Strength member assemblies and overhead electrical cables incorporating optical fibers
Strength member assemblies including a strength member and at least one glass optical fiber operatively coupled to the strength member. The optical fiber is coupled to the strength member in a manner such that mechanical strains experienced by the strength member are transferred to the optical fiber so that the optical fiber may be interrogated to assess the state of the strength member.
1 . An overhead electrical cable comprising:
a strength member assembly comprising at least a first strength element comprising a fiber-reinforced composite material comprising elongate carbon reinforcing fibers disposed in a binding matrix;
an electrical conductor surrounding the strength member assembly, the electrical conductor comprising a plurality of conductive aluminum strands that are helically wrapped around the strength member;
an optical fiber disposed along an outer surface of the first strength element;
a polymer layer disposed over the outer surface of the first strength element and the optical fiber, where the polymer layer is selected from the group consisting of a high performance plastic coating and a polymer tape helically wrapped around the strength element; and
an aluminum layer disposed over the polymer layer.
2 . The overhead electrical cable recited in claim 1 , wherein the strength member comprises a single strength element.
3 . The overhead electrical cable recited in claim 1 , wherein the strength member comprises a plurality of strength elements.
4 . The overhead electrical cable recited in claim 1 , wherein the elongate reinforcing fibers comprise carbon fibers.
5 . The overhead electrical cable recited in claim 1 , wherein the first optical fiber is disposed linearly along the outer surface of the strength element.
6 . The overhead electrical cable recited in claim 1 , wherein the polymer layer is the polymer tape helically wrapped around the strength element.
7 . The overhead electrical cable recited in claim 6 , wherein the polymer tape overlaps upon itself to cover the strength member with no gaps.
8 . The overhead electrical cable recited in claim 6 , wherein the polymer tape comprises aramid fibers.
9 . The overhead electrical cable recited in claim 6 , wherein the polymer tape has a thickness of at least about 0.05 mm.
10 . The overhead electrical cable recited in claim 6 , wherein the polymer tape has a thickness of not greater than about 3 mm.
11 . The overhead electrical cable recited in claim 1 , wherein the aluminum layer has a thickness of at least about 0.4 mm.
12 . The overhead electrical cable recited in claim 1 , wherein the aluminum layer has a thickness of not greater than about 1.5 mm.
13 . A method for the installation of an overhead electrical cable, comprising the steps of:
providing an overhead electrical cable as recited in claim 1 ;
supporting the overhead electrical cable on a plurality of support towers;
separating a portion of the optical fiber from the strength member at an end of the overhead electrical cable; and
operatively attaching the separated portion of the optical fiber to a detection device.
14 . The overhead electrical cable as recited in claim 1 , wherein the polymer layer comprises a high-performance plastic coating.
15 . The overhead electrical cable as recited in claim 14 , wherein the high performance plastic coating has a continuous service temperature of at least about 150° C.
16 . The overhead electrical cable recited in claim 1 , wherein the aluminum layer is a conformal aluminum layer having a thickness of at least about 0.4 mm.