply electrical power and transmit information. Cables for both energy and data transmission are designed and manufactured for many years of problem-free operation, normally in the range of 10 to 30 years. However, it is clear that, for a variety of reasons, these cables will reach a point at which they can no longer operate, the so-called end of life (EOL). At this point, actions need to be taken on the fate of these cables. Often the decision may be either leave in situ or remove. This paper focuses on some of the many issues that need to be faced when the remove option is selected. The paper does not explicitly address the issues associated with disposal of paper cables, which have the added complexities of mixed materials: paper and polymer, oil, and lead. However, it should be noted that some of the considerations (separation of metals, the importance of separation, reuse of materials that are no longer approved, and disposal of insulation materials) are likely.

Journal ArticleDOI
TL;DR: In this article, the authors provide a theoretical context for the types of errors that are likely to occur during the measurement of high frequency cable shield properties, and consider a RC dielectric system as it relates to measuring the dielectrics properties of cable shield materials.
Abstract: This paper provides a theoretical context for the types of errors that are likely to occur during the measurement of high frequency cable shield properties. The paper considers a RC dielectric system as it relates to measuring the dielectric properties of cable shield materials.

Journal ArticleDOI
G.G. Raju1
TL;DR: In this article, various aspects that are important in understanding the electron-neutral interaction in gas discharges are reviewed and the target particle classification is presented on the basis of these principles, and total scattering cross sections are presented in a number of gases, and the principle features of each are explained.
Abstract: This paper reviews the various aspects that are important in understanding the electron-neutral interaction in gas discharges. On the basis of these principles, the target particle classification is presented. Total scattering cross sections are presented in a number of gases, and the principle features of each are explained. The role of cross sections in practical applications is briefly elucidated

Journal ArticleDOI
TL;DR: In this paper, the authors examined what actually happens to water within a direct-buried cable throughout the day and year as the cable temperature, the soil temperature, and the water content of the soil vary.
Abstract: The balance of this article examines what actually happens to water within a direct-buried cable throughout the day and year as the cable temperature, the soil temperature, the water content of the soil vary. Water, which is almost present at 100% relative humidity at the typical 1 meter burial depth of direct-buried power cables, moves very quickly through any polymeric layers

Journal ArticleDOI
TL;DR: In this article, the authors present two areas of research relevant to the progression of HTS power apparatus design: electromagnetic design and dielectric phenomena, and demonstrate several demonstrator projects, including the design, manufacture, and testing of a 10 kVA transformer demonstrating the performance of the HTS tapes and the satisfactory use of electromagnetic models to calculate losses.
Abstract: This article presented two areas of research poignant to the progression of HTS power apparatus design: electromagnetic design and dielectric phenomena. To be accepted into service, HTS power apparatus must be economically competitive and technically viable, which includes the need for reliability. To maximize the potential savings of HTS power equipment, the view taken at Southampton has been to design apparatus to operate at LN2 temperatures, thus greatly reducing the refrigeration load, cost, and complexity. Several demonstrator projects have been undertaken, including the design, manufacture, and testing of a 10 kVA transformer demonstrating the performance of HTS tapes and the satisfactory use of electromagnetic models to calculate losses, a key design parameter. Strategies for controlling partial discharge and resulting damage to insulation include increasing the operating pressure or reducing temperature. This decision has an impact on refrigeration load and operational cost. Therefore, it will depend on the application. Future research effort is focused on solids for use at cryogenic temperatures, and the interaction of electric field and bubble dynamics affording a greater understanding or the performance of cryogenic dielectrics.

Journal ArticleDOI
J. Swiss1
TL;DR: In this paper, the authors present an introduction to Dr. Thomas W. Dakin, the author of the article, "Conduction and Polarization Mechanisms and Trends in Dielectrics" in this issue.
Abstract: Editor’s Note: This article is an introduction to Dr. Thomas W. Dakin, the author of the article, “Conduction and Polarization Mechanisms and Trends in Dielectrics” in this issue. This article is a reprint that was first published in the Transactions on Electrical Insulation, volume EI-13, August 1978, pp. 205– 210 and presented at a the Thomas W, Dakin Symposium on High-Voltage Insulation, held in Pittsburgh, PA in May 1978.

Journal ArticleDOI
TL;DR: Taylor and Francis as discussed by the authors published Gaseous Electronics: Theory and Practice G.G. Raju CRC Press, 2006, New York: CRC Press ISBN 0-8493-3763-1 680 pp.
Abstract: Gaseous Electronics — Theory and Practice G.G. Raju CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL33487-2742 Phone (800) 272-7737 Fax (800) 374-3401 In the UK Taylor & Francis Group Ltd 2 Park Square Milton Park Abingdon Oxford OX14 4RN, UK Phone: (+44) (0) 20 7017 6000 Fax: (+44) (0) 20 7017 6699 http://www.taylorandfrancis.com ISBN 0-8493-3763-1 680 pp. £79.99 (Hardcover), 2006

Journal Article
TL;DR: In this paper, total scattering cross sections have been presented of a number of gases and the principle natures of each have been explained, and the authors have discussed the effect of scattering cross-sections on the properties of different gases.
Abstract: Total scattering cross sections have been presented of a number of gases and the principle natures of each have been explained.

Journal ArticleDOI
TL;DR: In this article, the authors reviewed the state of the technology as of the time of this study, and the suitability for utility applications is the focus of this paper. But they focused on self-healing of epoxy polymers that crack on aging.
Abstract: Recent studies in the polymer and polymer-composite literature have focused on technology to facilitate self-healing of epoxy polymers that crack on aging, for which no outside intervention is necessary. The self-healing process is referred to as autonomic healing. The concept of self-healing is not new, but healing without the necessity of outside action to facilitate the process is novel. The state of the technology as of the time of this study is reviewed, and the suitability for utility applications is the focus of this paper.

Journal ArticleDOI
TL;DR: In this article, the authors use a molecular, rather than a mechanical, approach in describing polymer behavior, providing a good understanding of the fundamental concepts of viscoelasticity, which is the response of a polymer when subjected to forces of various kinds.
Abstract: Simply stated, viscoelasticity is the response of a polymer when subjected to forces of various kinds. Polymers respond to external forces that are between elastic solid and a viscous liquid. The authors use a molecular, rather than a mechanical, approach in describing polymer behavior, providing a good understanding of the fundamental concepts. The book will provide the reader with a very good understanding of viscoelastic behavior on a molecular scale and details the latest testing methods, some of which include dielectric and nuclear magnetic resonance (NMR) methods, impedance spectroscopy, and thermally simulated currents. The authors provide an excellent background for not only learning about these techniques but also explaining the similarities and differences that each technique provides. Other topics cover the theory of viscoelastic behavior using models, timetemperature relationships, transitions, and relaxations. Also, there is information of the effects of fillers, crosslinking, swelling, and crystallization on viscoelastic behavior and on interfacial polarization. There are some examples using real polymers and problems that involve numerical modeling and analysis, some of which are included in a CD-ROM. Each chapter has an extensive set of questions; the answers are included in the back of the book. This book would appeal to those wishing to learn about viscoelastic behavior and testing methods and would make a good book for graduate studies in polymer chemistry because the book assumes familiarity with polymers and basic chemistry.


Journal ArticleDOI
TL;DR: In this article, the authors present a combination of physics, materials science, and semiconductor books in a single reference, which is intended for students, engineers, and scientists engaged in materials science and semi-conductor fields.
Abstract: This handbook, from Springer, is like the combination of physics, materials science, and semiconductor books in a single reference. It provides fundamental constants and physical concepts along with detailed materials data. Each chapter provides succinct descriptions and representative data for many types of materials. It is intended for students, engineers, and scientists engaged in materials science and semi-conductor fields. The handbook is broken down in five parts. Part 1 covers fundamental physical constants, such as those found in a physics book, SI units, and the basics of crystallography. Part 2 covers the elements. It provides tables of the physical and physiochemical properties of the elements with emphasis given to elements in the condensed state. Part 3 describes various classes of materials, including metals, ceramics, polymers, and glasses. The majority of this section (260 pages) details a wide range of metals and the various properties of pure metals, alloys, eutectics, heat treating steels, electrical, mechanical, thermal, and others. Part 4 describes what is called functional materials. These are semiconductors, superconductors, magnetic materials, dielectrics and electro-optics, and ferroelectrics and antiferroelectrics. The dielectrics in this part are different from the polymers in that they are generally crystal structures with details on their low (dissipation factor) and high frequency (electro-optic) dielectric response. Unlike the polymers described in Part 3 that were various types of engineering polymers. Part 5 describes special structures. These are liquid crystals, the physics of solid surfaces, and nano materials. Although filled with a concise and indepth wealth of data and descriptive text, the limited number of materials presented will give the reader only a good idea of properties of a certain material, but, because many variations of materials exist, much of the data can be used only as a guide along with references given to obtain more in-depth data on a particular material. However, if the material of interest is contained in this book, the handbook would be an invaluable resource. The CD-ROM, an exact copy of the pages in the book and fully searchable Adobe pdf file, makes it easy to find materials or topics of interest.



Journal ArticleDOI
TL;DR: In this paper, a wide range of surface modifications of materials for many types of applications are discussed, including adhesion and tribology, surfaces for microelectronics, including patterning of polymer brushes and switching behavior on a fast or slow time scale.
Abstract: Surface coatings are an important part of any electrical or electronic system. Most of us would be familiar with coatings deposited by spraying, spin coating, dipping, or doctor blading. Even more exotic techniques of thermal evaporation, plasma deposition, Langmuir-Boldgett films, and self-assembly have become more common. For the most part, these methods rely on physical interaction between the coating and the substrate. A “polymer brush” is a system in which one end of the polymer molecules is chemically bonded to the surface such that the bonded ends are densely packed and the polymer chains stretch away from the surface. This microstructure gives films having unusual surface macroscopic properties, such as ultra-low friction surfaces. The chapters in this book are divided into three parts: synthesis, characterization, and applications. Several synthetic methods are discussed, including grafting, atom transfer radical polymerization, polypeptides, ring-opening polymerization, organic-inorganic hybrids, photoinitiated polymerization, and surface-grafted hyperbranched polymers. The characterization techniques described in the following chapters include spectroscopy, microscopy, and electrochemistry. Characterization of brushes on a flat surface as well as brushes on the surface of a particle are discussed. Applications of polymer brushes should be of particular interest to our readers. There are seven chapters in this section, covering a wide range of applications. Those include adhesion and tribology, surfaces for microelectronics, including patterning of polymer brushes and switching behavior on a fast or slow time scale. Because of the wide range of topics and contributing authors, this book will appeal to a variety of people working with surface modifications of materials for many types of applications.

Journal ArticleDOI
TL;DR: In this article, a rod of controlled resistivity was proposed to remove the threat of dry-band arc damage on all-dielectric, self-supporting (ADSS) cables.
Abstract: The retrofit rod of controlled resistivity clearly has the potential to remove the threat of dry-band arc damage on all-dielectric, self-supporting (ADSS) cables. This is achieved by reducing the maximum current available on the cable for arcing activity. Rods can be applied to polyethylene sheathed cables or arc-resistant sheathed cables and can improve the performance of both. Extensive trials in the UK have shown that the rod works and have confirmed predictions of computer models. However, the engineering of the application of such as solution is complex. Individual spans of different geometry, including cable sag, must be considered. In particular, local variation in pollution is critical; so knowledge of the proximity of the sea or industry must be considered. It is also very likely areas that do not experience much rainfall will be particularly onerous because the cable will not be naturally washed regularly, so the pollution on its surface will tend to build up, reducing its resistance in times of high humidity, fog, and dew

Journal ArticleDOI
TL;DR: The 12th International Symposium on Electrets (ISE 12) took place from September 11 to 14, 2005, in Salvador, Bahia, the old colonial capital of Brazil and a lively city of culture with a rich history.
Abstract: IEEE Electrical Insulation Magazine The 12th International Symposium on Electrets (ISE 12) took place from September 11 to 14, 2005, in Salvador, Bahia, the old colonial capital of Brazil and a lively city of culture with a rich history. More than 110 participants from all over the world enjoyed the atmosphere of Salvador and the high quality of the symposium presentations. The symposium, which was chaired by Professors José A. Giacometti (State University of São Paulo at Presidente Prudente) and Roberto M. Faria (University of São Paulo at São Carlos), ended with a half-day workshop at the Federal University of Bahia. The ISE 12 marked the 100th birthday of Professor Bernhard Gross, the founder of modern electret science and one of the pioneers of physics in Brazil. Professor Gerhard M. Sessler, a close collaborator of Professor Gross since the early 1970s, opened the symposium with the first Bernhard Gross Memorial Lecture. Professor Sessler devoted his lecture to the topic “Bernhard Gross and Electret Research: His Contributions, Our Collaboration, and What Followed”. He reminded his older colleagues, and informed the younger members of the audience, of several seminal ideas and contributions of Bernhard Gross [1], [2] and showed how these concepts still influence most of the present developments in electret science and engineering. Thirty years ago, in 1975, the 3rd International Symposium on Electrets had been held in São Carlos, São Paulo, Brazil, on the occasion of Professor Gross’ 70th birthday. Professors Sergio Mascarenhas (in a lively discussion with symposium co-chairman Roberto M. Faria) and Luiz Nunes de Oliveira remembered this event and the legacy of Professor Bernhard Gross, whose foresight and guidance were crucial for the successful development of physics and science in Brazil. Several of his former pupils and collaborators were present at the symposium and reported about recent advances in their respective fields. 2005 also marks the 120th anniversary of the introduction of the term “electret” by Sir Oliver Heaviside in a two-page article published in The Electrician of August 16, 1885. The 100th anniversary of the name “electret” had been celebrated together with Professor Gross’ 80th birthday at the 5th International Symposium on Electrets in Heidelberg, Germany, in 1985. Six invited lectures highlighted recent developments in the field of electrets and in closely related fields: 1. Siegfried Bauer (University of Linz, Austria, talk presented by Reinhard Schwoediauer) gave a survey on “Ferroelectrets: Polymer-Foam Space-Charge Electrets with Ferroelectric-Like Behavior”. The topic of cellular ferroelectrets [3] with its exElectret Science Has a Long History and a Bright Interdisciplinary Future. Specialists from all over the world meet in Salvador, Bahia, Brazil