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It bas been customary until very recently to report measurements of volume resistivity high quality insulating materials as greater than some figure such as 1015 ohm-cm. This was partially due to the lack of proper instruments for measuring the high values characteristic of the better insulating materials such as polystyrene, teflon and polyethylene, but primarily due to the fact that few insulator...
Ideas and organizations wear out if not reappraised at appropriate time intervals and adapted to changing circumstances. For our Conference the situation has changed completely since it was first launched after World War I. Inspired by Professor Whitehead's enthusiasm, a small band of insulation experts first met in an annual Round Table conference. Anyone contributing a paper was a member for that...
Two recent foreign publications have openly drawn attention to a type or, rather, class of failures which may beset electrical insulation, particularly wire and cable insulation: electro-endosmosis. Such failures are possible, and possible only, if the circuits operate on direct current, with the conductor at negative potential, and if the circuits are installed in moist locations. As usual, increased...
Industrial and utility engineers are becoming more demanding for fire and explosion resistant transformers for use in large generating stations, unit substations, and in network applications. Fire insurance companies are threatening and are raising rates for insurance protection on transformers installed in buildings or in industrial plants where human life is endangered. Oil-filled transformers are...
Fluid resins capable of complete solidification have been available since the end of the war. The contribution that these materials can make to the industry is based upon their ability to produce void-free structures, and to completely fill any cavity in which they are cured. The benefits which may be derived from this property can be itemized as: 1. Absence of corona from windings, operating at high...
The dielectric properties of a series of long-chain esters have been investigated in the solid state. Like other long-chain molecules containing 20 or more carbon atoms, most of the ester molecules showed evidence of hindered molecular rotation about their long axes in the crystal lattice. It was also found that higher dielectric constants resulted when the samples were rapidly frozen than when they...
This paper deals with one phase of a general study of the microbiological deterioration of rubber and similar insulations. In the earlier papers 2 types of microbial attack were shown: 1) direct eating of natural rubber insulation, 2) production of micropores thru walls of both natural and synthetic rubber insulation, or neoprene jackets.
The paper gives a calculation of the static dielectric constant of ice using Frőhlich's general theory of the static dielectric constant and a recent generalization of it for anisotropic materials2. The calculation is made with the principal assumption that an ice crystal containing N molecules can take up any of (3/2)N configurations, each with equal probability, in the manner proposed by Pauling...
Further measurements of dielectric constant and loss, in the microwave region have been carried out upon pure polar liquids and upon solutions of polar molecules in non-polar liquids of widely varying viscosities. Earlier measurements showed that the wavelength at which the loss was a maximum, that is, the critical wavelength, increased with increasing viscosity of the liquid and size of the molecule,...
It has been assumed that the potential energy barrier hindering the rotation of chain molecules about their long axes in the solid state has one deep minimum and equation other minima with a potential energy V above that of the deeper well. Reasons are given for believing this approximates the true situation. Application of the Bragg-Williams approximation to this system, leads to the prediction of...
Mica in the form of mica paper will soon make its appearance as a component, in electrical insulation. This revolutionary advancement in the use of mica will make available to the electrical manufacturer products which have heretofore been impossible to produce.
The stabilization of chlorinated capacitor impregnants by chemical additives has been practiced by a number of capacitor manufacturers for several years. Anthraquinone has been the most widely used stabilizer, and has been added to chlorinated diphenyl and chlorinated naphthalene to the extent of 0.5 to 1.0% by weight. The purpose of stabilization is to increase the d.c. life and to avoid undesirable...
Assuming the distribution function for relaxation times equation proposed by Fuoss and Kirkwood1, it can be shown that for equation equation where ω is the cyclic frequency of the applied field and equation is the most probable time of relaxation; equation and equation is the parameter of the distribution function of Fuoss and Kirkwood.
The electron emission characteristics of the surface of the cathode used in the study of the electric breakdown of insulators are believed to have a fundamental bearing on electric strengths observed. It has been suggested that the formation of a negative space charge is the mechanism through which this influence is exerted1.
The purpose of this study was to provide certain quantitative information on the, corrosion of metals in insulating oils, and simultaneously to throw more light on the anions present in hydrocarbons. The process under study was the deposition of metal salts on a metal surface in contact with oil containing an aliphatic acid in solution. The metals that gave positive effects were copper, lead, and...
From the general interest shown in high temperature materials and the inconclusive state of the art, it is the feeling of several spokesmen that non-partisan conferences should be held oftener than annually. The value of having, all prime manufacturers present was amply demonstrated, because of divergent viewpoints on ostensibly similar materials.
The first successful metallic rectifier was the cuprous oxide type first announced in 1920. In spite of the fact that several other types have been discovered since, there have been no other oxide rectifiers reported, and only a few patents have even referred to possibilities. The reasons for this presumably lie in the stringent requirements for a rectifier. First, the oxide must be formed as a thin,...
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