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Electrical Insulation, IEEE Transactions on

Issue 3 • Date Dec. 1967

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Displaying Results 1 - 12 of 12
  • Table of contents

    Page(s): c1
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  • IEEE Electrical Insulation Group

    Page(s): c2
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  • Holiday greetings

    Page(s): 129
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  • Editorial

    Page(s): 130
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  • Tracking in Polymeric Insulation

    Page(s): 131 - 137
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    Chemical mechanisms of tracking and erosion are reviewed by considering mechanisms of conduction and molecular structure of polymers. It is shown that track formation need not necessarily be by graphite formation and that degradation mechanisms cannot always be predicted by inspection of molecular steriochemistry. View full abstract»

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  • Dip-Track Test

    Page(s): 137 - 140
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    A new tracking test has been designed which substantially eliminates the faults of the standardized tracking tests. It has been used successfully over the past three years in the evaluation of the tracking resistance of cable insulations. Utilizing a liquid contaminant of ammonium chloride, tracking resistance measurements can be molded panels or on cable sections in a very short time with excellent reproducibility. A correlation of the results obtained using the Dip-Track Test and the Inclined Plane Test is shown. A test method for the evaluation of tracking resistance with the Dip-Track Test equipment is presented. Also, a description of the equipment with schematic electrical and mechanical drawings is given. View full abstract»

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  • Interaction of Varnish with Magnet Wire Enamel

    Page(s): 141 - 145
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    The interaction of varnish with magnet wire enamel can lead to a reduction in the thermal life rating of the insulation system (ASTM D2307-64T). The recognition of this reduction in life rating is encountered first by varnished twisted pairs of enameled wire. An attempt is made to determine the mechanism of this interaction by studying the system microscopically, by differential thermal analysis and by infrared analysis. The microscopic analysis defines the nature of the bond between magnet wires and the type of coverage that the varnish gives to the magnet wire. It also reveals some information on the type of attack on the enamel and varnish system. Thermal analysis and infrared analysis are used to determine, if possible, whether the thermal decomposition of the magnet wire enamel is accelerated by the presence of the varnish and to reveal some background information as to the nature of this accelerated decomposition. This can then act as guide for the selection of varnishes with enamels that will minimize interactions that reduce the thermal life of insulation. View full abstract»

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  • Thermal Endurance of Polyester Enameled Wires Using Twisted Wire Specimens: Statistical Analysis of Final Test Results

    Page(s): 145 - 150
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    Thermal endurance tests to AIEE Standard 57 [1] have been performed in six laboratories each using self-prepared varnished specimens made from a common sample of polyester enameled wire and polyester varnish. The results have been analyzed to test the hypothesis of the departure from linearity of the relationship between the logarithm of life and the inverse of the absolute temperature. A comparison is made between the experimental results at the lowest test temperature and the corresponding extrapolated values based on the experimental results at the higher temperatures. The variation between the results of different laboratories is considered. Comparison is made with previous work [2] undertaken in six laboratories on PVA enameled wire specimens, prepared and impregnated with an oil-modified phenolic varnish by a single laboratory, and with published AIEE results. Comparison is also made with the results of a previous interim statistical analysis, [3] applied to the test results at the three higher temperatures only. The main statistical analysis is performed both for the complete set of results, and for the median results only. The extrapolated thermal lives based on the two methods are shown, with one exception, to differ by less than 6 percent at 20°C below the lowest test temperature. The importance of the median method is that generally not all of the specimens are required to be tested to failure, with a consequent saving of a substantial amount of testing time, particularly at the lowest test temperature. View full abstract»

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  • Factors Affecting Stability of Electrical Insulating Oils

    Page(s): 150 - 155
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    Attempts to understand the mechanism of dielectric loss, based on laboratory testing of petroleum-derived transformer and cable oils, have led to several important conclusions. First, soluble copper at the parts per billion level has a large adverse effect on oil stability. Second, certain compound types tend to solubilize copper and thus lead to rapid oil degradation. Third, aromatic hydrocarbons tend to preserve oil stability. Laboratory comparisons of petroleum-derived cable oils with synthetic fluids have led to the conclusion that the petroleum oils are less reactive than the synthetic fluids. New, improved petroleum oils have been developed based on the above findings, and are briefly discussed. View full abstract»

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  • A Study of Internal Discharges in Cable Insulation

    Page(s): 155 - 159
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    A study has been made of discharges occurring in voids. A sample of convenient size is described. A method of mea suring the discharge pulse has been developed which reduces the inductance of the circuit to a minimum. As a result it has been found that the pulses have rise times of the order of 1 ns which is shorter than previously anticipated. Extremely fast discharges may be counted. A method of counting pulses larger than some predetermined magnitude is presented. Where one surface of the void is a semiconductor, the positive and negative pulses are shown to decrease at different rates. Evidence of pulse shape due to discharge in a void can be determined by instrument. View full abstract»

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  • The Armette Test for Evaluating Universal Motor Insulation Systems

    Page(s): 160 - 163
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    The "armette test" was devised to improve the quality of test data and reduce the cost of obtaining it. Test methods to date require the manufacture of an entire motor. Present data can be unduly influenced or even voided should the field change or failure occur during the test. The "armette" is a unit that consists of a simple shaft, laminations, magnet wire, insulation, and varnish. It differs from the standard armature in that it has fewer coils, no commutator, and no fan. When assembled in the test setup it makes use of a built-in fan and slip ring assembly for cooling and electrical connections. The armette test consists of mounting the armette in a fixture, connecting the leads to the slip ring, and starting the cyclic test. The cyclic test contains a stationary heating period, a high-speed spin, an electrical surge test, a coast-to-stop period, and a hypot test. The time for each part of the cycle and the input voltage for the heating period are the controlled variables for the test. The work done and correlations run in developing an armette test are presented. Results obtained indicate that the armette test produces data which correlate with present stall test data. View full abstract»

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  • Membership application

    Page(s): 164
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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