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Electrical Insulation, IEEE Transactions on

Issue 4 • Date Aug. 1982

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Displaying Results 1 - 22 of 22
  • Table of contents

    Page(s): c1
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  • IEEE Electrical Insulation Society

    Page(s): c2
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  • A Quantitative Method for Determining the Resistance of Polymers to Surface Discharges

    Page(s): 293 - 299
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    A method has been developed to characterize the resistance of polymers to erosion by surface discharges. It was found possible to produce surface discharges on wet, contaminated surfaces without the usual disturbing influences of metal electrodes and wetting agents. Instrumentation was devised to monitor continuously the electrical behavior of the test specimens. The test yields a quantitative erosion rate in mg/C which is characteristic of the material and test conditions used. In addition, the electrical measurements permit the detection of long-term changes in the surface properties. A method is proposed to use the test in conjunction with outdoor test station data to obtain an estimate of service life. View full abstract»

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  • Impurity Effect of the Dielectric Properties of Isotactic Polypropylene

    Page(s): 300 - 305
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    Two dielectric relaxation peaks, the crystalline and the primary relaxations, were observed in the temperature-dielectric loss curves in isotactic polypropylene. Among them the primary relaxation ß was studied in detail using different kinds of polypropylene films and their films purified with acetone. It was found that ß-relaxation consists of two peaks, denoted ß1 and ß2, being consistent with the dynamic mechanical characteristics. The lower temperature peak ß1 is assigned to the amorphous phase, which is rich in atactic chains, and the upper temperature peak ß2 is ascribed to an antioxidant contained in the amorphous phase which is rich in isotactic chains. The antioxidant also causes an increase in dielectric loss in the higher temperature region. The extraction of impurities from polypropylene films with acetone reduces the magnitude of the primary relaxation peaks. View full abstract»

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  • Radiation-Induced Conductivity in Polymeric Insulating Materials Degraded under Specified Conditions

    Page(s): 306 - 313
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    Various polymeric insulating materials for cables were degraded by simulated irradiation and environmental conditions for normal operation and under accident at a nuclear power reactor. Thermally stimulated currents were observed only in the crystalline samples, and the higher thecrystallinity, the larger the amounts of detrapped carriers. The change of fine structure of the degraded sample was investigated by the change of X-ray crystallinity, melting behavior, and glass transition temperature. The radiation-induced conductivity was studied during irradiationand a decay curve was measured after the irradiation. Analysis of the conductivity decay curve enabled us to detect at most four kinds of carriers with different time constants. Long-lived carriers were hardly observed in the non-crystalline samples, while many were seen in the crystalline samples. With the decrease of crystallinity by degradation, only short-lived carriers were observed, indicating the existence of trapping sites for the long-lived carriers in or aroundthe polymer crystallites. Treatment of samples with high temperature steam and chemicals showedno special effect on the samples except for polyimide which dissolved in alkaline solution. View full abstract»

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  • Acoustic Emission Associated with Tree Growth in Polymeric Materials

    Page(s): 314 - 318
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    The acoustic emission associated with the initiation and the growth of electrical trees inpolymeric materials is examined under ac voltage application. Two kinds of acoustic emission waveform, a burst type and an impulse type, are observed, which suggest different tree-forming causes. The procedure can provide not only a non-destructive testing technique but also a means for investigating the tree-forming mechanism. View full abstract»

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  • Electrical Breakdown of Polypropylene Film Under Electron Irradiation

    Page(s): 319 - 324
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    This report deals with dc breakdown phenomena of polypropylene film under electron irradiation in vacuum. Electrons emitted from a hot cathode irradiate and penetrate some depth into a polypropylene specimen. It is expected that deposited electrons produce an electric field in the specimen and may give a source of electron avalanches. In this investigation we studied a relation between the breakdown probability of the specimen and the electron acceleration voltage. During electron irradiation the specimen was stressed by a dc bias voltage that was low enough not to lead to any breakdown without the electron irradiation. Even if the bias voltage was lowenough, breakdown occurred under electron irradiation. The results show that the breakdown probability varies with change of the electron penetration depth. Using a 7.5 pm polypropylene film as a specimen, the highest breakdown probability was obtained when the distance between the back electrode of the specimen and the layer where the electrons were trapped was about 3 to 4 ¿m. For deeper electron penetration as well as for shallower penetration, a lower breakdown probability was obtained. It is inferred from these results that the breakdown was electronic under electron irradiation and that the length of avalanches necessary for a breakdown to take place was about 3 ¿m. View full abstract»

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  • Charge Simulation Modeling of Practical Insulator Geometries

    Page(s): 325 - 332
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    A brief review of the charge simulation technique used for the calculation of high voltageelectrostatic fields, and its application to a typical transmission line disc insulator sectionunder pollution-free conditions, is presented. The use of ring and line charges has been found to be quite adequate for the modeling of the field distribution in and around the insulator with an accuracy in the representation of electrode potentials well within 1% of the maximum potential difference. The discrepancy in representing the inter-dielectric interface conditions is usually a maximum of about 9% but may be as large as 17% for the tangential electric field. View full abstract»

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  • Accurate Field Solution in the Entire Interelectrode Space of a Rod-Plane Gap Using Optimized Charge Simulation

    Page(s): 333 - 337
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    Numerical field solutions employing the charge simulation method (CSM) have been obtained for the rod-plane gap geometry which is of considerable importance in High Voltage Engineering research. It is shown that conventional techniques do not necessarily lead to accurate solutions in the entire interelectrode space. A method is suggested which uses an optimization technique employing a modified objective function which minimizes not only the accumulated squared potential error but also the tangential electric field along the conducting surface. This method yields solutions with good accuracy in the entire interelectrode space. View full abstract»

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  • A Flash Point Behavior of Dimethyl Silicone Liquids

    Page(s): 338 - 344
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    In order to understand why dimethyl silicone liquid of 50 centistokes, whose flash point is more than 300°C, undergoes ignition, the volatile products evolved during heating at 300°C in a controlled atmosphere were identified by GC-MS analysis. It was determined that a cyclic oligomer, D3 was dominant of the oligomers identified. The boiling point and flash point behavior of D3, D4, etc. were measured. From these results, it is suggested that D3 plays a decisive role in the igniting process. On the grounds that the decrease in evolution of volatile products would result in some improvement in the flash point behavior, a chelate compound of cerium was added to inhibit the decomposition of the silicone liquid. It was concluded that the flash point behavior can be improved somewhat by the addition of this compound, suggesting that the chain rearrangement reaction could be inhibited to evolve less of the cyclic oligomer, D3. View full abstract»

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  • A New Analytical Method for the Determination of the Water Content of Transformer Oils

    Page(s): 345 - 349
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    A new analytical method is presented for the determination of the water content of transformer oil. The technique is based on the mass spectrometric determination of HD (m/e= 3) formed in the reaction of water and LiA1D4. The lower limit of detection was found to be 5 ppm water. The standard deviation characteristic to reproducibility was equal to 1.6 ppm, while the error of the mean value corresponding to 95 percent confidence level was found to be ±2.2 ppm inthe 20 ppm water range. View full abstract»

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  • Analysis of Paschen Curves for air, N2 and SF6 Using the Townsend Breakdown Equation

    Page(s): 350 - 353
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    It has been shown that it is possible to extend the validity of the Townsend breakdown criterion for evaluating the breakdown voltages in the complete pd range in which Paschen curves are available. Evaluation of the breakdown voltages for air (pd=0.0133 to 1400 kPa · cm), N2(pd=0.0313 to 1400 kPa · cm) and SF6 (pd=0.3000 to 1200 kPa · cm) has been done and in most cases the computed values are accurate to ±3% of the measured values. The computations show that it is also possible to estimate the secondary ionization coefficient ¿ in the pd ranges mentioned above. View full abstract»

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  • On the Comparability of Single and Double Needle Tests for Treeing Resistance

    Page(s): 356 - 358
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    An attempt has been made to find a relationship between the characteristic voltages obtained using the single-needle and doubleneedle tests. A conversion factor has been derived which is in good agreement with experiment. View full abstract»

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  • Dielectric Breakdown of Polyethersulfone (PES) Film under DC Voltage Conditions

    Page(s): 359 - 362
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    The dielectric breakdown characteristics of polyethersulfone (PES) film was investigated in a temperature range from 25 to 250°C, under dc voltage conditions. The temperature dependence of breakdown strength shows two distinct regions, referred to as I (25-150°C) and II (150-250°C). In region I, the breakdown appears to be electronic, as the breakdown strength is almost independent of the electric field rise time over times ranging from microseconds to seconds. In region II, impulse thermal breakdown due to ionic conduction appears to be a likely mechanism. The calculated ionic jumping distance 2¿i is found to be 1.5 nm at 200°C and 2 nm at 230°C, which are reasonable values for polymeric materials. View full abstract»

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  • Voltage and Frequency Dependence of Bow-Tie Trees in Crosslinked Polyethylene

    Page(s): 363 - 367
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    In this paper, various experimental results are described of bow-tie trees obtained in steam-cured crosslinked polyethylene which contains 103 to 105voids/mm3. The growth of bow-tie trees depends upon the applied voltage and the frequency. Void size has a great influence on the growth of bow-tie trees. View full abstract»

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  • Anomalous Breakdown Phenomena in PMMA under Combined Direct and Impulse Stresses

    Page(s): 368 - 372
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    The results of experimental investigations on the anomalous breakdown characteristics of polymethyacrylate (PMMA) immersed in transformer oil are reported in this paper. The insulation was subjected to a combination of direct and impulse voltages. The anomalous breakdown voltage was found to decrease when the polarity of superimposed impulse voltage was opposite to that of the direct voltage and to increase when the polarities of both are the same. The polarity of the resultant appled voltage was also found to affect the length of the breakdown path. An attempt is made to explain such anomalous behavior with the help of space charge accumulation in modern synthetic insulating materials. The variation of direct voltage prestress time on the anomalous breakdown voltage are also discussed. View full abstract»

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  • Meetings

    Page(s): 376
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  • IEEE Electrical Insulation Society

    Page(s): 376-a
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  • Information for authors

    Page(s): 376b
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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