MONITORING A FLEXIBLE POWER CABLE

• US 20100277329A1
• Filed: 11/28/2007
• Published: 11/04/2010
• Est. Priority Date: 12/12/2006
• Status: Abandoned Application

• Current Assignee: ABB Technology Limited (ABB Limited)
• Original Assignee: ABB Technology Limited (ABB Limited)
• Inventors: Worzyk, Thomas
• Application Number:
  US12/518,932
• Publication Number:
  US 20100277329A1
• Time in Patent Office: Days
• US Class Current: 340/679
• CPC Class Codes: G01M 11/085 the optical fiber being on or near the surface of the DUT
• CPC Class Codes: G01M 11/086 Details about the embedment of the optical fiber within the DUT
• CPC Class Codes: G01M 5/0041 by determining deflection or stress
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection
• CPC Class Codes: G02B 6/4417 High voltage aspects, e.g. in cladding
• CPC Class Codes: H01B 7/32 with arrangements for indicating defects, e.g. breaks or leaks
• CPC Class Codes: H01B 9/005 including optical transmission elements

Abstract

An offshore monitoring system, for an electrical power cable connected between a fixed point and a movable point, or for an electrical power cable connecting two movable points. The system comprises at least one optical fiber acting as a continuously distributed strain measurement sensor attached to or arranged in said power cable, a device arranged for sending optical signals and a device arranged for receiving optical signals to determine the time variant bending of said power cable.

Claims

1. An offshore monitoring system, for a power cable connected between a fixed point and a movable point, or for a power cable connecting two movable points, the system comprising:

at least one optical fiber acting as a continuously distributed strain measurement sensor, wherein the at least one fiber is attached to or arranged in said power cable,

a device arranged for sending optical signals into said at least one optical fiber,

a device arranged for receiving optical signals from said at least one optical fiber, and

a device arranged for analyzing the received optical signals to determine a time variant bending of said power cable.

2. The offshore monitoring system according to claim 1, wherein the at least one optical fiber is attached on an outside of the electrical power cable.

3. The offshore monitoring system according to claim 1, wherein the optical fiber is arranged in a material in the power cable or between two different materials in the power cable.

4. The offshore monitoring system according to claim 1, wherein at least one armoring wires in the power cable is replaced by optical fibers.

5. The offshore monitoring system according to claim 1, wherein a number of optical fibers are two or greater and the optical fibers are positioned equidistant around the power cable.

6. The offshore monitoring system according to claim 1, wherein two optical fibers are positioned 90 degrees apart with respect to a circumference of the power cable.

7. The offshore monitoring system according to claim 1, wherein the at least one optical fiber is arranged parallel to a long axis of the power cable.

8. The offshore monitoring system according to claim 1, wherein the at least one optical fiber is wound around the power cable in a spiraling or helicoidal geometry.

9. The offshore monitoring system according to claim 1, wherein the at least one optical fiber is included into the power cable during production of said cable.

10. The offshore monitoring system according to claim 1, wherein said optical signals comprise monochromatic pulses.

11. The offshore monitoring system according to claim 1, wherein said optical signals comprise a monochromatic continuous wave.

12. The offshore monitoring system according to claim 1, wherein said optical signals comprise monochromatic continuous waves with amplitude modulation.

13. The offshore monitoring system according to claim 1, wherein said optical signals received from said at least one optical fiber are analyzed by OTDR and/or OFDR.

14. The offshore monitoring system according to claim 1, wherein said analysis is adapted for estimating the bending of said power cable.

15. The offshore monitoring system according to claim 14, wherein said monitoring system is adapted to give an alarm if the estimated bending of said power cable exceeds an upper value.

16. The offshore monitoring system according to claim 14, wherein said monitoring system is adapted to record the bending of said power cable.

17. The offshore monitoring system according to claim 14, wherein said monitoring system is adapted to calculate an accumulated total bending stress of said power cable.

18. The offshore monitoring system according to claim 14, wherein said monitoring system is adapted to estimate time to future maintenance/repair from accumulated bending stresses of said power cable.

19. The offshore monitoring system according to claim 14, wherein said monitoring system is adapted to estimate future bending stress from accumulated measured bending stresses of said power cable.

20. The offshore monitoring system according to claim 1, wherein said power cable is bundled with other pipes and tubing and the monitoring system is adapted to estimate accumulated total bending stress of the bundle.