Showing papers by "Hydro-Québec published in 1971"
01 Sep 1971
TL;DR: In this article, the carbon content and the amount of retained austenite have been determined as a function of transformation temperature in an SAE-9262 steel, and it has been shown that this remarkably high carbon content falls short of the one predicted by the Kinsman-Aaronson extrapolation of the A3 curve thus indicating that the bainitic transformation cannot be considered simply as an extension of the proeutectoid transformation.
Abstract: The formation of bainite in steel is generally accompanied by an enrichment in carbon of the adjacent austenite which can become remarkably stable as evidenced by its very slow transformation rate and its very lowMs point. This paper presents the results of a study of this residual austenite in an SAE-9262 steel. Both the carbon content and the amount of retained austenite have been determined as a function of transformation temperature. It has been shown that the carbon content of the enriched austenite passes through a maximum of 1.7 pct at a reaction temperature of 400°C. However, this remarkably high carbon content falls short of the one predicted by the Kinsman-Aaronson extrapolation of theA3 curve thus indicating that the bainitic transformation cannot be considered simply as an extension of the proeutectoid transformation. In view of the inadequacy of the standard thermodynamics theory of theBs temperature, a kinetic point of view is proposed for the definition of this temperature.
85 citations
TL;DR: In this paper, it has been suggested that for sparking to occur, the normal tunnelling mechanism for the oxygen evolution must change over to a mechanism involving avalanche multiplications, and related considerations provide useful interpretative insights into the phenomenology of side reactions and sparking voltages on all valve metals.
82 citations
TL;DR: In this article, a short gap spacings are observed to occur in particular when dielectric surfaces are involved; the deviations are characterized usually by the appearance of pseudoglow discharges, which exhibit properties that are common to both pulse and glow discharges.
Abstract: Corona discharge results, obtained with a number of gases under atmospheric pressure using plane-parallel metallic and dielectric electrodes placed between 0.05 and 9.00 mm apart, are discussed. With short gap spacings, deviations from the pulse or spark-type discharge mechanism are observed to occur in particular when dielectric surfaces are involved; the deviations are characterized usually by the appearance of pseudoglow discharges, which exhibit properties that are common to both pulse and glow discharges. The practical significance of pseudoglow discharges in relation to corona measuring techniques, utilizing conventional pulse discharge detectors, are considered both on a short-and long-term test basis.
75 citations
TL;DR: In this paper, the authors studied the relationship between the wetting phenomena and double layer structure and showed the importance of studying the liquid meniscus rise as a function of the potential in demonstrating the mentioned relationship.
31 citations
TL;DR: In this article, it has been shown that high metal-metal bond energies and high lattice energies of metal oxides are responsible for lesser tendency of metal ions of Ti, Ta, Mo, W and Zr to leave the lattice of the corresponding metal or metal-oxide, respectively.
27 citations
TL;DR: In this article, a method of calculating turn-off overvoltages in a high voltage dc thyristor valve, and a computer program to perform the calculations, is presented, which is useful for valve design, and for optimization of valve and system parameters.
Abstract: A method of calculating turn-off overvoltages in a high voltage dc thyristor valve, and a computer program to perform the calculations, are presented. The effects of the statistical distribution of storage charge among thyristors and of valve and system parameters on turn-off overvoltages are shown through results of calculations for a representative thyristor valve. These results are supported by measurements performed on a model valve. The techniques presented are useful for valve design, and for optimization of valve and system parameters. The results presented are valuable in clarifying the effects of important parameters on valve performance.
21 citations
TL;DR: In this article, the authors describe the practical methods of shielding a high voltage laboratory and introduce a simplified method for shielding calculations which takes into account the effect of the seams, conducting gaskets, short-circuited slots and sound absorbing holes.
Abstract: A modern high voltage laboratory has to be shielded mainly to avoid the electromagnetic disturbances of the partial discharge measurements. The paper describes the practical methods of shielding a high voltage laboratory and introduces a simplified method for shielding calculations which takes into account the effect of the seams, conducting gaskets, short-circuited slots and sound absorbing holes. A numerical example illustrates the results in the case of a large hall.
13 citations
TL;DR: In this article, the dielectric constant and loss of a cable insulating oil have been measured as a function of frequency and temperature, and the distribution of relaxation times derived from the data is close to a log-normal (Gaussian in log?) distribution and is found to be dependent on temperature.
Abstract: The dielectric constant and loss of a cable insulating oil has been measured as a function of frequency and temperature. The distribution of relaxation times derived from the data is close to a log-normal (Gaussian in log ?) distribution and is found to be dependent on temperature. The activation energy for dielectric relaxation is non-Arrhenius, similar to the activation energy for viscosity. However, the temperature dependence of both activation energies is found to be significantly different.
11 citations
11 citations
TL;DR: In this article, it was shown that the solid state properties (i.e., band gaps, lattice energies) of anodic films may be correlated with electropolishing rates of these metals obtained from the potentiostatic polarization curves of Menzies, Marshall and Griffin.
9 citations
TL;DR: In this article, the authors evaluate the feasibility and performance of power transmission by direct current (HVDC) using the local values of the potential and potential gradient in the earth, where the potential gradient is a function of the current rate.
Abstract: The use of earth as the return path for the current presents a highly attractive aspect of power transmission by direct current (HVDC). This is not without raising considerable controversy on the possible corrosion and communication disturbances to existing pipe, cable and other systems buried in the earth. Since a close relationship exists between these various disturbing effects and the local values of the potential and potential gradient, a knowledge of these quantities are of prime importance in evaluating the feasibility and performance of this power transmission technique.
TL;DR: The focal properties of microwave lenses with F-numbers of the order of unity have been experimentally investigated and the results have been compared with theoretical predictions based on scalar diffraction theory.
Abstract: The focal properties of microwave lenses with F-numbers of the order of unity have been experimentally investigated. The intensity and phase distributions in the focal region have been studied for several systems of polystyrene lenses utilizing microwave frequencies between 9.2 GHz and 70 GHz. The results have been compared with theoretical predictions based on scalar diffraction theory. An assessment of the useful values of beam width and depth of field is given.
TL;DR: In this article, it was found experimentally that the illumination of a neon discharge results in reductions of both the electron density and the metastable population and thus there is evidence for cumulative ionization.
01 Nov 1971
TL;DR: In this paper, it was shown that the magnitude of the dielectric loss in these oils is a function of the total aromatic content, the dispersion in the values of the Dielectric constant and the change in the molar polarizability with temperature indicate that these oils behave dielectrically as dilute solutions of polar molecules in a non-polar medium.
Abstract: Mineral oils of the type used in cable applications contain varying amounts of aromatic, naphthene and paraffin structures together with some non-hydrocarbon (sulfur, oxygen, and nitrogen compounds). Although it was shown that the magnitude of the dielectric loss in these oils is a function of the total aromatic content, the dispersion in the values of the dielectric constant and the change in the molar polarizability with temperature indicate that these oils behave dielectrically as dilute solutions of polar molecules in a non-polar medium.1 The dielectric constant and dielectric loss is also characterized by a distribution of relaxation times.