Showing papers on "Liquid dielectric published in 1976"

Method of making a twisting ball panel display

Abstract: A method of making a display characterized by a plurality of particles which have an electrical anisotropy due to hemispherical surface coatings of different Zeta potential and their distribution in a volume of a dielectric liquid and which also have an optical anisotropy due to the hemispherical surface coatings having different optical characteristics. The particles are mixed with a light transparent liquid which is subsequently cured to form an elastomeric or rigid slab. Following curing of the liquid, the slab is emersed in a plasticizer (dielectric liquid) which is absorbed by the slab and which causes the slab to expand slightly. Expansion of the slab around the particles provides a plasticizer-filled cavity around each particle which cavities allow the particles to rotate to provide a display in accordance with their optical anisotropy but does not allow substantial translation of the particles.

Electrostatic water treatment

Abstract: A reliable and efficient device for the treatment of liquid system, to inhibit scale formation, subjects the liquid to an electrostatic field and includes a pair of concentric cylindrical electrodes mounted one within the other with a dielectrically isolated flow passage therebetween. The outer surface of the inner electrode and the inner surface of the outer electrode each have a layer of electrical insulation thereon to severely limit current flow to and from the liquid, and a circuit is provided for continually applying D.C. potential to the electrodes. Dielectric fluid fittings connect the device into a liquid system. The dimensions of the inner and outer electrodes and the thickness of the insulation thereon are determined, according to the parameters of the liquid system and the chemistry of the liquid, from a mathematical model of the treating device as the equivalent of three capacitors connected in series.

The effect of rotation on electrohydrodynamic instability

Abstract: The effect of uniform rotation on the onset of convective instability in a dielectric fluid confined between two horizontal planes under the simultaneous action of a vertical ac electric field and a vertical temperature gradient is considered. Applying linear perturbation theory and approximations analogous to the usual Boussinesq approximations, an equation of tenth order is derived. Under somewhat artificial boundary conditions, this equation is solved exactly and the eigenvalue equation is obtained. It is shown that (1) the principle of the exchange of stabilities is valid for most dielectric fluids; (2) the Coriolis force has an inhibiting effect on the onset of instability even if the electrical effect is taken into account; (3) as the speed of rotation increases the coupling between the two agencies causing instability (electrical force and buoyancy) becomes tighter.

Information display through deformation of liquid dielectric media

Abstract: The practice of this invention provides display of information which utilizes the inherent characteristic of the displacement by an applied electric field intensity distribution of the interface between two fluid dielectric media which are operationally immiscible in each other and have different total dielectric properties at the interface. In particular, the information handling and display in the practice of this invention are with an optical display device in which the two dielectric media are immiscible liquids, e.g., oil and water. The local displacement of the interface therebetween is accomplished by the local application of an electric field which effects movement of the interface by electrohydrodynamic interaction with the dielectric media at the interface. An embodiment of the invention includes an electrode structure for applying an electric field intensity distribution so that the interface can be displaced locally and selectively and preferentially in accordance with a particular information pattern.

Response of a liquid surface to the passage of an intense laser pulse

Abstract: The temporal hydrodynamic response of the free surface of a transparent liquid dielectric due to the passage of an intense, focused laser pulse is considered theoretically, and the calculated focal length of the surface lens is in satisfactory agreement with the recent experimental result of Ashkin and Dziedzic. An understanding of this effect is important for answering the question of the momentum of light in a material medium.

Existence of a hexagonal relief on the surface of a dielectric fluid in an external electrical field

Abstract: Institute of Automation and Electrometry, Siberian Division, USSR Academy of Sciences (Submitted November 20, 1975; resubmitted February 12, 1976) Zh. Eksp. Teor. Fiz. 71, 262-272 (July 1976) The transformation of a horizontal surface of a dielectric fluid into an immobile corrugated surface following application of an external electric field is studied. The destruction of the plane boundary as a result of development of instability in fields exceeding a critical value brings the system to a stable stationary state.

Gaseous dielectric mixtures for suppressing carbon formation

Abstract: Carbon formation on voltage breakdown and sparking, and consequent carbon deposits on insulators and other surfaces, is suppressed in dielectric gases of halogenated alkanes by adding SF 6 and/or CO 2 to the halogenated alkane to form a gaseous dielectric mixture. Moreover, certain of the gaseous dielectric mixtures evidence unexpectedly high dielectric breakdown voltages. The gaseous dielectric mixtures are useful in high voltage coaxial lines, in transformers, in minisubstations, and the like.

Dielectric fluids comprising non-halogenated mixtures of organic esters and aromatic compounds

Abstract: Dielectric fluids are disclosed which comprise about 20 to 95% of a non-halogenated organic ester which is liquid between -20° C. and 150° C. and which has a dissipation factor of less than about 10% at 100° C., and about 5% to 80% of a non-halogenated, aromatic hydrocarbon or ether, which is soluble in the ester, has 1 to 2 rings, and has a dissipation factor of less than about 10% at 100° C. The preferred dielectric fluid is about 75 to 90% diisononyl phthalate and about 10 to 25% diphenyl oxide. An anti-oxidant and/or an additive to resist the effects of corona (partial discharges) are preferably included in the dielectric fluid. A capacitor containing a paper, film, or composite of these, impregnated with the dielectric fluid, is also disclosed.

High voltage cable with air dielectric

Abstract: The present invention relates to a high voltage cable having a composite dielectric of solid insulation surrounded by an air dielectric. Spacers extend from the solid dielectric and through the air dielectric to maintain a dust cover in radially spaced relationship from the solid insulation and to define the air dielectric diameter.

Electrophoretic instability in a diffusion-free dielectric liquid in an annular geometry

Abstract: A hydrostatic electrophoretic isothermal equilibrium of a dielectric liquid between concentric cylindrical electrodes is considered, and the significance of the diffusive boundary layer in relation to the diffusion-free equilibrium determined. For a small charge injection situation a linear stability analysis introduces a stability parameter which, from experiments, decreases as the threshold voltage is approached from below and displays a strict minimum at the onset of instability.

Statistical analysis on the electrical failure properties of the form-wound insulation systems for rotating machines

Abstract: From the testing results on the electrical breakdown phenomena of various epoxy micaceous insulations for form-wound coils of a high voltage rotating machine, electrical failure properties such as breakdown voltage and voltage endurance time were analyzed statistically using Weibull distribution

Rapid Heating of Liquid Foodstuffs at 896 MHz

Abstract: The design parameters of a TM010 resonant cavity, operating at 896 MHz for the heat treatment of thin cylindrical samples of known dielectric properties, are presented. Comparison is made of the performance of such a cavity with various liquid foodstuffs. The influence of the dielectric liquid temperature on the matching characteristics is experimentally investigated. High utilization efficiencies and heating rates are obtained. The distribution of the axial electric field in the loaded cavity is computed. The electric field pattern pertaining to the TM010 mode is experimentally verified using an electric probe.

Vapor lift pump for vapor-cooled transformers

Abstract: Electrical inductive apparatus, such as a transformer, cooled by a liquid dielectric having a boiling point within the normal operating temperature range of the apparatus. A vapor lift pump, with few or no moving parts, recirculates the liquid dielectric through a conduit which extends between a supply reservoir and a distribution point, by means of a pressure to velocity energy conversion provided by an orifice in a chamber located in the supply reservoir. The use of a vapor lift pump enables significant improvement in the reliability and power requirements of the apparatus.

Optical phase modulation system - uses lens and electrode matrix plates with dielectric fluid interlayer

Abstract: The phase modulation system is for an optical matrix element unit and comprises front and rear side electrode plates (P1, P2), which are of transparent material mounted in a reference electrode matrix (ZE). In the interspaces are condenser elements filled with a dielectric liquid (S), above each being situated a small air cushion (L). Light impinges on the upper surface of the phase modulator from a lens array screen (LR). The electrode plates may be photo-electric semiconductors. The system is particularly relevant to Fourier transform applications.

Liquid dielectric radio frequency pulse generators

Abstract: A liquid dielectric radio frequency pulse generator capable of providing high energy pulses having an in-line construction includes an annularly shaped spark gap immersed in an aprotic liquid such as molten sulfur, sulfur monochloride or mixtures thereof. The input voltage is connected to the resonant element through a central aperture provided in the spark gap rings for high efficiency operation.

Some aspects of the electrical behaviour of a cryogenic coaxial wrapped insulation

Abstract: The paper summarizes some results obtained recently and relative to different aspects of the electrical bevaviour of a coaxial tape wrapped insulation in helium under high electric stresses and up to breakdown. The effect of various parameters-taping and impregnation- is analysed.

Influence of dielectric stress concentration on voltage endurance of epoxy-mica generator insulation

Abstract: The structure and shape of the coils in high-voltage apparatus have a pronounced effect upon their electrical life expectancy because of the dielectric stress concentration at the edges and corners of the conductors In these regions, as a result of the high dielectric stress, accelerated damage to the insulation can occur due to the partial discharges on the surfaces and in minute voids created during manufacture or in service The extent of the influence of these increased stresses on the electrical life expectancy of several types of epoxy-mica insulation for large electrical machines was investigated

Corona in insulating liquids and in combinations of paper and liquid

Abstract: Voltage breakdown is perhaps the most important factor in the performance of electrical equipment in service At high voltages corona* may lead to voltage breakdown especially over a period of time In liquid impregnated insulation systems, corona often varies tremendously with time in both magnitude and repetition rate, which complicates both its measurement and the understanding of its influence

Dielectric liquid pref. for transformers and condensers - comprises 2-ethylhexyl 2-ethyl hexanoate opt. with other dielectric liq(s).

Abstract: Dielectric liquids for insulating electrical apparatus, particularly condensers and transformers, consist wholly or partly of 2-ethyhexyl 2-ethylhexanoate (I). Because of its thermal and chemical stability, its conductivity after ageing is superior to organic esters currently employed. Pref. compositions contain the above cpd. and at least one known dielectric liquid selected from chlorodiphenyls, alkylchlorodiphenyls, trichlorobenzene, alkylated benzenes or diphenyl, particularly contng. >=10 wt.% (I).

Analysis of the species created by corona discharges and of their interactions with surfaces

Abstract: Electrical discharges in various gases may produce chemical species which can cause damage to solide surfaces of different materials. In air, for example, ozone, metastable states of molecular oxygen, atomic oxygen and nitrogen oxides are produced. Furthermore, in the case of corona discharges,those species are pushed in preferred directions by electrical wind. As a matter of fact, in the case of corona discharges, there is an electrical wind 1 resulting from the momentum given to the gas molecules by impact or drag of the ions as they move out of the high field region. The particles of the gas are swept away by this electrical wind towards low field regions and flow around encountered surfaces. The experiments presented in this paper were made with a point to plane system.

Dielectric system for an electrical apparatus

Abstract: An improved dielectric system for an electrical apparatus. The dielectric system includes a polymeric film impregnated with low molecular weight polybutene having an average number molecular weight in the range of 300 to 500. The dielectric system has improved dielectrical properties and the polybutene is biodegradable which minimizes the pollution of the atmosphere if the dielectric liquid is exposed to the atmosphere. Further extended service life can be achieved by the addition of a cyclohexyl amine to the liquid dielectric.

Study of simple models of partial discharges

Abstract: The paper describes the study of simple experimental models of partial discharges. The characteristics of discharges in point to plane gaps with air or air and solid dielectric, in parallel-plane cells with open air gap and solid dielectric or with artificial voids in the dielectric are studied with a view to contribute to a better interpretation of partial discharges in H. V. equipments.