Abstract: A power transformer is provided with a housing having a plurality of apertures for receipt of a bushing well of a bushing assembly. Each bushing assembly includes a bushing well adapted to be secure in one aperture of the power transformer, and a bushing adapted to be connected to a terminal in the bushing well to permit the conducting of electric current between the bushing assembly and the transformer. The bushing assembly further includes a connector for connecting the bushing conductor to a terminal positioned in the bushing well. The power transformer includes a cap to cover and isolate the unused bushing wells. The cap is preferably a plate structure that attaches to the lip of the bushing well and uses the dielectric formed by the air enclosed by the cap and the bushing well to prevent sparking over to adjacent sites, corona discharge, and accidental contact with a live terminal therein, and to guards against contamination of the bushing well.

Abstract: An improved hollow core composite bushing for use in, for example, a dead tank circuit breaker, is smaller and lighter and offers other advantages over previous designs. The hollow core bushing includes therein a fiber reinforced plastic (FRP) elongated tube that operates to increase the dielectric constant between a conductor and a transition shield. By placing the transition shield external to the hollow core bushing and providing the FRP tube between the conductor and transition shield, the dielectric constant between the shield and conductor is increased thus allowing the inner diameter of the shield and outer diameter of the bushing to be decreased. In addition, the transition shield may be an integral part of the flange that is mounted to the bushing current transformer support column or interrupter enclosure of the dead tank circuit breaker thus further reducing the diameter and overall size of the bushing. Further, the transition shield may be an integral part of the FRP tube.

Abstract: A vacuum-tight cable feedthrough device includes a metallic first flange that is penetrated by a slot. Passing through the slot is a flat stripline cable that includes a plurality of conductive signal channels encompassed by a dielectric material on whose upper and lower surfaces is disposed a conductive material including a ground. The stripline cable is sealed within the slot to provide a substantially vacuum-tight seal between the cable and the first flange. In a preferred embodiment, the cable feedthrough device includes a plurality, at least 16, of stripline cables. In a further preferred embodiment, the device includes a second flange and a bellows sealably connecting the first and second flanges, thereby providing a substantially vacuum-tight, flexible housing for the plurality of cables.

Abstract: A supporting insulator for installation between connecting flanges of a gas-insulated switching installation is provided with an outer ring, with an insulator body which is in the form of a disk and which is formed of a hardened cast resin, and with at least one cast fitting which is subjected to high voltage and is cast in the insulator body. The outer ring need not be assembled with the insulator body until after the outer ring has been colored. The outer ring includes two identically constructed rings that are joined together in a separable, but positively locking manner such that the insulator body can be separated from the outer ring when the rings are separated.

Abstract: A device for protecting the end of a high or very high tension electric cable having synthetic insulation from the effects of insulation breakdown, comprises an insulator and a metal enclosure defining a gastight chamber around said end, which chamber contains dielectric gas under pressure and that is separated from ambient air by a rupture disk provided in the metal enclosure. The device further includes a circularly symmetrical collar protecting said insulator and extending inside the chamber around said cable and terminating in a toroidal rim having a convex face directed towards the cable beyond the breakdown zone inside the chamber and at its end distant from the rupture disk. The device is applicable to protecting the end of a very high tension cable.

Abstract: A grommet is provided with a small diameter cylindrical portion defining a first aperture and an expanded diameter portion defining a second aperture which is in communication with the first aperture for inserting a wire harness. In the second aperture of the expanded diameter portion, one end of a bag-shaped portion enclosing the wire harness at a spaced relationship therewith is connected with an end face of the small diameter cylindrical portion. The other end of the bag-shaped portion is made as a tightening portion which sealingly fits with the outer periphery of the wire harness. A gelatinous filler material made of silicone or the like is sealed in the interior of the bag-shaped portion. The small diameter cylindrical portion and the tightening portion are bound with a clamping device against the outer periphery of the wire harness.

Abstract: The invention relates to a condenser body for field control in transformer bushings and the connection of the body to the conductor of a transformer winding for transformers used in HVDC converter plants. The condenser body is arranged as a solid of revolution with concentrically laid condenser layers. It is formed from one end with an outwardly-directed straight frustum of a cone and from the other end with an inwardly-directed straight frustum of a cone.

Abstract: A bushing system for high voltage electrical equipment includes a weathershed with integral annular shirts molded around an electrical conductor. The weathershed has a cavity at its base for mating with the opening in the housing for the high voltage electrical equipment. A dielectric gas in the housing communicates with the cavity in the weathershed. A flange and seal are provided at the base of the weathershed for sealingly connecting the bushing system to the housing. A secondary ground may also be provided.

Abstract: A method of producing a ceramic insulating bushing to be filed with dielectric gas under pressure and which is free from any risk of explosion, comprising the following operations:(1) manufacturing a ceramic bushing (10) having an inside surface which is conical over the entire length (L1) of the bushing;(2) making a conical sleeve (30) of strong insulating material, the sleeve having the same cone angle as the inside surface of the bushing and having a length (L2) which exceeds that of the bushing;(3) inserting the sleeve (30) into the bushing until it makes contact with the entire inside surface (20) of the bushing (10); and(4) cutting off the sleeve at the ends of the busing.

Abstract: Improved switchblade-type, air dielectric switchgear apparatus is provided which utilizes a minimum of supporting insulators and incorporates readily field-replaceable bushing assemblies so that the switchgear apparatus may be serviced in the field using only conventional tools. In preferred forms, the switchgear apparatus includes internal switch assemblies making use of substantially vertically oriented switchblades mounted for pivotal movement about an elevated, generally horizontal axis located above the corresponding stationary contacts. The replaceable bushing assemblies are advantageously mounted at a level for interconnection with the upper ends of associated switchblades, and the assemblies include a conical outermost connection and adapted to receive a line connecting elbow, together with an elongated, inwardly extending, electrically conductive intermediate portion carrying an innermost terminal.

Abstract: An electrical bushing of a gas insulated electrical apparatus comprises an insulating tube, a central conductor extending through the insulating tube and a cylindrical shield disposed between the central conductor which is electrically connectable to ground at one end and has an electrical field moderating ring integrally formed therewith at the other end thereof. The central conductor has a reduced diameter portion in the vicinity of the electric field moderating ring of the cylindrical shield and large diameter portions and tapered portions connecting the reduced diameter portion to the large diameter portions. Thus, since the reduced diameter portion is formed in a region where the electric field strength is high, the concentration of the electric field in that region is moderated, thereby resulting in an improvement in the withstand voltage characteristic of the bushing. The reduced diameter portion can be formed as a separate member.

Abstract: An electrical bushing for use with a gas insulated electrical apparatus comprises an insulating tube, a central conductor extending through said insulating tube, a grounded cylindrical shield disposed between the central conductor and the insulating tube, an intermediate shield disposed between, and electrically insulated from, the cylindrical shield and the central conductor so as to surround the latter. The intermediate shield has a reduced diameter portion in the vicinity of the free end of the grounded cylindrical shield, large diameter portions and tapered portions connecting the reduced diameter portion to the large diameter portions to provide a smooth distribution of the electric field between the central conductor and the field moderating ring, so that the concentration of the electric field is moderated by the grounded shield and the intermediate shield.

Abstract: A cover cap (40) is provided for covering the open end of a support insulator (38) having a discharge electrode hanger rod (28) passing coaxially therethrough. The cover cap (40) comprises a top (42) and a sloping side wall (44) extending coaxially outwardly and downwardly from the perimeter edge (54) of the top (42) and having a radial lip (46) and an axial lip (48) extending outwardly at substantially right angles to each other from its lower perimeter surface. A tubular gas injection nozzle (92) having an elbow subtending an angle of 135 degrees, is provided in the sloping side wall (44) for passing a jet of scavenging gas into the interior region encompassed by the sloping side wall (44). At least one access opening (70) is provided in the sloping side wall for permitting access into the interior region encompassed by the sloping side wall (44).

Abstract: This invention is directed to an improved seal for an electrical conductor bushing operable in service above about 69 kV. Typically, the seal is interposed between the bushing cap and the porcelain. Two flat, thin non-metallic gaskets are stacked together and separated from each other by means of a rigid washer. The rigid washer is provided with a pair of inner and outer upstanding flanges which form a trough for engagement therein of one of the gaskets. The gasket-washer assembly provides oil-tight integrity for the bushing under standard industry cantilever and thermal expansion tests.

Abstract: A high voltage feed-through bushing has a conductive gasket to connect a conductive coating to a metal enclosure. A central conductor rod of the bushing is surrounded by an insulating tube which is surrounded by a tubular conductor to establish a floating equipotential surface. The central conductor rod is located within a bushing shell by sealing means at the outer and inner ends of the bushing.

Abstract: An elongated electric bushing for a transformer, reactor, or the like is provided with a flexible intermediate flange (3) which comprises a plurality of spring devices (28) oriented in the longitudinal direction of the bushing, and a cardan assembly (11) for taking up longitudinally directed forces arising in case of an earthquake.

Abstract: A porcelain gas-filled bushing wherein a central conductor passes through a porcelain tube which is filled with an insulating gas, a fitting flange which is fastened to one end of the porcelain tube is grounded, and an electrode which encircles the central conductor at a predetermined spacing therefrom and which is covered with an insulating member is electrically connected with the fitting flange. Alternatively, several electrodes fitting within each other may be provided around the central conductor. In one embodiment the electrodes are conical and flare radially outwardly of said central conductor from a lower end toward an upper end thereof.

Abstract: A gas-insulated bushing including an insulating tube filled with an insulating gas, a central conductor centrally arranged within the insulating tube, and a capacitor unit connected to the central conductor and partitioning the interior of the insulating tube. The central conductor has an intermediate constriction to which the capacitor unit is connected and is formed of two connected conductor parts, at least one of which is terminally restricted to form the constriction. A pair of flanges is secured to the ends of respective of the conductor parts and connects the conductor parts at the constriction. A shield member is supported on one of the flanges and spaced apart from the conductor parts at the constriction in order to relieve the electric field at the constriction.

Abstract: A bushing for insulating a conductor in a high-voltage electrical transmission system is fabricated of paper and metallic foil disposed as coaxial layers about the conductor. At one end of the bushing, the paper is impregnated with oil. At the opposite end of the bushing, the paper is impregnated with a resin which cures to a solid form. The paper, oil and resin serve as electrical insulators, while the metallic foil serves to disperse uniformly the electric field. A mounting flange is positioned on an enclosing casing for setting the resin end of the bushing into the housing of an electrical apparatus to which the bushing may be mounted so as to prevent contamination of the interior of the housing with the oil.

Abstract: Described is a multi-element, high voltage radio frequency bushing for trmitting RF energy to an antenna located in a vacuum container. The bushing includes a center conductor of complex geometrical shape, an outer coaxial shield conductor, and a thin-walled hollow truncated cone insulator disposed between central and outer conductors. The shape of the center conductor, which includes a reverse curvature portion formed of a radially inwardly directed shoulder and a convex portion, controls the uniformity of the axial surface gradient on the insulator cone. The outer shield has a first substantially cylindrical portion and a second radially inwardly extending truncated cone portion.

Abstract: This high-voltage terminal bushing comprises a tubular shell of electrical insulating material having a passageway extending between its ends and an electrical conductor within the passageway that has an external surface spaced from the internal surface of the passageway. The external surface of the conductor is covered with a thin coating of insulating material spaced from the internal surface of the passageway by a cylindrical air gap. The coating has sufficient dielectric strength to prevent any corona streamers from the conductor from impinging against said internal surface at impulse voltages up to the rated impulse insulation level of the bushing.

Abstract: A gas-insulated bushing comprises an elongated epoxy insulating shell having a grounded mounting plate secured at one end thereof and an electrical connection terminal secured at the other end thereof. An inner conductor at high voltage is disposed within the shell and is secured to the terminal, with an insulating gas electrically insulating the inner conductor from the shell. An electrically grounded ground shield is cast into the epoxy shell and extends outwardly to physically and electrically contact the grounded mounting plate. A throat shield is secured to the mounting plate and extends longitudinally into the interior of the shell. The dual shield system disclosed functions to inhibit puncturing of the insulating shell, with a resultant loss of insulating gas, in the event of either internal or external flashovers.

Abstract: A bushing in which a conductor penetrates through the center of a porcelain tube of which the one end is closed, the other end of the porcelain tube is closed by a cone-shaped insulation spacer which protrudes into the porcelain tube and which also supports the conductor, a capacitor cone is disposed to surround the conductor and a predetermined portion of the insulation spacer in the porcelain tube, an insulating material is charged into the porcelain tube, the side opposite to the capacitor cone relative to the insulation spacer is coupled to a container which is filled with an insulating gas having a predetermined pressure and which accommodates electrical equipment, and the conductor is connected to the electrical equipment.

Abstract: The invention comprises a bushing surrounding an electrical conductor, including a porcelain tube which employs a gaseous insulator, an insulating tube disposed with a space of small volume set relative to the inner periphery of the porcelain tube, the small space being filled with an insulating medium which is deformable with a predetermined force. According to the construction, when the porcelain tube has been damaged, its fragments can thus be prevented from scattering far. The flashover of the bushing can be prevented by disposing compression springs in the lower part of the insulating tube, and the electric field distribution of the outer surface of the bushing can be improved by coating the surface of the insulating tube with an electrically-conductive coating material.

Abstract: A gas-filled insulating bushing includes a center conductor and a porcelain tube enclosing therein an insulating gas. A tubular insulating partition is arranged adjacent to an inner wall of the porcelain tube to define the space therein into two spaces communicated with each other through small diameter vents so as to eliminate pressure differences between the spaces, thereby making lower a back pressure in explosion to suppress scattering of fragments of the porcelain tube and hence prevent neighboring instruments from being damaged.

Abstract: An improved gas-insulated bushing having a high withstand voltage and an increased capacity to cool a conductor, wherein the upper end portion of a potential-controlling capacitor in the form of a stopped tube is directly airtightly fitted to the outer surface of the central conductor, thereby enlarging a distance between the capacitor and the inner wall of the porcelain insulator and elevating the withstand voltage of the bushing; an internal pipe open at the bottom is inserted into the central conductor; the upper portion of the internal pipe communicates with a cooling case provided at the top of the porcelain insulator; a cooling gas is circulated through a route consisting of the cooling case, a space defined between the outer wall of the internal pipe and the inner wall of the central conductor and the interior of the internal pipe; and a cooling mechanism completely separated from an insulation gas chamber is provided in the central conductor, thereby enabling a cooling gas having a higher cooling capa

Abstract: A gas-insulated bushing includes an elongated hollow insulating shell with an elongated inner conductor disposed therein spaced apart from the insulating shell, with an insulating gas electrically insulating the conductor from the insulating shell. A terminal is sealingly secured to the insulating shell and prevents the escape from the interior of the shell of the insulating gas disposed therein. The terminal includes an electrical connector which is external to the shell and which includes a portion extending inwardly into the shell. This electrical connector is aligned with, but spaced apart from, the electrical conductor to provide room for thermal expansion of the electrical conductor.

Abstract: A low-pressure gas-insulated bushing is provided including an elongated, hollow insulating shell having a terminal end and a throat end with a opening therethrough. A bushing terminal is secured to the shell terminal end, and an insulating gas at low pressure is disposed in the shell. A tubular electric conductor is disposed in the shell and extends outwardly therefrom through the throat end opening. The conductor is in electrical contact with the terminal end, thereby providing electrical connection to an overhead line. The conductor is expanded in diameter in the vicinity of the throat end to minimize the throat diameter required, while the conductor at the remainder of its length is sized to carry the rated current of the bushing.

Abstract: An electrical insulator assembly and method of manufacturing same, having a generally cylindrical or conical body portion formed of a breakable cast solid insulation system and a reinforcing member having a corrugated configuration and formed of a web or mesh type reinforcing fabric. When the breakable body member has been broken, the corrugated configured reinforcing web member provides a path of escape for pressurized insulating fluid while limiting the movement of body member fragments in the direction of escape of the pressurized fluid.

Abstract: The present invention is a condenser-type electrical bushing having a mounting flange, an upper weather casing connected to the mounting flange, a central electrode and a lower casing, both supported by the upper weather casing. A condenser is wound about the central electrode. The bushing further has a plurality of wedging blocks which are rigidly connected to the condenser and located above the mounting flange such that upon mechanical failure of the upper weather casing the central electrode and the condenser are prevented from falling into the electrical apparatus.

Abstract: A high voltage insulating bushing is formed of wound insulating foils and is provided with conductive parts which are at different electrical potentials and with a wound insulating body arranged between the conductive parts. The wound insulating body contains potential control inserts which are formed of embossed electrically conductive foils, and which are impregnated with an insulating medium. The resulting embossed potential control inserts are mechanically more stable than known potential control inserts which are formed of smooth foils. In one embodiment, the embossed potential control inserts may be wound between adjacent layers of embossed insulating foils so as to facilitate the evacuation of air occluded in the winding and the complete permeation of the portion of the winding near the potential control inserts with the insulating medium.

Abstract: A high voltage insulating bushing formed of wound insulating foils is provided with a double layer material interposed between preselected windings of the insulating foils. The double layer material is formed of insulating material which has been laminated with an electrically conductive material, such as aluminum, and serves to advantageously distribute the electric field potential throughout the insulator body. The double layer material is arranged so that the electrically conductive material faces inwardly toward a longitudinal axis of the insulator body. The edges of a double layer foil which are near the outer surface of the insulator body are folded inward to form an edge wherein the electrically conductive material is enclosed within the insulating layer. In some embodiments, voids formed between the insulating foils and the folded edges of the double layer material are filled with an insulating medium, such as SF.sub.6 gas.

Abstract: A high voltage insulator bushing is formed of wound insulating foils and is provided with conductive parts which are at different electric potentials and with a wound insulator body arranged between the conductive parts. The wound insulator body contains layers of an embossed insulating foil which consists of a plastic material which shrinks above a predetermined temperature. The embossed insulating foil is subjected to a thermal shrinking treatment prior to being wound as part of the insulator body. Such preshrinking prevents further shrinkage which would occur when the high voltage bushing is operated. Smooth insulating foil may be wound as part of the insulator body so as to be interposed between the layers of the embossed insulating foil. The gaps and voids which are formed between the layers of insulating foils caused by the irregular surface of the embossed insulating foil are filled with an insulating medium.

Abstract: A high voltage seismic bushing charged with an insulating material has a procelain tube having an adapter rigidly connected to one end of the tube. The adapter is flexibly connected to a mounting flange such that the porcelain tube is free to move relative to the mounting flange in the event of an earthquake. The means for flexibly connecting the adapter to the mounting flange utilizes a spring mechanism to absorb the energy through friction to attenuate the movement of the porcelain tube. A resilient buffer member is interposed between the adapter and the mounting flange to provide a predetermined spacing therebetween and absorb the impact due to the movement of the adapter relative to the mounting flange. A sealing member seals the interface between the adapter and the mounting flange for containing the insulating material charged therein.

Abstract: A high voltage electric bushing comprises a hollow elongated dielectric weathershed which encloses a high voltage conductor. A collar formed of high voltage dielectric material is positioned over the weathershed and is bonded thereto by an interface material which precludes moisture-like contaminants from entering between the bonded portions. The collar is substantially thicker than the adjacent weathershed which it surrounds, providing relief of the electric stresses which would otherwise appear on the outer surface of the weathershed. The collar may include a conductive ring or capacitive foil to further relieve electric stresses experienced by the bushing.

Abstract: Dielectric gas mixture including a binary pair of gases with electric strengths in uniform or quasi-uniform fields which are higher than that for either component of the gases alone. Such binary pairs include (a) SF.sub.6 and CF.sub.3 CFCF.sub.2, (b) SO.sub.2 and CF.sub.3 CFCF.sub.2, and (c) SO.sub.2 and SF.sub.6.

Abstract: A relatively low-cost dielectric gas mixture including a halogenated hydrocarbon such as CC1.sub.2 F.sub.2, subject to carbonization in the presence of an electrical discharge, and a minor portion of CF.sub.3 NO.sub.2 or CF.sub.3 SO.sub.2 F which suppresses carbonization of the halogenated hydrocarbon.

Abstract: An electrical bushing which contains a pressurized gas as the main insulation and which contains a metallic shield electrode therein near the grounded end of the tubular outer insulator for control of the voltage distribution, also includes a solid insulating body which is made of a material having a higher permittivity than the insulating gas, thus enabling the bushing to have a smaller diameter. The metallic shield electrode is at least partially embedded in the insulating body. The insulating body includes an upper field-controlling portion in the space between the tubular outer insulator and the central current conductor which includes an inner side that extends towards the conductor to form a tapered annular space, most of the upper portion being located beyond the metallic shield electrode with respect to the grounded end of the tubular insulator.

Abstract: A high voltage seismic bushing charged with an insulating material has a porcelain tube having an adapter rigidly connected to one end of the tube. A connecting plate is rigidly connected to a mounting flange. The adapter is flexibly connected to the connecting plate such that the porcelain tube is free to move relative to the mounting flange in the event of an earthquake. The means for flexibly connecting the adapter to the connecting plate utilizes a damping mechanism to attenuate the movement of the porcelain tube. A resilient buffer member is interposed between the adapter and the connecting plate to provide a predetermined spacing therebetween and absorb the impact due to the movement of the adapter relative to the connecting plate. A sealing member seals the interface between the adapter and the connecting plate for containing the insulating material charged therein.

Abstract: Electrical bushing having a plurality of individual condenser modules coaxially enclosing an electrical conductor. The condenser modules are spaced apart to define a gap therebetween. Each condenser module includes a plurality of concentric, axially extending, electrically conductive layers. The axial spacing between the ends of corresponding conductive layers in adjacent, coaxial condenser modules is varied across the condenser modules in order to control the voltage gradient across the gap between the condenser modules and to provide uniform capacitance across the bushing.

Abstract: First and second conductive flanges adjacent first and second ends of a hollow insulator column are biased together by a through-rod assembly such that the first and second flanges cooperate with the insulator column to form a substantially enclosed chamber. The through-rod assembly means includes three coaxial cylinders connecting the first conductive flange to the second conductive flange. The innermost cylinder is connected to the first conductive flange and extends internally into the enclosed chamber. An external shoulder extends from the distal end of the first cylinder and supports one end of a second cylinder. The remaining end of the second cylinder terminates at an internal flange extending from the distal end of a third cylinder which extends from the second conductive flange.

Abstract: High voltage bushings for use within SF.sub.6 circuit breakers are provided with a tandem arrangement of an outer acid resistant gasket and an inner gas impervious gasket to prevent contact between the bushing oil and the SF.sub.6 gas.

Abstract: An internal shield ring for the air entrance bushing of a gas-insulated bus system tapers inwardly at its free end and has a reduced spacing with respect to the central bushing conductor to increase the dielectric stress between the end of the shield ring and the central bus. This reduces the stress on the external bushing insulation material and thus permits a reduction in the bushing diameter.

Abstract: An electrical feed through bushing for transformers multifunctionally uses the transformer coolant to cool the bushing conductor. The bushing is piped into the transformer oil heat exchanger.

Abstract: A gas filled bushing having an insulating shell and a centrally disposed bushing conductor. Flexible means integrally formed with the flange ring are utilized to control the compression of sealing means against the insulating shell to minimize the leakage of gas through the joint between the flange ring and the porcelain or epoxy insulating shell, without using excessive force which might break the insulating shell.

Abstract: A gas filled bushing is disclosed as comprising an outer grounded shield, an inner grounded shield and an intermediate potential shield mounted on the inner grounded shield by means of an axial insulator and extending between the inner grounded shield and a central conductor. In a modified embodiment a plurality of intermediate potential shields are disposed concentrically between the central conductor and the inner grounded shield so as to more efficiently control the potential distribution along the outer surface of the bushing.

Abstract: A gas-insulated transmission line including an elongated outer sheath and a plurality of elongated inner conductors disposed within the outer sheath. An insulating gas electrically insulates the conductors from the sheath, and support means insulatably support the conductors within the sheath. The interior of the outer sheath is separated into a plurality of discrete compartments by walls, with each compartment having disposed therein one of the inner conductors. The compartmentalization of the outer sheath minimizes the possibility of a fault being transferred from one inner conductor to the other conductors.

Abstract: A fluid-filled electrical bushing for connecting an electrical conductor in a fluid-filled transformer to an electrical conductor in another enclosure. The electrical bushing includes a safety device consisting of two coaxial flexible capsules which are joined to a plate disposed therebetween and which respectively communicate with the dielectric fluid in the bushing and with the dielectric fluid in the transformer. The plate, which is movable in opposite axial directions in response to the pressure difference between the dielectric fluid in the bushing and the dielectric fluid in the transformer acting thereon, alternately engages first or second electrical contacts to complete an electrical circuit indicating an over-pressure condition caused by internal arcing, or the abnormal expansion or an insufficient amount of dielectric fluid within the bushing.

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.

Abstract: An electrical bushing assembly suitable for operation in an ambient temperature of 150.degree. C. The electrical bushing assembly includes a ferrous electrical conductor insulated with wholly aromatic polyamide fibers impregnated with silicone oil and surrounded by a ceramic insulating member which includes Al.sub.2 O.sub.3.