Showing papers on "Insulator (electricity) published in 1984"

Surface flashover of conical insulators in vacuum

Abstract: The surface flashover of a Macor glass‐ceramic conical insulator in ultrahigh vacuum is investigated using direct current (dc), alternating current (ac at 60 Hz), standard lightning impulse (1.2/50 μs), and combinations of dc+1.2/50 μs and dc+ac. The dc and the 1.2/50‐μs flashover voltages are found to be at about the same level when the cone angle θ, which the surface makes with the applied field, is varied from −55° to +55°. At a fixed positive value of θ and a fixed thickness of the insulator, the lightning impulse, and the dc flashover voltages are higher than the ac. The level and the polarity of the dc prestress influence the combined dc+impulse flashover voltage in conical insulators. The ac+dc flashover depends on the dc prestress level and increases with increasing the prestress until a saturation is reached which is at a slightly higher voltage than the dc flashover. The electric field and the potential distributions at the interface of the cone insulator are calculated for different cone angles...

Dc Interfacial Breakdown on Contaminated Electrolytic Surfaces

Abstract: This paper covers the results of investigations of interfacial breakdown on electrolytic surfaces. A water-channel model is used to simulate an insulator surface with different conductivity levels. Effects of the chemical nature of the contaminants and contamination levels on the critical flashover voltage are studied. A multiple-arc model is introduced where the phenomenon of multiple discharges existing simultaneously on an electrolytic surface is investigated. The phenomenon of cathode fall voltage is further examined in order to arrive at a reasonable estimate for the model. A glow discharge model is adopted to provide the theoretical basis for the study.

Laser make-link programming of semiconductor devices

Abstract: A semiconductor device is programmed by a laser beam which causes an electrical short between two conductors on a silicon substrate, as by melting an insulator between the conductors and fusing or shorting the conductors. The conductors may be first and second levels of polycrystalline silicon in a standard double-level poly process, and the insulator is thermal silicon oxide. The laser beam is focused on an area which is shielded from the silicon substrate by the first-level conductor, so heating and disruption of the substrate or underlying circuit structure is minimized.

Additive printed circuit boards with flat surface and indented primary wiring conductors

Abstract: High density primary wiring patterns are formed on printed wiring boards with far less than 0.005 inch spacings and wiring conductor widths, which surprisingly permit wider conductors of at least three times the wiring spacing thus less likely to have open circuit or substrate adherance defects. This is achieved by depositing on an irregular surface of a conventional "flat" panel insulator a thick liquid photopolymer layer of paste-like consistency, such as 0.006 inch thickness, flattening it with the image bearing side of a glass plate phototransparency to produce high resolution wiring patterns comprising ridge tops defining insulating spacing between channel conductor areas therebetween by means of uncollimated actinic radiation, forming thin conductive layers 0.0014 inch thick on the channel bottoms and sidewalls to produce wider conductors, and sanding off the flat ridge tops to assure that there are no short circuits between adjacent conductors.

AC Source-Insulator Interaction in HV Pollution Tests

Abstract: A dynamic model of ac source-insulator interaction during the critical arcing period of polluted high-voltage insulators is developed. The simulation accounts for arc dynamics, arc motion over the contaminated insulator surface, dielectric recovery, and restrikes as well as the most relevant parameters of the insulator and the source. The effect of the source parameters on the leakage current waveform, dynamic voltage drop and critical flashover voltage are systematically investigated. Whenever possible the simulation results are compared with experiments and the results are found quite satisfactory.

Microwave power GaAs MISFET's with undoped AlGaAs as an insulator

Abstract: A metal-insulator-semiconductor field-effect transistor using an undoped AlGaAs layer as an insulator has been fabricated and RF tested. Due to the higher breakdown field of the wide-band-gap AlGaAs, the gate breakdown voltage has been greatly improved as compared with a conventional GaAs MESFET. The prebreakdown gate leakage current of this new device structure is also much lower than that of the MESFET. The presence of the gate insulator also reduces the gate capacitance. All these factors result in a GaAs power FET structure with potentials for high power, efficiency, and frequency of operation. An unoptimized 750-µm gate-width device achieved an output power of 630 mW with 7-dB gain and 37-percent power-added efficiency at 10 GHz. At reduced output power levels, power-added efficiency as high as 46-percent was obtained at X-band.

An experimental investigation of the depth of penetration of charge into insulators contacted by a metal

Abstract: A method to find the depth of penetration of charge into an insulator contacted by a metal is described. Results are given for the polymer polymethylmethacrylate (PMMA) and these are discussed in terms of current models of contact electrification.

Coil support insulator for an electric heater

Abstract: An electric heater incorporating simple support structure therefor. A frame is insulated from an electric resistance heater coil by insulator supports mounted within beam members of the frame. The supports incorporate structural features enabling the use of simplified supporting beams. The support insulators include additional structural features for retaining the resistance wire in place and for simplified engagement therewith. The insulators may project on both sides of the support beams and retain heater wires in two planes. The support insulators further provide an integrated structure easily fabricated and simply assembled to the frame.

Optimal Electrode-Solid Insulator Geometry with Accumulated Surface Charges

Abstract: The electric field distribution along the interface of a solid insulator-vacuum (or gas) is analyzed for different solid insulator-electrode configurations with and without the presence of surface charges using the charge simulation technique. The tangential component of the electric field at the solid insulator-electrodevacuum (or gas) triple junction is found to be reduced in cases where the contact electrode extends into the solid insulator and where the solid insulator is placed in a recessed electrode. The reduction in the field increases with increasing the penetration length of the metal insert and the depth of the recess in the electrode. The results give a theoretical justification for the previously observed higher flashover values for insulators with metal inserts and for those placed in recessed electrodes.

SF6 Gas arc extinguishing electric apparatus and process for producing the same

Abstract: A SF 6 gas insulating electric apparatus usable as a circuit breaker, etc., containing a SF 6 gas insulator and a resin insulator, both of which insulators are present in an atmosphere to be exposed to arcs, characterized by making at least the surface portion to be exposed to arcs of the resin insulator from a polymer containing nitrogen atoms or a polyolefin resin, and if necessary together with an inorganic filler powder, is excellent in both surface and inner arc resistance and can maintain breaking performance for a long period of time.

Technique for thin insulator growth

Abstract: This invention relates to a process for forming thin insulator films on conductive or semiconductive substrates in a gas plasma and more particularly relates to a process for the growth of such thin insulating films wherein the rate of insulator growth on one surface of a substrate is controlled by predepositing specific amounts of insulating films such as silicon dioxide or silicon nitride on the other surface of the substrate. Substrates with predeposited insulators form insulating films much more slowly in a gas plasma than bare substrates and, after an initial fast growth phase, the insulator thickness reaches a steady growth phase. Because of the resulting slower rate of insulator formation, control of the desired insulator thickness is easy and it is even easier if the desired insulator thickness is close to the steady growth phase.

Terminal assembly and method of forming terminal assembly

Abstract: A primarily polycrystalline but partially amorphous electrical insulator can hermetically seal first and second spaced electrical terminals, one made from an anodized aluminum and the second made from a beryllium copper or Kovar or an alloy of beryllium, copper, nickel and gold. Nickel may be diffused into the beryllium copper and a noble metal may be deposited on the nickel. The insulator provides a flat meniscus to abut a corresponding electrical insulator in a cable. The insulator may provide an electrical impedance of approximately 50 ohms, an electrical resistivity greater than approximately 10 18 ohms and a dielectric constant of approximately 6.3. The insulator operates satisfactorily in a frequency range to approximately 40 gigahertz. The insulator may be made from the following mixture: Range of Relative Material Amounts by Weight Red Lead (PbO) 156-279 Silicon Dioxide (Quartz) 340 Sodium Carbonate 139-165 Potassium Carbonate 151-189 Lithium Carbonate 64-148 Boric Acid 111-183 Calcined Alumina 47-128 The mixture may be converted into a frit by heating it at about 400° F. for about 10 minutes, then at about 600° F. for about 60 minutes and then at about 1500° F. for about 120 minutes. The mixture may be stirred while being heated at about 600° F. and 1500° F. The mixture may then be quenched in water to form an electrical assembly. The frit may be disposed between the first and second terminals and the assembly may be formed by heating at about 200° F. for about 1 hour and then at about 1040° F. for about 40 minutes.

The image‐force effect at a metal‐semiconductor contact with an interfacial insulator layer

Abstract: The theory of image‐force lowering of the potential barrier at a metal‐semiconductor contact has sometimes been incorrectly applied to the metal‐insulator‐semiconductor system. In this paper the image‐force potential is derived for a finite‐thickness insulator bounded by a metal at one side and another insulator (or semiconductor) at the other side. The exact solution corresponds to an infinite series of images of the electron with respect to both interfaces. If the interfacial insulator permittivity is lower than that of the semiconductor, then the image force in the vicinity of the insulator‐semiconductor interface will pull the electron away from the metal.

Method of moulding the insulating covering of an organic electrical insulator of great length

Abstract: A method of coating insulating molding of an organic insulator of great length and electrical insulator obtained by this process. A method of molding the insulating covering of an organic insulator comprising a central rod (3) of great length with end fittings (5, 6). Is provided in the injection mold coating retractable supports (11,12, 21,22) arranged at regular intervals; we perform injection and end of injection, prior to vulcanization of the material, is retracted supports, lesvides left by these supports in the mold (1, 2) being instantaneously filled by the injected material. Protective sleeves (24, 25) are interposed between the rod and said supports.

Pre-Breakdown and Breakdown Phenomena along Pmma Surfaces in Vacuum and Nitrogen Gas Stressed by 60 Hz Voltages

Abstract: Predischarge current and breakdown measurements of solid Plexiglas® (PMMA) insulators in vacuum and nitrogen gas gaps, excited by 60 Hz ac voltages, are reported. Results show that for bridged vacuum gaps, the predischarge current is in the form of pulses. In addition to electron emission from the cathode, secondary emission from the insulator surface is postulated to play a significant role in determining the characteristics of the current pulses. It is reported that for bridged nitrogen filled gaps no partial discharges prior to breakdown were noted, except for the case of introduced artificial voids. Insulating spacers in the form of circular cylinders and conical frustrums of different angles have been studied. The breakdown characteristics are found to depend strongly on the shape of the insulating spacer and also on the surface condition. For any given gas pressure, the breakdown strength was found to decrease with decreasing angle of the cone frustrum at its base. A rough insulator surface exhibited considerable discharge track resistance compared to a smooth surface. For cylindrical spacers, the predischarge and breakdown characteristics are found to be strongly influenced by the shape and position of the introduced voids. The effect of gas pressure on the pre-discharge and breakdown characteristics are reported.

Optical fiber composite insulator

Abstract: PURPOSE:To prevent decrease in the surface leakage insulating distance of an insulator by having a through-hole at the axial center of a shaft part, inserting an optical fiber into the through-hole and packing an insulating material into the through-hole CONSTITUTION:An optical fiber composite insulator is formed by providing a through-hole at the axial center in the shaft part 11 of a rigid insulating body 13 and the center of a cap 14 and inserting an optical fiber 10 in the hole 17 then packing an insulating material 18 such as epoxy resin or the like into the hole 17 The longitudinal continuity on the outside surface of the fiber 10 is therefore shut off by the part of the hole 17 and the insulation in the part of the hole 17 is effected thoroughly by the insulating material packed therein Flow of surface leakage current along the outside surface of the fiber 10 is thus obviated by which the decrease of the surface leakage insulating distance of a long stem insulator 6 by the fiber 10 is prevented

Toroidal power transformer

Abstract: A toroidal power transformer having improved insulation between the primary and secondary windings. The insulation includes an insulator sleeve fitted to the primary winding and having the primary winding lead wires positioned therein such that the lead wires extend radially outward from the primary winding. This insulator sleeve is fitted to the primary windings by way of an insulator flange formed as an integral part of the insulator sleeve which insures good insulation between the primary and secondary windings and high creepage distance.

Underwater electrical cable connectors

Abstract: An underwater electrical cable plug and socket connector for connecting a marine seismic source for investigating subsurface geological conditions to a survey vessel towing the seismic source includes first and second body members (102, 202). The first body member includes a plurality of pin insulator receptors (114, 116) each disposed coaxially about an electrical pin connector (104, 106). The second body member includes a plurality of pin insulators (214, 216) each disposed coaxially about an electrical pin receptor (204, 206). The first and second body members mate such that the electrical pin receptors mate with the electrical pin connectors, and the pin insulator receptors mate with the pin insulators Sealing structure is included to render watertight the pin insulator-pin insulator receptor connections.

Electrical insulating and sealing apparatus and process for using same

Abstract: An electrical insulating and sealing apparatus, and process of using same, is described for use in an electrostatic precipitator. The apparatus employs a flexible insulator seal through which passes an electrical lead-in conductor with rubber boots to seal the insulator seal against gas leakage. Also provided are a manifold and venturi section surrounding the insulator seal to permit a pressurized gas to impinge on the insulator seal and flow downwardly over the seal through the venturi section at increased speed to help clean and keep clean the surface of the insulator seal.

Measurement of voltage of power cable

Abstract: PURPOSE: To make it possible to accurately measure the charged voltage of a high voltage power cable on the way of said cable, by detecting voltage between a suspended electrode provided by peeling the shielding electrode of the power cable and the shielding electrode by a light/voltage sensor. CONSTITUTION: A part of the shielding electrode 4 of a power cable 1 is peeled off to expose an insulator 3 and a conductive or semi-conductive member is partially wound around the outer peripheral surface of said insulator 3 to form a suspended electrode 5 while a lead wire 6 is embedded in and connected to said electrode 5. Thereafter, an insulating member 7 is wound around the outer peripheries of the suspended electrode 5 and the insulator 3 to cover both outer peripheral surfaces thereof and both terminals of a shielding electrode 8 wound around the outer peripheral surface of the insulating member 7 by using a semiconductive member are wound around the outer periphery of the cable shielding layer 4 in an overlapped state to connect both shielding electrodes 4, 8. At this time, because the charging voltage of the power cable 1 is divided between lead wires 6, 9 connected to the suspended electrode 5 and the shielding electrode 8, this voltage is converted to light by a light/voltage sensor 10 while light is transmitted to a light/voltage meter 12 by an optical fiber 11 to make it possible to display voltage. COPYRIGHT: (C)1985,JPO&Japio

Surface Conduction and Losses of an Insulator Wetted by a Liquid Dielectric

Abstract: After an overview of the present knowledge of surface conduction along solid insulators in vacuum, air, water vapor, or on solids wetted by conducting liquids, the authors present a discussion of results obtained with solid insulators immersed in insulating liquids. They emphasize how the standpoint of Interfacial Chemistry, using the concept of the electrical double layer, may be transposed to the field of insulator interfaces. The fundamental parameter is the electrochemical potential characterizing the physico-chemical interaction between the solid and the liquid; it is thought that it results from the specific adsorption of species (unknown at the present time) at the interface.

Conduction and charge storage in Cr-thin SiO2-pSi structures

Abstract: It is shown that Cr−SiO 2 −pSi devices with an SiO 2 layer obtained by thermal oxidation in HCl/O 2 /N 2 mixture have uniform and reproducible electrical properties at low injection level. Futhermore the breakdown phenomenon observed at high injection level has been associated with a positive charge storage within the insulator Il est montre que les structures Cr−SiO 2 −pSi ayant une couche de silice obtenue par oxydation thermique dans un melange HCl/O 2 /N 2 ont des caracteristiques electriques uniformes et reproductibles a faible niveau d'injection. De plus, le phenomene de claquage observe a haut niveau d'injection est associe a un stockage de charges positives dans l'isolant

Electric charge accumulation on HVDC insulators in compressed-SF 6 -insulated transmission lines

Abstract: This paper describes measurements of the magnitude and distribution of residual fields around a tri-post insulator in compressed SF 6 , after being subjected to sustained dc voltages of several hundred kV, of negative and positive polarity The effects of geometry associated with insulator leg fittings, particle-trap slots and residual dust were studied Comparative measurements were also made on an annular polyethylene insulator in the same coaxial system, and on uniform thickness disks of polyethylene and filled-epoxy resin in both uniform and non-uniform fields in air The decay of the residual field involved (in some cases) field reversal leading to the conclusion that some part of field measured initially was due to a slow polarization or bulk charging of the dielectric rather than conduction through and/or over the surface of the insulator and drift of ions through the gas This work was carried out under Department of Energy Contract DE-AC01-79ET-29059 for the design of a ±600kVdc gas insulated transmission line

The metal-insulator-semiconductor-switch (MISS) device using thermal nitride film as the tunneling insulator

Abstract: Silicon thermal nitride films grown by using direct thermal nitridation of silicon have been used as a tunneling insulator in the metal-insulator-semiconductor-switch (MISS) device. This paper has shown that better uniformity and controllability of the MISS characteristics can be easily obtained by using thermal nitride film as a tunneling insulator when compared to those using conventional thermal oxide film. The superior merits of using silicon thermal nitride film are mainly due to the fact that direct thermal nitridation of silicon in ammonia gas exhibits much lower growth rate and unique self-limiting growth. Moreover, the higher structure density of the as-grown thermal nitride film may provide higher endurance for the MISS device in integrated-circuit applications. In addition, the MISS devices operated at lower voltage ( V ) have been fabricated and their characteristics are discussed.

High-voltage insulator

Abstract: A high-voltage insulator which is suitable for use in chambers carrying gas highly charged with solid particles and is used particularly in electrostatic filters used for cleaning an exhaust gas derived from internal combustion engines used to drive motor vehicles. The high-voltage insulator is columnar in structure, having shield-like ribs succeeding one another at intervals, adjacent to each of which in the insulator is one recess. With the remaining insulator parts having a smaller diameter, this recess forms a sharp edge, which defines discharge paths toward the flank of the shield-like ribs. Inside these paths, the insulator is kept free of soot coatings or conductive coatings, so that the insulator itself offers high resistance to leakage currents, which would cause insupportable power losses.

Electric Strength of Small Creepage Distances under Natural Environmental Conditions

Abstract: The electric strength of insulating configurations of solid insulating materials mainly depends on the contamination of the creepage distance, the formation of creepage paths on the insulating material by creepage currents, and the micro-climate on the insulator surface. For the intended smaller and more precise dimensioning of insulation configurations for low voltage equipment, exact knowledge about the influence of these factors on the withstand voltage is necessary. Therefore test specimens which are made from insulating materials with different comparative tracking index were investigated. The test specimens have been exposed for some months under natural environmental conditions. During the period of exposure they were connected to ac or dc voltages in the 10 to 660 V range. The laboratory measurements of the withstand voltage are carried out with impulse voltage of the shape 1.2/50 ?s under well-defined climatic conditions. According to the measured withstand voltages, new dimensioning rules for creepage distances are proposed.

High voltage rotary electric machine coil

Abstract: PURPOSE:To obtain a high voltage rotary electric machine coil having high starting voltage of surface discharging and small irregularity by edgewisely winding a field alleviating sheet on a coil linear portion from a low resistance corona preventing end of a high surface field to the starting end of a curved portion. CONSTITUTION:A mica tape or sheet is wound on a conductor 2 to form a ground insulator 3. Then, a low resistance corona preventive tape or sheet is wound in a range of approx. 10-50mm. at both ends from the length of a core 1 to form a low resistance corona preventing layer 4. Then, SiC particles are filled in thermosetting resin, coated on a glass cloth at the end superposed at 10-30mm. in a semicured field alleviating sheet cut in a rectangular shape to edgewisely wind on the coil ground insulator 3 to form the first field alleviating layer 6. Then, a tape formed similarly by superposing at 10-30mm. on the end of the layer 6 is lap-wound in the prescribed range including the coil bent portion to form the second field alleviating layer 7.

Method of making an electrical synthetic insulator, and insulator made by the method.

Abstract: For producing such a composite insulator, rain protection screens (2), which extend the creepage path are pushed onto, for example, a fibre-glass-reinforced body (1), the rain protection screens (2) forming a gap (13) by means of centring cams (14) distributed on the inner circumference, the gap (13) forming a continuous intimate joint by filling with a plastic mass. With the aid of edge elements (9, 10), the continuous joint is also produced with fittings (5) which are used for suspending the insulator and for the attachment of an electrical conductor. In contrast to known composite insulators, the reliable formation of the joint is ensured by means of an adequate gap (13), while maintaining an exact centring, however, of the body (1) and the screen (2).

Improved Performance of Cylindrical Solid Insulators with Concave Curved Edges in Vacuum

Abstract: The withstand voltage capability of a cylindrical solid insulator can be improved considerably by incorporating a concave geometry. in the insulator ends at the contact region with the conductors. It is found that the higher the value of the angle ?between the curved edgeof the insulator and the ambient field the lower is the value of the tangential field at the triple junction. The influence of the relative dielectric constant of the material and the length of the insulator on the field at the triple junction is found to be negligibly small. Measurements of the. flashover voltage in. ultrahigh vacuum (< 10-8 Torr) are conducted for cylindrical rods made of glass-ceramic with concave curvature at both-ends. ?is varied in the range 0-65°. The DC, AC and 1.2/50 Ps lightning impulse flashover voltages are between 20 to 30% higher than the respective voltages of a straight cylindrical insulator of the same thickness. The DC pre-stress has negligible influence (< 10%) on the subsequent combined DC + impulse and DC + AC flashover voltages, of a concave insulator made of Macor glass-ceramic.