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Electrical Insulation, IEEE Transactions on

Issue 5 • Date Oct. 1986

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Displaying Results 1 - 13 of 13
  • IEEE Transaction on Electrical Insulation

    Page(s): c1
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    Freely Available from IEEE
  • IEEE Dielectrics and Electrical Insulation Society

    Page(s): c2
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    Freely Available from IEEE
  • The 1986 CEIDP Digest

    Page(s): 681 - 804
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    Freely Available from IEEE
  • Tribute Biography Professor Herbert A. Pohl

    Page(s): 682
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    Freely Available from IEEE
  • Superdielectrics Polymers

    Page(s): 683 - 692
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    A giant type of polarization appears in certain highly aromatized polymeric solids. It arises when (a) the structure can inherently dissociate to form electronic carriers, and (b) when there are long domains of equivalent sites for freed electroonic carriers to rove about in response to an external electric field. It is referred to as 'nomadic' polarization, and joins the familiar electronic, atomic, and dipolar orientation types as a fourth molecular mode of polarization. Applications for the new super-dielectrics based upon these concepts will be many; including improved capacitor materials for better energy storage and control, low visibility coatings, obscuration, and EMP shielding, while in microcircuitry applications are transducers and parametric circuits. Progress in this promising new field is reviewed. A discussion of structures essential for nomadic polarization is given, together with some new results exemplifying these concepts. Future work and trends are suggested. View full abstract»

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  • SF6 Decomposition in Gas-Insulated Equipment

    Page(s): 693 - 725
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    The increasing application of SF6 as an insulating gas has led to many studies on SF6 decomposition in gas-insulated equipment. In the presence-of an electric arc, spark or corona, SF6 decomposes to a wide variety of chemically active products which possess completely different properties from SF6. The accumulation of these decomposition products in the equipment has caused concerns regarding personnel safety and material compatibility problems. This paper reviews previous research in SF6 decomposition relating to the operation of gas-insulated switchgears, gas-insulated transmission lines, and electrostatic accelerators. Results on the qualitative and quantitative determination of the by-products and their formation ion rates in various modes of electrical discharges are summarized. The mechanisms leading to the formation of transient and stable products are described. In particular, the influence of discharge energies and impurities on the formation of SOF2 and SO2F2, the two dominant stable by-products, is discussed. The effects of the by-products on personnel safety and equipment ent dielectric integrity are presented. The application of SF6 gas analysis as a tool for diagnosing the internal condition of gas-insulated equipment is assessed. Based on the results of many phenomenological observations, future research activities are suggested to address the issues of safety, compatibility and equipment aging. More fundamental studies on electron, ion, and neutral reaction rates in an SF6 discharge are required to gain a better understanding of the decompositon mechanisms and the influence of the products on equipment operation. View full abstract»

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  • Mechanisms of Surface Flashover Along Solid Dielectrics in Compressed Gases: a Review

    Page(s): 727 - 746
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    Surface flashover in compressed-gas insulated systems is a much studied, but poorly explained phenomenon. In this paper we review the literature of surface flashover with primary emphasis on the understanding of physical processes leading to discharge initiation and insulator flashover under high voltage excitation. The flashover models presently in vogue will first be discussed, followed by the results of some recent experiments which are likely to have an impact on further modeling. Included in this context are phenomena such as ionization, surface charging, partial discharges, optical activity, and gas/dielectric interactions. Finally, the influence of system parameters such as insulator size, shape, surface condition, triple junction geometry, voltage waveform, gas formulation and particle contamination are discussed with regard to their effect on the flashover characteristics. Mechanisms are suggested in an effort to provide a physical explanation for the observed phenomena. Although the physics of the discharge initiation and propagation processes are presently not well understood, and the present models only account for a few of the mechanisms known to be important in the discharge development, all the work points to an interaction between the spacer and the various electron/photon processes in the surrounding gas volume. This interaction has not been accounted for in the discharge models proposed to date. Further modeling work should incorporate these interactions and the intrinsic properties of the dielectric ric which are related to these interactions. More basic research is suggested to provide a better understanding of the physics of the discharge initiation and breakdown phenomena. View full abstract»

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  • Reversals in Electrical Current and Other Anomalies in Insulating Polymers

    Page(s): 747 - 762
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    The literature on anomalous currents in polymers has been assembled. The effects have been classified into isothermal decay reversals, reversals in thermally stimulated depolarization, abnormal charging curves, oscillations, and other effects. It has not been possible to identify the conditions which lead to unusual behavior, owing to the disparate nature of the available experimental work. The models for these effects include space charge relaxation with detrapping, ionic drift and temperature dependence of the dielectric permittivity. Each model explains a large part of the effects within its range of applicability. However, several of the charge transport models are based on inconsistent assumptions, and invoke blocking effects at electrodes, for which there is little independent confirmation. It is noted that many of the experiments may be vitiated by artefacts such as imperfect conditioning and inadequate time delays for equilibration. It is recommended that careful sample preparation, rigorous tests of conditioning, and monitoring of charge location should be routinely employed. View full abstract»

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  • Fast Measurement Techniques for Research in Dielectrics

    Page(s): 763 - 780
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    Measurement techniques for research in dielectrics require very fast time resolution and extremely wide dynamic ranges. Additionally, the measured quantities may be very low in amplitude. These conditions can be met only partly by electrical measuring systems. Additionally, two-dimenstional or even three-dimensional spatial information concerning the prebreakdown phenomena is highly desirable. This can only be achieved by optical measuring systems, which also may provide other advantages. In order to provide adequate time resolution, only coaxial measuring systems are considered. These consist of voltage probes using ohmic or capacitive networks and electro-optical devices. For current measurements ohmic shunts are compared with inductive probes and optical current probes. Optical measurement techniques based on high-speed photography are described in detail. In this context, the widely used streak-cameras are compared with framing cameras. It is obvious that research in dielectrics requires special highspeed recording systems which are not readily available. Together with recent image recording systems, however, very precise optical measurements are possible. View full abstract»

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  • Acoustic Theory Applied to the Physics of Electrical Breakdown in Dielectrics

    Page(s): 781 - 792
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    In order to stimulate further thought and research within the science of dielectrics, this paper discusses the remarkable correlation between acoustic theory and the physics of electrical breakdown in dielectrics. Following a brief, simplified fied review of acoustic theory and the propagation and attenuation ation of soundwaves in gases, liquids and solids, three areas in dielectrics are addressed in which the breakdown mechanisms require further clarification. These are the relative electrical strengths of gases and mixtures; streamer initiation in liquid hydrocarbons; and the incubation period before treeing or breakdown own occurs within solid dielectrics. Acoustic analysis of gas breakdown clearly shows that the relative electrical strengths of gases and mixtures vary as the inverse square of sound velocity, and consequently, are closely related to both the molecular weight and specific heat ratio of the gas or mixture. For liquid hydrocarbons, an analysis of acoustic emission levels from partial discharges combined with acoustic cavitation theory, supports the hypothesis that cavitation (collapse) of microbubbles bubbles attached to dust particles may provide the conditions for streamer initiation. Finally, attention is drawn to the relationship between the velocity of sound within solid dielectrics and Young's modulus, Poisson's ratio and density, which suggests a potential application of acoustics for assessing the mechanical strength of dielectrics as they age. Thus, simple acoustic measurements performed on solid dielectrics may provide some information on the structural condition Qf these dielectrics before treeing and subsequent breakdown occurs. View full abstract»

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  • IEEE Dielectrics and Electrical Insulation Society

    Page(s): 804-a
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    Freely Available from IEEE
  • Conference on Electrical Insulation and Dielectric Phenomena

    Page(s): 804-b
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    Freely Available from IEEE

Aims & Scope

This Transactions ceased production in 1993. The current retitled publication is  IEEE Transactions on Dielectrics and Electrical Insulation.

Full Aims & Scope