Apparatus for heat curing electrical insulation provided on a central electrical conductor of an electrical cable

Claim 1

An apparatus for heat curing heat-curable electrical insulation provided on an electrical conductor of an electrical cable by curing said insulation from its outer portion inwardly and substantially simultaneously therewith curing said insulation from its inner portion outwardly, said apparatus comprising, an outer housing made of a metallic material and adapted to contain steam under pressure, an electrical induction heating coil supported concentrically within said housing, said housing and coil being adapted to receive said conductor therethrough with its insulation thereon, said coil serving to heat said conductor within said housing which in turn transmits heat to said inner portion of said insulation to provide said heat curing thereof from said inner portion radially outwardly, a magnetic flux shield arranged within said housing and surrounding said induction coil, said shield providing a path of least resistance for lines for magnetic flux generated by said coil to thereby prevent said housing from being heated excessively during induction heating action provided by said induction heating coil, and means operatively connected to said housing for providing steam under pressure into said housing and against said insulation for providing said curing of said insulation from said outer portion inwardly, said substantially simultaneous curing of said insulation from its outer portion inwardly and from its inner portion outwardly being provided by said steam and said induction heating action respectively in said housing.

Claim 2

An apparatus for heat curing heat-curable electrical insulation provided on an electrical conductor of an electrical cable by curing said insulation from its outer portion inwardly and substantially simultaneously therewith curing said insulation from its inner portion outwardly, said apparatus comprising, an outer housing made of a metallic material and adapted to contain steam under pressure, an electrical induction heating coil supported concentrically within said housing, said housing and coil being adapted to receive said conductor therethrough with its insulation thereon, said coil serving to heat said conductor within said housing which in turn transmits heat to said inner portion of said insulation to provide said heat curing thereof from said inner portion radially outwardly, a magnetic flux shield arranged within said housing and surrounding said induction coil, said shield providing a path of least resistance for lines for magnetic flux generated by said coil to thereby prevent said housing from being heated excessively during induction heating action provided by said induction heating coil, and means operatively connected to said housing for providing steam under pressure into said housing and against said insulation for providing said curing of said insulation from said outer portion inwardly, said substantially simultaneous curing of said insulation from its outer portion inwardly and from its inner portion outwardly being provided by said steam and said induction heating action respectively in said housing.

Claim 3

A apparatus for heat curing heat-curable electrical insulation provided on a central electrical conductor comprising, an outer housing made of an electrically conductive metallic material, an electrical induction heating coil supported concentrically within said housing, said coil having a plurality of turns provided with ambient space therebetween, said coil being adapted to receive said conductor therethrough with its insulation thereon and serving to heat said conductor which in turn transmits heat to the inner portion of the insulation to provide heat curing thereof from said inner portion radially outwardly, and a magnetic flux shied arranged within said housing and surrounding said induction coil, said shield providing a path of least resistance for lines of magnetic flux generated by said coil to thereby prevent said housing from being heated excessively, said shield being comprised of a plurality of shield sub-assemblies disposed in a roughly tubular configuration around said coil with each shield sub-assembly being comprised of a plurality of elongated ferroresonant laminations having an electrical insulating material thereon and a plurality of fastening assemblies holding said laminations of each sub-assembly compactly together at spaced positions therealong with said electrical insulating material therebetween to thereby prevent current flow and energy loss therebetween, each of said laminations being in the form of an elongated ribbon-like lamination which extends along at least the full height of said coil, each lamination being of rectangular cross-sectional configuration, said laminations being made of a material having low hysteresis loss characteristics thereby keeping magnetic dipole losses to a minimum.

Claim 4

A apparatus for heat curing heat-curable electrical insulation provided on a central electrical conductor comprising, an outer housing made of an electrically conductive metallic material, an electrical induction heating coil supported concentrically within said housing, said coil having a plurality of turns provided with ambient space therebetween, said coil being adapted to receive said conductor therethrough with its insulation thereon and serving to heat said conductor which in turn transmits heat to the inner portion of the insulation to provide heat curing thereof from said inner portion radially outwardly, and a magnetic flux shied arranged within said housing and surrounding said induction coil, said shield providing a path of least resistance for lines of magnetic flux generated by said coil to thereby prevent said housing from being heated excessively, said shield being comprised of a plurality of shield sub-assemblies disposed in a roughly tubular configuration around said coil with each shield sub-assembly being comprised of a plurality of elongated ferroresonant laminations having an electrical insulating material thereon and a plurality of fastening assemblies holding said laminations of each sub-assembly compactly together at spaced positions therealong with said electrical insulating material therebetween to thereby prevent current flow and energy loss therebetween, each of said laminations being in the form of an elongated ribbon-like lamination which extends along at least the full height of said coil, each lamination being of rectangular cross-sectional configuration, said laminations being made of a material having low hysteresis loss characteristics thereby keeping magnetic dipole losses to a minimum.

Claim 7

An apparatus fo heat curing heat-curable electrical insulation provided on an electrical conductor comprising, an outer housing made of an electrically conductive metallic material, an electrical induction heating coil supported concentrically within said housing, said coil being adapted to receive said conductor therethrough with its insulation thereon and serving to heat said conductor which in turn transmits heat to the inner portion of the insulation to provide heat curing thereof from said inner portion radially outwardly, and a magnetic flux shield arranged within said housing and surrounding said induction coil, said shield providing a path of least resistance for lines of magnetic flux generated by said coil to thereby prevent said housing from being heated excessively, said shield being comprised of a plurality of shield sub-assemblies, and a plurality of circumferentially spaced supporting members supporting said shield sub-assemblies around said coil, said shield sub-assemblies and supporting members being arranged concentrically within said housing, each of said sub-assemblies being comprised of a plurality of ferroresonant laminations having electrical insulating material therebetween and a pluraity of fastening assemblies holding said laminations of each sub-assembly compactly together with said electrical insulating materal therebetwen to thereby prevent current flow and energy loss therebetween.

Claim 8

An apparatus fo heat curing heat-curable electrical insulation provided on an electrical conductor comprising, an outer housing made of an electrically conductive metallic material, an electrical induction heating coil supported concentrically within said housing, said coil being adapted to receive said conductor therethrough with its insulation thereon and serving to heat said conductor which in turn transmits heat to the inner portion of the insulation to provide heat curing thereof from said inner portion radially outwardly, and a magnetic flux shield arranged within said housing and surrounding said induction coil, said shield providing a path of least resistance for lines of magnetic flux generated by said coil to thereby prevent said housing from being heated excessively, said shield being comprised of a plurality of shield sub-assemblies, and a plurality of circumferentially spaced supporting members supporting said shield sub-assemblies around said coil, said shield sub-assemblies and supporting members being arranged concentrically within said housing, each of said sub-assemblies being comprised of a plurality of ferroresonant laminations having electrical insulating material therebetween and a pluraity of fastening assemblies holding said laminations of each sub-assembly compactly together with said electrical insulating materal therebetwen to thereby prevent current flow and energy loss therebetween.