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Electrical Insulation, IEEE Transactions on

Issue 6 • Date Dec. 1981

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Displaying Results 1 - 21 of 21
  • Table of contents

    Page(s): c1
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  • IEEE Electrical Insulation Society

    Page(s): c2
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  • A Critical Comparison of XLPE-and EPR for Use as Electrical Insulation on Underground Power Cables

    Page(s): 469 - 482
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  • A Numerical Model to Simulate the Processing of Electrical Distribution Cables - Part I (Heat and Mass Transfer)

    Page(s): 483 - 489
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    A numerical model is developed to simulate the curing and quenching of electrical distribution cables. The model considers a moving cable with possible three dimensional variations in properties and boundary conditions. Both heat and mass transport ort are included. A finite difference appmationoxiation is used to solve the governing equations. The key to the numerical solution is a Landau type transformation, applied to eliminate the moving axial boundary. Potential applications of the program are illustrated by examining a laboratory scale and full-sized facility; for example, surface film coefficients may be determined by combining experimental results and numerical predictions. It is demonstrated that the rate controlling resistance to heat transfer is shifted as the relative thickness of the insulation is changed. View full abstract»

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  • A Numerical Model to Simulate the Processing of Electrical Distribution Cables - Part 11 (Curing Rates)

    Page(s): 490 - 495
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    A numerical model is developed to simulate the curing and quenching of electrical stridistribution cables. The model considers a moving cable with possible three-dimensional variations ions in properties and boundary conditions. An exponential decomposition of the crosslinking agent is assumed; decomposition is then expanded in a Taylor's series to provide a means of continuously updating the progress of cross-linking. The variables of curing are analyzed by examining both a laboratory scale and a full-size facility. With the larger cables, cross-linking may continue well into the quenching stage. Hydrogen abstraction from absorbed water molecules, a potential competing reaction, apparently is insignificant. View full abstract»

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  • The Use of Dielectric Analysis to Study the Cure of a Filled Epoxy Resin

    Page(s): 496 - 501
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    This paper presents the results of a study in which dielectric analysis was used to optimize catalyst concentration and minimize mold cycle time for an epoxy casting compound. The casting compound used was based on an anhydride cured hydantoin epoxy resin. Increasing the catalyst concentration to reduce mold time results in a reduced pot life. Using dielectric analysis, gel times and cure times were determined for several catalyst concentrations. Arrhenius plots for the gel times were obtained and minimum cure times for an optimum formulation were determined. The method described here is of general application ation and may be used to optimize formulations and cure cycles for many polymer processes. View full abstract»

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  • Apparatus for Continuously Monitoring Hydrogen Gas Dissolved in Transformer Oil

    Page(s): 502 - 509
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    This report presents an apparatus for continuously monitoring of hydrogen gas dissolved in transformer oil, in which a polyimide membrane is used to separate the hydrogen from the oil. The hydrogen is allowed to permeate through the membrane and contact a gas sensor every 72 hours. The characteristics of the permeation of the hydrogen gas through the polyimide membrane and of the detection of the hydrogen gas by the gas sensor are described under various conditions. Problems encountered when the apparatus is installed on a tran are also studied and solved. As a result, this new apparatus was found useful in determining whether a transformer is operating normally or not. View full abstract»

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  • Influence of the Electrolyte on Tracking Breakdown of Organic Insulating Materials

    Page(s): 510 - 520
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    This paper describes the influence of the electrolyte on tracking breakdown of organic insulating materials by the IEC (International Electrotechnical Commission) 112 Method. Two different kinds of electrolyte with surface active and non-surface active agents have been employed to study the influence of wetting agents on tracking breakdown. The effect of surface active agents on tracking breakdown of organic insulating materials with various contact angles is shown. Increasing applied voltage changes the location of the dry band formed on the sample's surface so that the droplet number to tracking breakdown does not always decrease with increasing applied voltage. For samples with lower contact angle, the violet corona discharge occurs locally across the dry band, tending to approach the surface of the samples. Consequently, the number of droplets to discharge inception and carbon formation are decreased for samples with low contact angle. There is a substantial influence of surface active agents on droplet number to tracking breakdown. View full abstract»

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  • Environmental Effects on the Rate of Aging of EP-Insulated Power Cable

    Page(s): 521 - 527
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    The accurate prediction of service life of extruded dielectric power cables from relatively short-term laboratory tests has been, and continues to be, a challenge for power cable engineers. Incomplete understanding of failure mechanisms and the effect of the many different in-service environmental factors, possible interactions between these factors, and the widely scattered nature of dielectric phenomena contribute to the uncertainties. In this laboratory investigation of the effects of water, water temperature, air temperature, voltage impulses, current loading and their interactions on a shielded 5 kV ethylene propylene rubber (EP) insulated power cable, water and water temperature were found to have the largest effect on dielectric strength. When aged in air for 3 years at 4.5 times rated voltage (the least harmful condition found in the experiment) the average dielectric strength declined to 92% of the original value; however this decline is not statistically significant. When aged in 35°C water for 3 years at 4.5 times rated voltage (the most harmful condition found in the experiment) the dielectric strength declined to 21% of the orginal value. View full abstract»

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  • Radiation Resistance of Ethylene-Propylene Terpolymer Vulcanized by Sulfur I. Basic Ingredient Compounding Material

    Page(s): 528 - 532
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    The radiation resistance of ethylene-propyleneethylidene norbornene terpolymer (EPDM) vulcanized with sulfur was studied. Several mechanical properties of original EPDM demonstrate maxima with irradiation. The property values at the maxima are observed to be a function of the gel fraction which was varied over a wide range by choice of the amounts of sulfur curing agent and accelerator. The deterioration of the materials by irradiation was evaluated by observing the change from these maximum values. EPDM with higher gel fractions showed less deterioration than that with lower gel fractions. The dose rate affects the mechanical properties. This is interpreted as evidence of a diffusion limited oxidation reaction during irradiation. At dose rates less than 1 x 105 rad/h, the effect is insignificant and the data are realistically considered to reflect changes which may occur in the containment area of a nuclear reactor with a nominal dose rate of 100 rads/h. Hardness can be taken as a parameter to evaluate the deterioration. View full abstract»

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  • Electrical Failure Properties of Cast Epoxy Resins

    Page(s): 533 - 542
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    Impulse and ac breakdown properties of transparent cast epoxy resins are reported having either a castin needle electrode or a needle-shaped recessed gold film electrode deposited by vacuum evaporation or sputtering, given a divergent electric field. Dielectric breakdown always initiates from the needle tip where the electric field strength is the highest. The dielectric breakdown process, which consists of tree initiation, tree propagation, and the complete puncture of the cast epoxy resin is investigated. This process varies considerably with the wave form of the applied voltage. Chemical analysis by Fourier transform infrared spectroscopy (FTIR) indicates that chemical reactions caused by voltage application take place in the epoxy during the induction period until the initiation of the tree. The dielectric breakdown strength is considerably influenced by the electrode configuration, and also by resin formulation. View full abstract»

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  • Erratum

    Page(s): 542
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  • Current Pulses Caused by Electrical Tree Development

    Page(s): 543 - 551
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    We have investigated the quantitative relation between the development of trees in polymethyl methacrylate resin subjected to ac voltage rising at a constant rate and the distribution characteristics of current pulses accompanying the development of trees. We also have estimated quantitatively the development of trees developed by a fixed value ac voltage using the results from ac voltage rising at a constant rate, The estimated values agree approximately with their measured values. View full abstract»

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  • Pre-Breakdown Discharges in Rod-Plane Gaps in SF6 under Positive Switchihg Impulses

    Page(s): 552 - 563
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    Pre-breakdown discharge currents in SF6 rod-plane gaps are measured under positive switching impulses and at different gas pressures. Four types of discharge currents could be distinguished, namely, single pulse discharges, multiple-pulse discharges, incomplete breakdown pulse, and corona-free direct breakdown. The effect of impulse magnitude, gas pressure, and gap geometry on the relative frequencies of occurrence of the four types of discharges are examined. The random dispersion in discharge pulse delays is related to the rate of production of initiatory electrons near the anode. A relationship between this rate of production and the electric field in the gap is derived, and its dependence on gas pressure and impulse front duration is investigated. View full abstract»

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  • An Attempt at Predicting Cable Breakdown Voltage from Dielectric Measurements

    Page(s): 564 - 567
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    For twenty slightly different ethylene propylene (EP) insulated model cables, an 0.8 correlation coefficient was found between dielectric strength after aging and both tan6 after aging and the change with aging of insulation resistance constant (IRK). Aging consisted of 3.5 months immersion of 60 cable specimens in 90°C water with 2 MV/m 60 Hz electrical stress continuously applied. However, tan6 and IRK measurements made regularly on EP and crosslinked polyethylene (XLPE) insulated 15 kV cables, similarly aged at 2 MV/m in 90°C water, did not predict how long a cable would withstand the aging stresses. View full abstract»

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  • Meetings

    Page(s): 568
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  • Author index

    Page(s): 569 - [569]-b
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  • Subject index

    Page(s): [569]b - [569]e
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  • IEEE Electrical Insulation Society

    Page(s): [569]-f
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  • Information for authors

    Page(s): [569]g
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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