Showing papers on "Insulator (electricity) published in 1991"

Trap‐enhanced electric fields in semi‐insulators: The role of electrical and optical carrier injection

Abstract: We report extremely large field enhancement near the anode of an electrically biased metal/semi‐insulator/metal structure. The large anode field results from a trap‐enhanced space‐charge region and is large enough to cause injection of holes at the anode. Our numerical simulations confirm this interpretation and show that for typical semi‐insulating GaAs, large trap‐enhanced fields (TEF) are to be expected. The TEF effect, contrary to that observed in doped materials, is enhanced by optical injection of carriers near the anode, and can be exploited for the efficient generation of ultrafast THz radiation.

Surface structural changes of naturally aged silicone and EPDM composite insulators

Abstract: In a long-term outdoor test with high direct and alternating voltages, silicone and ethylene propylene diene monomer (EPDM) rubber composite insulators have, at the beginning, shown a performance superior to that of glass and porcelain insulators. In the long-term test, however, the silicone rubber composite insulator has, in spite of the aging of both insulator types, kept its good performance, while the performance of the EPDM rubber composite insulator was drastically deteriorated. In order to get a better insight into the results obtained, the wettability and the surface structural changes of the insulators were studied by the drop deposition method using a goniometer and by advanced techniques such as scanning electron microscopy, electron spectroscopy for chemical analysis, Fourier-transform infrared spectroscopy, and secondary ion mass spectrometry. The results show that the differences in performance are related to the differences in the surface structural changes and in the dynamic ability of the surface to compensate the aging. Silicone rubber insulators have higher repellency than the EPDM insulators, especially when aged. The reason seems to be low silicone polymer diffusion from the bulk which covers the insulator surface, embeds the pollutants, and keeps the surface hydrophobic. Porcelain insulators with silicone elastomer coatings show lower water repellency than insulators with massive silicone rubber sheds. When aged, EPDM insulators do not, however, seen to possess the same dynamic recovery of their surface, thus becoming hydrophilic. >

Charge accumulation on insulating spacers for HVDC GIS

Abstract: A capacitive probe measurement that can be used to quantify the charge density on solid insulators is introduced. Studies performed in the development of a +or-125 kV high-voltage DC (HVDC) gas-insulated converter station and +or- 500 kV HVDC switchgear (HVDC-GIS) are reviewed. The properties and mechanisms of surface charging, the optimum design of the spacer and its breakdown characteristics are summarized. Problems associated with capacitive probe measurement of surface charge and a practical solution to obtain the charge distribution on the spacer are presented. >

Withstand voltage characteristics of insulator string covered with snow or ice

Abstract: The authors describe the results of an investigation into the withstand voltage characteristics of an insulator string covered with snow or ice and the application of these results to the insulation design and maintenance of a transmission line in a heavy snow area. It was found that the characteristics of withstand voltage were affected by the specific gravity of snow, the conductivity of water melted from snow, the height of snow, and the ratio of snow-covered length. The lightning impulse flashover voltage of insulator string covered with snow is much lower than that of nonsnow-covered insulator, indicating that the efficiency of lightning protection greatly decreases under snowing conditions. When transmission lines pass through a heavy snow area, an extension of the transmission system fault is feared in 54 and 275 kV transmission lines because the existing insulator string length does not have sufficient dielectric strength for temporary AC overvoltage and switching surge. >

Monocrystalline three-dimensional integrated circuit

Abstract: A monocrystalline monolith contains a 3-D array of interconnected lattice-matched devices (which may be of one kind exclusively, or that kind in combination with one or more other kinds) performing digital, analog, image-processing, or neural-network functions, singly or in combination. Localized inclusions of lattice-matched metal and (or) insulator can exist in the monolith, but monolith-wide layers of insulator are avoided. The devices may be self-isolated, junction-isolated, or insulator-isolated, and may include but not be limited to MOSFETs, BJTs, JFETs, MFETs, CCDs, resistors, and capacitors. The monolith is fabricated in a single apparatus using a process such as MBE or sputter epitaxy executed in a continuous or quasicontinuous manner under automatic control, and supplanting hundreds of discrete steps with handling and storage steps interpolated. "Writing" on the growing crystal is done during crystal growth by methods that may include but not be limited to ion beams, laser beams, patterned light exposures, and physical masks. The interior volume of the fabrication apparatus is far cleaner and more highly controlled than that of a clean room. The apparatus is highly, replicated and is amenable to mass production. The product has unprecedented volumetric function density, and high performance stems from short signal paths, low parasitic loading, and 3-D architecture. High reliability stems from contamination-free fabrication, small signal-arrival skew, and generous noise margins. Economy stems from mass-produced factory apparatus, automatic IC manufacture, and high IC yield. Among the IC products are fast and efficient memories with equally fast and efficient error-correction abilities, crosstalk-free operational amplifiers, and highly paralleled and copiously interconnected neural networks.

Method and apparatus for writing or etching narrow linewidth patterns on insulating materials

Abstract: A method and apparatus for producing fine line patterns on insulating surfaces utilizing a conductive spring-like cantilever having a pointed tip which is in proximity to the surface to be affected. Electrons emitted from the tip travel toward the insulator surface and cause changes therein or affect molecules located in the proximity of the insulator surface. Tunneling current is not required, and a highly conducting return current path for electrons through the insulator is not necessary. The incident electrons can be used to provide patterned, narrow-width features either by deposition of a material onto the insulator surface, or by producing etching in localized regions of the insulator surface, or by changing the insulator surface so that it can be etched.

Corona discharge treatment

Abstract: Corona discharge treatment apparatus for treating or coating a surface of a conductive substrate includes a high voltage radio frequency power supply and a cable having a number of flexible conductors and other components. The cable has a first end connected to the power supply and a second end wherein the other cable components have been removed and the conductors extend from the remainder of the cable. The free ends of the conductors at the second end are disposed in a general non-parallel arrangement and the free end of each conductor is held in a separate insulator which extends beyond the free end it holds. Each free end is movable independently of the other free ends. The conductive substrate is held beneath the cable second end so that the upper surface is engaged by the insulators. The conductive substrate is grounded, and relative movement is effected between the second cable end and the conductive substrate while a gas mixture is introduced into the area of engagement between the upper surface and insulators.

Electrical connector with interlocked components

Abstract: An electrical connector 1 comprises, an insulative housing 2, a conductive shell 3 having electrical terminals 4, an insulator 5, conductive switch contacts 7, 8, an electrical circuit element 9 constructed to engage the shell 3 and the switch contact 8, and a conductive clip 10 is constructed to engage additional electrical circuit elements 11, and the housing 2, the shell 3 and the insulator 5 interlock for ease of assembly.

Manufacture of semiconductor device

Abstract: PURPOSE:To enhance the yield and to improve reliability by applying coating of an insulator on the peripheral part of a conductor pattern other than the tips of inner leads, heating and compressing the tips of the inner leads of the conductor patterns and an electrode on a semiconductor chip through an insulating film, and connecting the tip and the electrode. CONSTITUTION:The peripheral region of a conductor pattern other than the tips of an inner lead 10 is thinly coated with an insulator 9. The conductor pattern is formed on the surface of a tape carrier on which semiconductor chips are mounted. The insulator is dried. The conductor pattern of a carrier 11 is made to face downward and mounted on a semiconductor chip 5. The position of an electrode on the chip is aligned with the position of each bump 6 at the tip of the inner lead 10 of the conductor pattern. Then, a bonding tool 7 is applied from the side of an insulating film 1, and heating and compression are performed. Thus, the semiconductor chip 5 is connected to the conductor pattern. In this way, the peripheral part of the semiconductor-chip mounting surface of the tape carrier 11 other than the tip of the inner lead 10 of the conductor pattern 10 is thinly coated with the insulator 9. Thus electric defects due to short circuits can be prevented.

Surface charging and flashover of spacers in SF/sub 6/ under impulse voltages

Abstract: The authors describe a series of experiments to study prebreakdown spacer charging and subsequent flashover in a compressed gas insulated rod-spacer-plane system under positive impulse voltages. Prebreakdown corona is identified as the most likely source for spacer charging. Surface charges were measured in situ with capacitive probes after the applied lightning impulse voltage had decayed to zero. Numerical computation of resultant electric fields, using the surface charge simulation method, shows that the electric field due to surface charges significantly lowers the electric field near the rod electrode but enhances the overall electric field over the rest of the spacer surface. The flashover voltage with a spacer is higher than for a rod-plane gap. A reversal of the applied impulse polarity may lower the flashover voltage for a rod-spacer-plane gap. >

SF6 decomposition under power arcs : chemical aspects

Abstract: In order to define the origin and the production rate of the CF4 formed under the effect of arcing in circuit breakers containing SF6 as gaseous insulator, a series of measurements was carried out in two Alsthom circuit breakers in which the gaseous insulator (SFs, Nz), the material from which the nozzle is made (PTFE + CaFz, pure PTFE, PPS Ryton R4) and the electrode metal (Cu/W alloy, copper) was changed. Moreover, with the aim of refining the results concerning the influence of the chemical composition of the insulator used to make the nozzle, a large series of insulators (Megelite, PPS Ryton R4, Kel'F, Teflon, polypropylene and nylon) were exposed to sparking in an SF6 atmosphere.

Electrical protective device

Abstract: An electric protective device for protecting a cable, its termination or other apparatus from the effect of lightning strikes on an overhead line to which the apparatus is connected comprises a tubular insulator combined with a surge arrester and integrated by common terminals at the ground and high voltage ends. The insulator and the surge arrester are concentrically disposed about the conductor in a common insulated structure to eliminate connecting leads therebetween and the voltage drop which occurs across such leads during a rapid rise in current. The surge arrester may contribute all or part of the electrical stress grading required in the termination.

Electrical insulator protector

Abstract: A flexible sheet of material for mounting about a vertical or horizontal type porcelain insulator of electrical equipment to physically protect the insulator from falling objects during maintenance when the electrical equipment is deenergized. The sheet is formed of flexible PVC material and is foldable into a conical configuration and secured about the insulator by VELCRO strips attached to the sheet. Additional rectangularly- shaped sheets of similar material also are provided with VELCRO fasteners are formed into a cylindrical configuration and placed around the insulator and secured to the conically wrapped sheet to provide physical protector for taller porcelain insulators.

Vacuum heat insulator

Abstract: PURPOSE: To eliminate a defect generation the shrinkage, warp and crook of a vessel material by applying a plastic laminate film as the vessel material of a vacuum heat insulator, and a glass wool as a core material CONSTITUTION: A vacuum heat insulator 1 is formed by inserting a glass wool mat 4 in the inner bag 3 and setting the inner bag 3, in which inner pressure is reduced and which is sealed in a vessel 2 for the vacuum heat insulator, and evacuating and sealing the vacuum heat insulator vessel vacuous COPYRIGHT: (C)1992,JPO&Japio

Determination of the characteristics of an electric arc plasma contaminated by vapors from insulators

Abstract: Results are presented from an experimental study (at atmospheric pressure) carried out on plasma penetrated by vapors from different industrial insulators. The data describe the influence of each insulator type upon the characteristics of the electric arc plasma, i.e. the resulting increase of the temperature, electronic density, electric field, and extinction velocity of the arc. Measurements were made spectrometrically and by means of probes. >

Surface gap igniter

Abstract: An improved low voltage igniter of the type having an annular spark gap between a center electrode and annular ground electrode which is arranged coaxial with the center electrode. The spark gap is shunted by an insulator surface. Semiconducting material is deposited on the insulator surface as one or more rings which are coaxial with and spaced from the electrodes. The semiconducting rings reduce the voltage required to initiate a spark across the spark gap.

Development of advanced ceramic matrix composite insulators for electromagnetic railguns

Abstract: Stiff, erosion-resistant insulator materials are currently needed as bore insulators for electromagnetic railguns. A status review is given of an ongoing program to develop stiff, erosion-resistant ceramic composite materials capable of withstanding the severe mechanical, electrical, and thermal environment that exists in the bore of such devices. Analytical predictions were made in order to establish property goals. A wide variety of advanced ceramic composite insulator panels have been fabricated and tested. A railgun was modified to serve as a test device for evaluating the insulator materials. Work has been initiated to scale up the fabrication of selected advanced ceramic composite insulator parts to be tested in full-size railguns. >

Transistor action based on field‐effect controlled current injection into an insulator/SrTiO3 interface

Abstract: Transistor action with both voltage and current gain exceeding 1 was observed in structures consisting of metal electrodes, insulating barriers, and high‐dielectric‐constant insulating SrTiO3. These structures were made on insulating (100) single‐crystal SrTiO3 substrates having a dielectric constant of 2×104 at 4.2 K. A Nb emitter and collector electrodes were placed on the substrates, with Si or SiO2 barriers between the emitter and substrate. Base leads were made with silver paste on the back of the SrTiO3 wafers. Devices both with and without barrier layers between the collector and substrate showed transistor action at 4.2 K. Essentially no current was required to control the collector current, which ranges from a few microamperes to a few milliamperes. For devices with a 30‐μm‐diam circular emitter having a minimum emitter‐collector spacing of 15 μm, the voltage gain was 2.5–4 and the maximum transconductance 1.4 mS.

Solid state device fabrication method including a surface treatment step with a neutral particle beam with an energy between 10ev and 100ev

Abstract: To improve the characteristics of oxides and other insulators formed by conventional techniques, particularly to improve its density, relative dielectric constant, resistance to acid, resistance to reduction and other characteristics, and to provide solid state devices or socharacteristics, the surfaces of the silicon oxide insulator, or the like, is irradiated with electrically neutral particles.

An approach to the spacer design of HVDC SF/sub 6/ gas insulated equipment

Abstract: Some of design and technological measures employed to increase SF/sub 6/ insulation reliability are discussed. It is pointed out that the insulation characteristics of SF/sub 6/ HVDC equipment markedly differ from those of analogous HVAC equipment. The minimum discharge electric stress values measured with long-term voltage application and reduced gas pressure are approximately equal to 20 MV/m*MPa, which is substantially lower than values measured with smooth voltage rise; a decreased electric strength on the insulator surface is directly associated with transient processes in the insulation, caused by free surface charge distortion. The generalization of the calculated and experimental data concerning the electric characteristics of CEI/SF/sub 6/ DC insulation has enabled the formulation of a general approach to choosing proper HVDC SF/sub 6/ equipment spacer configurations. This approach is based on the criterion of spacer-accumulated surface charge minimization. As a technological measure the abrasive treatment of the insulation surface as well as using external shielding electrodes with dielectric coating is recommended. >

Reference electrode for chemical sensors

Abstract: The invention relates to a reference electrode for chemical sensors based on ion-selective field-effect transistors (CHEMFETs) in an electrolyte/insulator/semiconductor system. The reference electrode is essentially composed of a polyglutamate-coated insulator/semiconductor substrate or of a polyglutamate-coated phthalocyaninato-polysiloxane polymer film applied to an insulator/semiconductor substrate.

Matrix circuit substrate with connecting component

Abstract: PURPOSE:To obtain improved heat efficiency by forming a flat mesh type three- dimensional wirings by alternately weaving the vertical and lateral threads of metal conductive lead covered with insulator. CONSTITUTION:A circuit substrate 1 is formed by impregnating the gaps between plain-woven mesh type three-dimensional wiring 2 with an insulating agent 3 and the insulating part for mounting electric components such as an LED, diode, lamp and resistance elements, etc., to the wirings 4, 5 exposed on the surface is ground to expose a metal conductive lead 1 in the plan view of the insulator-covered metal conductive lead 1 wired in a three-dimensional manner like a mesh. A monochromatic light emitting diode bare chip 6 is connected to the wire 4 via the solder and is coupled with a bonding pad 8 and a wire 7 provided for the wiring. Thereby, electric components and a circuit of metal conductive wire 1 insure effective heat radiation.

Dc power cable

Abstract: PURPOSE: To improve a DC power cable used for a high-voltage DC power transmission line such as a submarine cable CONSTITUTION: In a DC power cable formed with an insulator 3 made of a polymer on the outer periphery of a core conductor 1, the grain size of the insulator 3 is set to 50μm or below, and the specific surface area by the BET method is set within the range 20-80m 2 /g The effect of the decomposition residue at the time of cross-linking adversely affecting the DC insulation property is resolved, and good DC breakdown characteristic is provided COPYRIGHT: (C)1992,JPO&Japio

Estimating the erosion and degradation performance of ceramic and polymeric insulator materials in high current arc environments

Abstract: Modeling the erosion and holdoff degradation performance of various commercially available polymeric and ceramic insulators is addressed. The insulators are tested on a surface discharge switch at approximately 300 kA in atmospheric air. Test diagnostics include the surface voltage holdoff recovery and the eroded mass loss of the insulator and electrode materials used. The ceramic materials tested include several types of aluminum and magnesium silicates, several alumina and zirconia composites, and aluminum and silicon nitride. The polymeric insulators include polyvinyl chloride, low- and high-molecular-weight polyethylene, polytetrafluoroethylene, polyamide, acetyl, polyamide-imide, and several types of glass-reinforced epoxies, melamines, and phenolics. The test results indicate that the holdoff degradation resistance and erosion rates can be qualitatively predicated by the use of merit figures which are based on the thermochemical properties of the insulator. The results also show that the holdoff degradation and erosion rates can be improved for some thermoset polymers by a suitable choice of electrode material and/or by the ultraviolet stabilization of the insulator. >

Phenomena Relating to Charge in Insulators: Macroscopic Effects and Microscopic Causes

Abstract: Conservation of current under steady-state conditions makes it possible to determine the sign of charges trapped in an insulator subjected to ionizing radiation. The maximum va lue of the surface potential can thus be estimated. On the basis of a given trapped charge distribution, the pattern of the electrical field and of the potential can thus be es tab 1 i shed, and the influence of the shape of the sample and its environment can be clearly shown. Change of trapped charges with time (at the start and after i rrad i at ion) is then examined. Finally, the microscopic causes of trapping of charge is suggested by ana 1 ogy with sem i conductors . Each stage is i 11 ustrated with ex amp 1 es and a number of pract i ca 1 consequences are deduced. To facilitate the understanding of the phenomena, this analysis begins with the better known macroscopic effects and works back to microscopic causes, which are often poorly contro 17 ed . Si nee the inverse process wou 1 d be more 1 ogi ca 1 , we have mentioned it in the conclusion, while pointing out some of the difficulties which arise.

High performance, vacuum compatible electromagnetic lens coil

Abstract: A high performance, vaccum compatible electromagnetic electron lens coil for electron beam systems has reduced gaseous emissions and improved heat dissipation capability. It comprises a wound coil (48) of electrically conductive wire (56) sheathed in a selected thermoplastic resin insulator (58). The wire insulator is coated with a hermetic layer of low vapor pressure metal (60). The low vapor pressure and hermetic sealing properties of the layer provide ultra high vacuum compatibility of the coil. The high thermal conduction property of the layer provides high heat dissipation capability and therefore permits high current densities in the coil.

Exhaust emission control device for vehicle diesel engine

Abstract: PURPOSE:To provide an exhaust emission control device for a diesel engine by which insulating degradation of an insulator caused by accumulation of diesel particulates can be prevented CONSTITUTION:Since an insulator 3 supports an electrode 42 and a diesel particulate incinerating means (nichrome wire) 95 is arranged close to a surface of an insulator, insulating resistance on the surface of the insulator 3 is restored by burning diesel particulates accumulated on the surface of the insulator 3 by the heating action