Electrical cable with self-repairing protection and apparatus for manufacturing the same

• US 6,534,715 B1
• Filed: 08/30/2000
• Issued: 03/18/2003
• Est. Priority Date: 08/30/1999
• Status: Expired due to Term

• Current Assignee: Prysmian Cavi E Sistemi Italia Srl (Prysmian SPA)
• Original Assignee: Pirelli Cavi e Sistemi S.P.A. (Prysmian SPA)
• Inventors: Maunder, Andrew L., Belli, Sergio, Balconi, Luca, Pozzati, Giovanni, Bareggi, Alberto, DellʼAnna, Gaia
• Primary Examiner(s): Nguyen, Chau N.
• Application Number:
  US09/651,276
• Time in Patent Office: 930 Days
• Field of Search: 174/102.SC, 174/102.SP, 174/106.R, 174/120.R, 174/110.R
• US Class Current: 174/110.00R
• CPC Class Codes: H01B 7/184 Sheaths comprising grooves, ribs or other projections
• CPC Class Codes: H01B 7/185 Sheaths comprising internal cavities or channels
• CPC Class Codes: H01B 7/187 Sheaths comprising extruded non-metallic layers

Abstract

An electrical cable includes a conductor, an outer sheath, and a self-repairing material layer between the conductor and outer sheath. The self-repairing material layer is distributed around the conductor in a discontinuous manner. An anchor portion is formed between the conductor and the outer sheath.

Claims

1. An electrical cable with self-repairing protection comprising:

at least one conductor;

at least one outer coating sheath;

at least one layer of self-repairing material interposed between the conductor and the outer coating sheath, the self-repairing material layer being distributed around the conductor and having at least one region wherein its extension is interrupted, the self-repairing material being dielectric and having a predetermined cohesiveness and a controlled flowability at a working temperature of the cable; and

at least one anchoring portion between the conductor and the outer coating sheath disposed at said interruption region.

2. The cable of claim 1, having a plurality of anchoring portions homogeneously distributed around the conductor, each portion being at an interruption region of the extension of the self-repairing material layer.

3. The cable of claim 2, wherein the layer of self-repairing material extends around the conductor following a distribution line along which the ratio between the extension of the self-repairing material layer and the extension of the interruption regions is at least 0.5.

4. The cable of claim 1, wherein the layer of self-repairing material and said at least one anchoring portion are directly in contact with the conductor.

5. The cable of claim 1, wherein at least one inner coating layer is interposed between the conductor and the layer of self-repairing material.

6. The cable of claim 5, wherein said at least one anchoring portion is directly in contact with the inner coating layer.

7. The cable of claim 5, wherein said at least one anchoring portion is joined in one piece to the inner coating layer.

8. The cable of claim 1, wherein said at least one anchoring portion is directly in contact with said outer coating sheath.

9. The cable of claim 1, wherein said at least one anchoring portion is joined in one piece to the outer coating sheath.

10. The cable of claim 1, wherein the self-repairing material layer has a thickness not less than 0.1 mm.

11. The cable of claim 1, wherein the self-repairing material has an alternating current dielectric strength higher than 15 kV/mm and a resistivity higher than 10¹⁴ Ω

cm.

12. The cable of claim 1, wherein the self-repairing material has a cohesive force, measured at room temperature, of at least 0.05 kg/cm².

13. The cable of claim 1, wherein the cohesiveness of the self-repairing material is such that a re-cohesion force, measured at room temperature, has a value which is not less than 80% of the value of a cohesive force measured on the material as such.

14. The cable of claim 1, wherein the controlled flowability of the self-repairing material is such that a sample of about 3 grams of the self-repairing material, placed on an aluminium plate inclined at 60°

relative to a horizontal plane and maintained at 60°

C. for 24 hours, shows a displacement of the front of the material along the inclined plate which is between 0.5 and 400 mm.

15. The cable of claim 1, wherein the self-repairing material comprises an amorphous polymer having properties of a high-viscosity liquid or of a semi-solid.