Showing papers on "Insulator (electricity) published in 1977"

Breakdown in silicon oxide−A review

Abstract: A review is given concerning measurement techniques and experimental results obtained on electrical breakdown in SiO2. Breakdown dependence on parameters such as time, thickness, temperature, and electrode material are covered, as well as the effect of various high‐temperature processing steps and the effect of ion implantation. The effects of sodium in causing time‐dependent breakdown are also reviewed. Special attention is given to the intrinsic breakdown mechanism in MOS capacitors where mechanisms involving impact ionization and positive charge buildup in the insulator are favored.

Theory of the secondary electron avalanche at electrically stressed insulator‐vacuum interfaces

Abstract: Several aspects of the secondary emission avalanche along an insulator surface (which is believed to play a role in insulator flashover) are addressed theoretically. The saturation condition for the two extremes of supply‐limited and space‐charge‐limited current are obtained in analytic form, and comparison with the computer simulation of Anderson is made. Also, the effect of a strong magnetic field parallel to the insulator surface and perpendicular to the electric field is analyzed, taking account of the distribution of emission angles. It is found that the critical magnetic field for inhibition of flashover is reduced by a factor of about 2 when the distribution of angles is included in the calculation.

Prebreakdown Processes Associated with Surface Flashover of Solid Insulators in Vacuum

Abstract: A computer simulation of the insulator surface charging in vacuum under the application of a high voltage, is presented for alumina (A1203) insulator and for alumina insulators coated with cuprous oxide (Cu2O) and chromium oxide (Cr2O3). It is shown that the mode of surface charge distribution is dependent on the secondary emission yield of the insulator surface. Mleasurements of insulator- electrode junction fields, using an electronic microforce balance, show the effect of surface coatings on the cathode and anode junction fields. High speed streak photography showing the time development of an arc in the case of coated insulators is presented. The experimental results support the insulator surface charging model which is simulated on a digital computer.

The importance of insulator properties in a thin-film electroluminescent device

Abstract: AC-coupled thin-film electroluminescent devices employ insulating layers to limit the current density through the active layers. The requirements and limitations in driving such devices are then dependent upon the properties of the dielectric layers. We define an external efficiency for an ac thin-film electroluminescent device and consider two limiting cases, current response 1) fast, and 2) slow, compared to an applied voltage change. Relationships are then derived among external efficiency, relative luminance, and the two principal characteristics of the insulating layer, specifically charge density at breakdown and thickness. It is shown, for example, that charge density at breakdown for the insulators should be at least three times the corresponding quantity for the active layer.

Miniature pyrotechnic squib switch, single pole, normally open

Abstract: A piston, backed by a resilient disc, both slidable within a cylindrical case, is provided, on its leading end, with a penetrable conductor pellet, sheathed within an insulator cap. Upon firing of an explosive charge of disc form, arranged behind the piston with a polyethylene disc interposed between the charge and the piston, the latter will be driven forwardly against a pair of piercing points on the ends of a pair of conductor wires mounted in an insulator header in the leading end of the case, the driving force of the explosion being sufficient to cause the conductor wire points to pierce entirely through the insulator cap and to become embedded in the conductor pellet, thus closing a circuit across the conductor wires. A fusible bridge wire, embedded in the explosive charge, is fused by application of an electric current to a pair of conductors extending through an insulator header in the rear end of the case, the forward ends of these conductors being embedded in the explosive charge, and the fusible bridge wire being attached to these forward ends within the explosive charge, in bridging relation to the ends of these conductors.

Gas filled surge arrester

Abstract: A gas-filled surge arrester includes a pair of electrodes extending inwardly of an insulating spacer. The electrodes have end faces which are aligned oppositely within the insulator to define an arc or discharge gap therebetween. Each of the electrodes includes at least one cavity formed in the end face thereof adjacent and extending away from the discharge gap. The cavities are lined with a substance of relatively high electron emission ability.

Improvement of the photovoltaic efficiency of a metal-insulator-semiconductor structure: Influence of interface states

Abstract: We study the working of a photovoltaic MIS structure. We point out the important influence of the insulating layer and of the interface states on the improvement of the photovoltaic yield; both their kinetic and electrostatic actions are examined. Our study shows that there exists an optimum thickness δopt of the insulating layer which provides a maximum electrical power at the output of the device. We give general basic equations for the calculation of δopt and present some results concerning silicon.

Structurally strong heat insulator for high transient temperatures

Abstract: A structurally strong heat insulator is depicted in the backing plate and pressure plate regions of an aircraft multiple disc brake assembly. The insulator is constructed from a plurality of perforated metal sheets in order to withstand the large compressive forces experienced during a brake application. The sheets are compiled randomly into an insulating stack which thereby offsets the holes in adjacent sheets. The holes decrease the surface area and the offset increases the heat conduction path, both which reduce the amount of heat cnducted through the stack.

Propagation velocity of cathode-initiated surface flashover

Abstract: A polymethyl methacrylate insulator rod in vacuum is stressed by high‐voltage pulses having 3‐ns rise times, with the result that 40‐mm‐long incomplete discharges occur at the end of the rod. Time‐resolved measurements of electron emission from different areas on the insulator surface indicate that a discharge propagates toward the anode at approximately 2×107 m/s during a pulse. A velocity of this order is expected if surface flashover results from an avalanche of electrons due to secondary emission at the insulator surface. Dependence of the velocity on the angle of the electric field relative to the insulator surface is predicted.

Flashover breakdown of an insulator in vacuum by a voltage impulse in the presence of a magnetic field

Abstract: The flashover strength of Plexiglas insulators subjected to submicrosecond voltage impulses in vacuum and in the presence of a magnetic field that is perpendicular to the insulator surface is studied. Flashover breakdown strength is reduced by magnetic fields of a few kilogauss. Observation by fast‐framing photography does not reveal curvature of the breakdown arc greater than 20°.

Method of making hermetic coaxial cable

Abstract: There is described a hermetic coaxial cable particularly adapted to be produced in miniature form and having a completely solid cross section with a solid metal central conductor, a tubular metal outer conductor, and a continuous glass dielectric insulator therebetween.

Grounded grid static discharge apparatus

Abstract: Grounded grid static discharge apparatus having a pair of spaced insulator blocks mounted in a shell. A grounded grid is fixed to the shell located adjacent to a sheet travel path. The insulator blocks have openings which serve as radial locators for a high voltage corona wire, extending between the blocks. A contact member, housed within one of the blocks, captures one end of the corona wire and positions the corona wire in relation to the respective opening of the block. A high voltage electrical coupling is made to the corona wire by inserting a male connector from a high voltage source into direct engagement with the contact member to complete the coupling with a minimum of electrical interfaces. The other insulator block has an end cap for capturing the opposite end of the corona wire. The end cap is urged in a direction to provide tension in the corona wire to maintain the wire in the radial locators for proper spatial positioning of the wire with respect to the shell and grid.

Insulator bushing for high voltage input

Abstract: An insulator bushing for high d-c voltage input to be used in an electric precipitator, etc. is designed to internally produce jet flows of sealing gas covering the insulator member. While ingress of dust-laden gas passing through the precipitator into the bushing is thereby prevented thus keeping the interior of the bushing clean, the necessary quantity of sealing gas to be supplied can be economically reduced.

Thickness dependence of internal voltage in metal‐insulator‐metal structure with dissimilar electrodes

Abstract: A study of the thickness dependence of internal voltage in a metal‐insulator‐metal structure with barium stearate as the dielectric film has been carried out with aluminum and tin electrodes and the internal voltage has been found to decrease linearly with thickness of the dielectric film. The internal voltage is directly related to the difference of the work function of the two metals when the dielectric film has no net dipole moment. For the case when the insulator has a net dipole moment, the internal voltage is found to increase when aluminum is the bottom and tin the top electrodes. The measured internal voltage is found to be consistent with that derived from the study of tunneling currents.

Self-venting battery

Abstract: A self-venting battery is disclosed herein and includes a casing, two terminals and an assembly of components located within the casing for producing a voltage across the terminals. An insulator is provided between and bonded to these terminals for electrically insulating them from one another. This insulator is constructed such that increasing pressure within the casing will cause the insulator to crack a sufficient amount to vent the pressure in the casing before causing the bond between the insulator and terminals to fail.

System for underground distribution of electrical power and electrical cable construction for use therein

Abstract: A system for the underground distribution of electrical power is provided and includes an electrical cable construction particularly adapted for use underground; and, the cable construction has a central conductor, a tubular insulator system for the conductor, a dual-purpose sacrificial anode supported by the insulator system and extending along substantially the full length of such insulator system, and a concentric neutral conductor supported by the insulator system and engaging the anode at a plurality of points therealong, with the dual-purpose sacrificial anode protecting the concentric neutral conductor against galvanic and soil corrosion as well as reducing AC corrosion of the concentric neutral conductor by providing additional surface area for the dissipation of currents leaving the neutral conductor.

Concrete electrical insulator

Abstract: An improved electrical grade concrete insulator is prepared from a mixture of aggregate, a hydantoin epoxy resin and, optionally, cement.

Electric floor polisher

Abstract: PURPOSE: To prevent electric shock by attaching a motor base to an insulator ring fitted to an outer case and attaching a gear case of a speed reducer to the insulator ring. COPYRIGHT: (C)1979,JPO&Japio

Insulators with increased surface conductivity and method for increasing the conductivity on surfaces of insulators having high electrical resistance made of inorganic and organic materials such as ceramic, glass, plastic and resin

Abstract: A solid insulator having high electrical resistance of inorganic and organic materials such as ceramic, glass, plastics, resins which is treated by application of an ion beam to the insulator surface to effect incorporation by controlled implantation of ions in the insulator adjacent its surface to produce an insulator surface of desired conductivity. This overcomes the difficulties due to uneven voltage distributions on the insulator surface which can cause discharges and even the destruction of the insulator.

Arrangement for semiconductor power components

Abstract: An arrangement for semiconductor power components in an installation, in which at least one semiconductor power component is placed between contact pieces and is enclosed in a housing exhibiting an insulator and connecting pieces. The arrangement includes current conductors which promote safety and prevent explosion by absorbing electric arcs formed in the installation. The current conductors are placed laterally adjacent to the contact pieces and annularly surrounding the latter, separated from the interior wall of the insulator by narrow gaps. Additional embodiments of the present invention employ reinforcing elements around the housing, and explosion guards around the housing, thereby further enhancing installation safety.

An, RI and TVI from single unit flashover of HVDC suspension insulator strings

Abstract: This paper presents the results of a study on the unusual discharge activities on dc insulators. The phenomenon, designated as "single unit flashover", completely bridges one or two insulators in a long string, and generates very high AN, RI and TVI. Since this is caused by the extreme voltage concentration on the units resulting from the thermal phenomenon on the insulator surface determined by the rate of wetting and drying, the tests were made in natural humidity conditions at the Shiobara laboratory, which has been converted to a ± 500 kV dc laboratory. This poses a serious problem for dc HV transmission design.

Modular guyline insulator

Abstract: A modular lightweight, high voltage guyline insulator for VLF antennas. A glass fiber or "Kevlar" rod tension member that provides high tensile strength is enclosed by a porcelain jacket, which serves as a good high voltage insulator, preventing an arc breakdown along the surface and protecting the tension member from exposure to ultraviolet radiation which could cause the tension member to deteriorate. A rubber sleeve extends between each end of the porcelain jacket and a guyline fastening means, and together with the porcelain jacket forms a cavity or chamber around the tension member which is filled with SF6 gas, pressurized to 2 to 4 atmospheres (29.4 psia to 58.8 psia). Metal strips and metal toroid corona rings act to diffuse the electric field.

Criterion of Surface Stability to Arc Discharge

Abstract: A criterion for appraisal of arc-resistance is obtained from analysis of heat action of electrical discharge on insulator surfaces. The criterion is a function of thermo-physical characteristics, and is independent of arc current. Thus it is possible to classify all insulator materials uniquely. The useful thermophysical characteristics are discussed and a table of values of the criterion is given.

Electric field light emitting plate

Abstract: PURPOSE:To obtain an electric field light emitting plate which prevents leak s current, has improved dielectric strength and has much higher brightness, by providing a conductor layer between an insulator layer and zinc sulfide light emitting layer.

Orbital disc insulator for SF.sub.6 gas-insulated bus

Abstract: An insulator for supporting a high voltage conductor within a gas-filled grounded housing consists of radially spaced insulation rings fitted to the exterior of the bus and the interior of the grounded housing respectively, and the spaced rings are connected by trefoil type rings which are integrally formed with the spaced insulation rings.

Two fire ceramic sealed oxygen sensing device and method of forming same

Abstract: A solid electrolyte oxygen sensing device, and a method for making the same, wherein an electrolyte wafer is sealed within a ceramic insulator by the shrinkage of the ceramic insulator when it is fired. The wafer is formed from an electrolytic material and is fired. The vitrified wafer is placed in a recess in the unfired ceramic insulator and the insulator is then fired, with the resulting shrinkage of the insulator material sealing the wafer in place.

Production of semiconductor integrated circuit

Abstract: PURPOSE:An IC of high output and high dielectric strength is produced by connecting insulating and isolating grooves to a buried layer, insulating side faces, burying the grooves with a conductive material and covering the surface with an insulator film

Conditions for the absence of thermal breakdown in silicon nitride

Abstract: Conditions for thermal current runaway and breakdown are investigated for the case when the temperature dependence of the electrical conductivity decreases with increasing field. Calculations show that thermal runaway does not arise at fields higher than an upper bound, even though large currents heat the insulator. Conditions found for the absence of thermal runaway are confirmed by experimental observations on silicon nitride. Unless the thermal conductance of the sample is poor and the electrical conductivity unusually large, thermal breakdown is not expected to arise in silicon nitride films.