Electrothermomechanical film (ETMF) is a cellular, biaxially oriented plastic film which is coated with electrically conductive layers. It is an elastic impedance. ETMF relates electrical, mechanical, and thermal energies as well as parameters. The functional basis of the film comprises the compression of gases, the mechanical parameters of the film, and the electric or magnetic field. By exploiting these basic characteristics, the film can be used in measuring techniques, in acoustics, in ultrasonics, in motion elements, in energy transformation, etc.

Materials for electrical insulating and dielectric functions

Electrothermomechanical Film. Part I. Design and Characteristics

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Engineering Dielectrics: Volume III Electrical Insulating Liquids

Insulating materials exist in a variety of different forms, including gas, liquid, solid, and vacuum, and different forms of insulating materials have significantly different dielectric strengths and insulating properties. Power transmission/substation facilities for UHV AC and 500 kV DC power transmission and 500 kV underground power transmission facilities have been designed and constructed by taking advantage of the insulating properties of various insulating materials and structures so that they conform to the demanded insulation specifications. Conventionally, insulating material technology has been developed by making a close study of apparatuses and insulating materials individually. In this paper, as a new attempt, the insulating properties of various insulating materials/apparatuses are cross-sectionally compared and examined from an entirely new viewpoint through the assessment of commonalities and differences between them. A listing of lightning impulse and AC dielectric strength data is prepared and systematically positioned from the standpoint of material and structure, and compared and evaluated in a unified way from the viewpoint of typical indices of insulating properties including the "n" value of the V-t characteristic, Weibull parameters, and impulse ratio. Further, an insulation assessment of apparatuses is systematically made with consideration given to their sizes and structures as well as the insulating materials themselves. As a result, it was found, for example, that the design field strengths of power capacitors were high and those of generators were not, and there was a noticeable difference in design field strength between SF/sub 6/ gas insulated apparatuses and oil-immersed transformers. It is expected that the analysis conducted from an entirely new angle may provide a new approach to the development of apparatus insulation technology and to the rationalization of insulation design.

Common insulating properties in insulating materials

A fundamental matter bearing on the use of dielectric gases is the delineation of the possible correlations between their molecular properties and dielectric strengths, under comparable conditions of electrode surface, electrode geometry, electrode separation, etc. Based on the criticism that a much larger number of dielectric gases be employed in the explorations of the foregoing type, it was decided to investigate whether some more general correlations could be established between the dielectric strength of gases and their molecular properties. The object of the present paper is to examine aspects of this matter with particular attention to the fact that a large number of gases will be considered in order to arrive at some general conclusions. It would be ideal to calculate the electron capture cross sections for the various gases (starting, e.g., from their molecular structure) and attempt to correlate them with the dielectric strength of gases, with an aim to formulate a quantitative measure of their "electronegativity" predictable from electron attachment cross sections, and, thence the molecular structure. It is believed, however, that a calculation of electron attachment cross-sections cannot be carried out, especially for multi-atomic gases possessing usefully high dielectric strengths. Here, we adopt an empirical, qualitative approach to the problem in which it is concluded that the electron attachment cross sections of gases would be proportional to their molecular volumes. However, for complex gases, molecular volumes are not easily calculated since one does not have data on the bonding arrangement, bond lengths, and the covalent radii of the constituent atoms of multiatomic dielectric gases of interest. As an approximation, however, one may take the molecular weight of a gas as an index of its molecular volume since a gas containing numerous and bulky atoms would tend to have both a large molecular weight and volume; the reverse would, of course, be true for a gas possessing fewer atoms, especially those of lower atomic weights.

Electric strenght and molecular properties of gaseous dielectrics

Studies were continued on unitary gases and gas mixtures in order to determine the effects of basic physical properties - such as electron attachment, electron scattering, and electron-impact ionization - on the breakdown strength of gaseous dielectrics. The uniform field dc breakdown strengths (relative to SF/sub 6/ of 1) of some of the new unitary gases investigated are: 0.80, 1.32, 2.5, 2.5, 0.94, 0.41, 1.16, and 0.94 for C/sub 2/F/sub 6/, n-C/sub 4/F/sub 10/, 1,1,1-CC1/sub 3/CF/sub 3/, 1,1,2-CC1/sub 2/FCC1F/sub 2/, OCS, 1,1,1-CH/sub 3/CF/sub 3/, C/sub 2/C1F/sub 5/, and 1-C/sub 3/F/sub 6/, respectively. Mixtures of electron attaching and electron thermalizing gases have been studied with emphasis on optimizing the contribution of the electron thermalizer to the dielectric strength of a multicomponent gas mixture. Results are presented on mixtures containing electron attaching gases, such as SF/sub 6/, 2-C/sub 4/F/sub 6/, and c-C/sub 4/F/sub 8/, and dipolar electron slowing-down components, such as CHF/sub 3/, CH/sub 2/F/sub 2/, and 1,1,1-CH/sub 3/CF/sub 3/, which exhibited synergistic behavior. Similar behavior was exhibited by the binary mixtures SF/sub 6//1-C/sub 3/F/sub 6/, c-C/sub 4/F/sub 8//1-C/sub 3/F/sub 6/, and SF/sub 6//OCS. These and earlier studies demonstrate the important role of electron scattering processes at subexcitation energies in effecting synergisticmore » behavior in dielectric mixtures and in tailoring gaseous dielectrics for industrial application.« less

Materials for electrical insulating and dielectric functions

Citations

Electrothermomechanical Film. Part I. Design and Characteristics

Engineering Dielectrics: Volume III Electrical Insulating Liquids

Common insulating properties in insulating materials

Electric strenght and molecular properties of gaseous dielectrics

New unitary and multicomponent gaseous dielectrics

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