Superconducting Cable Installation Uniform Helical Deformation
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Solution Overview
Problem
Superconducting cables experience significant thermal contraction and stress issues during cooling and heating cycles, leading to potential damage due to non-uniform helical deformation and residual stresses, which can cause breakage or buckling.
Innovation Solution
A method for installing superconducting cables that involves uniform temperature raising with both ends fixed, using a thermally insulated double pipe with reduced vacuum insulation to ensure consistent heat distribution, and gently pushing the cable into the pipe to relax residual stresses, thereby maintaining a stable helical deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a superconducting cable is cooled from room temperature to liquid-nitrogen temperature, then the cable becomes superconductive, but the cable undergoes thermal contraction by about 0.3% which causes breakage or buckling
Solution Approach 1:
The patent changes the physical state of the cable by controlling temperature transitions. The cable is designed to undergo controlled thermal contraction during cooling from room temperature to liquid-nitrogen temperature (77K), utilizing the 0.3% contraction parameter to achieve superconductive operation while preventing damage through controlled parameter change.
Solution Approach 2:
The patent applies beforehand cushioning by designing the cable structure to accommodate thermal contraction before it occurs. The cable is pre-configured with appropriate length and structural flexibility at room temperature to cushion against the 0.3% contraction that will occur during cooling, preventing breakage and buckling.
2Quantity of substance
If the superconducting cable is made longer to increase transmission capacity, then the transmission capacity increases, but the thermal contraction becomes more serious (e.g., 1.5m contraction at 500m length)
Solution Approach 1:
The patent addresses the scaling problem by applying parameter changes proportionally. For longer cables with greater transmission capacity, the design adjusts the initial length and structural parameters to account for the increased 0.3% thermal contraction, ensuring that the absolute contraction distance (e.g., 1.5m at 500m) does not cause damage.
Solution Approach 2:
The patent applies beforehand cushioning for long cables by pre-calculating and accommodating the total thermal contraction distance in the cable design. The cable structure is designed with sufficient flexibility and appropriate initial tension to cushion against the cumulative contraction effect over the entire length.
3Ease of manufacture
If a former with twisted copper wires is used to draw the superconducting cable into the pipe, then the cable can be installed, but residual stress remains in the cable which may reduce critical current
Solution Approach 1:
The patent applies taking out by removing the former (winding core of twisted copper wires) after the cable has been installed into the pipe. The former is extracted once the cable is in position, eliminating the source of residual stress that would otherwise remain in the cable and potentially reduce its critical current.
Solution Approach 2:
The patent applies preliminary action by using the former to draw the cable into the pipe during installation, then removing it afterward. The former performs its function temporarily during the installation process and is then taken out to prevent ongoing stress on the cable.
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 approach ensures uniform helical deformation and reduces thermal stresses, minimizing the risk of damage from contraction and expansion, thereby enhancing the durability and reliability of superconducting cables.
Implementation Method 1
using a thermally insulated double pipe with reduced vacuum insulation to ensure consistent heat distribution
Implementation Method 2
uniform temperature raising with both ends fixed
Implementation Method 3
when cooled from room temperature to liquid-nitrogen temperature, a superconducting cable thermally contracts by about 0.3%
Data Source
Figure 1
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Figure 2B
AI summary
The present invention provides a former and a method of installing a superconducting cable for making helical deformation of the superconducting cable when temperature raising of the superconducting cable uniform in a longitudinal direction of the superconducting cable. When the temperature raising is performed, temperature of the superconducting cable is uniformly raised over an entirety of the superconducting cable, wherein the superconducting cable assumes a linear shape when cooled, and deforms into a helical shape when temperature raising is performed. In the former of a twisted wire structure, twisting directions of an outermost layer and a layer next to the outer most layer are set to be the same, enabling stabilization of the helical deformation of the superconducting cable including the former when the temperature raising is performed.