Showing papers on "Insulator (electricity) published in 1988"

dc surface flashover mechanism along solids in vacuum based on a collision‐ionization model

Abstract: Selected experimental results are presented from an extensive experimental investigation of dc prebreakdown and breakdown processes in vacuum along solid insulators made of a variety of alumina ceramics and polymers. The investigations included measurements of predischarge current, x‐ray intensity, insulator surface charge density, breakdown behavior as influenced by insulator surface characteristics and insulator profiles, and the analysis of the spectral characteristics associated with insulator surface luminescence. The prebreakdown and breakdown phenomena were found to be strongly influenced by surface microstructure and the chemical state of the insulator surface. The experimentally observed phenomena in our studies strongly point to a new breakdown model based on collision‐ionization by electrons of defect sites and/or traps within the dielectric subsurface at the vacuum interface.

VLSI coaxial wiring structure

Abstract: A coaxial wiring structure that is constructed by depositing and etching a series of conductor layers and insulator layers. More specifically, the shielded transmission line of the invention comprises a first plate structure disposed on a first insulator layer disposed on a substrate; a second insulator layer disposed on the first insulator layer and the first plate structure, the second insulator layer having first troughs exposing end portions of the first plate structure; a central conductor and at least two peripheral conductors disposed on the second insulator layer, the two peripheral conductors contacting the end portions of the first plate structure through the first troughs; a third insulator layer disposed on the second insulator layer, the two peripheral conductors, and the central conductor, the third insulator layer having second troughs exposing respective ones of the peripheral conductors; and an upper plate structure formed on the third insulator layer, the upper plate structure contacting the peripheral conductors through the second troughs. In combination, the upper plate structure, the peripheral conductor structures and the lower plate structure surround the central conductor and are insulated therefrom by the respective insulator layers. The surrounding conductors are coupled to ground potential, and high frequency transmission signals are propagated along the central conductor.

AC withstand voltage characteristics of insulator string covered with snow

Abstract: Results of an investigation into the withstand voltage characteristics of a UHV-class tension insulator string covered with snow are reported. AC withstand voltage tests were conducted in a testing room and at an exposure testing station constructed in a heavy snow area. For insulator strings up to 10 m long, the withstand voltage was almost roughly proportional to the length of the insulator string. The relations between the withstand voltage and the characteristics of the snow are reported. A design example for determining the length of the snow-covered string is presented. >

Wildlife guard for electrical insulator bushings

Abstract: A wildlife guard, designed to prevent an electrically grounded animal, such as a bird or small mammal, from contacting energized electrical equipment. A one-piece construction fabricated from an insulating material, such as a high-density polyethylene, the wildlife guard can be installed on energized electrical equipment using standard live-line tools, thereby obviating the need to shut down the electrical power. The guard includes inner protrusions to fit below the topmost skirt of an insulator bushing, outer protrusions to be grabbed by a live-line tool, and a lengthwise slot through which a conductor is forced during installation.

Breakdown phenomena in high power klystrons

Abstract: In the course of developing new high-peak-power klystrons, high electric fields in several regions of these devices have become an important source of vacuum breakdown. In addition, a renewed interest in breakdown phenomena for nanosecond-pulse, megavolt-per-centimeter fields has been sparked by recent work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The experiments and results on the breakdown in these regions are discussed, as well as the solutions to alleviate this breakdown problem. >

Improvement of the DC voltage insulation efficiency of suspension insulators under contaminated conditions

Abstract: The authors describe the results of the research and development on a suspension-type insulator having a DC contamination withstand voltage 1.25 to 1.3 times higher than that of the standard DC fog insulator, as measured by the fog-withstand or the clean-fog method. Also described are the withstand voltage characteristics of the suspension insulator contaminated with soluble materials and nonuniformly contaminated, simulating natural-field conditions. Design criteria taking these results into account are also discussed. >

New varistor material

Abstract: A composite varistor material containing silicon carbide, a conductor, and an insulator has been developed. The material has rubberlike flexibility and is easily formed. A higher leakage resistivity (∼1012 Ω cm) and greater nonlinearity (∼10) than for silicon carbide varistors permit the material to be used as a gapless surge suppressor. The breakdown voltage (1–10 kV/cm) and other properties of the material vary with composition. High current capability (>200 A/cm2) and good energy absorption (>40 J/cm3) are obtained. Also, the material exhibits a low‐temperature coefficient (∼4×10−3/K) and a low dielectric constant (∼10) with no observed loss peak.

Failure of transmission line cap and pin insulators under DC stresses

Abstract: The available statistics on the failure rates of transmission line ceramic cap and pin insulators due to self-shattering for most HVDC operating lines indicate an unacceptably high value. The authors discuss these statistics and the possible primary causes for the high failure rate. They describe some of the research carried out as well as the major results obtained. Some means to improve the quality of insulators for DC applications, and areas for further research are indicated. >

45 degree insulator surface flashover: A review and new results

Abstract: Insulator surfaces are often the cause for component electrical failure at high voltages. Previous work concerning insulator flashover, conducted previously by other researchers, is reviewed and summarized. Additional measurements relevant to 45 degrees insulators in vacuum have been performed. These measurements include optical measurements of surface electric fields and electrical measurement of surface currents and charge. The results of these measurements, in the context of the reviewed work, are presented. >

Composite material of aluminum and glass fiber mat, method for its production, and method for utilization as insulator for vehicles

Abstract: A layered composite material of aluminum and glass fibers for use as an insulator and a clamping device for use in conjunction with such composites.

Digital simulation of source-insulator interaction in HVDC pollution tests

Abstract: A technique is presented for digital computer simulation of the interaction between a polluted insulator and a high-voltage, direct-current test source. Both uncontrolled and feedback-controlled voltage-double sources are considered. The polluted insulator is represented by one or more arcs in series with the wet conducting layer. The arc is represented by a simple dynamic equation, and an attempt is made in the model to account for thermal phenomena in the unbridged wet layer. The simulation technique is then used to investigate the effect of the DC source parameters on the error obtained in the insulator flashover voltage. Both the effects of maximum and mean dynamic voltage drops are studied. It is shown that the approach applies well for both controlled and uncontrolled sources, while the effect of an external damping resistor is treated separately. Wherever possible the simulation results are compared to experiments, and in view of the complexity of the problem, the agreement is satisfactory. >

Electric fence insulator adaptor and fence insulator combined therewith

Abstract: An adaptor for converting an electric fence post insulator from a wire electric conductor support to a tape conductor support. The adaptor connects to the wire holding fingers of the insulator.

Electric radiant heating element for heating a plate, in particular a glass-ceramic plate

Abstract: In the case of an electric radiant heating element (11) positioned below a glass ceramic plate (12), a rod-like temperature sensor (23) of a thermostat (24) projects over and beyond the heating zone. There are spacers (35) for maintaining a minimum spacing between the insulator (15), which carries the heating resistors (20), and the glass ceramic plate (12).

Printed circuit board with inorganic insulating matrix

Abstract: A printed circuit board has a base made from fibers (e.g., ceramic) and an inorganic coating (e.g., silicon carbide) covering the fibers to provide the base with inorganic properties. The base may have a particular coefficient of thermal expansion (CTE) as by providing the fibers with particular characteristics in the plane of, and perpendicular to, the base. The base may be isotropic thermally as by disposing the fibers in two adjacent transverse layers. An inorganic material (e.g. copper) on the base provides a radio frequency barrier. An inorganic material (e.g., silicon dioxide) on the RF barrier constitutes a dielectric insulator. An electrically conductive layer (eg. copper) partially covers the dielectric layer in a pattern defining an electrical circuit. A dielectric material (eg., silicon dioxide) fills the remaining space in this layer in a flush relationship with the conductive layer. Electrically conductive posts are added to coincide with the pads of an integrated circuit chip mounted on the board and having the particular CTE and an electrical continuity with the electrical circuit. A dielectric material fills the remaining space in flush relationship with the conductive layer. Alternatively, an electrically conductive layer defining a second printed circuit may be disposed on the first circuit and may communicate electrically with the first circuit via posts. A dielectric material may be disposed in the spaces between such circuits. The chip may then be disposed on the second circuit and may be electrically connected to the first and second circuits.

Streamers in Liquids

Abstract: Faults in devices subjected to an electric field are mostly due to electric breakdown of the insulations. Such a breakdown is the ultimate stage of irreversible processes which make any material switch from the insulating state to a conducting one (via an arc between two conductors). The situation is more or less catastrophic according to the nature of the insulator: solids, afterwards, are generally unable to sustain a further application of the voltage, whereas fluids (gases, liquids) can often do so, since they are easily renewed in the gap (by natural or forced convection).

Single-wafer optical processing of semiconductors: Thin insulator growth for integrated electronic device applications

Abstract: This paper presents an overview of the single-wafer optical processing techniques for integrated circuit fabrication with an emphasis on their applications to insulator growth. Rapid thermal growth of various thin homogeneous and heterogeneous dielectrics on silicon substrates including silicon dioxide, silicon nitride, nitrided oxides, and composition-tailored insulators will be described and some electronic device applications of the rapidly grown dielectrics will be examined. Multicycle rapid growth processes have been used for dielectric structural engineering and in-situ formation of thin layered insulators. The compositional depth profiles and the electrical characteristics of devices are controlled through the synthesis of an appropriate sequence of the wafer temperature-vs-time profiles and process gas cycles. The ongoing developments and future prospects of single-wafer rapid processing for advanced microelectronics manufacturing will also be discussed.

Pressure sensing electric conductor and its manufacturing method

Abstract: A pressure-sensing electric conductor, has an elastic electric conductive layer made of silicone rubber, on which a flexible insulating layer made of resin having a number of holes in a form of net pattern is overlaid. The pressure-sensing electric conductor is produced by applying a silicone adhesive compound to which toluene and silicone ink are added over the flexible sheet of resin insulating layer having a number of holes, and adhering said sheet to said electric conductor formed by means of vulcanization into an elastic sheet, and by bonding them together by applying pressure to both sides of the resin insulator and electric conductor.

Electrically connecting member, and electric circuit member and electric circuit device with the connecting member

Abstract: An element for use in electrical connection comprises a holding member (125) having an insulator (111) and metallic powder dispersed in said insulator and a conductive member (107) laid in said holding member said conductive member has an end which is exposed on the surface of one side of said holding member and another end which is exposed on the surface of the other side of said holding member.

Improving the high-voltage quality of alumina insulators in vacuum by surface doping

Abstract: Insulators surface doped with Ti and a Mn/Ti mix were studied. The results always show an exponential relationship between resistance and the reciprocal temperature. At high voltages, a 'self-heating effect' of the insulator was observed, because the ohmic loss across the doped insulator surface is larger than the heat transport away from the insulator. The onset voltage of this effect is dependent on the temperature. It was found that the pure Ti dopant has the highest onset voltage. Therefore, alumina insulators doped with Ti have higher operating temperatures than those doped with a Mn/Ti mix. However, all the doped insulators have significantly lower flashover rates than plain insulators in the temperature range studied, from room temperature up to about 300 degrees C. >

Beam strengthened cutout insulator

Abstract: An improved, integrally cast, synthetic resin insulator (22) especially adapted for use in an electrical cutout device (20) is provided which can be readily fabricated and gives greatly enhanced beam strength and arc track resistance characteristics The preferred insulator (22) is cast using an epoxy resin such as bisphenol A filled with a relatively large quantity of glass beads and hydrated alumina The filler fraction contributes to lowered viscosity, deaerability and improved settling properties while the resin is in an uncured state, and moreover enhances the arc track resistance and mechanical strength of the resin system after curing The preferred insulator (22) is cast to present a longitudinal bow giving the insulator (22) an arcuate central axis Further, the periphery of the insulator (22) is formed with a series of superposed, generally oval-shaped in cross-section, outwardly flaring skirts (30) interconnected by smooth transition regions (32) free of stress-inducing sharp corners By virtue of the oval-shaped skirts (32), the insulator (22) has a greater effective width than thickness, thus maximizing the beam strength of the insulator (22)

Potential and electric field distributions at a high voltage insulator shed

Abstract: The charge simulation method is applied to a two-dielectric rotationally symmetrical geometry, consisting of a single section from an approximately periodic sequence of sections of a practical post-type insulator. The dependence on the physical dimensions is determined of the potential and the electric field at various locations inside and outside of the solid dielectric and at the interface. The dependence of these quantities on the radius of the curved portions as well as on the relative dielectric permittivity of the insulator material is found in the range 2.1 to 12000 for symmetrical and asymmetrical applied voltages. A study of the errors in the potential and the field components is carried out. The extension of these results to a practical insulator case is discussed and recommendations regarding some aspects of the design are provided. >

Clinical thermometer device

Abstract: PURPOSE:To contrive to take a measurement continuously by varying the thickness of a heat insulator so that plural temperature sensors are different in heat radiation resistance to the external field. CONSTITUTION:A probe is provided with the temperature sensors 11 and 12 which come into thermal contact with the surface of the body and has the discoid heat insulator 13. A discoid heat conductive layer 15 is fitted to the center of the contacting surface 14 between the surface 21 of the body and heat insulator 13 and a ring-shaped heat conductive layer 16 is fitted to the peripheral part. Further, the heat insulator is made thicker than the peripheral part where the sensor 12 is provided at the center part where the sensor 11 is provided, so the position of the sensor 11 is higher in heat radiation resistance than the position of the sensor 12. Temperature sensors 17 and 18 are arranged opposite the sensors 11 and 12 across the heat insulator 12 and respective measured temperature data of the sensors 11, 12, 17, and 18 are inputted to an arithmetic part and displayed. Thus, the thickness of the heat insulator is varied to make the heat radiation resistance different, so that continuous measuring operation is performed by the simple device.

DC contamination performance of station insulators

Abstract: The authors describe the results of an investigation of the contamination performance of equipment insulators under the application of a DC voltage. Artificial contamination tests on insulators with various shed profiles were carried out. In addition to total leakage distance, shed profile is found to play a role in determining the DC withstand voltage. Deep-rib-type insulators exhibit a superior DC contamination performance compared to other types of insulators. Anticontamination design criteria that are based on the results of the investigation are given for DC equipment insulators. >

Studies on the use of propylene carbonate as a high-voltage insulator

Abstract: A research program has been initiated to determine if propylene carbonate can be used as an insulator in the high-voltage accelerator field. Electrical properties, such as dielectric strength, resistivity, frequency response, and surface tracking, have been investigated. Initial tests show that propylene carbonate can be deionized to several M Omega -cm and that the electric field strength of plastic laminates immersed in it is several times higher than that of laminates immersed in oil. These tests reveal that a materials compatibility problem exists but that it will not be so severe as to limit propylene carbonate usage in this field. >

Film with air cells, fire resistant heat insulator, manufacturing process and device for use thereof

Abstract: The invention relates to a film of synthetic material enclosing uniformly distributed cells (8), especially air cells, wherein at least one (2) of its external faces (2, 3) is formed from a continuous layer (4) of non-inflammable material for external protection against flames. The invention also relates to a fire-resistant thermal insulator product comprising at least one layer of film according to the invention.

Composite electrical insulator and method of forming same

Abstract: The invention provides an electrical insulator comprising a cylindrical core (2) of an insulating refractory material, such as porcelain, onto a portion of the curved surface of which a sleeve (8) of insulating polymeric material is fitted. Metal end-caps (4), for electrically connecting the insulator, are fitted to the ends of the porcelain core such that there is an exposed portion (10) of the curved surface of the core between the sleeve and each end-cap. Thus, any damaging electrical activity which takes place at the metal end-caps is directed primarily onto the surface of the porcelain core (2), and not onto the surface of the electrically vulnerable polymeric sleeve (8), which serves to protect mechanically the relatively brittle porcelain core. Optionally, the polymeric sleeve (8) may have a convoluted or a shedded outer surface (12) to increase the leakage path length of the insulator, or to prevent the formation of a continuous moisture path, or both.

Ac discharge tube

Abstract: PURPOSE:To prevent a high electric field from being formed thereby to eliminate the danger of dielectric breakdown between a pair or more of electrodes by providing the electrodes on the outer surface of a pipe of a dielectric and covering by molding the electrode ends along the longitudinal direction of the electrodes with an insulator. CONSTITUTION:A pair of electrodes 2, 2' are formed on the outer surface of a pipe of a dielectric 1, and molding films 3, 3' of predetermined insulating material are formed to cover the electrode ends E along the longitudinal direction of the electrodes 2, 2'. A silicone polymer insulator or fluorine polymer insulator (e.g., Teflon polymer) is adapted as an insulating material for covering it by molding. That is, the insulators become rubberlike insulators to cover the ends E to fill the gap densely to eliminate a void, thereby obviating the room of generating a corona discharge at all. Further, the dielectric strength is large, a thermal stability is obtained, and organic gas to reduce the breakdown strength in gas is not exhausted.

Method of spot-welding flat-type electrical wires to metal terminals

Abstract: In a method of spot-welding flat-type electrical conductors, sandwiched between insulators, to metal terminals, a portion of one insulator layer is removed from an end portion of a flat-type electrical conductor to expose the electrical conductors on one side. The end portion of the electrical conductors is put between two metal plates which is connected to form a metal terminal. A projection is formed on the metal plate which is disposed on the exposed conductor side such that it is in contact with the conductor before the conductor is spot-welded to the metal plates.

Aging degradation of the mechanical properties of composite insulators and its analytical approaches

Abstract: An investigation of the aging degradation of mechanical performance of composite insulators is reported. Useful approaches for analyzing their long-term performances to develop reliable composite insulators is reported. The static-load time-test data are examined to see how well they can be represented by a Weibull distribution. Degradation of mechanical strength and the behavior of a FRP (fiberglass-reinforced plastic) rod are analyzed by the acoustic emission method. Cyclic load tests are performed to check the delayed rupture characteristics. >

Locating system for thunderbolt point

Abstract: PURPOSE: To accurately perform actual measurements for the position of thunderbolt point and the measuring data by providing a detecting sensor for thunder lighting, appearance monitor, measuring part for processing voltage and current sensors, and transmission part for transmitting the data, in a steel tower. CONSTITUTION: A sensor box 8 is arranged in the direction vertical to an electric power transmission line 4 so as to be able to surely keep the field of view 11 for the appearance monitor for suspension insulator 3. In the sensor box 8, the detecting sensor 13 for thunder lighting and the appearance monitor 14 are arranged at the inside of a small window 12 in a case. By the above mentioned arrangement, a surface of the suspension insulator 3 is put into the field of view 11. The charged power transmission line 4 is fixed at a lower part of tip of the insulator 3 which is hung with the steel tower. By the voltage sensor 5, the detection can be made from the capacitances ratio, when a detection wire is led out from one insulator position at the steel tower 1 side of the insulator 3. The sensor box 8 is joined to the measurement transmission part 9 by a cable 16, after the data of the sensor 6, sensor 13 and monitor 14 are inputted and processed. COPYRIGHT: (C)1990,JPO&Japio