Showing papers on "Insulator (electricity) published in 1976"

Interface states on semiconductor/insulator surfaces

Abstract: It is well known that impurities and defects in semiconductors are associated with energy levels in the forbidden gap. Similar states occur at the surface of a semiconductor where the crystal lattice and the symmetry are strongly disturbed. These states are called surface states. Owing to the two-dimensional nature of the surface, their density is measured per unit area, in contrast to bulk states, which are measured per unit volume. A third type of states, similar to surface states, occurs at the interface between two adjacent materials. These states are called interface states. Very often they are also simply called surface states.

High‐field transport in SiO2 on silicon induced by corona charging of the unmetallized surface

Abstract: A study has been made of high‐field electronic transport in thermally grown SiO2 in which the injection and transport of carriers were induced by charging the exposed surface of the insulator with ions extracted from a corona discharge. This technique totally avoids destructive breakdown through weak spots in the insulator. Auxiliary developments included a comparison technique for measuring the steady‐state potential difference across the unmetallized insulator and a p‐n junction method for determining the sign of the principal charge carrier in the oxide. Using a corona discharge in dry air, breakdown fields of approximately 6.5 and 13.5 MV/cm were obtained for charging with positive and negative ions, respectively. Electrons were identified as the current carriers for both polarities of applied field. Measurements of the discharge of the samples, made with a Kelvin probe, yield results that are consistent with Fowler‐Nordheim tunneling of electrons from the silicon into the oxide, with an electron effective mass in the oxide m*ox=0.48m. Positive charge accumulation was observed in the oxide after charging with negative corona to fields above 11 MV/cm.

Dielectric instability and breakdown in SiO2 thin films

Abstract: Dielectric instability and breakdown in SiO2 have been well characterized by many experimental techniques, including measurements of thickness dependence, contact barrier dependence, and time dependence of breakdown as well as a determination of radiation sensitivity and prebreakdown charge buildup within the insulator. All of the various types of data can be explained consistently by an impact ionization model, which predicts a negative‐resistance type of instability; electrons are injected from the cathode, the electron distribution is heated, hot electrons ionize the lattice, and the residual positive charge distorts the electric field and further increases impact ionization. The model is sensitive to two key parameters, the ionization bandgap Ei, and the electron–phonon scattering length λ.

High pressure electrical insulated feed thru connector

Abstract: A feed-thru type hermetic electrical connector including at least one connector pin feeding through an insulator block within the metallic body of the connector shell. A compression stop arrangement coaxially disposed about the insulator body is brazed to the shell, and the shoulder on the insulator block bears against this top in a compression mode, the high pressure or internal connector being at the opposite end of the shell. Seals between the pin and an internal bore at the high pressure end of the insulator block and between the insulator block and the metallic shell at the high pressure end are hermetically brazed in place, the first of these also functioning to transfer the axial compressive load without permitting appreciable shear action between the pin and insulator block.

Static field anode corona characteristics in sulphur hexafluoride

Abstract: This paper reports the results of an experimental investigation of the static field anode corona characteristics in SF 6 over a wide range of gas pressures and field non-uniformities. In addition to the experimental study the theoretical streamer onset voltages of the various test gap geometry-pressure configurations were calculated and these are compared with the experimentally determined breakdown voltages and onset levels of the various stages of prebreakdown current activity. Also discussed is a method of estimating the minimum gas. pressure at which breakdown occurs in the absence of positive DC corona in a non-uniform field.

A Direct Tunneling Model of Charge Transfer at the Insulator-Semiconductor Interface in MIS Devices

Abstract: : A general model of charge transfer at the insulator-semiconductor interface of metal-insulator-semiconductor (MIS) devices is developed. The model is based upon direct WKB tunneling of electrons from the semiconductor substrate into localized trap states within the forbidden gap of the insulator. Both an arbitrary distribution of the insulator states in energy as well as spatial variation in the trap densities in the interface region are treated. Advantage is taken of the strong spatial decay of the tunneling transition probability to obtain valid approximate solutions of the tunneling equations in a form directly amenable to numerical evaluation. The effects of internal electric fields in the insulator are included in a self-consistent manner. The results of several representative model calculations of post-irradiation annealing and field- injection characteristics of MIS capacitors are described.

Magnetic inhibition of surface flashover of insulators in vacuum

Abstract: The possibility of preventing high‐voltage surface flashover of insulators in vacuum by means of a strong magnetic field perpendicular to the electric field and parallel to the insulator surface is investigated theoretically. A simple model predicts that with the right choice of insulating material one can design diodes and transmission lines so that the magnetic field from the line current inhibits the secondary‐electron‐emission avalanche which is believed to play an important role in the flashover process.

Phase cable for overhead power lines - is for simultaneous power and signal transmission and has signal carrying element including optical fibre (nl 9.8.77)

Abstract: The system enables overhead power lines to be used simultaneously for the transmission of electrical power and optical information. The data signal carrying element is a light conductor (6) placed instead of a wire (5) in the cable outer layer. Its light waveguide (7) is insulated by an insulating layer (8) and embedded in a closed metal tube (9) whose outer dia. corresponds to that of a wire (5) in the outer layer. The metal tube (9) is sealed by a longitudinal weld, in order to contain the insulator typically of polyvinylchloride, and the optical conductor typically of glass fibre.

Helical wave guide

Abstract: A helical wave guide comprising a hollow conductor coated on its outside with an electrically conductive screen and formed by an electrically conductive wire coated with a thermoplastic insulator, wound in a helix and welded turn by turn by surface melting of the thermoplastic insulator. It is applicable to signal transmission.

Flexible plastics HV insulator for overhead lines - has core embedded in plastics layer with plastics screen to resist pollution and moisture

Abstract: A plastic flexible h.v insulator for overhead lines is resistant to electrical erosion. The core of the insulator is fitted with an insulator screen. There is also a plastic layer between the screen and the core of the insulator. It is therefore resistant to polluted and moist environments. The insulator core (10) is embedded in the plastic layer (12) which forms an integrated unit with a plastic screen. The dia. of the screen varies alternately between a smaller (16) and a larger (14) screen. The screens are at right angles to the axis of the insulator. The thickness of the plastic layer surrounding the core is at least 2 mm.

Disconnect contact assembly for metal-clad switchgear and the like

Abstract: This disconnect contact assembly comprises a tubular insulator projecting forwardly through a grounded metal plate and surrounding the usual bridging contact subassembly. A current transformer secondary assembly surrounds the tubular insulator. Two separate metallic coatings are provided on the tubular insulator, the first one on the outer peripheral surface of the insulator and the second one on the inner peripheral surface of the insulator. The first metallic coating is normally at ground potential and the second one is normally at the potential of said bridging contact subassembly. In addition, two semiconductor coatings, each having non-linear resistivity properties, are provided on the tubular insulator. The first semiconductor coating is disposed on the external surface of the tubular insulator at the forward end of said first metallic coating. The second semiconductor coating is disposed on the internal surface of the tubular insulator at the forward end of said second metallic coating. The two metallic coatings act to confine the electric stress in the region of the current transformer secondary and the bridging contact subassembly to the solid dielectric material of the tubular insulator, and the two semiconductor coatings act to grade the electric stresses at the forward ends of the metallic coatings where the equipotential lines of the electric field emerge from said dielectric material.

Cable corded into quads on central insulator - has exposed conductors embedded in longitudinal recesses in central support strand

Abstract: A cording element consists of several electrical conductors for use in telecommunication cables. The cable is corded into quads or similar configuration and consists of a central support strand made from insulated material. The exposed electrical conductors (9) are embedded in longitudinal recesses formed by the shape of the central strand. The corded conductors are then surrounded by an insulating sheath (14). The conductor strands and the central support strand are twisted in a spiral shape by the machine. The central strand is made from a foam plastic with reinforcement. The quads or star quads produced by this technique are mechanically very stable.

Method of making high resistance cermet film

Abstract: A cermet film includes metal particles in an insulator with the metal particles having an average diameter of from about 30A to about 120A. The cermet film has a high resistivity, and low temperature coefficient of resistivity, and is stable under electric fields of up to 105 volts/cm. The cermet film can be formed by co-sputtering the metal and the insulator onto a substrate. The sputtered cermet film is then annealed in a reducing atmosphere whereby its resistivity is increased without a corresponding change in its temperature coefficient of resistivity.

Single core screened cable with plastics outer covering - has its end fitted with plug or socket in rubber insulator

Abstract: One end of the cable is shaped as a plug or socket. It is embedded in an insulator which is made of natural or synthetic rubber. The insulator (4, 5) is made in the form of a cylinder and the cylinder is open towards the cable and it surrounds the cable end (1). It has projections (41) on the inside, and the space between the insulator (4, 5) and cable end (1) is filled with epoxy resin. The cable screen (13) is brought out backwards from the insulator.

Process of extrusion-coating the central core with an insulator of high pressure-processed polyethylene

Abstract: Provided hereinbelow is a process of extrusion-coating the central core, said core being used in a submarine coaxial cable, with an insulator of high pressure-processed polyethylene having a density of from 0.925 to 0.940 g/cm 3 and a melt index of from 0.01 to 0.3 g/10 min with advantages in that said coaxial cable is allowed to be placed on a sea bottom of not less than 500 meters in depth and to effectively transmit alternating current signals with a maximum frequency of not less than 30 MHZ, while attenuation of said signals is reduced, and thus, said coaxial cable has a transmission capacity of not less than 3000 circuits or channels with a frequency band of from 3 to 6 KHz per each circuit or channels, wherein the insulator-covered-core is continuously extruded from an extruder and then is gradually cooled in cooling water troughs to room temperature so that the water content of said insulator, without formation of voids between said central core and said insulator, is reduced by as much as possible.

Cct. breaking terminal strip with flat insulator - has opposing screw contacts electrically connected by central removable screw clamp inside insulator

Abstract: The circuit-breaking terminal strip has a flat insulating housing with two sets of terminal clamps on opposite faces. Wires are inserted through holes into the terminal contacts (3, 4) and clamped by their screws. The first contact (3) is extended into a flap (7) facing towards the centre of the housing, and the second contact (4) is extended into two parallel, longer flaps (8). The flaps are electrically connected by a removable and slidable screw clamp (5) inside the body of the housing and accessible from the top. The screw clamp consists of two metal blocks drawn together by a screw and sandwiching the flaps between them.

Continuous manufacture of flat separated insulation conductors - using a machine which deposits an insulating layer on each side of a parallel conductor set

Abstract: A system for the continuous manufacture of a set of parallel insulated flat conductors is presented. The conductors form an insulated broad flat band, inside which they are insulated from each other only by the separation between them. Basically, the machine consists of two roller (3, 4) between which the parallel set of flat copper conductors (1) is continuously fed. Two layers of polyester or polymide insulating tape (7, 8) are fed on to the rollers so that they stick to the conductors under the roller pressure and the whole flat band emerges in the form required. Short conducting sets are made in precisely this way continuously whilst for longer sets, additional stiffening separating strips (8, 10) are interposed between the conductors and insulator, at right angles and at regular intervals.

Oil-impregnated polypropylene capacitor

Abstract: An oil-impregnated capacitor comprising a thin insulator sheet solely consisting of a plastic film and impregnated with an insulating oil, the aptitude of which is defined by both the oil absorption and the expansion coefficient of the film.

Method for injecting charge in field effect devices

Abstract: A method is presented for accelerating the injection of minority carriers into an insulating layer overlying a semiconductor substrate under conditions less severe than required to produce impact ionization. The method is useful in characterizing parameters of field effect integrated circuit components subject to various charge instability mechanisms and may also be useful as a means for altering charge conditions in various non-volatile memory devices. A field effect device structure comprising a semiconductor p-n junction adjacent to an insulated gate electrode is utilized in which a depletion region is created under the gate electrode in the presence of alternating forward and reverse biasing of the p-n junction. During the forward bias condition minority carriers are injected into the semiconductor substrate adjacent to the gate electrode structure. During the reverse bias condition previously injected free minority carriers are accelerated by the depletion field produced by the gate electrode such that significant quantities of carriers exceed the semiconductor/insulator barrier potential and are injected into the insulator. The presence of traps in the insulator allows the capture of some of the minority carriers causing a charge to be built up in the insulator which reduces the effective field in the insulator which reduces the effective field in the semiconductor caused by the gate electrode potential. This effect in an MOSFET results in a reduction of threshold voltage. The charge injection technique may be used in combination with majority charge injection techniques, such as drain avalanching, to provide a re-writable non-volatile memory element.

Suspension insulator with surface leak current-proof, envelope - of GFR plastics rod, disc-shaped envelope, elastic insulator and pre-tensioned spring system

Abstract: A suspension insulator for power transmission lines comprises a glass-fibre-reinforced (GFR) plastics rod with dis-shaped enveloping elements arranged on same; an elastic insulating material between the enveloping elements, and a spring system, pre-tensioned during installation and adapted to absorb tensile stresses on the plastics rod. The disc-shaped enveloping elements are slidably arranged on the GFR rod. The spring system consists of single spring rings mounted between the envelopes. The rings are made of highly elastic insulating material that retains its resilience even at a low temp. Silicone rubber is suitable. The springs are frontally under load exerted by the enveloping elements. Their circumferential surface forms part of the outer mantle of the insulator. The insulator has high resistance to weathering and surface current leakage; non-flammable; out-standing mechanical strength.

High voltage electrical insulator having magnetic elements to prevent flashover

Abstract: An electrical insulator composed of one or more electrical insulating skirts or sheds or shells; at least some of which skirts or sheds or shells have embedded therein or otherwise associated therewith a permanent magnet (usually annular in shape) that serves to create a magnetic field region through which an arc, in the event of incipient flashover, must pass as it proceeds radially from one terminal of the insulator to the other terminal thereof. The magnetic field is oriented to have a component at the surface of the insulator, that is orthogonal to said surface. As the arc passes through the field region it is deflected sideways or circumferentially and rotates in a circle, thereby dissipating the energy in the arc. The effect of the field can be increased by having two or more annularly shaped permanent magnets embedded in the insulator and spaced radially from one another, successive magnets having oppositely directed fields to the magnet or magnets immediately adjacent the same.

Ep rubber insulation cable having outer semiconductive layer

Abstract: PURPOSE: To a good stripping performance by using the co-polymer of ethlene vinyl acetate containing vinyl acetate of 10 to 25 weight % for the semi-conductive layer in the EP rubber insulation cable having the semi-conductive layer push-coated on the insulator. COPYRIGHT: (C)1978,JPO&Japio

Cable fixing method

Abstract: PURPOSE: To prevemt breakdown of insulator due to rumple produced in shielding layer through heatcycle. COPYRIGHT: (C)1978,JPO&Japio