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The absolute magnitude of the coulomb or electron charge in a corona pulse can be obtained from a measurement of the instantaneous voltage change produced by the pulse on the device, or test piece. This voltage, ΔV, is most easily measured by measuring the maximum amplitude of the damped high frequency oscillation generated across a small inductor connected in series with the test piece showing corona...
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It has been known for a long time that the gases containing Fluorine have in general a higher dielectric strength relative to air and therefore offer practical applications as dielectrics. For instance, sulfur hexafluoride has been used to insulate X-ray transformers, Van de Graaff and telephone cables.
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Mason(1) and Caspari and Merz(2) have made measurements of the electromechanical properties of barium titanate. Working with polycrystalline ceramics Mason(1) observed only a second order electro-strictive effect, since the first order piezoelectric effect was annulled because of the random orientation of crystal axes. Caspari and Merz(2) made static and dynamic electromechanical measurements on single...
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The non-linearity of the dielectric behavior of Barium Titanate single crystals above the 120°C transition has been investigated in the temperature range 120°C to 150°C. The single crystals used in this experiment were grown in our laboratory. They are characterized by a very high peak of the dielectric constant at the Curie point (16,000).
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In the usual technique for the display of ferroelectric hysteresis loops, the specimen is excited from a sinusoidal a.c. voltage source, signals proportional to D and E are derived and these are respectively applied to the vertical and horizontal deflection plates of a cathode ray oscilloscope. Ordinarily, the frequency of excitation is 60 c.p.s., the choice being purely one of convenience. Actually,...
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A sufficiently high a.c. voltage impressed upon a sample of dielectric containing a void will result in discharges (corona) in the void, and thus to degradation of the dielectric. The discharge current is in the form of very rapid pulses, < 0.1 μsec in duration, and it is the ultimate purpose of this work to examine the factors controlling the number and size of these pulses and to correlate these...
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This is essentially a continuation of a paper I presented before this group in 1948 and which was printed, with discussions, in the June 1949 Electrical Engineering. Much debate has occurred on the extent to which failure of an insulated single conductor is governed by the maximum stress or the average stress and the relation of failure voltage to the geometry. The behaviors with d-c, a-c, and impulse...
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The direct current surface resistivities of some ceramic and organic materials at 91 and 100 per cent relative humidity were evaluated. Particular emphasis was devoted to the study of glazed high alumina ceramics from many of the commercial sources.
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A new instrument has been developed which displays simultaneously on two meters the difference in magnitude and phase angle between an unknown and a standard impedance. These impedances may be resistors, capacitors, inductors, or any complex impedance. No balancing operation is used, but instead the vector components of the bridge unbalance voltage are measured and displayed independently.
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The possibility of obtaining oxidation-ions from aromatic hydrocarbons was investigated. Ozone at room temperature and without a catalyst was used as an oxidizing agent. Under these conditions no increase in electrical conductivity is observed. If, however, a small amount of an aliphatic acid is added prior to the oxidation, a very large increase in electrical conductivity is found.
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The physical properties of succinonitril, NCCH2CH2CN, have made it suitable for inclusion in a program of research at microwave frequencies on solids possessing high dielectric constants because of the rotational freedom of their polar molecules. At radio frequencies, White and Morgan found no drop in the high dielectric constant when liquid, succinonitrile solidified at 54.2°C. Below the freezing...
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Silver possesses a combination of properties which encourages its use for a variety of purposes in electrical components such as electrical contacts, printed circuits, and metal-ceramic combinations. Its electrical resistivity is 17 × 10−6 as compared with 21.3 × 10−6 for copper and 30.8 × 10−6 for gold. Its oxide decomposes at temperatures slightly above 100°C where the dissociation pressure equals...
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The problems encountered with dielectric materials presently used in submarine antenna systems emphasize the need for improved materials. It is essential that a submarine be able to transmit its message as soon as the small whip antenna, for example, breaks water. The antenna insulator not only may have an accumulated coating of dirt from prolonged exposure to the weather but also may have been submerged...
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For the investigation of the relations between dielectric properties and molecular characteristics, the tetrahalogenated methanes provide a series of molecules which deviate in shape only a little from that of a sphere and in dipole moment only a little from zero. The dielectric constants of many of them have been measured in the liquid and solid states over a wide range of temperature at a frequency...
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Continuing research and development work in the field of silicone rubbers has lead to three new products described in this paper.
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Temperature classification of insulating materials by functional tests is now a reality rather than an ideal. With the advent of many new binding and impregnating resins such as the epoxy, silicones and polytetra-fluoroethylene, the task becomes hopeless in establishing temperatures on an organic or inorganic basis as has been done in the pasto Hence, the reasons are clear for the recent actions by...
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Measurements of dielectric constants and loss in seven alcohols (from methyl to secondary butyl) have been made at frequencies from 15 c/s to 2 Mc/s over considerable ranges of temperature to extreme values of −150°C and 110°C. Also, solutions of water in ethyl and iso-propyl alcohols and of methyl with n-propyl alcohol have been studied.
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Presents the table of contents/splash page of the proceedings record.
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The negative corona extinction voltage or breakdown extinction voltage has been determined in air and SF6 at atmospheric pressure for the sphere to plane configuration. Spheres or points ranging in size from a 0.250″ radius sphere to a 0.0024″ radius phonograph needle were used with gaps of the order of 1–10 millimeters. The negative corona extinction voltage was also determined for the coaxial cylinder...
