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Electrical Insulation, IEEE Transactions on

Issue 4 • Date Aug. 1980

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Displaying Results 1 - 15 of 15
  • Table of contents

    Page(s): c1
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  • IEEE Electrical Insulation Society

    Page(s): c2
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  • Impulse Breakdown in PMMA under Miegavolt, Nanosecond Excitation

    Page(s): 313 - 321
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    Single impulse dielectric breakdown tests were performed on thick (0.16 to 1.91 cm) polymethylmethacrylate (PMMA) specimens using a uniform field geometry with 7.5 cm diameter Bruce contour electrodes. The applied voltage rose within 20 ns to 2 MV, remained there about 30 ns and decayed in about 65 ns. In some cases, specimens were deliberately altered by surface scribing, pin pricking, drilling small dimples, drilling holes in portions of laminated specimens, and combinations of these. Light emission during the breakdown pulse and damage morphology were studied. Results of these experiments include the following: Each specimen contained many partial channels as well as a main breakdown path. The number varied greatly with overvoltage. Specimens 0.16 cm thick (peak field 12 MV/cm) contained about 2000 partial tree-like channels in various stages of growth, while 1.91 cm thick specimens (peak field 1.1 MV/cm) contained about 20 partial channels. In all unaltered specimens, the channels originated at the anode surface. However, when deep cavities were intentionally introduced into the cathode surface, channels originated at these artificially produced defects as well as on the defect-free anode surface. Intense light emission occurred from both the partial channels and the main discharge channel. The main discharge path is formed only after one of the partial discharge channels has grown completely across the specimen. View full abstract»

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  • Study on Corona Suppression for Fusion Reactor Coils

    Page(s): 322 - 330
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    Fusion reactor coils are subjected to 50 Hz ac voltages (for overvoltage tests) and impulsive voltages whose rise time ranges from 1 ¿s to 1 ms (for fusion experiments). This paper shows that SiC paint is ideal as a corona suppression coating for such coils. Also, in a fusion reactor, two coils may be arranged in parallel facing each other across a narrow air gap. In such parallel coils, the junction of the conducting paint and SiC paint may shift. This paper shows that, in such cases, the corona starting voltage at the air gap is lowered and a method to raise it is proposed. View full abstract»

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  • Thermal Aging Predictions from an Arrhenus Plot with Only One Data Point

    Page(s): 331 - 334
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    Arrhenius plots are useful in predicting long-term use temperatures of organic materials and in choosing parameters for accelerated aging. For materials and components without established Arrhenius curves, a conservative value for the slope of the curve (which is also a measure of the activation energy of degradation) would allow longer-term predictions from a few short-term tests. Conversely, a required long-term temperature target can be extrapolated on the same slope to a range of short-time exposure temperatures suitable for accelerated tests. A review is made of available activation energies, from which values can be selected for conservative extrapolations on an Arrhenius plot. View full abstract»

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  • Thermal Aging of Bi-axially Orifnted Pet Films: Relation between Structural Changes and Dielectric Behavior

    Page(s): 335 - 339
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    The structural changes in bi-stretched poly(ethylene-terephthalate) films induced by thermal aging have been studied by recording the variations of crystallinity, orientation of aromatic rings, and elongation at break. An attempt has been made to correlate the variations of the activation energy of the a relaxation process to the changes in physical properties. A simultaneous decrease of activation energy and of elongation at break has been observed on aged samples. View full abstract»

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  • New Evaluation Method of Dielectric Materials Using a Microwave Technique

    Page(s): 340 - 349
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    A new nondestructive method of evaluating changes in characteristics or detecting internal defects in insulation materials with microwave techniques is discussed. The main feature of the method is that the amplitude and phase angle of a detected signal are displayed in a polar co-ordinate system, which allows changes in both the dielectric constant and loss tangent of a dielectric material to be obtained at the same time. The results of experiment on deterioration, the detection of foreign materials, and differences in the inner structure of complex insulation materials are shown. View full abstract»

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  • Electrical Conduction in 3-Percent Carbon-Filied Polyethylene-Part 11: High-Field Results

    Page(s): 350 - 358
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    The high-field conduction properties of 3% carbon-filled polyethylene were investigated. Detailed step-response measurements were made as a function of temperature and applied field. A near-quadratic dependence of the steadystate conduction current upon applied voltage was observed. The steady-state and transient absorption and resorption currents are discussed in the framework of physical models of space-charge limited conduction and charge carrier trapping. View full abstract»

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  • A Study of Morphology in Polyethylene Filled with 3-Percent Carbon

    Page(s): 359 - 361
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    Samples of polyethylene filled with 3-percent carbon were cooled from the melt at rates ranging from 104 to 10-1 C/min. The resulting degree of crystallinity, as measured from wide angle X-ray diffraction and density, was studied. Variations in the degree of crystallinity between 46 and 68% were observed. The role of morphology on the conduction properties of partially crystalline polymers is discussed. View full abstract»

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  • A Theory of Non-Steany State Moisture Absorption by Annular Polymeric Dielectrics

    Page(s): 362 - 365
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    Equations are derived describing the isothermal, non-steady state diffusion of moisture into an annular dielectric enclosing a cylindrical, impermeable conductor. The correct solution of the diffusion equation is compared with approximations based on the plane sheet or the solid cylinder. It is shown that these approximations can lead to considerable error when estimating diffusion coefficients from cable water absorption data, or when calculating water contents using known diffusion coefficients. View full abstract»

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  • Toward a Credible Aging Test for Extruded Cable

    Page(s): 366 - 370
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    The introduction of extruded cable designs claiming resistance to water treeing has generated a need for valid accelerated aging tests to evaluate such claims. However, some of the phases of the water-treeing failure process (water permeation, water-tree initiation and growth, final breakdown) are not yet completely understood. Accelerated tests proposed to date may not affect these aging sub-processes in the same way for different cable designs, and consequently such tests may yield misleading results. To simulate the entire aging process, a separate accelerated test for each of the sub-processes may be more practical than a single comprehensive test. Neither a comprehensive test nor a collection of separate tests can be developed into a universally valid accelerated life test until the treeing process itself is better understood. Inherent limitations of various approaches to the development of accelerated aging tests are discussed and the conclusion is drawn that progress may be most economically achieved by fundamental or analytical approaches, rather than by purely statistical studies. View full abstract»

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  • Meetings

    Page(s): 371
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  • Open Letter to Electrical Insulation Society members

    Page(s): 372
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  • IEEE Electrical Insulation Society

    Page(s): 372-a
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  • Information for authors

    Page(s): 372b
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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