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Dielectrics and Electrical Insulation, IEEE Transactions on

Issue 6 • Date December 2011

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Displaying Results 1 - 25 of 46
  • IEEE Transactions on Dielectrics and Electrical Insulation [Front cover]

    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
  • From the Editor-in-Chief

    Page(s): i - ii
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  • Study of the effects of alternating magnetic field on point-plane corona

    Page(s): 1813 - 1820
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    Although corona is a phenomenon known, measured and analyzed for many decades, there are still some aspects which could be further explored; one of them being, analysis of the effect of magnetic field on the corona process and its measurement. This paper addresses the phenomenon from a physical level, and the effect of magnetic field and its influence on the ultra-high frequency (UHF) measurement is analyzed from a plasma perspective. Calculations are made using various formulae, pertaining to plasma, to identify the influence of magnetic field on corona. The theory developed is backed by experimental work involving UHF based measurements. The effect of the magnetic field in the form of gyro-frequency influences the UHF measurement. Magnetic field is seen to reduce the power spectral density of corona in the 650-800 MHz band. View full abstract»

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  • Portable hvac and pulsed plasma sources for control of NOx in diesel engine exhaust

    Page(s): 1821 - 1828
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    In this paper studies were carried out on two compact electric discharge plasma sources for controlling nitrogen oxides (NOχ) emission in diesel engine exhaust. The plasma sources consist of an old television flyback transformer to generate high frequency high voltage ac (HVAC) and an automobile ignition coil to generate the high voltage pulses (HV Pulse). The compact plasma sources are aimed at retrofitting the existing catalytic converters with electric discharge assisted cleaning technique. To enhance NOχ removal efficiency cascaded plasma-adsorbent technique has been used. Studies were reported at different flow rates and load conditions of the diesel engine. View full abstract»

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  • Excitation temperature determination of an arc formed over an ice surface using optical emission spectroscopy

    Page(s): 1829 - 1834
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    Optical emission spectroscopy has been used to study an arc formed over an ice surface. DC positive voltage was applied to a flat ice surface with a 6 cm air gap to initiate electric discharge. Time-resolved spectra were recorded during the propagation of arc along the surface. Excitation temperature was measured using copper and oxygen lines and employing the relative line intensities method. Deviation from the local thermodynamic equilibrium was considered using the Burton and Blade correction factor. The investigation results showed that the excitation temperature does not vary monotonically with the discharge current. View full abstract»

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  • Improving the accuracy of SF6 leakage detection for high voltage switchgear

    Page(s): 1835 - 1846
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    Even though average leakage rates of SF6 in high voltage equipment are very low, there is no guarantee for a 100% leakage-free system, especially when considering the generally long lifespan of high-voltage equipment. Taking in view the rather strict maximum allowed leakage rate of SF6 per year, regulated by international standards, these facilities should be equipped with suitable monitoring devices. However, accurate detection of low rates of gas leakage is not an easy task. This paper sheds light on the challenges of leakage detection by thorough analysis of physical aspects. Furthermore, it proposes two methods for high-fidelity leakage monitoring and detection with special emphasis on their suitability for use in substations. Application of these methods in the laboratory environment revealed an accuracy of detection levels of 0.3% per year. This is a substantial improvement from the present monitoring systems that show fluctuation levels of the indicator to be as high as up to several percent, which is clearly above the acceptable level. View full abstract»

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  • Improving the sensitivity verification method of the UHF PD detection technique for GIS

    Page(s): 1847 - 1853
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    In the paper, several proposals to improve the sensitivity verification method for the application of UHF partial discharge monitoring systems in GIS, as described in CIGRE Electra No. 183, are presented. Verification results, which depend on the rise time of the test pulse signal, have previously been proposed to compensate for the various rise time pulses with their voltage magnitudes. As a complementary test method to the CIGRE Electra method, a network analyzer measurement is proposed. The influence of the rise time was experimentally investigated using a test GIS setup that had two internal type PD couplers. The scattering parameters of the test GIS were measured, and the computer simulation results corresponded well with the measurement results. The CIGRE method was applied to a 400 kV GIS and the test results of two different rise time conditions were analyzed. An increase of the magnitude due to a longer coaxial cable was demonstrated. The network analyzer method enables compensation of the test pulse specifications, and the scattering parameter data can be used to obtain a GIS trade certificate with the PD coupler. Pulse generators with a rise time shorter than 500 ps are subject to export control regulations when implementing the CIGRE method internationally, which makes the network analyzer advantageous in that it is free from this regulation in terms of using it for UHF measurements. View full abstract»

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  • Multi-electrode assisted corona discharge for electrohydrodynamic flow generation in narrow channels

    Page(s): 1854 - 1863
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    The present article proposes a multi-electrode discharge, called the assisted corona discharge as a possible solution to the challenges facing the miniaturizing of ionic wind blowers. Ionic wind blowers utilizing a corona to generate electrohydrodynamic (EHD) flow have garnered increased interest as a cooling mechanism for electronic devices. As the size of these devices reduces, miniaturization of EHD blowers becomes essential. This offers many challenges including reducing the operating potentials (voltages), sustaining a stable discharge, and generating appreciable flow rate in a miniaturized configuration. An electrode configuration consisting of multiple collecting electrodes in an asymmetric geometry and electrostatically unbalanced configuration can generate a discharge regime termed an assisted corona discharge. The multiple collecting electrodes increase the overall current production at the corona source, but the discharge onset to both collecting electrodes is only controlled by the closer, primary collecting electrode. The utilization of multiple collectors inside a 4 mm high duct increased flow rates significantly in comparison to a standard corona discharge between a source and single collecting electrode, while also consuming less power, thus increasing efficiency. View full abstract»

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  • Electrical discharge behavior of micro-gaps

    Page(s): 1864 - 1868
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    Electrical discharge characteristics of micro-gaps, ranging from 50 to 1000 μm in air are investigated under ac, dc and high frequency (5 kHz) by using blade electrodes that possess a high aspect ratio: 20 μm edge thickness and 15 mm length. Three micro-gap configurations (single, series and parallel) are studied for the breakdown strength and partial discharge characteristics. An exponential increase in the breakdown strength with air gaps below 1000 μm is observed. The finite element models revealed that the electric stress at 1000 μm is about 4 times the applied field. The electric stress magnitude is found to reduce as a function of air gap up to about 100 μm where the actual field is equal to the applied field. The breakdown strength of the series gap configuration is significantly higher than that of the parallel configuration. The partial discharge activities are observed in the series configuration whilst the same is absent in the parallel configuration. View full abstract»

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  • Effect of DBDS concentration and heating duration on copper sulfide formation in oil-immersed transformer insulation

    Page(s): 1869 - 1876
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    Copper sulfide is found to be more likely formed on Kraft paper in oil-immersed transformers with an increase in either dibenzyl disulfide (DBDS) concentration or heating duration, which is verified by heating tests stipulated by IEC 62535. Two effects of DBDS concentration on the formation rates of copper sulfide were obtained. The formation rates of investigated oils are proportional to the DBDS concentration when the concentration is low. However, the amounts of copper on the Kraft papers are constant when the DBDS concentrations are more than certain values, which is considered to reflect the saturation of dissolving DBDS-Cu complex in the oil. These concentrations depend on oil brand. Copper sulfide begins to form after some duration of heating and the duration decreases with an increase in the DBDS concentration. Copper sulfide formed on the Kraft paper is a portion of the total copper reacted with DBDS by comparing the amount of copper formed on the Kraft paper with the total amount of reacted copper calculated from the amount of consumed DBDS. View full abstract»

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  • Influence of inhibitor and oil components on copper sulfide deposition on kraft paper in oil-immersed insulation

    Page(s): 1877 - 1885
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    Copper sulfide deposition on Kraft paper in oil-immersed transformers is found to be accelerated by di-tert-butyl p-cresol (DBPC), which is widely used as an antioxidant, and paraffinic hydrocarbons in their oils, which is verified in laboratory experiments. DBPC can prolong the lifetime of precursors of the copper sulfide deposition by reacting decomposition products of copper dibenzyl disulfide (Cu-DBDS) complex and by creating the Cu-DBPC complex. Because the lifetime of the Cu-DBPC complex is far longer than that of the Cu-DBDS complex, considerable amounts of copper sulfide are deposited on Kraft paper instead of being formed on the surface of copper. A good correlation is obtained between the concentration of paraffinic hydrocarbons and the amount of copper sulfide deposited on Kraft paper in the three commercial oils. View full abstract»

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  • Effects of N,N-dimethylaniline and trichloroethene on prebreakdown phenomena in liquid and solid N-tridecane

    Page(s): 1886 - 1896
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    Prebreakdown phenomena in 0.1 M N,N-dimethylaniline (DMA) and 0.1 M trichloroethene (TCE) in n-tridecane have been investigated experimentally in liquid and solid phases in a needle-plane geometry with impulse voltage. Light emission and charge injection from the high-field electrode were measured. Results have been compared with results obtained in neat n-tridecane and in cyclohexane with the same additives. Adding TCE to n-tridecane increases the p re-inception current and decreases the inception voltage for negative and positive polarity. The increase in pre-inception current is probably caused by trap assisted conduction, and may be responsible for the decrease in inception voltage. TCE had no effect on propagation of streamers in n-tridecane. The main effect of DMA in n-tridecane is to enhance the propagation of streamers and electrical trees with positive polarity. This is in line with what has been reported for cyclohexane, and is explained by the low ionization potential of DMA. Charge injection for negative streamers is reduced by the addition of DMA in n-tridecane, while the emitted light is increased. This indicates that some of the energy otherwise used for propagation is emitted as light. A low electronic excitation energy for DMA at 3.8 eV supports this hypothesis. The additives have the same effect on prebreakdown phenomena in solid and liquid phases with positive polarity, and thus the same mechanism is suggested to be responsible for electrical treeing and streamer inception and propagation. The scatter is generally found to increase when going from liquid to solid phase, which is explained by the inhomogeneity in the solid phase. The transition to solid phase with negative polarity typically results in an even larger scatter than for positive polarity. The effect of additives seems to be secondary to the morphology at the point electrode with negative polarity. View full abstract»

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  • Particle swarm optimization feature selection for the classification of conducting particles in transformer oil

    Page(s): 1897 - 1907
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    The determination of particle type and dimensions in transformer oil is accomplished by using a Particle Swarm Optimization (PSO) technique in terms of the features extracted from the measured partial discharge (PD) pulse patterns. PSO selection of effective features is shown to be successful with intelligent classification for both electrical and acoustically measured data. Classification results of individual measurements were also reliable and far surpassed the efficiency of classification results obtained using the classifier solely for the same dimension of input features. The approach in this paper provides a solid basis for a data mining technique that can be used for the interpretation of both time and phase resolved raw PD patterns by searching a wide range of statistical attributes. View full abstract»

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  • Streamer characteristic and breakdown in synthetic and natural ester transformer liquids with pressboard interface under lightning impulse voltage

    Page(s): 1908 - 1917
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    This paper presents experimental studies on streamer and breakdown of synthetic and natural ester liquids with the presence of pressboard interface in a divergent point-plane field under lightning impulse voltage. Based on the current, light signals and streamer images, characteristics of both positive and negative streamers on pressboard surface were described, which resemble the features of streamers in open liquid gaps. Introducing pressboard in parallel does not influence the streamer stopping length and thus not weaken the oil gap breakdown voltage, under both positive and negative polarities at gap distances up to 75 mm. However, presence of parallel pressboard significantly reduces the acceleration voltage in mineral oil but seems have no influence on ester liquids under positive polarity, while it tends to accelerate the streamer velocity at larger gap distance and under higher voltage in both ester liquids and mineral oil under negative polarity. Generally, streamer on ester/pressboard interface propagates further than on mineral oil/pressboard interface at the same voltage level; both breakdown voltage and acceleration voltage on ester/pressboard interface are lower than those on mineral oil/pressboard interface at the investigated gap distances up to 75 mm. View full abstract»

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  • Novel characteristic parameters for oil-paper insulation assessment from differential time-domain spectroscopy based on polarization and depolarization current measurement

    Page(s): 1918 - 1928
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    For achieving the aging characteristic parameters of transformer oil-paper insulation, oil impregnated pressboard samples are acceleratedly thermally aged at high temperature (~150°C) in laboratory, and on the same sample before and after being aged, polarization and depolarization current (PDC) tests are performed at different temperatures (30, 40, 50 and 60°C), respectively. Besides analyzing the PDC results, the differential time-domain spectroscopy (DTDS) technique is introduced to investigate the aging status of oil-paper insulation and the influence of measurement temperature. The DTDS parameters such as polarization component Qn, polarization response time τn and line-shape parameter anare extracted with DTDS unscrambling method based on PDC data. It is revealed that DTDS represents similar polarization process and mechanism to PDC, and all the DTDS curves calculated with the obtained parameters (Qn, τnn) are in good fit with those measured. By analyzing the effect of temperature and aging, two types of relaxation polarization mechanism are observed, i.e., the interfacial polarizations between oil and paper insulation and inside the pressboard. The polarization components, response speeds and line-shape parameters of both the polarization mechanisms increase evidently on the whole with temperature rising or sample aging. It is demonstrated that, the DTDS theory is suitable for oil-paper insulation material, the DTDS unscrambling method is effective and objective, and such DTDS parameters are sensitive and can quantitatively reflect the changing of temperature and aging condition with regularity. Consequently, the parameters (Qn, τn, αn) can be considered as the novel characteristic parameters for aging condition estimation of oil-paper insulation to upgrade the application effect of PDC curves. View full abstract»

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  • N-tridecane as a model system for polyethylene: comparison of pre-breakdown phenomena in liquid and solid phase stressed by a fast transient

    Page(s): 1929 - 1946
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    Pre-breakdown phenomena in pure n-tridecane in liquid and solid state have been investigated experimentally in a needle-plane geometry with impulse voltage. Light emission and charge injection from the high-field electrode were measured. Pre-inception currents in liquid and solid state were recorded and compared to finite element calculations to find plausible high-field conduction models for n-tridecane and cyclohexane. n-tridecane was chosen as a model system for polyethylene based on the known similarities in energy bands for polyethylene and alkanes. The results obtained in pure n-tridecane were compared to similar experiments on cyclohexane and polymer systems. High-field conduction in liquid n-tridecane was found to have a similar field dependence as previously reported for cross linked polyethylene (XLPE). Conduction currents and inception probabilities were found to be almost independent of polarity in frozen and liquid n-tridecane, which is also in line with results obtained for XLPE. Conduction currents were observed at lower voltages in n-tridecane than in cyclohexane, reflecting the lower space charge limited field (SCLF) in n-tridecane. Inception of streamers in liquid cyclohexane occurs at lower voltages than in liquid n-tridecane, and a stronger polarity dependence for all phenomena was observed in cyclohexane compared with n-tridecane. A possible explanation for the differences between n-tridecane and cyclohexane is given based on the field needed for electron avalanches and the SCLF in the two liquids. Inception voltages, light emission and charge injection were found to be similar in liquid and solid n-tridecane. This indicates that the same processes are responsible for inception and propagation of electrical trees in solids and streamers in liquids when the material is stressed by a fast transient. The similarity between the measured properties in solid and liquid phases leads to the conclusion that electrical treeing mainly takes place in the a- orphous regions of the solid phase. View full abstract»

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  • Assessment of impact of impurities in epoxy - anhydride vacuum impregnation (vi) resin system

    Page(s): 1947 - 1954
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    Epoxy-anhydride based resin system is widely used as an impregnant for the high voltage rotating electrical machines. The present paper brings out the significance and key role played by the quality control parameters in assessing the cumulative effect of various kinds of impurities present in the raw materials of VI resin. An experimental study was carried out on vacuum impregnating (VI) resin systems of three brands to demonstrate the effectiveness of the quality control test parameters for assessing the cumulative impact of impurities on the tank life and degree of penetration of VI resin into the insulation. Effect of resin to hardener ratio, humidity and accelerator on the reactivity of VI resin system has also been determined. The results of experimental study demonstrate that the normal quality control tests i.e. viscosity and reactivity are essential for assessing consistency of the quality of the incoming materials from an approved source. However, these tests are not sufficient for evaluation and screening of VI resin systems of different brands. The rate of rise of the viscosity at a given temperature of the sample from a new source in comparison to approved sample is also to be determined for assessing their relative storageability (tank life) which is an important aspect for cost effective utilization of the materials. Further, the investigation reveal that the temperature of measurement of 60°C and the composition of resin & hardener mix of ratio of 100:100 are relatively more sensitive to detect the impact of impurities in comparison to the temperature measurement of 70 °C and the ratio 100:120 and preferred for assessing the impact of impurities present in fresh resin and hardener. The hardener is relatively more sensitative to the humidity than the resin for increasing reactivity of VI resin system. View full abstract»

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  • Statistical analysis of electrical breakdown behavior of polyimide following degrading processes

    Page(s): 1955 - 1962
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    Polyimide (PI) tape has been widely used as electrical insulation for wires and cables due to its excellent balance of electrical, mechanical and thermal properties. However, insulation materials are exposed to various environmental degradation mechanisms during service, which can cause deterioration of their insulation properties. In this paper, the effects of thermal exposure and immersion in water on dielectric strength of Kapton® HN PI film are investigated statistically by two-parameter Weibull distribution analysis. The PI samples were heated at 475°C for 1 to 4 h, and at 450 to 480°C for 4 h, to study the influence of thermal exposure. Moreover, to explore the effect of moisture absorption, other PI samples were immersed in distilled water for up to 96 h at room temperature. After the degrading process, breakdown voltage and thickness were measured at 20 different points on each sample. The Weibull cumulative distribution function for each of the degraded samples was plotted, and compared with that of a sample dried by heating at 200°C for 1 h. Significant decreases in both the scale parameter and the shape parameter of the Weibull distribution, obtained through least-squares regression, are observed, indicating a statistical decrease in dielectric strength and a more dense dispersion of electrical weak points in PI. This observed deterioration of insulation capability of PI is attributed to chemical degradation and formation of ionic side groups during heating and immersion in water, respectively. View full abstract»

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  • Development of epoxy/BN composites with high thermal conductivity and sufficient dielectric breakdown strength partI - sample preparations and thermal conductivity

    Page(s): 1963 - 1972
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    The aim of this research is to find a way to achieve the epoxy composites with both high thermal conductivity and acceptable dielectric breakdown (BD) strength. As high thermal conductivity, low permittivity and low thermal expansion coefficient of filler can endow composite with higher thermal conductivity, higher BD strength and lower thermal expansion coefficient respectively, BN (boron nitride) with high thermal conductivity, low permittivity and low thermal expansion coefficient was adopted as main filler in the research. Thermal conductivity was investigated in this part. The BD strength of samples will be discussed in Part II. Neat epoxy and other 25 kinds of epoxy/BN composites were prepared by a hot press method. Most of BN fillers were surface modified with silane coupling agent through ethanol/water reflux method to improve thermal conductivity. The values of 2.91 W/m·K, 3.95 W/m·K and 10.1 W/m·K as thermal conductivity were obtained for the composites that was single-loaded with h-BN(hexagonal boron nitride), c-BN (cubic boron nitride) or conglomerated h-BN, respectively. They were further improved to 5.26 W/m·K, 5.94 W/m·K and 12.3 W/m·K, respectively, by adding extra smaller A1N (aluminum nitride) to fill the voids in sample. Thermal conductivity of samples changes with the ratio of c-BN and h-BN when c-BN and h-BN were co-loaded. A value of 5.74 W/m·K as maximum was obtained at their ratio of 1 to 1 when total filler content is 80 wt%. A much higher value of 7.69 W/m·K was obtained by adding extra AIN. From the experiment data, it is concluded that the filler orientation in vertical direction of sample surface and the decrease of voids in sample are very important to obtain high thermal conductivity, and that the filler surface modification is also necessary to improve thermal conductivity especially for epoxy/c-BN composites, and addition of nano silica in small amount can also increase- thermal conductivity if sample is prepared appropriately. View full abstract»

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  • Development of epoxy/BN composites with high thermal conductivity and sufficient dielectric breakdown strength part II-breakdown strength

    Page(s): 1973 - 1983
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    The aim of this research is to find a way to achieve the epoxy composites with high thermal conductivity and acceptable dielectric breakdown (BD) strength. A value 12.3 W/m·K is the highest thermal conductivity obtained for epoxy composite in Part I. Dielectric breakdown performances such as short-time dielectric breakdown strength (BD strength), partial discharge (PD) resistance and BD time for composites were investigated in the Part II. In general, micro filler inclusion will increase thermal conductivity and decrease dielectric breakdown performance. Influencing factors are considered to be the orientation of filler, the content of void space, the content ratio in the case of co-mixing, the addition of nano filler, and filler surface modification. Twenty six kinds of composites were prepared in consideration of the above influencing factors. There are two options for most appropriate ones among the composites evaluated in the research. One is an epoxy/ conglomerated h-BN composite with co-loaded nano SiO2 and micro AIN filler. It has 12.3 W/m·K in thermal conductivity, 75.1 kVpeak/mm in BD strength and 260 % of BD time for neat epoxy. It is most suitable when low BD strength and high thermal conductivity is needed. The other one is an epoxy/ h-BN composite with co-loaded nano silica and AIN filler for requirement of very high BD strength but lower thermal conductivity. Optimum thermal conductivity is obtained if flaky h-BN filler is oriented in parallel to heat flow. Since it is difficult to realize full orientation, the use of conglomerated h-BN filler is a suitable option. Optimum BD performance is obtained if void space is reduced by certain methods such as co-dispersion of different size fillers and addition of nano filler. View full abstract»

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  • AC and DC zone-induced ageing of HTV silicone rubber

    Page(s): 1984 - 1994
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    On the way of making efforts to standardize the selection of polymeric materials for high voltage outdoor environments, the resistance to corona and ozone has been recognized as one among twelve parameters to be evaluated within the OGRE Working Group D1.14. Our previous related work reported on the evaluation of the resistance of five commercially available polymeric materials to ac corona-ozone treatment, according to the test procedure recommended by this Working Group. With the same test arrangement in use, this report focuses on comparing the influences of ac and dc corona-ozone exposures on high temperature vulcanized (HTV) silicone rubbers. For this purpose, two types of HTV materials were used, each one characterized by different resistivity levels and tensile strength. For defining the treatment conditions, the ac and dc coronas were characterized by measuring the associated discharge current as well as the power released from the electrode. The intensity of ac corona discharge was found to be higher than that of dc corona, the latter being controlled by electrostatic charging of the treated polymeric surfaces, which also resulted in significant differences of the resulting ozone concentration. Experimental investigations after the treatments concentrated on evaluating dielectric properties (e.g. surface and volume resistivities, dielectric response (DR)), mechanical properties (e.g. tensile strength and elongation at break), as well as chemical and structural analyses (e.g. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR)). Results obtained from the measurements of dielectric properties indicated a strong sensitivity of surface resistivity to the treatments, though the impact of the dc corona remained less pronounced. On the other hand, the dielectric response and volume resistivity did not exhibit a high susceptibility to the exposure. No substantial differences were also found among the ac and dc corona treated s- mples as regards the mechanical properties. The XPS and FTIR analyses revealed proofs of surface oxidation for the samples treated by ac corona, while the samples treated by dc corona showed much less tendency for oxidation. View full abstract»

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  • Dry-band discharges on polluted silicone rubber insulation: control and characterization

    Page(s): 1995 - 2003
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    Inclined-plane tests of silicone-rubber samples prepared with textured patterns of hemispherical protuberances are described. These are compared with the results obtained for conventional non-textured plane-surface samples of the same material. A remarkable improvement is achieved by such texturing: a material which normally fails the test is enabled to satisfy the standard test criteria, and the tracking and erosion of the samples caused by the tests are significantly reduced. These texturing techniques are currently being extended to prototype composite insulators. It is shown that this improvement for textured samples is a result of the formation of a stable, controlled dry band on the polluted surface. Although discharge inception occurs across the band, these discharges result in a fall, rather than an increase, of the leakage current. The transition to a higher current arc phase is thus inhibited, compared with non-textured samples for which stable dry bands did not occur. These observations of reproducible dry band breakdown also provide an opportunity to characterize experimentally the electrical properties of these discharges. A recent proposed model represents the dry-band discharge as a streamer-spark structure, in contrast to the standard model of an arc-like interdependence of current and voltage. These two models are tested against the present new data, and the discharge is shown to have streamer characteristics. View full abstract»

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  • Installing insulation jacket to improve outdoor insulation performance of composite insulator

    Page(s): 2004 - 2012
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    In the paper, a new approach is proposed to improve the outdoor insulation properties of transmission lines. It is achieved by installing the insulation jackets and additional grading rings onto transmission line conductors. The impact of insulation jacket parameters on the electrical field distribution along a 220 kV composite insulator was simulated by a finite element program assuming dry surface contamination. The corona inception voltage was measured on real composite insulators and the measurement results verified the conclusion from the simulation. Furthermore, the correlation between the insulation jackets' length and the contamination flashover voltage of composite insulators was studied. Based on the measurement and simulation results, the optimal insulation jacket parameters are suggested. In the last part of this paper, insulation jackets manufactured according to the optimal parameters are installed onto the transmission line conductor in the field. During one year of operation, the positive effect on the electric field distribution and the reliability of the installed insulation jackets have been confirmed. View full abstract»

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  • Electromagnetic waves from partial discharges in windings and their detection by patch antenna

    Page(s): 2013 - 2023
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    The electromagnetic (EM) radiation accompanying partial discharges (PDs) in enameled-wire winding is analyzed assuming the Gaussian currents in the basic PD model. A simplified procedure is proposed to evaluate the response of patch antenna or microstrip antenna to the EM wave based on the transient circuit calculus. Analyses on the twisted pair specimen show that EM radiation from the wire currents contribute to patch antenna output much more than that from the PD itself. The analytical results are verified by an experiment on the twisted pair. It is confirmed that the patch-antenna sensor is potentially capable of detecting PDs in actual motor winding. View full abstract»

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Aims & Scope

IEEE Transactions on Dielectrics and Electrical Insulation contains topics concerned with dielectric phenomena and measurements with development and characterization of gaseous, vacuum, liquid and solid electrical insulating materials and systems.

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Editor-in-Chief
Reuben Hackam