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Electrical Insulation, IEEE Transactions on

Issue 5 • Date Oct. 1979

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Displaying Results 1 - 14 of 14
  • Table of contents

    Page(s): c1
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  • IEEE Electrical Insulation Society

    Page(s): c2
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  • The Application of Weibull Statistics to Insulation Aging Tests

    Page(s): 233 - 239
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    The results of accelerated aging tests on solid electrical insulation are difficult to evaluate objectively, primarily due to the inherently large variability of the test data. This variability is often represented by the Weibull or other extreme-value probability distributions. This paper demonstrates an hypothesis test procedure which permits the objective and unambiguous evaluation of comparative dielectric tests on two different sets of data. The computation techniques are facilitated through the use of a Fortran computer program. A significant difference must be established at low probabilities of failure. Analysis of typical aging tests from the literature indicate that many experiments performed to date may not be statistically significant at utilization levels. The number of tests required to achieve unambiguous significance at low probability levels may render meaningful accelerated aging tests uneconomic. View full abstract»

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  • Statistical Model of the Creep Discharges in Air at the Dielectric Surface

    Page(s): 240 - 249
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    The relation between the successive surface discharges across a dielectric surface under applied ac voltage was measured and analyzed. The discharges were measured by way of flash of light registration. The electronic set-up included two memories each having 32 x 32 channels working in two-dimensional regimes. The analysis of experimental data forces us to use Poisson's statistics and consequently imposes a simple formula describing the probability of the creep discharges. The statistical model of the discharge cascades (for small overvoltages) and the average statistical model of the discharges (for larger overvoltages) are described by the formula. It has been postulated that a certain number of electrons is attached to the dielectric sample surface during the discharge. In effect, electrons liberated from the surface initiate the discharge. View full abstract»

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  • Neasuring Electric Field by Using Perssure Sensitive Elements

    Page(s): 250 - 255
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    The electric forces acting on an electrode surrounded by gas or liquid can be substituted by a system of surface forces alone. The resulting surface force density, foundby using the Maxwell stress tensor, is proportional to thesquare of the electric field in the dielectric. Thisrelation between pressure and electric field is used fordevelopment of a method for measuring electric fields nearelectrode surfaces.The method is based on the use of a thin circular metalmembrane which is mounted over a cavity in the electrodesurface so that the membrane forms a part of this surface.An electric field will set up forces which try to pull theelectrodes together. When the membrane is thin enough itwill bend out. This movement, only fractions of a micrometer,er, can be detected by using fier-optic transmissiontechniques.Measurements have shown the practicality of the method.As an example of the application of the method, measurementshave been performed on the "Skagerrak Cable". View full abstract»

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  • The Space Charge Behavior and Luminescence Phenomena in Polymers at 77 K

    Page(s): 256 - 263
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    Electroluminescence phenomena were observed at the needle tip in polymer samples with a point-plane electrode system under an applied ac voltage at liquid nitrogen temperatures. This luminescence was considered to be caused by the recombination between positive and negative charges injected from the point electrode. The nature and behavior of the charges injected into the polymer became clear through a detailed study of luminescence. A degenerate rate region of polymer was also found at the needle tip after prolonged ac voltage application, which may indicate a depolymerized region caused by the attack of then injected charges. The fact that tree channels started from the degenerate region in the polymer led us to theon conclusion that the injection of charge can be hazardous for polymer solid insulation systems. View full abstract»

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  • HPLC and DSC Analysis of Crosslinked PE from HV Cables

    Page(s): 264 - 271
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    High performance liquid chromatography (HPLC) has beenused to simultaneously determine the amounts of antioxidant(Santonox(R) R), peroxide, acetophenone and ¿-methylstyrenepresent in crosslinked-polyethylene cable samples andmolded specimens, as well as to detect some other peroxidedecomposition products.It was found that the antioxidant is grafted to thepolymer chains after curing (even after partial curing).Results also seem to suggest that a reduction of the phenoliccharacter and perhaps of the effectiveness of thentiantioxidant might result from this grafting process. Peroxidedecomposition products were found to depend on the curingconditions used and to affect the dielectric behavior insome cases.Various XLPE and EPR materials have also been examined bydifferential scanning calorimetry (DSC), and experimentalprocedures were developed for evaluating the degree ofcrosslinking by DSC.This work was part of a program supported by the Electric Power Research Institute. View full abstract»

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  • Effect of Dose Rate on Degradation Behavior of Insulating Polymer Miaterials

    Page(s): 272 - 277
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    The dose rate effect on the mechanical and electrical properties of representative insulating and jacket materials has been studied. Crosslinked polyethylene (XLPE),thylene ethylene-propylene terpolymer (EPDM), and some chlorine containing polymeric materials are irradiated in air at several dose rates. XLPE degrades significantly at lower dose rates, but EPDM shows opposite dose rate dependency to XLPE. Dose rate effect is interpreted as a competition between the dissolution and diffusion of oxygen into the sample and the oxidation reaction by irradiation. Ingredient compounding in chlorine containing polymeric materials may depress the dose rate effect. View full abstract»

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  • Application of Infra-Red Thermography to the Study of Temperature Distribution on Energized Polluted Insulators

    Page(s): 278 - 280
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    Temperature distribution on the surface of an energized polluted insulator has been measured using infra-red hermo thermovision techniques. Temporal variation of temperature has also been determined. Tests were carried out on a conventional ional cap and pin insulator unit. Results show that the maximum temperature of the energized insulator could be as high as 100°C at the regions around the pin. View full abstract»

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  • Calibration of Partial Discharge Detectors for Pulse-Height Distribution Analysis

    Page(s): 281 - 284
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    The effect of the calibration-pulse fall times, ranging from 0.52-56 ¿s, on the response of partial-discharge detectors using a multichannel analyser has been investigated. Although the equalization of fall/rise time ratio results in a single peak distribution, the latter is sensitive to small variations in this ratio. It is shown that a single peak, single-spectrum, can be obtained for ratios of the order of 50. View full abstract»

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  • Partial Discharge Studies in Non-Uniform Fields with Insulation Barriers

    Page(s): 285 - 287
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    Partial discharge inception voltages (Vi) were measured in non-uniform electric fields with insulating barrier plates. The inception voltage was found to decrease with increasing thickness of barrier plate for a given electrode separation. A semi-empirical formula for Vi has been proposed. The results obtained with this formula are found to be in good agreement with experimentally determined values. View full abstract»

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  • An invitation to Membership

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  • Editorial policies and criteria

    Page(s): 287-b
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  • Information for authors

    Page(s): 287c
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Aims & Scope

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

Full Aims & Scope