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Electrical Insulation, IEEE Transactions on

Issue 3 • Date June 1982

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Displaying Results 1 - 24 of 24
  • Table of contents

    Publication Year: 1982 , Page(s): c1
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  • IEEE Electrical Insulation Society

    Publication Year: 1982 , Page(s): c2
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  • The Effect of the Temperature Dependence of the Dielectric Constant on Thermally Stimulated Currents in Polymers

    Publication Year: 1982 , Page(s): 189 - 193
    Cited by:  Papers (2)
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    A dipolar theory of thermally stimulated currents taking into account the thermal dependence of the equilibrium polarization has been tested in the glass transition range of a series of polymers selected for their well-resolved relaxation spectra and the absence of any significant bulk conductivity (triblock, diblock, and star-shaped styreneisoprene copolymers). Systematic studies of the effect exercized on thermally stimulated polarization currents (TSPC) and thermally stimulated depolarization currents (TSDC) by varying parameters such as field strength, electrode material, field polarity, and type of heating-cooling sequence, have been carried out and full qualitative agreement with the predictions of the theory has been found. In particular, these results imply that the variations of equilibrium polarization occurring during the nonisothermal steps of TSDC and TSPC experiments cannot be a priori neglected, as is still commonly done in classical treatments of experimental data. View full abstract»

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  • The Current in Nylon-6 Following Voltage Reversal

    Publication Year: 1982 , Page(s): 194 - 198
    Cited by:  Papers (1)
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    Previously, it has been found that absorption charge is associated with the accumulation of a fixed number of charges at the electrode. Also, under short-circuit, the accumulated charges are scarcely discharged, but a considerable part of them can be discharged by heating. In this paper, the current under a field with reversed polarity is described. A considerable part of the accumulated charges can be mobilized toward the counter electrode by applying a reverse field, being accompanied by a transient current peak. The residual part of the accumulated charges is likely consumed at the electrodes. The conditions for accurately estimating the ionic mobility by the voltage reversal method are also presented. View full abstract»

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  • Thermally Stimulated Discharge of Polyethylene Following Ac Stressing

    Publication Year: 1982 , Page(s): 199 - 202
    Cited by:  Papers (12)
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    Electron injection into polymers from field stress concentration sites is now generally accepted as important for the initiation of electrical trees, although very few published studieshave so far provided direct evidence for this. By means of the thermally stimulated discharge (TSD) technique in low density polyethylene (LDPE) double needle samples, electronic space charge densities of 2.7×10-3 Ccm-3 have been shown to exist in shallow (~3 ¿m) regions surrounding the needle tips following ac stressing at a maximum field of 1.2×108 Vm-1. The present TSD results agree well with ¿conventional¿ TSD data (planar samples, dc polarization) in the literature. View full abstract»

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  • The Dynamics of Electrical Breakdown in Liquid Hydrocarbons

    Publication Year: 1982 , Page(s): 203 - 220
    Cited by:  Papers (27)
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    The electrical breakdown process in highly purified and degassed liquid hydrocarbons has been studied, using high speed schlieren photography as well as photomultipliers and an optical multichannel analyzer. It was shown that the breakdown process appears to be initiated primarily on the cathode surface. The ensuing formation of tree-like streamers was found to be associated with light emission. This light appears to be of the same spectral composition as that given off during actual breakdown. Spectral analysis of the emitted light indicated the presence of atomic and molecular hydrogen, carbon molecules of the type C2 and C3, as well as metal atoms emanating from the electrode surface. The significance of these findings is discussed in detail. View full abstract»

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  • Prebreakdown Phenomena in High-Viscosity Dielectric Liquids

    Publication Year: 1982 , Page(s): 221 - 227
    Cited by:  Papers (5)
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    The shadowgraphic image reflects only those regions of disturbance occurring in a dielectric liquid, which differ in refractive index from their surroundings. The time required for the onset of a prebreakdown disturbance after the application of a step voltage, and the rate of growth of the disturbance depend strongly on the viscosity (or the temperature) of the liquid. The refractive index is lower inside the disturbance region than outside. The variation of the external current is consistent with the temporal change of the disturbance. It is proposed that the formation of a disturbance region is due to the coulombic repulsion of local homocharges which in turn causes a decrease in local density and hence a decrease in refractive index. At highfields the anode injects holes to form positive ions and the cathode injects electrons, and theelectric conduction is filamentary. The electric breakdown in condensed materials (liquids and solids) involves double injection and the creation of low density regions to enable the charge-carrier multiplication processes to take place. Thus the breakdown strength is governed by the parameters which control the conditions for such prebreakdown phenomena to arise. View full abstract»

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  • Impulse Breakdown of Prestressed Polyethylene Films in the Ns Range

    Publication Year: 1982 , Page(s): 228 - 233
    Cited by:  Papers (2)
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    This paper describes the effect of prestressing on the breakdown strength and time lag of lowdensity polyethylene films subjected to square pulses of 100 ns width. When prestress and impulse fields are opposite in polarity, the 50% breakdown strength Eb decreases from 4.9 to 3.4 MV/cm as the prestressing field is increased from 0 to 4.6 MV/cm. When prestress and impulse fields have the same polarity, Eb increases to 5.4 MV/cm as the prestress is increased to 4.1 MV/cm. The dc break-down strength is 5.8 MV/cm. The formative time lag tf decreases with increasing applied field. The value of tf is insensitive to the level of prestress within a given mode. The mode of opposite prestress yields considerably larger values of tf than the other two modesof no and same prestress, and at relatively low applied fields. The apparent electron mobility calculated from tf increases from 2.2×10-2 to 2.4×10-1 cm2/Vs as the total (prestress +pulse) applied field is changed from 3.0 to 6.0 MV/cm. The results are attributed to a modification of the field intensity near the electrodes due to space charge accumulation during the period of prestressing. The breakdown mechanism is discussed on the basis of an avalanche-streamertransition in the gaseous breakdown theories. View full abstract»

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  • Effects of Mechanicl Stresses on the Dielectric Breakdown Strengths of PET and FRP

    Publication Year: 1982 , Page(s): 234 - 240
    Cited by:  Papers (11)
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    Organic materials to be used for the electrical insulation of superconducting magnet coilsin large fusion reactors must withstand electrical stresses under high mechanical loads, extreme temperatures, and intense nuclear radiation. In this paper, measurements at room temperature are reported on the effects of mechanical compressive and tensile stresses on the dielectric strengths of bi-stretched polyethylene terephthalate (PET) and epoxy glass cloth (FRP, G-10) which are widely used for the insulation of superconducting magnet coils. For PET, the breakdown strength increases with increase of compressive stress in the region of elastic deformation but decreases in the region of inelastic deformation. The value of compressive stress showing maximum dielectric strength is independent of film thickness and is approximately 100 MPa, smaller than the stress appearing in large fusion reactors. In the case of FRP, the behavior of breakdown characteristics under compressive stress is nearly the same as that of PET but the relationship between characteristics of electrical breakdown strength and mechanical properties of FRP isnotclear because it is a composite of two materials: epoxy resin and glass filler. The effect of tensile stress on the dielectric strength is small for PET, but significant for FRP. View full abstract»

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  • Processes Contributing to Low DC Tracking Failure

    Publication Year: 1982 , Page(s): 241 - 247
    Cited by:  Papers (2)
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    This paper describes the correlation between tracking phenomena and the behavior of dissolved and deposited metals from copper or brass electrodes at the interface between an electrolyte and paper phenolic laminate. The test method resembles the IEC tracking test, but with the application of a low dc voltage. The paper also describes the results of an analysis of the dissolved and deposited metals obtained by electron microscopy and X-ray diffraction. It was found that the dissolved metallic compounds from positive copper or brass electrodes were Cu(OH)Cl and Cu2OH)3C1, or Cu(OH·Cl)2·2H2O and Cu2(OH)3C1, respectively. On the other hand, the deposited metals originating from the negative copper or brass electrodes were Cu or Cu and Zn, respectively. When the deposited metals bridged the electrodes, the test solution was evaporatedby joule heating caused by leakage current in the deposited metals on the insulation surface, after which scintillation appeared at the edge of the positive copper or brass electrodes. Theseprocesses were repeated until tracking took place. View full abstract»

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  • A Study of the Gaseous Degradation Products of Corona-Exposed Polyethylene

    Publication Year: 1982 , Page(s): 248 - 252
    Cited by:  Papers (14)
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    The gaseous degradation products of low density polyethylene exposed to corona discharges were investigated. Temperature and applied voltage were varied independently in order to determine the effect of each on the chemical processes involved in the degradation. Based upon statistical analysis of the results, temperature was found to have an anomalous effect on the accumulation of organic gas products in that increased temperature resulted in lesser amounts of these gases being found. View full abstract»

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  • Multi-Stress Endurance Tests on High-Voltage Motor Insulations, With Equal Acceleration Of Each Stress

    Publication Year: 1982 , Page(s): 253 - 261
    Cited by:  Papers (9)
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    An ageing test was performed on two high-voltage motor insulation systems using three principal ageing stresses: temperature, electric field, and mechanical stress. An equal acceleration of each stress was used with the goal of an ageing process identical with that at service conditions. For the determination of the true acceleration factor a parallel ¿ageing¿ test at service conditions was run, up to so long testing times that changes in characteristic properties (flexural modulus, tan¿, and capacitance) could be determined. Humidity tests and high-voltage withstand tests were also performed after each ageing cycle. The observed acceleration factor for both systems was lower than predicted. In one of the systems the changes in characteristic properties were measurable and of the same type at both test conditions, so that the test acceleration could be evaluated reliably. Both systems show good class F performance connected with appropriately defined severe service conditions. View full abstract»

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  • Low Frequency Complex Fields in Polluted Insulators

    Publication Year: 1982 , Page(s): 262 - 268
    Cited by:  Papers (5)
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    A general method for the solution of ac low frequency electric fields in insulating systems is proposed. The method is based on decoupling Maxwell's equations, and their solution can beimplemented analytically or numerically. The finite difference numerical method is easily implemented to solve the field in polluted insulators. View full abstract»

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  • Effect of Conduction on Field Behavior Near Singular Points in Composite Medium Arrangements

    Publication Year: 1982 , Page(s): 269 - 275
    Cited by:  Papers (6)
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    The electric field configuration has been analyzed numerically by the charge simulation method near a contact point where two media having surface or volume conductivity meet an electrode. Surface conduction with uniform surface resistivity moderates the field singularity, resulting in a uniform field throughout both media for very low resistivity. On the other hand, volume conduction magnifies the field singularity if only one medium has conductivity. For these capacitive-resistive fields, it appears impossible to derive a simple analytical expression of field strength such as can be derived for purely capacitive cases. View full abstract»

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  • Dielectric Behavior of Solid/Liquid Insulation System

    Publication Year: 1982 , Page(s): 276 - 280
    Cited by:  Papers (4)
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    Dielectric loss of the PP/oil system was decreased by high voltage application beofe the dielectric measurement. The extent of decrease depends on the magnitude and the duration of the prestress voltage. This decrease in dielectric loss is caused by trapping of the impurities on the interface of the PP/oil. We found that the dielectric loss tends to go back up to the initial value with time after the voltage has been removed. The experimental results can be interpreted in terms of trapping of ions if the following process are assumed: in the very low voltage region, ionic carriers are accumulated near the interface without trapping; and as the voltage increases, they are trapped near the interface, causing a decrease in ionic concentration in the thin oil layer. View full abstract»

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  • Insulation Hysteresis in Micaceous Composites

    Publication Year: 1982 , Page(s): 281 - 283
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    The dissipation factor, sensitive to voltage stress, is invariably used for quality assessment of high voltage rotating machine insulation. When it is subjected to higher electrical stresses, insulation hysteresis occurs during these measurements, which is similar to those exhibited by ferromagnetic materials. The influence of the insulation hysteresis coefficient for micaceous composites used in high voltage machines is discussed in this paper. View full abstract»

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  • Detection of SF4 in Sparked SF6

    Publication Year: 1982 , Page(s): 284 - 286
    Cited by:  Papers (3)
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    First Page of the Article
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  • Environmental Effects on the Rate of Aging of EP-Insulated Power Cable

    Publication Year: 1982 , Page(s): 287
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  • Thermal Stability of Micaceous Insulation

    Publication Year: 1982 , Page(s): 288 - 289
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  • Meetings

    Publication Year: 1982 , Page(s): 290
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  • Erratum

    Publication Year: 1982 , Page(s): 290
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  • International Contributions to the Transactions

    Publication Year: 1982 , Page(s): 291 - 292
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  • IEEE Electrical Insulation Society

    Publication Year: 1982 , Page(s): 292-a
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  • Information for authors

    Publication Year: 1982 , Page(s): 292b
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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