Cables with improved water blocking capabilities

Abstract

A cable includes a cable core having one or more conductors. Each of the one or more conductors includes a plurality of conductive wires, at least a portion of which is coated with a water blocking compound. An insulation layer surrounds each of the one or more conductors. The cable further includes a laminated metallic tape surrounding the cable core and a protective polymeric layer surrounding the laminated metallic tape. The protective polymeric is formed of a foamed polymer. A sheath surrounds the protective polymeric layer and forms the outermost layer of the cable.

Description

[0001] Title of Invention : CABLES WITH IMPROVED WATER BLOCKING CAPABILITIES

[0002] The present application relates to cables. More specifically, the present application relates to cables for the transmission or distribution of medium-voltage power that are capable of preventing or limiting ingress and migration of water within the cable.

[0003]

[0004] The penetration of water into the electrically conductive core of a cable is problematic since, in the absence of suitable solutions designed to plug the water, once the latter has penetrated it is able to flow freely inside the cable. Water can vaporize due to the temperatures reached during the use of the conductor and migrate into the insulation of the power cable where “trees” may form, potentially causing a decrease in the electrical properties of the insulation, an increased risk of electrical perforation, and an acceleration of the aging of the cable. Water penetrating the electrically conductive core is also problematic because it can cause corrosion of the metal wires forming the conductive core. Migration of water can further lead to damage of joints, terminals, and other equipment connected to the cable.

[0005] This water penetration issue is particularly felt in underground and underwater cable deployments where the risks of the entry and spreading of water along the entire cable are very high. Such penetration can occur, for example, by simple diffusion of water through the outer polymeric sheath of a cable or as a result of abrasion, accidental impact, or the action of rodents, factors that can lead to an incision or even to rupture of the outer sheath of the cable and, therefore, to the creation of a preferred route for ingress of water to the interior of the cable.

[0006] International Patent Publication No. WO2001 / 046965 to Belli et al. (“Belli ‘965”) describes an electric cable resistant to water penetration. Specifically, Belli ‘965 discloses a cable having a water swellable layer that forms a barrier to the penetration of water in a position radially external to a metallic screen. A water swellable material, preferably in the form of powder, is embedded within an expanded polymeric material, where the water swellable material is capable of expanding on contact with water.

[0007] International Patent Publication No. WO2004 / 003940 to Belli et al. (“Belli ‘940”) describes an impact resistant compact cable. In particular, Belli ‘940 discloses a cable having a semiconductive water-blocking layer made of an expanded polymeric material in which a water swellable material is embedded or dispersed. Because the electrical property of the outer semiconductive layer is partially performed by said water-blocking semiconductive layer, the thickness of the outer semiconductive layer can be advantageously reduced.

[0008] International Patent Publication No. WO2020 / 027844 to Horton et al. (“Horton”) describes a cable having a conductor strand filled with recycled crosslinked compounds. In particular, Horton discloses a power cable comprising an electrically conductive core made of a plurality of wires that are stranded and impregnated with a water-blocking composition to prevent ingress and migration of water through the conductive core.

[0009] While certain methods for resisting water penetration have been disclosed in the art, what is desired is a cable that provides sufficient protection against both longitudinal and radial water penetration, particularly for usage near seashores where heat and saltwater may provide for a harsh environment and corrosion is a major concern. It is also desired to have a cable that provides improved mechanical protection and longer cable life.

[0010]

[0011] Accordingly, an exemplary embodiment of the present invention provides a cable comprising a cable core including one or more conductors, each of the one or more conductors including a plurality of conductive wires, wherein at least a portion of the plurality of conductive wires is coated with a water blocking compound; and an insulation layer surrounding each of the one or more conductors. The cable further comprises a laminated metallic tape surrounding the cable core; a protective polymeric layer surrounding the laminated metallic tape, the protective polymeric layer being formed of a foamed polymer, wherein a foam rate of the foamed polymer is from about 10% to about 50%; and a sheath surrounding the protective polymeric layer and forming the outermost layer of the cable.

[0012] The present invention may also provide a cable comprising a cable core including one or more conductors, each of the one or more conductors including a plurality of conductive wires, wherein at least a portion of the plurality of conductive wires is coated with a water blocking compound; an insulation layer surrounding each of the one or more conductors; a first water blocking tape surrounding the insulation layer of each of the one or more conductors; and a metallic screen surrounding the first water blocking tape of each of the one or more conductors; and a second water blocking tape surrounding the metallic screen of each of the one or more conductors. The cable further comprises a laminated metallic tape surrounding the cable core; a protective polymeric layer surrounding the laminated metallic tape, the protective polymeric layer being formed of a foamed polymer, wherein a foam rate of the foamed polymer is from about 10% to about 50%; and a sheath surrounding the protective polymeric layer and forming the outermost layer of the cable. The cable provides protection against radial water penetration and longitudinal water protection.

[0013] The present invention may also provide a cable comprising a cable core including one or more conductors, each of the one or more conductors including a plurality of conductive wires, wherein at least a portion of the plurality of conductive wires is coated with a water blocking compound and interstices between the conductive wires are filled with the water blocking compound; an insulation layer surrounding each of the one or more conductors, wherein the insulation layer is formed from a tree-retardant crosslinking polyethylene; a first water blocking tape surrounding the insulation layer of each of the one or more conductors, wherein the first water blocking tape is semiconductive; and a copper metallic screen surrounding the first water blocking tape of each of the one or more conductors; and a second water blocking tape surrounding the metallic screen of each of the one or more conductors. The cable further comprises a laminated aluminum tape surrounding the cable core; a protective polymeric layer surrounding the laminated metallic tape, the protective polymeric layer being formed of a foamed polymer, wherein a foam rate of the foamed polymer is from about 20% to about 30%; and a sheath surrounding the protective polymeric layer and forming the outermost layer of the cable.

[0014] Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses embodiments of the present invention.

[0015]

[0016]

[0017]

[0018]

Claims

A cable comprising:a cable core comprising:one or more conductors, each of the one or more conductors including a plurality of conductive wires, wherein at least a portion of the plurality of conductive wires is coated with a water blocking compound; andan insulation layer surrounding each of the one or more conductors;a laminated metallic tape surrounding the cable core;a protective polymeric layer surrounding the laminated metallic tape, the protective polymeric layer being formed of a foamed polymer, wherein a foam rate of the foamed polymer is from about 10% to about 50%; anda sheath surrounding the protective polymeric layer and forming the outermost layer of the cable.The cable of claim 1, wherein the water blocking compound comprises:a thermoplastic polymer; anda powdered crosslinked polymer dispersed in the thermoplastic polymer.The cable of claim 2, wherein the water blocking compound comprises about 10% to about 30%, by weight, of the powdered crosslinked polymer..The cable of claim 2, wherein the thermoplastic polymer and / or the crosslinked polymer are semiconductiveThe cable of claim 1, wherein interstices between the plurality of conductive wires are filled with the water blocking compound.The cable of claim 1, further comprising:a semiconductive conductor screen surrounding each of the one or more conductors and positioned radially inward of the insulation layer; anda semiconductive insulation screen surrounding the insulation layer of each of the one or more conductors and positioned radially inward of the metallic screen.The cable of claim 1, wherein the insulation layer is formed from a tree-retardant crosslinked polyethylene.The cable of claim 1, wherein the cable core further comprises a metallic screen surrounding the insulation layer of each of the one or more conductors.The cable of claim 1, further comprising a first water blocking tape surrounding the insulation layer of each of the one or more conductors and positioned radially inward of the metallic screen.. The cable of claim 9, wherein the first water blocking tape is semiconductive.The cable of claim 9, further comprising a second water blocking tape surrounding the metallic screen and positioned radially inward of the laminated metallic tape.The cable of claim 1, wherein the laminated metallic tape comprises aluminum.The cable of claim 1, further comprising a polyethylene layer surrounding the laminated metallic tape and positioned radially inward of the protective polymeric layer.The cable of claim 1, wherein the foamed polymer comprises polypropylene.The cable of claim 1, wherein the foam rate is from about 20% to about 30%.The cable of claim 1, wherein the sheath is formed from a polymer selected from the group consisting of polyvinyl chloride, polyethylene, polychloroprene, and chlorosulfonated polyethylene.A cable comprising:a cable core comprising:one or more conductors, each of the one or more conductors including a plurality of conductive wires, wherein at least a portion of the plurality of conductive wires is coated with a water blocking compound;an insulation layer surrounding each of the one or more conductors;a first water blocking tape surrounding the insulation layer of each of the one or more conductors;a metallic screen surrounding the first water blocking tape of each of the one or more conductors; anda second water blocking tape surrounding the metallic screen of each of the one or more conductors;a laminated metallic tape surrounding the cable core;a protective polymeric layer surrounding the laminated metallic tape, the protective polymeric layer being formed of a foamed polymer, wherein a foam rate of the foamed polymer is from about 10% to about 50%; anda sheath surrounding the protective polymeric layer and forming the outermost layer of the cable;wherein the cable provides protection against radial water penetration and longitudinal water protection.The cable of claim 17, wherein interstices between the plurality of conductive wires are filled with the water blocking compound.The cable of claim 17, further comprising:a semiconductive conductor screen surrounding each of the one or more conductors and positioned radially inward of the insulation layer; anda semiconductive insulation screen surrounding the insulation layer of each of the one or more conductors and positioned radially inward of the first water blocking tape.

20. A cable comprising:a cable core comprising:one or more conductors, each of the one or more conductors including a plurality of conductive wires, wherein at least a portion of the plurality of conductive wires is coated with a water blocking compound and interstices between the conductive wires are filled with the water blocking compound;an insulation layer surrounding each of the one or more conductors, wherein the insulation layer is formed from a tree-retardant crosslinked polyethylene;a first water blocking tape surrounding the insulation layer of each of the one or more conductors, wherein the first water blocking tape is semiconductive;a copper metallic screen surrounding the first water blocking tape of each of the one or more conductors; anda second water blocking tape surrounding the copper metallic screen of each of the one or more conductors;a laminated aluminum tape surrounding the cable core;a protective polymeric layer surrounding the laminated aluminum tape, the protective polymeric layer being formed of a foamed polymer, wherein a foam rate of the foamed polymer is from about 20% to about 30%; anda sheath surrounding the protective polymeric layer and forming the outermost layer of the cable.

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