Covering for cable joints, elements of a device for realizing cable joints and cable joint comprising said covering

Claim 2

Covering according to claim 1, characterized by the fact that the ratio between the outer diameter D₃ of the first sleeve (3, 3′, 3˝, 3‴) when separated from the second sleeve (2, 2′, 2˝, 2‴) and in absence of any mechanical stress applied thereto, and the inner diameter D₂ of the second sleeve (2, 2′, 2˝, 2‴), when separated from the first sleeve and in absence of any mechanical stress applied thereto is not lower than 1.2.

Claim 3

Covering according to claim 1, characterized by the fact that the second sleeve (2, 2′, 2˝, 2‴) is at least partially constituted by a compound having a residual deformation smaller than 35% for an imposed elongation of 50% applied for a period of time of 500 hours and at a temperature of 100°C.

Claim 4

Covering according to any one of the claims 1 and 2, characterized by the fact that the first sleeve (3, 3′, 3˝, 3‴) comprises two tubular layers, the radially innermost tubular layer being constituted by a cross-linked polymeric material compound having a dielectric constant ε not lower than 6 to which a tubular layer of an electrically insulating cross-linked polymeric material is superimposed and that the second sleeve (2, 2′, 2˝, 2‴) comprises two tubular layers of which the radially outermost one is made up of the cross-linked polymeric material compound having a residual deformation smaller than 35% for an imposed elongation of 50% applied for a period of time of 500 hours and at a temperature of 100°C and the tubular layer, lying below said radially outermost layer, is constituted by a semiconductive compound of a cross-linked polymeric material.

Claim 5

Covering according to any one of the claims from 1 to 3, characterized by the fact that the first sleeve (3, 3′, 3˝, 3‴) is formed by three tubular layers, said layers being coaxial and superimposed one upon the other, the radially innermost one being constituted by a cross-linked polymeric material compound having a dielectric constant ε not lower than 6, the intermediate one being constituted by an electrically insulating cross-linked polymeric material compound, the radially outermost one being constituted by a semiconductive compound of a cross-linked polymeric material and that the second sleeve (2, 2′, 2˝, 2‴) is entirely constituted by a cross-linked polymeric material compound to which no electric and/or dielectric characteristic is required, but a residual deformation smaller than 35% for an imposed elongation of 50% applied for a period of time of 500 hours and at a temperature of 100°C.

Claim 6

Covering according to claim 5, characterized by the fact that at least an electrically conductive metallic element (16) is interposed between the first (3, 3′, 3˝, 3‴) and the second sleeve (2, 2′, 2˝, 2‴), said electrically conductive metallic element projecting from both the ends of said sleeves.

Claim 7

Covering according to claim 6, characterized by the fact that the electrically conductive metallic element (16) is constituted by a plurality of circumferentially spaced conductors, independent of one another, selected from copper and/or aluminium wires, plaits of copper and/or aluminium wires and a braiding of copper and/or aluminium wires.

Claim 8

Covering according to claim 5, characterized by the fact that in axial direction the second sleeve (2, 2′, 2˝, 2‴) has both its own end portions projecting from the ends of the first sleeve (3, 3˝ 3˝, 3‴).

Claim 9

Covering according to claim 8, characterized by the fact that the end portions of the second sleeve (2, 2′, 2˝, 2‴) projecting from the ends of the first sleeve (3, 3′, 3˝, 3‴) are turned-up on the radially outermost surface of the second sleeve (2, 2′, 2˝, 2‴).

Claim 10

Covering according to claims 8 and 9, characterized by the fact that the length of the end portions of the second sleeve (2, 2′, 2˝, 2‴) projecting from the first sleeve (3, 3′, 3˝, 3‴) or turned-up on the radially outermost surface of the second sleeve (2, 2′, 2˝, 2‴) is not shorter than 10% of the length of the first sleeve (3, 3′, 3˝, 3‴).

Claim 11

Covering according to any one of the claims 1 and 2, characterized by the fact that the first sleeve 3, 3′, 3˝, 3‴) comprises two coaxial and superimposed tubular layers, the radially innermost tubular layer being constituted by a cross-linked polymeric material compound having a dielectric constant not lower than 6 to which a tubular layer of an electrically insulating cross-linked polymeric material is superimposed and that the second sleeve (2, 2′, 2˝, 2‴) comprises three coaxial and superimposed tubular layers of which the radially outermost one is formed by the cross-linked polymeric material compound having a residual deformation smaller than 35% for an imposed elongation of 50% and applied for a period of time of 500 hours and at a temperature of 100 °C, the intermediate tubular layer is constituted by a semiconductive cross-linked polymeric material compound and the radially innermost tubular layer is constituted by an electrically insulating cross-linked polymeric material compound.

Claim 12

Covering according to any one of the preceding claims, characterized by the fact that the cross-linked polymeric material compound of the second sleeve (2, 2', 2'', 2''') have a percentage ultimate elongation not lower than 300 %, while the cross-linked polymeric material compounds of the first sleeve (3, 3', 3'', 3''') have a percentage ultimate elongation not lower than 150 % .

Claim 13

Covering according to the preceding claims, characterized by the fact that the modulus E of the cross-linked compounds of the second sleeve (2, 2', 2'', 2''') is not lower than 0,2 MPa, while the modulus E of the compounds constituting the first sleeve (3, 3', 3'', 3''') is comprised between 0,2 MPa and 20 MPa.

Claim 14

Joint for electric cables comprising an electrical and mechanical connection between the conductors of two cables and a covering for said connection comprising at least a first (3, 3', 3'', 3''') and a second (2, 2', 2'', 2''') sleeve, both sleeves being elastically expansible in radial direction, coaxial, superimposed and independent of each other and formed by cross-linked polymeric material compounds, the first sleeve (3, 3', 3'', 3''') radially inside the second sleeve (2, 2', 2'', 2''') being constituted at least for a part of its thickness by an electrically insulating cross-linked polymeric material compound, said joint being characterized by the fact that the second sleeve (2, 2', 2'', 2''') when separated from the first one (3, 3', 3'', 3''') and from the cables and in absence of any mechanical stress applied thereto has the diameter of its own cavity smaller than the outer diameter of the first sleeve (3, 3', 3'', 3''') when separated from the second sleeve (2, 2', 2'', 2''') and from the cables and in absence of any applied mechanical stress too.

Claim 15

Joint according to claim 14, characterized by the fact that the ratio between said outer diameter of the first sleeve (3, 3', 3'', 3''') when separated from the second sleeve (2, 2', 2'', 2''') and from the cable and in absence of any mechanical stress applied thereto and the inner diameter of the second sleeve (2, 2', 2'', 2''') when separated from the first sleeve (3, 3', 3'', 3''') and from the cable and in absence of any mechanical stress applied thereto is not lower than 1,2.

Claim 16

Joint according to claim 14, characterized by the fact that the second sleeve (2, 2', 2'', 2''') is at least partially constituted by a compound having a residual deformation smaller than 35 % for an imposed elengation of 50 % applied for a period of time of 500 hours and at a temperature of 100 °C.

Claim 17

Joint according to any one of the claims from 14 to 16, characterized by the fact that the first sleeve (3, 3', 3'', 3''') comprises two tubular layers, the radially innermost tubular layer being constituted by a compound of cross-linked polymeric material having a dielectric constant ε not lower than 6 to which a tubular layer of electrically insulating cross-linked polymeric material is superimposed and that the second sleeve (2, 2', 2'', 2''') comprises two tubular layers of which the radially outermost one is constituted by a cross-linked polymeric material compound having a residual deformation smaller than 35 % for an imposed elongation of 50 % applied for a period of time of 500 hours and at a temperature of 100 °C, the tubular layer laying below said radially outermost layer, is constituted by a semiconductive compound of cross-linked polymeric material.

Claim 18

Joint according to any one of the claims from 14 to 17, characterized by the fact that the first tubular body (3, 3', 3'', 3''') is formed by three tubular layers, said layers being coaxial and superimposed one upon the other, the radially innermost one being made up of a cross-linked polymeric material compound having a dielectric constant ε not lower than 6, the intermediate one being made up of an electric insulating cross-linked polymeric material compound, the radially outermost one being constituted by a semiconductive compound of cross-linked polymeric material and that the second sleeve (2, 2', 2'', 2''') is entirely formed by a cross-linked polymeric material compound to which no electric and/or dielectric characteristic is required, but having a residual deformation smaller than 35 % for an imposed elongation of 50 % applied for a period of time of 500 hours at a temperature of 100 °C.

Claim 19

Joint according to claim 18, characterized by the fact that at least an electrically conductive metallic element (16) is interposed between the first (3, 3', 3'', 3''') and the second (2, 2', 2'', 2''') sleeve, said electrically conductive metallic element being connected to the metal screen of the cables.

Claim 20

Joint according to claim 19, characterized by the fact that the electrically conductive metallic element (16) is constituted by a plurality of independent conductors selected from copper and/or aluminium wires, plaits of copper and or aluminium wires, a braiding of copper and/or aluminium wires.

Claim 21

Joint according to claim 18, characterized by the fact that in axial direction the second sleeve (2, 2', 2'', 2''') has both its end portions projecting from the ends of the first sleeve (3, 3', 3'', 3''') and superimposed upon the cable sheaths.

Claim 22

Joint according to any one of the claims 14 and 15, characterized by the fact that the first sleeve (3, 3', 3'', 3''') comprises two coaxial and superimposed tubular layers, the radially innermost tubular layer being constituted by a cross-linked polymeric material compound having a dielectric constant ε not lower than 6 to which a tubular layer of electrically insulating cross-linked polymeric material is superimposed and that the second sleeve comprises three coaxial and superimposed tubular layers of which the radially outermost one is made up of a cross-linked polymeric material compound having a residual deformation smaller than 35 % for an imposed elongation of 50 % applied for a period of time of 500 hours and at a temperature of 100 °C, the intermediate tubular layer is constituted by a semiconductive cross-linked polymeric material compound and the radially innermost tubular layer is constituted by an electrically insulating cross-linked polymeric material compound.

Claim 23

Joint according to any one of the claims from 14 to 22, characterized by the fact that the cross-linked polymeric material compounds of the second sleeve (2, 2', 2'', 2''') have a percentage ultimate elongation not lower than 300 %, while the cross-linked polymeric material compound of the first sleeve (3, 3', 3'', 3''') have a percentage ultimate elongation not lower than 250 % .

Claim 24

Joint according to claims 14 to 22, characterized by the fact that the modulus E of the cross-linked compounds of the second sleeve (2, 2', 2'', 2''') is not lower than 0,2 MPa, while the modulus E of the cross-linked compound of the first sleeve (3, 3', 3'', 3''') is comprised between 0,2 and 20 MPa.