Cable Insulation Conductivity Measurement Using Core Sampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for measuring the conductivity of high voltage cable insulation are inadequate as they either rely on uncertain sample similarity to the actual cable, fail to assess the conductivity profile, or require lengthy and expensive measurements, and do not provide accurate information on the final quality of the insulation.
Innovation Solution
A method involving the extraction of small plaque samples from various radii of the cable insulation, which are then cut into cylindrical samples and flattened into plaque samples for precise measurement of conductivity and other electrical properties, allowing for the assessment of both level and profile of conductivity, and enabling comparison across different cables and accessories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If plaque samples are made from raw material before molding, then conductivity measurement can be performed, but the similarity between sample and actual cable insulation is uncertain
Solution Approach 1:
The invention extracts a cylindrical sample directly from the finished cable insulation layer using a core sampler, rather than making samples from raw material. This extraction method ensures the sample is taken from the actual cable structure, guaranteeing representativeness of the measurement to the real insulation properties.
Solution Approach 2:
The invention performs preliminary sampling from the finished cable insulation before final testing. By taking the cylindrical sample from the completed cable structure and preparing it in advance for conductivity measurement, the method ensures the sample accurately represents the final insulation quality.
2Measurement precision
If leakage current measurement is performed on a long cable length, then overall conductivity can be measured, but the measurement becomes expensive and difficult to realize as routine testing
Solution Approach 1:
The invention segments the cable insulation measurement into a small, manageable cylindrical sample that can be easily extracted and tested. Instead of measuring the entire long cable, the method divides the insulation into a small representative segment that can be tested quickly and routinely without requiring long cable lengths.
Solution Approach 2:
The invention extracts a small cylindrical sample from the cable insulation, enabling conductivity measurement on a minimal sample length rather than requiring long cable sections. This extraction approach makes routine testing practical and cost-effective while still providing accurate conductivity data.
3Measurement precision
If a long cable sample is required for conductivity measurement, then measurement can be performed, but the sample length and complexity increase
Solution Approach 1:
The invention divides the cable insulation into a small cylindrical segment for measurement purposes. This segmented approach allows conductivity measurement on a short sample length while maintaining measurement accuracy, eliminating the need for long cable sections.
Solution Approach 2:
The invention extracts a compact cylindrical sample from the cable insulation using a core sampler. This extracted sample requires minimal length to perform accurate conductivity measurements, dramatically reducing the sample length requirement compared to conventional methods.
4Measurement precision
If samples are taken from raw material before extrusion, then conductivity can be measured, but the manufacturing process effects on insulation quality are not reflected
Solution Approach 1:
The invention performs sampling and measurement as a preliminary action on the finished cable insulation, after all manufacturing processes including extrusion and crosslinking are complete. This timing ensures the measurement reflects the actual insulation quality as it exists in the final product, incorporating all manufacturing process effects.
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
This method allows for the accurate and efficient determination of conductivity and other electrical properties of high voltage cable insulation, enabling quality control and comparison of fresh, heat-treated, and aged cables, as well as cable accessories, with minimal sample length and high geometrical accuracy.
Implementation Method 1
A DC voltage is applied between two electrodes, where one of the electrodes is in contact with a surface of the insulation sample and the other electrode is in contact with the opposite surface of the insulation sample
Data Source
Figure 1
Figure 2a~3
Figure 4~6
AI summary
A method for determining conductivity of cable insulation of a cable comprising at least one conductor (10) that determines the central axis of the cable and insulation layer (12) surrounding the conductor (10) longitudinally and radially comprises steps of retrieving a cable sample (17) from a cable, which sample includes a length of at least one insulation layer (12) and preparing an insulation sample (18a - 18d) from the cable sample (17). The insulation sample (18a - 18d) is prepared from cable sample (17) by cutting a circular layer (18a - 18d) having a set thickness at desired radius from the central axis of the cable.