Abstract: A method and apparatus for retarding electrochemical type decomposition of electrical insulation by flushing moisture from the insulation of installed power cables with a fluid having a low moisture content. The insulation of the power cables is dried and maintained dry by a continuous flow of dry fluid through the conductor and insulation while the cable is energized. An apparatus is disclosed which provides for the fluid to enter and exit from the cable. The disclosed method provides an effective retardation of the growth of electrochemical trees in the insulation structure and thereby significantly extends the useful life of the cable system.

Abstract: A multilayer, heat shrinkable composite tube covering is provided for a cable joint structure in which intimately joined layers define a semiconductive inner or conductor shield, an insulation layer, and an outer or insulation shield for the joint. Furthermore, a highly resistive semiconducting layer is provided over the joint under the innermost layer of the composite tube, forming a dual layer conductor shield for the joint. In the preferred embodiment, the entire composite tube is pressure extruded in a common operation and all three layers are simultaneously chemically cured and cooled under pressure to provide the intimately joined layers of the composite tube. Subsequently, when the tube is shrunk over the joint, the three layers shrink as a unit, so that there is no possibility of trapping impurities or gas bubbles between layers.

Abstract: An improved method and apparatus for fabricating insulated cables, particularly polymeric insulated electrical power cables, resistant to the formation and growth of electrochemical trees is disclosed. Internal pressure on the conductor side of the cable is maintained lower than the external pressure on the outer surface of the insulation during extrusion. Extrusion pressure higher than the external pressure results in expansion of the insulation following extrusion. This expansion or swelling reduces the number and size of cracks and voids which are precursors of electrochemical trees. In addition, pressure curing the extruded, insulated cable with a curing medium above its melting point followed by gradual gradient cooling under internal pressure and higher external cooling fluid pressure to around room temperature optimizes the resistance of the cable to nucleation and growth of electrochemical trees.

Abstract: A cable for cryogenic use includes an inner conductor and a solid polymeric insulator loosely positioned about said inner conductor above 0.degree. C. A collapsible spacer can be positioned between the inner conductor and the polymeric insulator to further space the insulator away from the conductor and thereby accommodate greater shrinkage of the insulator. In fabricating the cable, the cable is sealed and pressure is applied to the cable to expand the insulation. The cable is placed inside a rigid cylinder having an inside diameter larger than the outside diameter of the cable. The cylinder is heated to facilitate expansion of the insulation, and the cylinder is subsequently cooled while maintaining pressure to the cable.

Abstract: A cable for cryogenic use includes an inner conductor and a solid polymeric insulator loosely positioned about said inner conductor about 0.degree. C. A collapsible spacer can be positioned between the inner conductor and the polymeric insulator to further space the insulator away from the conductor and thereby accommodate greater shrinkage of the insulator. In fabricating the cable, the cable is sealed and pressure is applied to the cable to expand the insulation. The cable is placed inside a rigid cylinder having an inside diameter larger than the outside diameter of the cable. The cylinder is heated to facilitate expansion of the insulation, and the cylinder is subsequently cooled while maintaining pressure to the cable.

Abstract: A method and apparatus for retarding electrochemical tree-type decomposition of polyolefin electrical insulation by saturating the insulation with a liquid having high resistivity and a low dielectric constant. The insulation of cables which have already been in service is dried prior to being saturated with the liquid. One embodiment of the invention provides a continuing supply of liquid to the cable after it has been buried underground.

Abstract: This invention relates to stress control cones for terminations of high-voltage power transmission cables. Such cones are used beyond the end of the cable insulation shielding, and for the purpose of providing thicker insulation for reducing the stress at and beyond the unshielded insulation on a high-voltage power cable. This invention builds up greater thickness of insulation beyond the end of the cable insulation shield, preferably by wrapping the cable with layers of insulating tapes that are then heated and fused to one another and to the outside surface of the cable insulation. The hot build-up of additional insulation is fused, or brought to incipient fusion, to merge the build-up to the cable insulation and the build-up layers to one another, instead of using preformed stress relief cones which are unsuitable for very high voltage.

Abstract: An improved method and apparatus for fabricating insulated cables, particularly polymeric insulated electrical power cables, resistant to the formation and growth of electrochemical trees is disclosed. Internal pressure on the conductor side of the cable when it is maintained lower than the external pressure on the outer surface of the insulation during extrusion. Extrusion pressure higher than the external pressure results in expansion of the insulation following extrusion. This expansion or swelling reduces the number and size of cracks and voids which are precursors of electrochemical trees. In addition, pressure curing the extruded, insulated cable with a curing medium above its melting point followed by gradual gradient cooling under internal pressure and higher external cooling fluid pressure to around room temperature optimizes the resistance of the cable to nucleation and growth of electrochemical trees.

Abstract: A coaxial electric power transmission cable has an inner conductor within an outer conductor with solid dielectric material provided in the space therebetween. The dielectric material is solid at operating temperatures but non-solid at ambient temperature. An insulative spacer is provided for maintaining the coaxial alignment. The spacer includes insulative material which is identical to the solid dielectric material and may include a solid insulative insert having a solidification point higher than the insulative material whereby at least approximate coaxial spacing may be maintained should the insulative material not be maintained as a solid.

Abstract: A high voltage cable which has a composite jacket having inner and outer parts. A corrugated moisture barrier is sandwiched between the parts and bonded to them. The jacket prevents both radial and longitudinal flow of moisture in the cable. The moisture barrier may serve as a return conductor or the jacket may include additional return conductors.

Abstract: A cable such as used in cryogenic and superconductive applications includes an inner conductor, an outer conductor or shield, and a solid dielectric between the inner and outer conductors. The dielectric is introduced into the space between conductors in liquid or gaseous form, preferably under pressure, and the temperature of the dielectric is lowered to or below the freezing point for the material. Pressure relief should the solid dielectric suddenly vaporize by rapid heat rise is provided by holes in the outer conductor or by scoring the inner surface of the outer conductor to provide rupture points in the conductor.

Abstract: This telephone service wire has metal conductors insulated with polyethylene plastic insulation or equivalent, assembled in a core having a flame-retardant polyvinyl chloride jacket. Space between the individual insulated conductors is filled with an improved filling compound for preventing access of water into the core of the service wire. The filler compound is an ester-based compound that avoids the disadvantages of the usual petrolatum-based filler compound which extracts not only antioxidants and copper-inhibitors from a polyethylene component but plasticizers from a polyvinyl chloride compound. Depletion of these essential compounding materials can seriously affect the physical characteristics of either the insulation or jacket of such filled telephone service wires.

Abstract: This cable for high-voltage, alternating current power transmission cables not only reduces the access of moisture into the cable but reduces access of moisture to the inner face of the insulation to such an extent as to make the cable highly resistant to the formation of electrochemical trees in the solid extruded insulation of the cable. A compressible layer of closed cell, foamed plastic is extruded over the outside surface of the insulation; and a metallic shield fits tightly around the compressible layer, the metallic shield being a longitudinally folded tape with a lap seam which is preferably bonded to prevent ingress of air or other fluid into the cable. If the conductor is stranded, sealant is used to prevent ingress of moisture, or of air, and the humidity it contains into the cable at cable ends.

Abstract: High-voltage power cables with extruded dielectric plastic insulation, installed underground, have their life shortened by the formation of electrochemical trees in the insulation. This invention provides a high-voltage power transmission cable constructed with sealant in interstices of a stranded conductor that are not filled by the semi-conducting material of a conductor shield of the cable. The construction prevents or greatly delays the formation of electrochemical trees in the insulation of the cable. The sealant prevents entrance of air into the cable at cable ends, and the passage of the humidity of the air through the conductor shield to an interface between the conductor shield and the inside surface of insulation that surrounds the conductor shield.

Abstract: This apparatus is for evaluation installed cable systems, including those that are already in use. The apparatus measures dissipation factor, partial discharge (corona) and insulation resistance of the cable system; all of these being necessary to determine the condition of the cables. This invention is unique, in that it can be used with installed cable systems that have their metallic shielding grounded; and the apparatus can be mounted on a truck or trailer for movement to any place where an installed system is to be evaluated.

Abstract: This improved stop joint is used at connections of one length of electric cable to another, for the purpose of preventing fluid in one length of cable from contacting fluid in the next length of cable. The joint includes a stop tube that surrounds the end portion of one length of cable and that is made with a mid-portion of resin base material, preferably reinforced, and end portions of metal connected to the resin base material by fluid-tight connections. These metal end portions are secured to the pipe or shield that surrounds one or both of the lengths of cable. Parts are constructed so as to minimize the time and cost of making the connections between the cable lengths and the connecting of the stop joint with the pipe or shield that surrounds the respective cables.

Abstract: This invention makes extruded, vulcanized, high voltage cables insulated with thermosetting compounds at much higher rates of production and with superior insulation of reduced thickness and with reduced cavities or voids in the insulation. As the cable comes from an extruder, it passes into a curing chamber with a heat booster that quickly raises the insulation to a temperature at which it is cured much more quickly than with steam heating of the prior art. A high temperature liquid in contact with the insulation maintains the high temperature; and because of the greater curing heat, the cable can travel through the curing chamber at a faster rate and into a cooling tube where it contacts with a cooling liquid under high pressure. The insulation compound is treated to reduce the size of cavities; and the high pressure maintained by the curing and cooling mediums prevent expansion of cavities before the insulation is set.

Abstract: Extruded dielectric power cables installed underground have their life shortened by the formation of electrochemical trees in the insulation. Tree formation can be prevented if the insulation is initially dry and the cable construction is such that moisture cannot gain access to the insulation under operating conditions encountered during installation and underground use. This invention eliminates initial moisture and has a construction that greatly retards ingress of moisture to the insulation during installation when the cable is in service and prevents longitudinal movement of water along the cable due to accidental damage to the cable or electrical failure.

Abstract: This invention carries a power cable from a floating power plant to a fixed connection from which the power cable can transmit to a distributing system on shore. The cable support distributes the bending of the cable over a length of cable so that no deterioration of the cable occurs as the result of successive bending and unbending with the tidal motion of the floating power plant. A jointed cover protects the cable support from exposure to the weather and from icing.

Abstract: This electrostatic shielding tape is a metal strip of low resistance and low reactance folded longitudinally over the length of an insulated power cable having a semi-conducting insulation shield surrounding its insulation. The longitudinally folded metallic tape has its edges free to permit expansion of the insulation and insulation shield, located directly under it, without significant deformation of the insulation and the insulation shield. When the tape is of a metal requiring a thin corrosion-protective coating, the coating on the side adjacent to the insulation shield is preferably semi-conducting to accept charging current from the insulation shield. It is a feature that the metal of the electrostatic shield is in electrical communication with the insulation shield. .Iadd.