General Cable Corporation

Electric Power Research Institute Incorporated

Cable Technology Laboratories, Inc.

Other

Gk Technologies, Incorporated, General Cable Company Division

Cable Technology Labs., Inc.

George Bahder

George S Eager, Jr

Mario Rabinowitz

Carlos Katz

David A Silver

Attila F Dima

Paul F Thompson

Louis A Bopp

Rafael Suarez

Adolf S Knott

John J Dougherty

James J Walker

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.

Electrical cable joint structure and method of manufacture

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.

Tree resistant power cable

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.

Method of making cryogenic cable

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.

Cryogenic cable and method of making same

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.

Extension of cable life

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. The build-up material is shaped to the most effective contour by the application of force from hydraulically-operated molding shapes made of metal and forced against the build-up by hydraulic motors attached to portable shaping apparatus.

Apparatus for molding stress control cones insitu on the terminations of

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.

Electrochemical tree resistant power cable

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.

Insulative spacer for a low temperature coaxial cable and coaxial cable

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.

Moisture resistant cable

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.

Method of forming dielectric material for electrical cable and resulting

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.

Telephone service wire with ester-based filling compound

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.

Solid dielectric cable resistant to electrochemical trees

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.

Method of making extruded solid dielectric high voltage cable resistant

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.

Mobile bridge test apparatus and method utilizing a sub-power frequency

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.

Growing community of inventors

Edison, NJ, United States of America

George Bahder