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Electrical Insulation, IEEE Transactions on

Issue 6 • Date Dec. 1980

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Displaying Results 1 - 17 of 17
  • Table of contents

    Publication Year: 1980 , Page(s): c1
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  • IEEE Electrical Insulation Society

    Publication Year: 1980 , Page(s): c2
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  • Water Treeing in Polyethylene - A Review of Mechanisms

    Publication Year: 1980 , Page(s): 437 - 450
    Cited by:  Papers (29)  |  Patents (1)
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  • Accurate Corona Detector Calibrator

    Publication Year: 1980 , Page(s): 451 - 454
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    This paper describes an accurate corona detector calibrator for use with test specimens of more than 150 pF. For a wide range of capacitance, built-in calibrators on conventional single-ended corona detectors show errors of two orders of magnitude or more, due to the inductance of their long leads and the single valued calibration coupling capacitors. This portable calibrator is accurate to 10 percent for sample capacitances from 300 pF to above 100 ¿F. There are three switch-selectable calibration pulse heights. The unit attaches across the test specimen with short leads, and is designed for use with no test voltage present. View full abstract»

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  • A Simple Method of Calculating Corona Loss on Unipolar DC Transmission Lines

    Publication Year: 1980 , Page(s): 455 - 460
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    A simple method of calculating corona loss on a unipolar dc transmission line, without a ground wire, is presented in this paper. The simplification occurs due to the avoidance of double integration involved in Sarma and Janischewskyj's [1] method and also due to a justifiable linear approximation of the corona current density on the conductor surface for this simple geometry. The computer program has less than 100 statements and the typical computation time involved in plotting a V-I characteristic is less than 4 seconds on an IBM 370/145 computer. The error in the computed results, due to the above simplifications, is less than 1%. View full abstract»

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  • An Investigation into the Mechanism of Water Treeing in Polyethylene High-Voltage Cables

    Publication Year: 1980 , Page(s): 461 - 472
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1793 KB)  

    Water treeing is a well known fracture phenomenon in polyethylene (PE) and crosslinked polyethylene (XLPE) high voltage cable insulation. We studied two phenomena: (1) The insulation material is mechanically fatigued by electrostriction as is shown by measuring the relevant electrostriction constant, which moreover is compared with literature values on other polymers. The observed "electrostriction" is found to originate mainly from the Coulomb force. Using a simple model, the deformation mode at the end of a water tree channel can be described and the strain amplitude of the PE at the water interface can be calculated. (2) Under high voltage, the surface tension at the PE-water interface decreases strongly as we found experimentally. The observation that this decrease is proportional to the square of the applied field strength is explained. The joint effect of the Coulomb force and the reduced surface tension may cause a fracture phenomenon, well known in the field of polymers, called environmental fatigue failure (or thermal softening). The same assumption is made as in "common" environmental stress cracking of PE with aqueous detergents, viz. that the low surface tension plays an essential and not a coincidental role. View full abstract»

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  • A Study on Microvoids and Their Filling I Crosslinked Polyethylene Insulated Cables

    Publication Year: 1980 , Page(s): 473 - 480
    Cited by:  Papers (7)
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    Morphological changes of microvoids in steam-cured XLPE cable insulation by heat treatment were investigated using a scanning electron microscope. The observations showed that the voids are filled with low molecular weight material composed of crystalline and amorphous polyethylene which exuded from the surrounding bulk polymer. The filling rate and the properties of the LMWPE are dependent on the temperature and the heat treatment. Void filling, especially partial filling, tended to accelerate bow-tie tree generation. On the other hand, the microvoids in steam-cured XLPE insulation, which contained some special additives, did not change by heat treatment even at temperatures higher than the bulk polyethylene melting point, and furthermore, few bow-tie trees were observed in this cable insulation. View full abstract»

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  • Capability of Insulation Diagnosis for Mica-Resin Insulated Coils

    Publication Year: 1980 , Page(s): 481 - 490
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1158 KB)  

    A group of bar coils were subjected to accelerated insulation degradation, and the correlations between various nondestructive test results and insulation breakdown voltage were investigated. Nondestructive test values measured for only the flat part of the insulation layer of the coils showed good correlation with breakdown voltage. For the nondestructive test results measured on the entire insulation, including both flat parts and edge parts, better correlation with breakdown voltage was observed with those results which depend most strongly on the properties of the flat (or the slot) part. The edge part of the insulation does not undergo degradation even under static flexural strain; voltage degradation is saturated at an early date. In the flat part of the insulation, degradation proceeds at the same pace under either flexural voltage aging. Thus, better correlation with breakdown voltage is shown by those nondestructive measurements which more clearly express the change in the flat part of the insulation and occur without saturation of degradation. Among these correlations, it was found that as far as static flexural strain and voltage degradation are concerned, they fit on the same correlation curve. View full abstract»

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  • Polymeric Insulation Damage Due to AC Surface Flashover

    Publication Year: 1980 , Page(s): 491 - 497
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4475 KB)  

    Damage to various insulators used in telephone equipment, by a 60 Hz flashover between electrodes on the surface in air at atmospheric pressure, has been examined using a scanning electron microscope. Breakdown voltages between electrodes mounted on the insulating material and separated by approximately 1 mm were obtained. Insulation resistance before and after breakdown was measured. Each material examined showed a different damage pattern, although of those tested, only the mica-filled phenolic showed low insulation resistances after flashover. These resistances fell into three Gaussian distributions centered at 300, 1000, and 22000 ¿. Damage in all cases appeared to be due to the bombardment and thermal effects of the discharge. In most cases, melting of the surface, followed by resolidification occurred; under these circumstances the insulation resistance did not appear to have been degraded when measured shortly afterwards. However, the long term stability of the insulation after exposure to surface discharges has not been measured. Asperities on electrode edges that could lead to enhanced field emission were also observed. View full abstract»

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  • The Signifcance of the Density of Transformer Oils

    Publication Year: 1980 , Page(s): 498 - 499
    Cited by:  Papers (2)
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    New evidence is presented to affirm the importance of density as a significant property of electrical insulating oils, under certain conditions; and to support the validity of literature references that claim that the density of ice can vary over a relatively wide range. View full abstract»

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  • Initial Results of a Study of Water Trees in XLPE by Infrared Spectroscopy

    Publication Year: 1980 , Page(s): 500 - 501
    Cited by:  Papers (9)
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    First Page of the Article
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  • Effect of Temperature on the Breakdown Probability of Liquid Dielectrics

    Publication Year: 1980 , Page(s): 502 - 505
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (521 KB)  

    The effect of temperature on the probability of breakdown of mineral oil usinig power-frequency voltages has been investigated. Results of the breakdown probability are plotted on a Weibull distribuion and fit well in two straight lines intersecting at a certain transition point. This transition corresponds to a breakdown probability and a breakdown voltage which are temperat ure dependent. Results suggest that different breakdown initiating mechanisms may be simultaneously active, and the dominance of one of them on the other is responsible for the observed transition in the breakdown probability characteristics. View full abstract»

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  • Meetings

    Publication Year: 1980 , Page(s): 506
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  • Author index

    Publication Year: 1980 , Page(s): 507 - 507-b
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  • Subject index

    Publication Year: 1980 , Page(s): 507b - 507e
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  • IEEE Eelectrical Insulation Society

    Publication Year: 1980 , Page(s): 507-f
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  • Information for authors

    Publication Year: 1980 , Page(s): 507g
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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