Scheduled System Maintenance:
Some services will be unavailable Sunday, March 29th through Monday, March 30th. We apologize for the inconvenience.
By Topic

Dielectrics and Electrical Insulation, IEEE Transactions on

Issue 6 • Date December 2009

Filter Results

Displaying Results 1 - 25 of 38
  • IEEE Transactions on Dielectrics and Electrical Insulation - Table of contents

    Publication Year: 2009 , Page(s): c1
    Save to Project icon | Request Permissions | PDF file iconPDF (72 KB)  
    Freely Available from IEEE
  • IEEE Dielectrics and Electrical Insulation Society

    Publication Year: 2009 , Page(s): c2
    Save to Project icon | Request Permissions | PDF file iconPDF (47 KB)  
    Freely Available from IEEE
  • Dielectric liquids

    Publication Year: 2009 , Page(s): 1505
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (99 KB)  

    The present issue of the Transactions is devoted to papers which deal with the subject of dielectric liquids. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Some general remarks on the dielectric loss mechanisms in mineral oils

    Publication Year: 2009 , Page(s): 1506 - 1510
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB) |  | HTML iconHTML  

    The mechanisms of conduction and dielectric loss pertaining to electrical insulating oils, are examined with specific reference to the conduction and dielectric loss processes involving ionic and macroscopic particle charge carriers. Specific examples are presented; one of the most serious types of conduction by particles is that due to semiconductive copper sulfide particles, which are formed in a reaction between copper conductors or copper particles and the corrosive sulfur components contained in the oils. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparative PD pulse burst characteristics of transformer type natural and synthetic ester fluids and mineral oils

    Publication Year: 2009 , Page(s): 1511 - 1518
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (837 KB) |  | HTML iconHTML  

    The partial discharge (PD) pulse burst behavior in natural and synthetic organic ester fluids and mineral oils of the type used in transformers has been examined, using simultaneous wide and narrow band measurement techniques. This permitted the determination and comparison of both the overall charge transfer of the PD pulse as well as that of the discrete PD pulses comprising the PD pulse burst in the evaluated dielectric fluids. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The effect of four torques on dielectric behavior

    Publication Year: 2009 , Page(s): 1519 - 1523
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (474 KB) |  | HTML iconHTML  

    In his notable book 'Polar Molecules' published in 1929, Debye showed that for polar dielectric liquids, dispersion and absorption could be described by the operation of a relaxation mechanism characterized by a frequency-dependent complex permittivity. On the basis of certain assumptions, he developed an expression for that dependence. Among those assumptions was that the polar molecules were taken to have no inertia, and in consequence they can not have any net torque acting on any of them at any time. The polar molecules were taken to be present in a very dilute solution of a polar liquid in a non-polar solvent. Therefore dipole-dipole interactions were ignored, and the driving torque on any dipole was taken to be caused by the applied field alone. That torque was taken to be counterbalanced at all times by a frictional torque proportional to the instantaneous angular velocity of each particular polar molecule. This retarding torque arises from an inner friction, and is not the same as, but is in some way related to, the macroscopic viscosity of the liquid. However, the action of the frictional torque in cancelling the applied torque does not account for energy storage in the liquid. Debye establishes the necessary phase relationships by the postulate that the dipole moment of the polar molecules is complex. While this postulate is quite permissible, it does not give an insight into the physical mechanism involved. In addition to the two torques taken into account by Debye, in a paper published in 2005 Calderwood proposed that there is a third torque acting on the dipoles which is responsible for the electrostatic energy stored when a specimen of a polar dielectric liquid is charged, and which is released on specimen discharge. A detailed account of the behavior of this torque and its significance is given in that paper. One of the features of the third torque is that, in contrast to the friction torque which is dissipative, it is conservative. That is to say, - it is spring-like in nature. It is that characteristic which enables the specimen to store and release energy. The presence of spring-like elements in any mechanical or electrical system can also significantly modify its behavior. In this paper a criterion is derived which indicates whether or not significant features of dielectric behavior might be attributed to the third torque. The treatment of Debye did not take the inertial effect of the polar molecules into account. However, these molecules do possess some inertia and so a fourth torque is necessarily associated with any acceleration to which they may be subjected. Account is taken of this in the present analysis by the introduction of the fourth torque. This treatment, like that of Debye, does not take account of dipole-dipole interaction. It is therefore only applicable to dilute solutions of polar molecules in a non-polar solvent. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effects of electron-attaching and electron-releasing additives on streamers in liquid cyclohexane

    Publication Year: 2009 , Page(s): 1524 - 1535
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4418 KB) |  | HTML iconHTML  

    The effects of electron-attaching and electron-releasing additives in cyclohexane on the initiation and propagation of positive and negative streamers have been studied quantitatively. Fast impulses (<20 ns, <40 kV) were applied on a 10 mm point-to-plane gap and studied by shadowgraphic imaging and a differential charge measurement technique. The properties of both positive and negative streamers depend on the specific electronic characteristic of the additives. Electron-attaching additives facilitate the propagation of negative streamers, whereas the most effective electron-releasing additives reduce initiation voltages and facilitate the propagation of positive streamers. Depending on the reactivity and concentration of the additives, streamer filaments become thinner and fewer while propagating faster and further. The Townsend-Meek theory for streamer inception in gases has been adapted to a solution and applied to analyze the voltage dependence of the positive streamer propagation. Results show a quantitative dependency on the ionization potential and concentration in agreement with experimental trends. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Initiation and propagation of the negative leader in transformer oil under impulse voltage

    Publication Year: 2009 , Page(s): 1536 - 1542
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1556 KB) |  | HTML iconHTML  

    The complex experimental studies of the discharge mechanism in transformer oil under negative polarity (NP) of the lightning impulse were carried out using alternative diagnostic methods. Novel data concerning propagation mechanism and parameters of the predischarge channels were obtained. The results indicate that oil breakdown both under negative and positive polarities are similar in a number of properties to the breakdown in the long air gaps. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Density-induced modifications of the IR emission spectrum of Xe2 excimers in dense gas

    Publication Year: 2009 , Page(s): 1543 - 1551
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (887 KB) |  | HTML iconHTML  

    The infrared emission spectrum of Xe2 excimers produced by irradiating Xe gas with high-energy electrons has been monitored as a function of density up to 3.3 MPa at room temperature. Excimer decay yields a broad continuum centered around 7800 cm-1 of width 900 cm-1 at 0.1 MPa. The spectrum shape is consistent with a bound-free molecular transition between 0u + and 0g + states correlated with 6p and 6s atomic limits. Upon increasing density, the spectrum is strongly red-shifted and broadened. The present measurements confirm preliminary results obtained in a smaller density range. The shift is explained by the dielectric screening exerted by the gas atoms on the optically active electron-ionic molecular core interaction, and by quantum multiple scattering effects of the electron scattered off the gas atoms. The latter effect links this experiment to electron transport experiments in non-polar gases. The different spectrum broadening in pure Xe and in an Ar-Xe mixture is believed to be due to quantum indistinguishability of identical particles. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The effect of conductivity on streamer initiation and propagation between dielectric-coated sphere-plate electrodes in water

    Publication Year: 2009 , Page(s): 1552 - 1557
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3029 KB) |  | HTML iconHTML  

    A dielectric-coated sphere-plane electrode system was designed and used for the generation of streamer discharges in water. To study the streamer initiation and propagation mechanisms, the effect of conductivity was investigated under pulse voltage. Increasing water conductivity caused the decrease of streamer initiation voltage and streamer formation time delay. Under the same applied voltage, the maximum streamer length was inversely proportional to water conductivity, whereas the streamer brightness was proportional to the water conductivity. The mean streamer velocities were dramatically different with different water conductivity and the influences of interactions between streamer branches on the streamer propagation were inevitable under high applied voltage. Based on the analyses of these experimental results, it can be concluded that streamer initiation in water is triggered by the microgap breakdown in the coating while streamer propagation may be a gaseous or electronic process, which is dependent on applied voltage and water conductivity. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of water on permittivity of nanodielectrics exposed to the atmosphere

    Publication Year: 2009 , Page(s): 1558 - 1565
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1815 KB) |  | HTML iconHTML  

    Relative dielectric constant and dissipation factor (tan¿) values as a function of frequency have been measured for a variety of water types. The effect of water absorption on the permittivity properties of crystalline powders or nanopowders when exposed to various humidity levels is also examined. Powdered materials were characterized by XRD and were consisting of calcite (CaCO3), anatase, rutile (TiO2), ¿- and ¿-alumina (Al2O3). The induced polarization changes in the materials by the applied dehydration process, i.e. either high vacuum of 10-4 Pa (10-6 mbar) drying, or calcination in air at temperatures of up to 600°C, were investigated. The advantage offered by vacuum dehydration is that nano-dielectrics maintain their particle size and crystal integrity. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Space charge behavior in palm oil fatty acid ester (PFAE) by electro-optic field measurement

    Publication Year: 2009 , Page(s): 1566 - 1573
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (969 KB) |  | HTML iconHTML  

    For power transformer insulating oil, we focused on palm oil fatty acid ester (PFAE). It has satisfactory insulating performance, excellent cooling ability and superior biodegradability. Recently, investigations for application of PFAE to environment-friendly power transformers installations have been started. In this paper, the space charge behavior in PFAE was investigated from the measurement results of the electric field by using Kerr electro-optic method under dc voltages applications. For the field measurement, the Kerr constant of PFAE was identified first. Then, the electric field strength and its temporal change were measured in several PFAE / pressboard (PB) insulation systems. The electric field in PFAE was determined by the capacitive distribution at the moment of the voltage application, and decreased rapidly with time and reached the steady state determined by the resistive distribution. The transition time of the capacitive distribution to the resistive one and the strength of electric field in PFAE were much different from those in mineral oil. The influence of oil flow on the time transition of the electric field was also measured. Their differences were discussed with the charge behavior in liquids, based on electro-chemical properties of the oil. We discussed the difference of the flow electrification characteristics between PFAE and mineral oil, and its mechanism was discussed based on the charge behavior in oils. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Influence of the voltage waveform and hydrostatic pressure on morphology and final length of discharges propagating over solid-liquid interfaces

    Publication Year: 2009 , Page(s): 1574 - 1581
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6176 KB) |  | HTML iconHTML  

    This paper is aimed at the influence of the voltage waveform (lightning impulse, dc and ac) and hydrostatic pressure on the morphology and final length of creeping discharges propagating over solid/liquid insulating surfaces in a point-plane electrode arrangement. Different solid materials immersed in mineral oil are tested. It is shown that under ac and dc, the discharges do not present a radial shape as observed with the negative discharges under lightning impulse voltages. For a given solid sample, the final length Lf (i.e. the maximum extension) of discharges is longer with ac than with lightning impulse voltage and dc. The currents waveforms are similar to those observed in liquids. On the other hand, the length of discharge branches is reduced when the hydrostatic pressure is increased whatever the voltage waveforms and polarity. Lf increases quasi-linearly with the voltage and decreases when the hydrostatic pressure is increased. And for given voltage and pressure, the thinner the solid sample and/or the higher its dielectric constant, the longer the discharges are, indicating the important role of capacitive effects in the propagation mechanisms of discharges. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Streamer propagation and breakdown in natural ester at high voltage

    Publication Year: 2009 , Page(s): 1582 - 1594
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1184 KB) |  | HTML iconHTML  

    This paper reports an experimental investigation about streamer propagation and breakdown in natural esters (rape-seed oils). Experiments are carried out over a large range of gap distances (from 2 to 20 cm) and voltage (up to 460 kV), in order to determine the properties of natural esters for high voltage insulation. A detailed description of positive and negative streamers is obtained by the measurement of propagation velocity, stopping length, transient currents, charge, streak photographs of the emitted light. As in previous studies carried out in mineral transformer oil, several propagation "modes" can be observed in rape-seed oil. They show the transition from "slow" streamers (velocity about 1 km/s), to fast streamers (velocity up to 200 km/s). Fast positive streamers propagate at much lower voltage in rape-seed oil compared to mineral oil. In turn, this induces lower breakdown voltages and shorter time to breakdown in this liquid. Measurements of currents and streak photographs bring the evidence of the stepped character of fast positive streamers and show the constancy of their velocity under very high voltage. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Lightning impulse testing of natural ester fluid gaps and insulation interfaces

    Publication Year: 2009 , Page(s): 1595 - 1603
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2182 KB) |  | HTML iconHTML  

    A significant amount of lightning impulse breakdown and withstand testing has been accomplished in mineral oil to understand this important electrical characteristic for transformer insulation system design. To be considered as viable insulating fluids for high voltage equipment, alternative dielectric liquids should have similar lightning impulse characteristics as compared to mineral oil to provide the clearances necessary for common dielectric design. This paper reviews the testing for establishing the lightning impulse breakdown characteristics of natural ester fluids relative to mineral oil test results. The key variables of the testing included: various oil gap and solid insulation creep distances, electrode configurations, electrical stress characteristics, and solid insulation surfaces. The fluid gaps ranged from 3 mm to 55 mm. The electrode configurations included quasi-uniform in oil gaps, with some attached to pressboard, and nonhomogeneous contacts in oil gaps combined with a phenolic interface. The range in gap distance was selected to reflect the range commonly used in liquid insulated transformer core/coil designs. The electrical stresses used included 1.2 × 50 ¿s lightning impulses of both positive and negative polarity. The solid insulation materials consisted of high density pressboard, Kraft paper and a high density phenolic composite. It is concluded that the impulse breakdown voltage of the natural ester fluid is similar to mineral oil for the oil gaps and electrode configurations tested. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Degradation of 4-chlorophenol by pulsed arc discharge in water - estimation of the energy consumption

    Publication Year: 2009 , Page(s): 1604 - 1608
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB) |  | HTML iconHTML  

    Pulsed arc (electrohydraulic) discharge process (PAED) has been studied for the removal of some organic pollutants. Firstly, the destruction of para-chlorophenol by PAED system was studied under some different experimental conditions (ionic content, pH, conductivity and organic initial concentration) in a 5.6 L reactor, with the following configuration: 2.9 kV of potential, 140 ¿F of capacitors. Secondly, the energy consumption for the degradation of 4-CP was estimated. From four initial concentrations of 4-CP, the energy consumption was found to be about 3.5 105 kJ/mol. A comparison between PAED efficiency and UV-254 nm, O3 and O3/H2O2 systems is finally presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Classification and separation of partial discharge signals by means of their auto-correlation function evaluation

    Publication Year: 2009 , Page(s): 1609 - 1622
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1236 KB) |  | HTML iconHTML  

    This paper describes a K-Means Clustering classification algorithm for the separation of Partial Discharge (PD) signals and pulsating noise due to multiple sources occurring in practical objects. It is based on the comparison of the Auto-Correlation Function (ACF) of the recorded signals assuming that the same source can generate signals having similar ACF while ACF differ when signals with different shapes are compared. The ACF has been selected for its capability of well summarize both time- and frequency-dependent features of the signals. A correlation index that presents the best compromise between strong and weak discrimination among pulses, has been selected out of different distance measurements. The final result of the algorithm is a set of classes containing signals having similar shape which can be processed successively for signal source identification. Meaningful applications of the proposed algorithm are also reported. Improvements in separation effectiveness can enhance the clearness of the PD patterns and, consequently, the quality of the defect identification. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An experimental study on the effect of DC bias on streamer initiation and propagation in a dielectric liquid under impulse voltage

    Publication Year: 2009 , Page(s): 1623 - 1631
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (759 KB) |  | HTML iconHTML  

    The role of composite voltage waveforms on prebreakdown processes was studied at atmospheric conditions in a small point-plane gap with a synthetic ester Midel 7131 fluid, representing a model for the insulation in power electronic components. Shadowgraphic imaging and photomultipliers to record emitted light were used to measure streamer initiation voltages, streamer propagation lengths and velocities. The applied voltages were step voltages (100 ns rise time) with or without a dc bias. Results have demonstrated the presence of space charges in the vicinity of electrodes. With a step voltage with the same polarity as the dc prestress, initiation voltages increased and propagation lengths were reduced. For a polarity reversal for positive steps the initiation voltages were reduced and propagation lengths increased as expected, while for negative step the opposite was seen. The latter is explained by an electron "cleaning" effect of the positive dc prestress reducing possibilities for electron avalanches. It is shown that streamers may be initiated by a sudden turn off of a dc stress. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Formation of negative cluster ions with water molecules in nonpolar liquid

    Publication Year: 2009 , Page(s): 1632 - 1639
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (965 KB) |  | HTML iconHTML  

    Formation of negative cluster ions with water molecules in nonpolar liquid is considered in a wide range of water concentration. The experimental approaches based on the photoconductivity technique have been developed which allow one to measure the ion mobility and investigate the electron photodetachment from negative ions as well as the electron autodetachment kinetics for short-lived negative ions. It has been established that, in the range of low water concentrations 10-5-10-4 M, the main part of ions exists in a form of the smallest clusters A-(H2O). The big ion clusters were observed when the water concentration was close to the solubility limit (~10-3 M). The rate constants of formation and decay of the smallest cluster ions were determined. The estimations of the equilibrium constant for formation of the cluster ions with two water molecules were obtained. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Partial discharge characteristics over differently aged oil/pressboard interfaces

    Publication Year: 2009 , Page(s): 1640 - 1647
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (601 KB) |  | HTML iconHTML  

    The choice of the materials used as the dielectric media in large transformers continues to be a combination of pressboard and mineral oil. However, a number of failures in the field have been attributed to the surface discharge or creeping discharge over the oil/pressboard interface. This paper reports on an experiment to study surface discharge over oil/pressboard. The TJ (triple-junction) model was used to study the characteristic of partial discharge (PD) from inception to flashover. The max PD charge, pattern, frequency and current pulse were measured during the flashover process. Four oil/pressboard specimens with different aging degrees were used and their influence on the flashover process over oil/paper interface was studied in this experiment. The results indicate that the max PD charge and PD frequency increase with the increase of applied voltage. The oil aging has great influence while the pressboard aging has little influence on PD characteristic over oil/pressboard. The PD pattern and current pulse shape show great difference for various applied voltages. The results therefore suggest that the PD detection on the oil/pressboard can be used effectively to implement the early monitor of surface discharge thereby to avoid the formation of surface flashover. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Partial discharge development and detection in dielectric liquids

    Publication Year: 2009 , Page(s): 1648 - 1654
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (968 KB) |  | HTML iconHTML  

    PD measurements in dielectric liquids have been normally performed in the past only using conventional narrow bandwidth detectors. The more recent use of ultra-wide bandwidth instruments has permitted to support once again the thesis that the PDs in oils are the consequence of the streamer (vapor phase) formation and its development. In the paper simultaneous PD measurements in insulating liquids using both narrow and ultra-wide bandwidth detectors are presented. Whilst PD detection with narrow bandwidth instruments gives only integrated signals, the use of ultra-wide bandwidth techniques permits to have much more precise information on PD phenomena, which appear to be in the form of pulses (bursts) of ascending magnitude as the bubble within the liquid expands in volume. As reported in the paper, the use of the ultra-wide bandwidth instruments permits also to distinguish the PD pulses occurring in regular voids of oil-paper insulations and PD pulses formed directly in the liquids as consequence of the streamer development. Also in the paper the meaning of the PDIV in oils is discussed, showing its dependence with the definition used, the unpredictable level of the background noise as well as the randomness of the PD initiation process. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Corrosive sulfur effects in transformer oils and remedial procedures

    Publication Year: 2009 , Page(s): 1655 - 1663
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4053 KB) |  | HTML iconHTML  

    The behavior of corrosive sulfur in mineral oils is examined in terms of the failures observed in transformers, the surfaces of the copper sulfide covered conductors and degraded paper insulating tapes. The role of dissolved gas analysis (DGA) in the evaluation of the risk of copper sulfide formation is described. The degree of corrosiveness of some sulfur compounds is examined and compared using a Kraft paper wrapped-copper test (standard IEC 62535). The occurrence of DBDS as the most relevant corrosive compound is compared with the presence of other corrosive species in insulating mineral oils. A number of mitigation techniques for corrosive sulfur are described and evaluated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An ageing study of blends of dodecylbenzene and mineral oil

    Publication Year: 2009 , Page(s): 1664 - 1675
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1009 KB) |  | HTML iconHTML  

    The practice of backfilling existing paper/mineral oil insulated cables with dodecylbenzene (DDB) in the UK has produced systems where the fluid phase is, in reality, a mixture of these two oil types. This investigation therefore set out to study the ageing behavior of a range of DDB/mineral oil blend systems. Samples ranging in composition from 100% mineral oil to 100% DDB were aged in air (oxidising) and nitrogen (inert) atmospheres and the resulting systems were analyzed using a range of physical and chemical techniques. All approaches produced a consistent picture, demonstrating that the addition of between 10 and 25 % of mineral oil to DDB significantly improves its resistance to ageing under the various conditions imposed in this study. Such blend systems exhibit a combination of properties that renders them superior to either mineral oil or DDB alone. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of recovery voltage parameters of paper-oil insulation obtained from simulation investigations using the Cole-Cole model

    Publication Year: 2009 , Page(s): 1676 - 1680
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1033 KB) |  | HTML iconHTML  

    The paper presents the application of the Cole-Cole model for determining the runs of the return voltage of the paper-oil insulation sample through a computer simulation. Different insulation conditions were simulated through an adequate selection of parameters ¿ and ¿ of the Cole-Cole model. For calculation purposes, a series - parallel substitute scheme, obtained through approximation of discrete characteristic operator impedance Za of the model applied, was used. The diagnostics of the simulated insulation condition was based on the analysis of a few selected parameters of the return voltage, obtained from time characteristics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Measurements of distribution of streaming electrification current inside a pipe

    Publication Year: 2009 , Page(s): 1681 - 1685
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (559 KB) |  | HTML iconHTML  

    The paper presents streaming current distributions measured in an overflow system in both laminar and turbulent conditions. For lower values of Reynolds number the profile of current is parabolic. For higher values of Reynolds number the profile is flattened. In this paper also charge density distributions were determined in both cases. In the turbulent regime the volume charge density is distributed in the pipe more evenly compared with the laminar regime. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Reuben Hackam