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At the outset it was observed that the flexibility of phenyl methyl silicone varnished glass fabric was very variable. One. lot of the material was found to have satisfactory flexibility, while the next lot might be otherwise, in that it is “too stiff”, thus making it extremely difficult, if not impossible, to work or pull the material into position without mechanically damaging the varnish film,...
A systematic study has been made of the permanent surface charges, which can be produced on discs of carnauba wax and lead to the formation of the electret. Different electrical and thermal treatments have been used-A complete experimental cycle included a) application of the polarizing voltage concomitant with thermal treatment, b) period of short-circuit at room temperature, and c) reheating, The...
The steadily increasing use of electrical components at higher voltages and altitudes has presented a problem in the design of bushings to meet the requirements of being corona-or radio-interference-free in the range of 10,000 volts and altitudes of 50,000 feet. There have been several papers written about the problem but with no concrete design procedure given. In this paper a design procedure is...
The advent of single or multiple oxide ceramic compositions wholly lacking in clay, and hence in plasticity, has necessitated the development of new forming techniques. One such technique employs organic, thermo-plastic resins for the development of plasticity and bond.
The nature of the insulating film formed on 99.99% pure aluminium electrodes when subjected to high voltages in a solution of boric acid was investigated in an attempt to explain its assymetric electrical behavior in electrolytic capacitors.
Although there is a record of the Westinghouse Company having applied for a patent, and possibly having made some tiny flakes of synthetic mica, the first sizable pieces were made by the Germans. Several pieces were produced that measured over four square inches. However, this appears to have been a rare occurrence, and the Germans never got out of the early experimental stages, and did not produce...
In any discussion of the electrical properties of cellulose plastics, it is realized that the power factors of any of the cellulose nitrates, acetates, propionates and ethyl cellulose are not as low as some other type's, but this very fact may be an advantage in certain applications. The use of dielectric heating in molding or fabricating is one of these. Since the heat developed due to dielectric...
Fiberglas cloth, in order to be successfully used for high temperature cable insulation, must be given a special water-repellent and heat-treatment at 650°F to 700°F before coating. When this treated cloth is properly impregnated with 996 silicone resin or 123 silastic rubber and cured at temperatures of 500 to 650°F., the resultant product gives excellent performance at elevated temperatures.
One of the important, functions of insulating varnishes is to provide protection against the entrance of moisture and dirt within the insulation system of electrical apparatus. A considerable amount of effort has been spent in studying the effect of moisture on the electrical properties of insulating varnishes as well as the moisture transmissivity of perfect varnish films. However, to be effective...
Ceramic dielectrics, as we know them today, are quite different from those in use 25 years ago. In fact, at the turn of the century, the American ceramic literature only briefly and sparingly mentions ceramic dielectrics. In 1901 and 1902 A. S. Watts writes on porcelain insulators stating that, “The essential properties of an electrical insulator are: first, that it possess, first of all, a high efficiency...
The function of trapping centers in dielectrics has been discussed by Fröhlich1 who postulates the existence of energy levels due to such centers to explain the breakdown characteristics of amorphous solids at high temperatures. Meyer and Herman2 have also considered the effect of such centers on breakdown at low temperatures. The purpose of the present paper is to determine the charge distribution...
Sintered semiconductors of various compositions were described in a previous paper, with special emphasis on sintered materials with zero temperature co-efficient of resistance. The material was described as an electrical network, the resistance of which was composed of the total of the particle resistances and the resistances between the particles called contact resistances. Figure 1 shows a diagrammatic...
While the sequence of events leading to electric breakdown in gases is today fairly well understood, research in the case of solids asks still the basic question about the mechanisms causing the destruction of dielectrics under high field-strength. This lag in advance is partly inherent in the experimental difficulties of handling such fields, and partly-due to the complexities of the solid state...
The second rotational transition, J=1 to J=2, of SiH3Cl35 and SiH3Cl37 has been measured and analysed. The Hughes-Wilson Stark modulation technique was used for detection of the absorption lines; and absorption frequencies were determined by comparison with a crystal-controlled secondary frequency standard.
Interest in this problem arose on observing that equipment operating at high unidirectional voltages and at relative humidities of 55% to 75% exhibited erratic and rather low breakdown strength. Electrode configuration was indicated as an important variable in the problem, A literature search revealed little quantitative information on the d-c breakdown voltage of air gaps.
The mechanism of electrical failures at power frequency is fairly well established and accepted. An analysis of the process helps to correlate the observed performance of cable insulation and to explain the underlying characteristics of the different types. It appears also that dielectric failures of any solid or quasi-solid body are of the same general character. This discussion is not intended to...
One of the problems encountered when evaluating the dielectric constant and power factor of either impregnated or unimpregnated paper is the variation in apparent density of the sheets. It is important to know whether measured differences in the electrical properties are due to differences in sheet density or to differences in the fibers themselves.
Stop joints are desirable in pipe-encased gas-pressure cable lines both to facilitate the location of leaks that may develop and to save gas should the gas escape from one section because of alterations or accident. The saving of the gas is particularly desirable for high-pressure cable lines in areas where the supply of immediately available gas is limited.
The equipment used in this work consists of a very stable 2000 watt radio transmitter, an r.f. transformer with tuned secondary, an immersion type specimen cell and a vacuum tube voltmeter. Figure 1 shows the circuit arrangement of these components.
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