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Dielectrics and Electrical Insulation, IEEE Transactions on

Issue 5 • Date Oct 1994

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Displaying Results 1 - 10 of 10
  • High-field conduction and breakdown in insulating polymers. Present situation and future prospects

    Page(s): 934 - 945
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    We review the results of electrical conduction and breakdown research reported mainly after 1980 in Japan, and comment on the present situation and future prospect of research work in this field. Effects of introduction of polar groups into polymers on electric strength Fb are summarized. Influences of copolymerization and modification of morphology and chemical structure on Fb of polyethylene are also reviewed. Finally, we show currently used experimental techniques for direct observation of space charge, prebreakdown current and localized heat generation View full abstract»

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  • Survey of arc tracking on aerospace cables and wires

    Page(s): 896 - 903
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    The paper gives a survey of the phenomenon `Arc Tracking of Wires' which has been observed for the first time in wiring systems of aircraft and which recently has occurred also in spacecraft. Aircraft organizations are aware of this phenomenon and have tried to provide solutions to cope with this new wire failure, i.e. modification of cable design and manufacture, avoiding pure polyimide insulation, and development of test methods. As regards space systems, the recognition of this phenomenon with its possible consequences has led to the development of test methods and to the introduction of new wire requirements within the framework of the Columbus Program. The available data do not establish with certainty a correlation between test results obtained for aircraft systems and the behavior expected on spacecraft. The untidy nature of arc tracking has been shown with the different kinds of events reported. In test laboratories, significant variations of results make this failure phenomenon even more difficult to define. From the data summarized in the survey it is apparent that the failure conditions vary with numerous conditions of electrical network, environment, cable design and aging parameters. Whereas the arcing phenomenon is essentially influenced by the environment and network conditions, the susceptibility to tracking is more dependent on the chemical nature of the insulation. Definitions are also presented in the survey to complete the understanding of the phenomenon View full abstract»

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  • Capacitor theory

    Page(s): 826 - 839
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    A new linear capacitor model is proposed. It is based on Curie's empirical law of 1889 which states that the current through a capacitor is i(t)=U0/(h1tn), where h1 and n are constants, U0 is the dc voltage applied at t=0, and 0<n<1. It implies that the insulation resistance is Ri(t)=h1tn, that is, it increases almost in proportion to time since n nearly equals 1.0. For a general input voltage u(t) the current is i(t)=Cdnu(t)/dtn where use is made of the fractional derivative, defined by means of its Laplace transform. The model gives rise to a capacitor impedance Z(iω=1/[(iω)nC], with a loss tangent that is independent of frequency. The model has other properties: the capacitor `remembers' voltages it has been subjected to earlier, dielectric absorption is an example of this. Capacitor problems require solving integral equations. The model is dynamic, i.e. electrostatic processes are simply slow dynamic processes. The model is applied to several problems that cannot be treated with conventional theory View full abstract»

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  • Space charge measurement techniques and space charge in polyethylene

    Page(s): 923 - 933
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    Recently, several new techniques such as LIPP, PIPS, PEA and TP methods have been developed to measure directly the space charge distributions in insulating polymers. Many papers have been published on space charge in insulating materials. In this paper, the space charge measurement techniques and space charge in polyethylene are reviewed. The space charge distributions in polyethylene depend strongly upon additives (antioxidants, antistatic agents, etc.), oxidation products, byproducts from the crosslinking reaction (acetophenone, etc.). Some of them enhance electron (or hole) injection from the electrode and, as a result, homo space charge is formed. Ionic carriers are supplied from some impurities to form hetero space charge. Space charge distributions are also sensitive to the electrode material and the interface between different materials. From the space charge behavior observed, the space charge effects on the high-field conduction and breakdown phenomena have been discussed quantitatively and some of the high-field phenomena in polyethylene have been elucidated View full abstract»

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  • Activity of plasma on insulating materials. Critical time of interaction and synergistic effects

    Page(s): 785 - 811
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    The transformation and the degradation of insulating materials interacting with cold plasma discharges have certain common points. This is examined in the present review where the discharge activity is regarded from a physico-chemical point of view. A critical time of interaction seems to be observable in many studies, which defines the line between transformation and degradation. The role played by the plasma species like electrons or ions depends on the conditions of discharge initiation. The synergistic aspect of these species is also presented, and experimental modeling considered View full abstract»

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  • Electrostatic charging in transformer oils. Testing and assessment

    Page(s): 840 - 870
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    This review outlines the charging tendency test methods that have been used in the electricity supply industry especially as applied to large transformers. Methods that have been used to generate charge and to measure charge are discussed and the results of various experiments are presented View full abstract»

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  • Nanometric dielectrics

    Page(s): 812 - 825
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    It is suggested that a major field of study in the future development of dielectrics will concern their properties when relatively few molecules are involved. Such smallness arises naturally at interfaces of nanometric thickness and will occur also when dielectrics are employed in the nano-technical devices of the future. It already occurs in living systems where the dielectric and conductive properties of biomaterials are vital in sustaining activity. The transverse and lateral properties of interfaces, including the effects of molecular ordering, are considered and it is suggested that the advent of scanning tunneling and atomic force microscopies provides a significant opportunity for nanometric dielectric studies. An important feature, suggested for future exploitation, is the cross-coupling in interfaces of force fields arising from electrical, mechanical, chemical and entropic potential gradients. Application of these concepts to biology and to the behavior of polymer gels which may lead to development of muscle-like actuators and transducers are considered. Finally, attention is drawn to the likely role of nanometric interfacial processes in the initiation of electrical breakdown in insulating materials View full abstract»

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  • Physics and chemistry of partial discharge and corona. Recent advances and future challenges

    Page(s): 761 - 784
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    Results of recent research on physical and chemical processes in partial discharge (PD) phenomena are reviewed. The terminology used to specify different types or modes of PD are discussed in light of a general theory of electrical discharges. The limitations and assumptions inherent to present theoretical models are examined. The influence of memory propagation effects in controlling the stochastic behavior of PD is shown. Examples of experimental results are presented that demonstrate the nonstationary characteristics of PD which can be related to permanent or quasi-permanent discharge-induced modifications (aging) of the site where the PD occur. Recommendations for future research are proposed View full abstract»

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  • The fundamentals of aging in HV polymer-film capacitors

    Page(s): 904 - 922
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    This paper covers the basic phenomena involved in the aging of capacitors constructed using polymer films as the major dielectric material. A wide variety of aging phenomena can be identified, ranging from simple electrical, dielectric, thermal, radiation, chemical and physical aging, to aging originating from the specific construction of the capacitor. Some phenomena occur quickly, such as some morphological changes in the polymer, others occur progressively, and others occur later in the life of the capacitor. The polymers covered range from biaxially-oriented polypropylene, which is widely used in commercial utility and industrial capacitors, to polymers like polycarbonate, polysulfone, polyimide, and polyvinylidene fluoride, which are used in high-energy density, outer-space, high-temperature, or other special applications. The paper addresses two constructions of polymer film capacitor where the aging phenomena are significantly different due to the differences in construction: polymer/foil capacitors and metalized film capacitors. Metalized polymer film capacitors have the quality of clearing or self healing that is not present in film/foil capacitors. The discussion of aging in this paper is given from the perspective of these two designs View full abstract»

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  • Electromagnetic hydrodynamics

    Page(s): 871 - 895
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    A broad survey has been conducted of electrohydrodynamic phenomena in which the electric field may be simply static or electrodynamic in nature. Recent developments of new materials have made it possible for relatively high electromagnetic fields to penetrate flow tubes and containers, thus emphasising the need for an electrodynamic approach to the subject. Some engineering problems are introduced in which electromagnetic hydrodynamics plays an important role. The review of the current state of the art is intended to supplement earlier ones and to broaden the scope of the topic to include two-phase flow and electrodynamic field effects View full abstract»

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Aims & Scope

IEEE Transactions on Dielectrics and Electrical Insulation contains topics concerned with dielectric phenomena and measurements with development and characterization of gaseous, vacuum, liquid and solid electrical insulating materials and systems.

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Reuben Hackam