Showing papers on "Insulator (electricity) published in 1990"

Wettability of naturally aged silicon and EPDM composite insulators

Abstract: The wettability of aged surfaces and of the bulk of naturally aged silicone and EPDM (ethylene-propylene diener monomer) insulator housings and silicone elastomer insulator coatings was studied. The samples were taken either directly from the insulators or treated by exposing them to corona discharges and/or to saline pollution. The results show that the contact angles of the silicone rubber insulator surfaces are larger than the contact angles of the RTV (room-temperature vulcanizing) silicone rubber coating and of the EPDM rubber insulator surfaces, especially when the surfaces are aged. When the insulators were exposed to corona discharges, the contact angles of the silicone rubber insulators are reduced but after exposure recover with time. The contact angles of the EPDM rubber insulators, however, continue to reduce after the exposure. When exposed to artificial saline pollution, the silicone rubber insulators show a limited recovery of their contact angles with time, while when exposed to corona discharge after saline pollution, they show a recovery of the contact angle after the exposure. The recovery time is dependent on the exposure time to the corona discharges. The EPDM samples do not show any recovery of their contact angles, either when left to rest after the salt deposition or, when after the salt deposition, they undergo a subsequent exposure to corona discharges. Furthermore, such an exposure may be deleterious for the EPDM polymer and the insulator surface may become completely hydrophylic. >

Calculation of DC and AC flashover voltage of polluted insulators

Abstract: The phenomena and the propagation processes of DC and AC arcs on the surface of polluted insulators were observed and investigated by means of a high-speed camera. Time-resolved photographs indicate that there is an obvious distinction between DC and AC flashover processes. Based on the alternating character of an AC arc on the polluted surface, the relationship between its reignition and recovery conditions is analyzed. The most important factor is the recovery rather than the reignition condition. A formula expressing the resistance of the pollution layer on the insulator is derived. From this, the flashover voltage of a polluted insulator of complex shape can be calculated. A computer program has been developed to calculate the flashover under both DC and AC. Some arc phenomena, such as arc bridging between the sheds or ribs of insulators, the drift of the arc from the insulator surface, and the number of arcs in series before flashover, are taken into account. Much experimentation has been done to determine the flashover voltages of polluted insulators with complex shapes under both DC and AC. Experimental data are in good agreement with the calculated results. >

Composite rod insulators for AC power lines: electrical performance of various designs at a coastal testing station

Abstract: The electrical performance of 36 composite insulators comprised of four commercial types for each AC-system level of 34.5 kV, 230 kV, and 500 kV is determined. The weathershed materials are epoxy-resin, ethylene propylene rubber and silicone rubber; half of the 230 kV insulators had no stress rings. Surface leakage current is recorded for surge levels of 25 mA, 150 mA, and 500 mA. A special technique is developed to obtain the flashover statistics of the 500 kV insulators, thereby allowing performance of the composite insulator to be quantified relative to that of a string of cap and pin porcelain insulators of antifog design. The deterioration of the insulators is observed by making regular visual inspections. The practical consequences of the findings and the causes of the degradation are discussed. >

Enhanced partial discharges due to temperature increase in the combined system of a solid-liquid dielectric

Abstract: Partial discharges which emanate from solid dielectrics immersed in insulating oil when high impulse voltages are applied under different environmental temperatures (20, 40 and 80 degrees C) are discussed. The solid dielectrics used for the measurements are phenol-impregnated pressboard and industrial bakelite. The samples are cut in wafers of 150 mm diameter and are 1 or 2 mm thick. The insulating oil is a typical transformer oil. The switching type of the impulse voltage used, 250/2500 mu s, corresponds to functional situations and is long enough to produce the effects that can be detected without the consideration of charge transfer phenomena due to fast rates of field changes. Experimental results show that the total charge transfer due to partial discharge is increased by temperature. A possible explanation of the undergoing physical process may be that in the low-field regime, temperature perturbation effects on the injected current are characterized by the conductivity changes in the volume of the dielectric, while as partial discharges start occurring, avalanche multiplication of conduction electrons appears to be the dominant phenomenon, characterizing the behavior of a metal/thick insulator/metal structure in the high-field regime. The circuits, measurement, and measuring procedures are discussed. >

Planar insulator for electrical machine or appts. - is laminated construction withstanding high mechanical loading and with curved edges for fitting into grooves

Abstract: The electrical insulator, used as the slot insulation for a rotating electrical machine, has two superimposed layers (2,3) of a flexible insulating material, formed with a curved edge (8,9) between a first section (4) which can carry a high mechanical loading and two further sections (6,7) respectively used to line the base and the walls of the winding slot. The first section is semi-rigid the insulating layers of the other two sections bonded together by an adhesive, with relative displacement between them at each curved edge. ADVANTAGE - Simple adaption to shape of slot without causing damage.

Polymer insulator profiles evaluated in a fog chamber

Abstract: The authors present the results of fog chamber experiments done to examine the tracking and erosion performance of polymer insulator profiles. The effect of weathershed material, construction, orientation, and AC and DC voltage are examined. Correlation between cylindrical rod specimens of materials and insulator profiles is shown. The protected leakage path provided by the weathershed is found to play a major role in the tracking and erosion performances of polymer insulators. The resistance to tracking and erosion of insulator profiles with DC is shown to be reduced in comparison to AC. Cylindrical rods of material yielded the same ranking of material performance as insulator profiles but in a shorter time. >

Solar array arcing in plasmas

Abstract: Solar cells in space plasma conditions are known to arc into the plasma when the interconnects are at a negative potential of a few hundred volts, relative to plasma potential For cells with silver-coated interconnects, a threshold voltage for arcing exists at about -230 V, as found in both ground and LEO experiments The arc rate beyond the threshold voltage depends nearly linearly on plasma density, but has a strong power-law dependence on voltage, such that for small increments in operating voltage there is a large increment in arc rate The arcs generate broadband radio interference and visible light In ground tests, interconnects have been damaged by arcs in cells having insufficient isolation from a source of high current Models for the arcs are highly dependent on the choice of interconnect conductor material exposed to the plasma and possibly on the geometry and choice of adjacent insulator material Finally, new technology solar cells use copper for the cell interconnects, a material which may have a lower arcing threshold voltage than silver It is expected, from ground tests of simulated solar cells, that any junction of conductor and insulator exposed to space plasma conditions will arc into the plasma at a few hundred volts negative potential, relative to the local plasma

Process and apparatus for preventing the pulse discharge of insulators in ionizing radiation

Abstract: A semi-insulating coating or surface layer is applied over insulating materials such as a circuit board or wiring harness or feedthrough insulator. The paint is electrically fixed to ground and as a result leaks away charge buildup before large pulse discharges occur. For example, pure tin oxide particles in phenoxy resin binder forms a paintable application for the invention.

High voltage semiconductor device having silicon-on-insulator structure with reduced on-resistance

Abstract: A high-voltage metal-oxide-semiconductor transistor device having a semiconductor-on-insulator structure comprises a substrate (21, 41), an insulator layer (22, 42a) provided on the substrate, a semiconductor layer (23, 44) of a first conductive type provided on the insulator layer, a source region (27, 48) of a second conductive type defined in the semiconductor layer, a drain region (28, 49) of the second conductive type defined in the semiconductor layer, a gate insulator film (24, 45) provided on the semiconductor layer so as to cover a part of the surface of the semiconductor layer adjacent to the source region, a gate electrode (25, 46) provided on the gate insulator film, an offset region (29, 47) defined in the semiconductor layer between the part of the semiconductor layer covered by the gate insulator film and the drain electrode, a less-doped region (29a, 47a) defined within the offset region at an upper part thereof, a control electrode (26, 43) provided between the substrate and the insulator layer so as to extend along a boundary between the insulator layer and the substrate at least under the offset region, and a driving circuit (20) for supplying a control voltage to the control electrode simultaneously and in response to the gate voltage with such a magnitude that an inversion layer is formed in the semiconductor layer along the control electrode when the control voltage is applied to the control electrode.

Electrical properties of chemically bonded ceramic insulators

Abstract: The electrical properties of commercially produced, chemically bonded ceramic insulators are compared with conventional porcelain and phenolic resin insulators. The influences of relative humidity and temperature are presented and correlated with adsorption of water in a connected pore system.

Current-controlled circuit interrupter

Abstract: Two electrodes with current connections are sepd. through an insulator with a penetrating opening. In the opening of the insulator there is a fluid conductor, and a supply container is present for the fluid conductor.

Measuring and controlling the thickness of a conductive coating on an optical fiber

Abstract: A method for manufacturing a coated optical fiber includes depositing aconductive coating on the optical fiber and measuring a value of conductance of that coating. Featured within the manufacturing method is a method for measuring the thickness of the conductive coating on an insulator, e.g., carbon on an optical fiber, including the following steps. An electromagnetic field is established by an input signal. The conductively coated insulator is moved through the energized electromagnetic field. The conductive coating on the insulator is oriented with respect to the electric field so that their interaction increases transmission loss from input to output. An output signal is extracted from the electromagnetic field. From changes in the output signal with respect to a predetermined standard, or reference, the conductance and the thickness of the conductive coating are determined. From the measured thickness of the coating, a control signal is generated for dynamically controlling one or more of the process parameters for depositing the coating on the insulator from a precursor gas. The coated insulator continuously moves through the apparatus without any physical contact. No interruption of the production process occurs.

Fail safe gas tube

Abstract: A fail-safe arrestor for electrical circuits utilizes a gas-filled tube to conduct at an over-voltage and also provides a clip to solidly couple the circuit to a ground lead at the melting from continuous current flow of an insulator interposed between an electrode and the ground lead, which insulator is a mesh with a plurality of passages allowing arcing between the electrode and clip at or above a predetermined voltage, and thus the ground lead, for a vented gas-filled tube.

High voltage insulator component - comprising plastics matrix contg. finely dispersed sub-micron size oxide particles

Abstract: A component with high electric field load capacity and long term stability, used as an insulator in high voltage equipment, is based on an organic dielectric matrix in which fine inorganic additive particles are finely dispersed. The novelty is that the particles consist of at least 80 wt. % inorganic oxides (pref. Al203 or Ti02) make up 1-40 wt. % of the total component material and have a particle size of max. 1 micron. Pref. the dielectric consists of plastics (e.g. polyethylene or epoxy resin). ADVANTAGE - The component has a high electric field strength peak value (e.g. up to 12 MV/cm) before breakdown and has longterm stability.

Cap and pin insulator

Abstract: An insulator member comprises a porcelain insulator head and a polymeric shed secured to the insulator head. The insulator member can be used, for example, in an improved electrical line insulator which comprises a) an insulator unit comprising a porcelain head, and a polymeric shed secured to the porcelain head; b) a metal cap and a metal pin each situated at a surface of the insulator unit opposite to the other, the porcelain head forming a recess to receive the pin; c) cement mechanically securing the cap to the insulator unit; and d) cement within the recess and about the pin mechanically securing the pin within the recess. Methods of manufacture are also disclosed.

Image intensifier monitoring of power line insulator leakage

Abstract: A method for detecting incipient flashover of power line insulators by use of an image intensifier to detect electromagnetic radiation generated by electrical leakage. To improve detection sensitivity, a stimulus such as ultraviolet radiation or an externally applied RF pulse is used to momentarily increase insulator leakage to generate detectable electrical leakage at contaminated insulators.

Conductivity probe for use in the presence of high intensity nuclear radiation

Abstract: A conductivity probe (10) able to withstand high water temperatures and pressures, and intense nuclear radiation is suitable for use within the core of the nuclear reactor. The probe is made with a ceramic insulator (12), such as sapphire, and a central electrode (14) that is mounted on the insulator (12). A sleeve (18) that supports the insulator (12) and the central electrode (14) is made from metals having a coefficient of thermal expansion compatible with the coefficient of thermal expansion of the insulator, such as Kovar. The central electrode (14) and sleeve (18) are bonded to the insulator (12) by a brazed compressive seal (38) that protects an internal conductor in the probe from intrusion of the reactor water. A counter electrode (16) made from a corrosion resistant metal, such as Kovar, is attached to the sleeve (18) so that it extends over the central electrode (14) a fixed, spaced distance. A positioning and signal transfer arrangement operatively supports the sleeve (18) and conveys electrical signals to and from the two electrodes (14, 16).

Line cutout for electrical distribution system

Abstract: An in-line cutout comprises an elongated insulator having high tensile strength to support a length of cable between poles. Electrically conductive caps are secured to the ends of the insulator, and a fusible link is connected between the caps. One cap is electrically connected to the main line and the other cap is secured physically and electrically to the end of a branch line.

Bridged stream corona generator

Abstract: The present invention provides a bridged stream corona generator including a first electrode comprising an electrical conductor having projections on its surface; a second electrode again comprising an electrical conductor, which is located in opposition to the first electrode; insulator means applied on at least the side of the second electrode in opposition to the first electrode; a high voltage power source connected to the first and second electrodes; and means for feeding a viscous oil onto the side of the insulator means which directs to the first electrode. With this arrangement, it is possible to smooth out irregularities caused by deposits on the side of the insulator means which faces the first electrode, thereby contributing to maintaining bridged stream corona discharge in a stable manner. The present corona generator lends itself well to purifying exhaust fumes from automobiles by corona discharge.

Photo-electric converter with intervening wirings for capacitive shielding

Abstract: A photo-electric converter having linearly arranged photo-electric elements. Common lines are each connected to at least two discrete output electrodes of corresponding photoelectric elements. A conductor arranged between insulator layers at crosspoints of the discrete output electrodes and the common lines is maintained at a constant potential. A wiring is formed between the discrete electrode and the common electrode and is maintained at a constant potential.

Method of producing a single-layer or multilayer electrical power circuit, and circuit obtained by this method

Abstract: Method of manufacturing a "printed" power circuit which, if it is multi-layered, includes a plurality of pre-blanked, parallel metal strips 3, 4 separated by a space containing an insulating material. The strips 3, 4 are positioned in a mould 1, 2 by providing for positioning dowels 8, 9 and lugs 14, 15 which can leave passages for access to the components and their welding to these strips. Then an insulator is injected through the entrance 24, and the lateral connections are cut out after removal from the mould.

Hybrid integrated circuit

Abstract: PURPOSE:To prevent an IC from moving when a lead is subjected to a reflow treatment and to enable the dense mounting of components on a board by a method wherein two or more second conductor patterns provided under a non-circuit lead on the board are covered with an insulator, and the tip of the non-circuit circuit lead is positioned at a trough part formed at he insulator between the conductor patterns CONSTITUTION:Two or more second conductor patterns 16a and 16b are provided under a non-circuit lead 13 on an insulating board 11 and covered with an insulator 17, and the tip of the non-circuit lead 13 is positioned at a trough part X of the insulator 17 between the second conductor patterns 16a and 16b Therefore, the non-circuit lead 13 is restrained from moving from the trough part X while the lead is subjected to a reflow treatment, and a pad region can be effectively utilized By this setup, an IC can be prevented from moving and the mounting high in density can be attained

Theory of electrical characteristics for metal‐oxide‐insulator Schottky barrier and metal‐insulator‐metal structures

Abstract: The metal‐insulator or metal‐amorphous semiconductor blocking contact is still not well understood. Here, the intimate metal‐insulator and metal‐oxide‐insulator contact are discussed. Further, the steady‐state characteristics of metal‐oxide‐insulator‐metal structures are also discussed. Oxide is an insulator with wider energy band gap (about 50 A thick). A uniform energetic distribution of impurities is considered in addition to impurities at a single energy level inside the surface charge region at the oxide‐insulator interface. Analytical expressions are presented for electrical potential, field, thickness of the depletion region, capacitance, and charge accumulated in the surface charge region. The electrical characteristics are compared with reference to relative densities of two types of impurities. ln I is proportional to the square root of applied potential if energetically distributed impurities are relatively important. However, distribution of the electrical potential is quite complicated. In ge...

Improving insulator reliability with insulating barriers

Abstract: When an insulating barrier is set up on an insulator with an inner electrode, suppression of negative surface leaderlike discharge and increase in AC flashover voltage are observed over a range of barrier distance (the distance between the HV electrode and the barrier) of >

Effect of Soot Particles on Corona Discharge

Abstract: A study has been made on the corona charging of soot particles in diesel engine exhaust for the purpose of collection and removal of these particles. Continuous operation was achieved by a specially designed corona charger in which the insulator surfaces were kept clean by a protective film of cleaning gas. This measure prevents shorting of high voltage caused by the soot deposited on the surface of the insulators. The system makes possible a basic study of the effect of soot particles on the corona discharge, the space charge effect, and the electrical conductivity of the gas-particle mixture through experimental measurements and numerical computation.

Influence of pollution of HV insulators

Abstract: The factors affecting pollution-layer conductivity are reported and discussed. Pollution-layer conductivity is shown to depend on the contamination material, the wetting method, and the pollution-layer density. Tests to simulate pollution conditions in the desert and near cement factories are also discussed. The tests were carried out using the cap-and-pin type of insulator, which is commonly used in overhead networks in Egypt and neighboring countries. The process of wetting the polluted surfaces of transmission line insulators has a great effect on the conductivities and flashover voltages of the transmission line insulators. >

Method of making an EEPROM with improved capacitive coupling between control gate and floating gate

Abstract: According to the invention, an integrated circuit with improved capacitive coupling is provided, and includes a first conductor (20), a second conductor (16), and a third conductor (22). The second conductor (22) and third conductor (16) are disposed adjacent each other, separated by an insulator region (60). The first conductor (20) contacts the third conductor (16) and extends across a portion of the third conductor (22). The first and third conductors are separated by an insulator region (54). A voltage applied to first conductor (20) and second conductor (16) is capacitively coupled to third conductor (22).

Manufacture of circuit board

Abstract: PURPOSE:To prevent insulator from deteriorating due to an electrolytic corrosion at the time of application of voltage between wiring conductors on and in an insulating board by interposing nickel of substance having less transfer of components due to an electric field between copper of wiring conductor and the board. CONSTITUTION:An inner layer circuit conductor 2 is formed of metal copper foil on an insulating board 1. A metal nickel layer 3 is formed by nickel plating on the conductor 2. However, an insulating layer 4 made of an insulating base material must be provided between inner layer circuit conductor layers and between it and a board surface circuit conductor layer 5. Then, a hole to become a through hole is opened. A metal nickel plate 7 is formed by nickel plating on the inner wall 6 of the hole. Thus, an insulation deterioration can be effectively prevented not only on the board but between the conductor and the inner wall of the hole.

Configuration effect on DC flashover on polluted insulators

Abstract: DC pollution discharge phenomena and flashover voltages of models made of glass plates, simulating a real insulator of the cap and pin type, were observed and measured. The influence of the main dimensions, such as the distance between sheds, the height of ribs, the width of ditches and the diameter of the disk, on the DC pollution flashover voltages of insulators is investigated and discussed. Some useful results are obtained relating to the prevention of bridging over clearances by local arcs and the improvement of the withstand voltage per unit leakage distance. Based on these results, suggestions for the rational design of DC insulators are presented. >