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The accurate measurement of dielectric losses in modern power cable is best achieved by means of a suitable bridge circuit. In particular, when reasonably high voltage must be used, the Schering bridge, in one form or another, has proven itself universally.
Electrostatic generators, now produced commercially for a variety of scientific medical and industrial users, depend for their successful operation upon good-quality solid insulation. For the most compact generators, in which the solid insulation is continuously under a stress of over 60 KV per inch d.c., the structure is immersed in nitrogen or other inert gas at a pressure of 400 pounds/square inch,...
The problem in high voltage cables is to contain voltages of the order of 100,000 to 500,000 volts by means of a suitable insulating medium around a conductor of diameter between l/2 in. and 2 in., the cable being of sufficient flexibility to permit being transported in long lengths on reels. An overall diameter of about 4 in. is about the largest practical size.
A. In the device described below, two phase motors are used as discriminating elements. Basically, the scheme of operation of this self-tracking detector is as follows. The driving signal is applied to one winding of a two-phase motor, arid the output signal of the bridge is applied to the second winding.
For most solids, including the highly ionic alkali halides, the molar polarizabilities at optical frequencies, RQ (defined by the Lorentz-Lorenz equation), and at low frequencies, Rs (defined by the Clausius-Mosotti equation), are strongly dependent on temperature and pressure. This arises from the fact that the molar polarizability of a medium is determined by the absorption frequencies and optical...
One of the main objectives of the Conference on Electrical Insulation is to establish an intimate contact and exchange of ideas between the science devoted to fundamental research on dielectrics and the industry concerned with their applications. In the last few years it appeared as if this purpose was not being accomplished. Our program has oscillated between a too scientific approach, frightening...
Mixtures made by milling into polystyrene the powdered metals copper, magnesium, aluminum, and a non-tarnishing magnesium-aluminum alloy were found to have a wide variety of dielectric behavior, Explanation is proposed on the basis of the Maxwell-Wagner-Sillars∗ theory with the additional hypothesis of particle-particle contact of varying resistance dependent upon the nature of the oxide coating on...
The electrical conductivities of the high polymer materials used in this investigation (polystyrene, methylmethacrylate, and polyvinylbutyral) were so low that special equipment was required for their measurement. A Compton electrometer was used as a null indicator in a circuit similar to that described by P.J. Higgs, Journal of Sci. Instruments, Vol. 10, page 169, June 1933. This circuit is shown...
This paper is concerned only with the effect of the dissipation factor of the liquid upon the overall dissipation factor of impregnated paper insulation.
Integrated mica derives its name from the fact that it consists of numerous flakes of mica, which are held together by their own cohesive force so as to form a continuous sheet. The process begins at the mine, where mica schist or giant granite is crushed and the mica flakes removed. These are then washed and split in such a manner that the cohesive force between the laminae is retained. The flakes...
Loss angle and dielectric constant of various celluloses were measured at frequencies of 500, 1000, 2000, and 4000 cycles by means of a conjugate Schering bridge equipped with a Wagner ground. A transition type oscillator was the source of variable frequency. The test capacitor system permitted measurement of electrode separation at the time of electrical measurement. The system could be evacuated...
Mica occurs in nature in “books” consisting of a number of layers or laminae which can be readily split and separated along basic cleavage planes. Most of the mica pieces are too small in size for industrial use, so that it is necessary to split the mica into very thin laminae (0.0006 to 0.0013 in.) and to build up plates from these laminae using a suitable binding material. When in this form it is...
Previously this group reported on the testing of salt-fog penetration and the failure, in heat endurance tests of varnished insulation, that is, on Coated fabrics and paper. The tests were based upon the use of the electrographic printing method which, has been described in the 1948 Annual Report of the Conference. The present paper is a progress report. It shows the application of the test method...
The invention of the transformer some sixty years ago, made possible the tremendous growth and present importance of the power generating, transmitting and distributing industry, to the point where today it is the very backbone of our industrial civilization.
When studying the color of rutile, a project sponsored by the Geophysics Branch of the O.N.R., W. A. Weyl and T. Forland∗ discovered that the blue-grey color which is characteristic for partly reduced rutile may be obtained in an oxidizing atmosphere if an occasional Ti4+ ion is replaced by a cation of a valency higher than four (Sb5+, Cb5+, W6+).
This paper deals with the use of the temperature of the dissipation factor maximum for the plasticiser, the, base resin and the plasticized composition itself end draws some conclusions concerning the use of this data both to predict the low temperature performance of the plasticized composition and the olasticizer-polymer interaction.
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