Showing papers on "Liquid dielectric published in 1973"

Radiation Pressure on a Free Liquid Surface

Abstract: The force of radiation pressure on the free surface of a transparent liquid dielectric has been observed using focused pulsed laser light. It is shown that light on either entering or leaving the liquid exerts a net outward force at the liquid surface. This force causes strong surface lens effects, surface scattering, and nonlinear absorption. The data relate to the understanding of the momentum of light in dielectrics.

Metal evaporation under powerful optical radiation

Abstract: The experimental results of our studies of metal evaporation under powerful optical radiation are presented. The theory of this phenomenon based on a liquid-vapor phase transition is developed. An approximate solution of the Clapeyron-Clausius equation is applied to the present problem. The method permits calculations of metal surface temperature versus incident light intensity I 0 . When a certain critical intensity is exceeded ( I_{md} \sim 10^{7}-10^{8} W .cm-2) a new effect is shown to arise due to disappearance of the metallic properties of the target. The new effect is a "transparency wave" in whose front a liquid metal turns into a liquid dielectric. For I_{0} > I_{md} it is the surface "transparent" (dielectric) layer that is evaporated. Its temperature is no longer raised and it remains below a critical value. This layer is separated from the metal by the transparency wave front, which propagates towards the interior of the metal. The transparency wave causes some other effects to arise, such as a sharp drop of the reflectivity from the metal surface, an essential change in the dependence of the observed evaporation front speed on I 0 , and, finally, occurrence of a maximum on the curve of specific recoil impulse versus I 0 . These other effects may be used to identify the transparency wave. The experimental results support some corollaries of our theoretical model. The vapor dynamics of metal evaporation under powerful millisecond optical radiation are investigated. Vapor heating near the target under laser light has been observed. The initial conditions of vapor motion are studied. From the gas-dynamic measurements the mass flow of the gas phase j 1 is calculated. The dependence of j 1 upon the incident light intensity is indicative of the fact that the metal surface has attained the temperature T = T_{md} , which corresponds to the liquid metal-liquid dielectric transition.

Use of a Multichannel Analyzer for Corona Pulse-Height Distribution Measurements on Cables and Other Electrical Apparatus

Abstract: A method in which use is made of a multichannel analyzer to measure the distribution of the corona pulse heights of insulating systems of various electrical apparatus such as transformers, capacitors, and cables is described. Suitable pulse-shaping circuitry is used in conjunction with an RCL-type corona pulse detector to provide a basic sensitivity level of 1 pC and corona pulse resolution limit of about 10-15 ,?s. A calibration technique is described and particular attention is given to the interpretation of calibration results obtained under high ambient noise conditions normally prevalent in electrical apparatus production areas. It is shown that electrical interference may degrade the corona charge resolution of the analyzer display to as much as 4.0 pC as compared to the half-peak width value of about 0.5 pC in the near absence of noise. Typical corona pulse-height distribution spectra obtained on solid dielectric insulated power cables are presented.

Stabilized ester impregnant

Abstract: A high temperature and extended time method of impregnating electrical capacitors with an epoxy stabilized dielectric liquid aromatic ester.

Optimization of Insulators for Gas Insulated Systems

Abstract: The general problem of which insulator configuration is best for gas-insulated systems is considered. A smooth disc is compared with both a corrugated disc and a cone and the cone is seen to have considerable potential. Impulse and switching surge voltages are more severe than 60 Hz when contamination is present on the insulators. When insulators are contaminated, the dielectric strength cannot be increased by increasing pressure.

Dielectric insulation employing open-celled microporous film

Abstract: An electrical conductor having a dielectric insulation material formed from a partially heat-shrunk open-celled microporous film is disclosed. The dielectric insulation material is impregnated with a dielectric liquid selected from halogenated organic compounds having from 1 to 5 halogen substituents and from 1 to 3 aryl groups; perfluorobutylamines and ethers; perfluorohydrocarbons; silicone oils; mineral oils; castor oil and cottonseed oil.

Investigations of Some Electric Force Effects in Dielectric Liquid

Abstract: The rising effect of dielectric liquids along a high-voltage electrode has been investigated. The height of the rise of dielectric liquid has been found to be proportional to the square of the applied voltage between the electrodes. The measurements of potential distribution have shown that the electric field in the vicinity of the electrode along which dielectric liquid climbs is highly enhanced by the presence of the predominant ions in the liquid. The force exerted to the electrode along which the dielectric liquid climbs has been found to be proportional to e. The analysis of experimental results leads to the conclusion that the origin of the rising effect is attractive electrostatic force. The pumping effect of dielectric liquid into a capillary electrode due to the electric force has been observed.

Electrical apparatus with high voltage electrical conductor insulated by material including high dielectric constant inserts

Abstract: A high voltage, insulated conductor for electrical equipment such as dynamoelectric machines where non-uniform electric stresses occur. The insulation has inserts of a material of high dielectric constant incorporated in the insulation in regions of maximum stress to change the stress distribution in a manner to reduce the maximum stress.

Liquid dielectric cooled terminations

Abstract: A termination for terminating or absorbing a signal transmitted along a transmission line is disclosed as comprising a short circuit disposed across the transmission line and a thin film of a resistive material disposed a critical length from the short circuit to absorb substantially the signal transmitted along the transmission line. A cooling chamber is formed about the thin film and a cooling liquid of given dielectric constant and relatively low microwave loss is directed through said cooling chamber to remove the heat absorbed by the thin film. A window is disposed across the transmission line to form the cooling chamber. The cooling liquid of given dielectric constant acts as a matching transformer to reduce the impedance seen by a wave propagated along the transmission line. The resistivity or impedance of the thin film is selected to be substantially equal to that of the transformed impedance effected by the cooling liquid. To establish the desired matching transformer, the spacing between the window and the resistive film is selected to be an odd integral multiple of one-fourth the wavelength of a signal as transmitted through the cooling liquid. Further, to ensure that the resistive film absorbs substantially the energy of the signal transmitted along the transmission line, the aforementioned critical distance is selected to be an odd integral multiple of one-fourth the wavelength of the signal as transmitted through the cooling medium. The given dielectric constant of the cooling medium in turn determines the wavelength of a signal transmitted therethrough, and therefore the spacings between the window and the resistive film, and the resistive film and the short circuit.

Apparatus and method for shifting the phase of microwaves

Abstract: Microwave phase shift is obtained by using a liquid dielectric provided by a polymer solution through which the microwaves propagate and across which a controllable electric field is established.

Liquid impregnated capacitor

Abstract: Electrical capacitors are impregnated with liquid dielectric compositions comprising mixtures of diaryl sulfones and esters of carboxylic acids.

Capacitor and dielectric impregnant composition therefor

Abstract: Electrical capacitors are impregnated with liquid dielectric compositions comprising mixtures of diaryl sulfones and esters of carboxylic acids.

Technique for charging dielectric surfaces to high voltage

Abstract: A technique for charging a stationary dielectric surface by corona discharge is described in which the voltage applied to a stationary corona wire is steadily increased over a time period to cause the gradual increase in voltage level on the dielectric surface over the same time period. The dielectric surface voltage increases with the wire voltage. The potential difference between wire and plate is kept below the sparking or arcing voltage and above the threshold voltage. In an arrangement employing a moving dielectric surface, plural corona wires are maintained at successively higher voltages to increase the charge on the dielectric in steps, each step being such as to maintain the potential difference between wire and surface below the arcing voltage.

Electrical devices containing nitroarylsiloxane dielectric fluid

Abstract: Improved electrical devices such as transformers and capacitors containing nitroarylsiloxanes as dielectric fluids are disclosed.

Dielectric composition for impregnating electrical capacitors

Abstract: Electrical capacitors are impregnated with liquid dielectric compositions comprising mixtures of diaryl sulfones and halogen-free aromatic organic compounds

Influence of Inorganic Fillers on the Voltage Endurance of Solid Dielectric Power Cables

Abstract: Results of work undertaken to evaluate solid dielectric materials containing inorganic fillers with respect to voltage endurance are reported. The results obtained are associated with degradation caused by the growth of dendrites within the solid dielectric when under voltage stress.

Recording of ionizing radiation by a dielectric liquid located in the electric field

Abstract: The height of a liquid dielectric column changed with the absorbed dose, the difference between the theoretical and experimental DELTA h being only 0.53 mm. The relative error was plus or minus 40 due to the short height of the liquid column in the lower part of the curve. An empirical formula is given which shows the change, within plus or minus 15%, in the time constant of the capacitor with change in the absorbed dose. The possibility of using such a liquid colunm for measuring the absorbed dose is considered. (auth)

Internal discharges in a liquid nitrogen filled cavity

Abstract: Liquid-nitrogen impregnated polymer-paper insulated cables are considered to be most promising as cryoresistive cables. The cables have low values of e tan δ and seem to have dielectric breakdown strengths high enough for UHV cables. Such a type of insulation, however, does not necessarily show sufficient resistance against internal discharges (corona). Since liquid nitrogen is used near its boiling point, it can easily vaporize due to heat generated by heavy current loads or shortage of liquid nitrogen supply. It is anticipated that discharges take place in these vapor bubbles, which could lead to discharges of the liquid phase followed by the breakdown of the whole cable insulation. Internal discharges and their effects on polymer paper and films were investigated in a cavity filled with liquid nitrogen to simulate a butt gap created by winding the polymer paper around the conductor. These results are described in the paper.

Initiation and growth of trees in polymeric dielectric materials

Abstract: Recently, as a result of the use of a great variety of polymeric dielectric materials as the insulation for high voltage electric devices, the importance of treeing breakdown has been established. This paper describes some results of a study on tree initiation and growth using the short time supply of voltage and the single needle and direct ground system in polystyrene and polyvinylchloride over the temperature range from 20° to 80°C.

Method of reducing solid arcing product build-up between electrical contacts in pressurized fluid ambients

Abstract: A method of substantially reducing the build-up of solid arcing products between contacts for making and breaking electrical circuits including the steps of adjusting the contacts to an arbitrary opening distance at which arcing will occur, placing the contacts in the dielectric fluid under greater than atmospheric pressure, opening and closing the contacts at a fixed operating circuit voltage to determine if the solid arcing product build-up forms, and readjusting the contact opening distance to minimize the value of the parameter (V/N)2/d where V is the operating circuit voltage, N is the number of sets (or pairs) of serially connected contacts and d is the distance between the contacts when in the fully open position. The value of the parameter may be further reduced by distributing V across a plurality of sets (or pairs) of such contacts connected in series and provided to be simultaneously actuated.