Power Cable Monitoring for Hotspot and Strain Localization

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Solution Overview

Problem

Fatigue and hotspot issues in power cables, particularly at the transition from the seabed to offshore structures, lead to premature failure due to mechanical stress and thermal resistance challenges, with over 60% of faults occurring in the first 40 meters from the suspension point.

Innovation Solution

A system with temperature and/or strain measuring elements, such as fiber Bragg gratings and flexible rods with embedded optical fibers, distributed along the power cable to detect excessive mechanical strain and temperature, using distributed sensing techniques to identify hotspots and mechanical constraints early on, connected to a computing device that alerts for threshold exceedance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If temperature and strain measuring elements are distributed along the power cable to detect hotspots and mechanical stress, then the reliability of cable operation is improved, but the device complexity increases

Engineering Contradiction:
Improvecable operation reliabilityVSAvoidmonitoring system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The monitoring system divides the cable into multiple monitored sections by distributing temperature and strain measuring elements at specific locations along the cable length. Each measuring element independently monitors its local section, enabling segmented detection of hotspots and mechanical stress points throughout the cable route.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces temperature and strain measuring elements as intermediary components between the cable and the monitoring system. These measuring elements act as mediators that convert physical parameters (temperature, strain) into measurable signals that can be processed by the control unit, enabling indirect but accurate monitoring of cable conditions.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If measuring elements are placed at pre-defined locations along the cable, then the detection precision of hotspots and strain is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improvehotspot and strain detection precisionVSAvoidcable assembly ease
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent applies local quality by placing measuring elements at specific pre-defined locations along the cable where temperature and strain are most critical. Rather than uniformly distributing sensors throughout the entire cable, the system concentrates measurement capability at key positions such as potential hotspot areas and high-stress zones, optimizing detection precision where it is most needed.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The measuring elements are positioned at pre-defined locations during the cable manufacturing or installation phase, before the cable enters service. This preliminary placement ensures that sensors are correctly positioned at critical locations from the outset, avoiding the need for complex post-installation adjustments and simplifying the overall manufacturing process.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the monitoring system uses distributed sensing techniques, then the early detection capability of faults is improved, but the loss of time for data processing increases

Engineering Contradiction:
Improvefault detection capabilityVSAvoiddata processing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system implements partial monitoring by focusing measurement efforts on critical sections of the cable rather than continuously monitoring the entire cable length with equal intensity. The control unit is configured to process data from measuring elements at pre-defined locations, providing sufficient monitoring coverage to detect faults early while avoiding the excessive data processing burden of continuous full-cable monitoring.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The monitoring system establishes a feedback loop where the control unit continuously receives data from measuring elements, compares readings against threshold values, and triggers alerts when anomalies are detected. This feedback mechanism enables rapid fault detection and response, compensating for any data processing delays by immediately acting on critical information when thresholds are exceeded.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively monitors power cables, enabling early detection of hotspots and mechanical stress, reducing the risk of cable failure by providing real-time alerts for potential faults, thus extending the lifespan of the cables.

Implementation Method 1

temperature and/or strain measuring elements, such as fiber Bragg gratings and flexible rods with embedded optical fibers

Methodology Applied
Scientific EffectFiber Bragg Gratings:

Implementation Method 2

EP3314279B1 regards using fiber optic sensors/Rayleigh scattering/Bragg gratings for detecting deformation of a power cable

Methodology Applied
Scientific EffectRayleigh scattering: Rayleigh Scattering

Data Source

PatentEP4484910A1A system for monitoring a power cable
Publication Date: 2025.01.01 NEXANS SA
  • EP4484910A1 patent drawingFigure 1
  • EP4484910A1 patent drawingFigure 2a~2b
  • EP4484910A1 patent drawingFigure 2c

AI summary

The present invention relates to a system (1) for monitoring a power cable (15). The system (1) comprises temperature and/or strain measuring elements (31) arranged on or within the power cable (15) at pre-defined locations distributed in a section (11) of the power cable (15). The system further comprises a computing device (17) configured to receive parameters representative of temperature and/or strain from the temperature and/or strain measuring elements (31), and to identify a location of any temperature and/or strain measuring element (31) experiencing temperature and/or strain exceeding a predetermined threshold value.