Self-supporting Electrical Cable with Phase-Change Polymer
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Solution Overview
Problem
Electrical connecting lines in transformers face contradictory requirements: they need to be flexible during assembly for easy shaping but rigid during operation to absorb short-circuit forces without complex support devices, which existing technologies have not satisfactorily resolved.
Innovation Solution
A self-supporting electrical line is created by incorporating a hardenable polymeric material between conductor strands, which remains flexible during assembly and hardens upon heat treatment to provide rigidity, similar to solid copper cables, eliminating the need for complex bending or support devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flexible stranded wire is used for connecting lines, then ease of shaping during assembly is improved, but ability to absorb short-circuit forces deteriorates
Solution Approach 1:
The connecting line dynamically changes its mechanical properties through the phase transition of the polymeric material. During assembly, the polymer is in a soft, flexible state allowing easy shaping. After heat treatment, it transitions to a hard, rigid state providing short-circuit force absorption. This temporal dynamic property change resolves the contradiction between flexibility during manufacture and rigidity during operation.
Solution Approach 2:
The mechanical parameters of the connecting line are changed through temperature-induced phase transition of the polymeric material. The material transitions from a rubbery state at assembly temperature (flexible) to a glassy state after heat treatment (rigid). This parameter change allows the same structure to satisfy both contradictory requirements at different stages of the product lifecycle.
2Strength
If solid conductors are used for connecting lines, then ability to absorb short-circuit forces is improved, but ease of shaping during assembly deteriorates
Solution Approach 1:
The connecting line dynamically changes its mechanical properties through the phase transition of the polymeric material. During assembly, the polymer is in a soft, flexible state allowing easy shaping. After heat treatment, it transitions to a hard, rigid state providing short-circuit force absorption. This temporal dynamic property change resolves the contradiction between flexibility during manufacture and rigidity during operation.
3Ease of operation
If flexible stranded wire is used, then ease of handling during assembly is improved, but rigidity during operation deteriorates
Solution Approach 1:
The connecting line dynamically changes its mechanical properties through the phase transition of the polymeric material. During assembly, the polymer is in a soft, flexible state allowing easy shaping. After heat treatment, it transitions to a hard, rigid state providing short-circuit force absorption. This temporal dynamic property change resolves the contradiction between flexibility during manufacture and rigidity during operation.
Solution Approach 2:
The polymeric material undergoes a phase transition from rubbery to glassy state through heat treatment, fundamentally changing the mechanical behavior of the connecting line. This phase transition enables the same structure to provide both flexibility during assembly and rigidity during operation, resolving the contradiction between ease of handling and operational stability.
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 solution allows for cost-effective manufacturing of transformers by enabling flexible lines to be easily shaped during assembly and hardened for self-support, effectively absorbing short-circuit forces without additional support, thus simplifying the manufacturing process and reducing costs.
Implementation Method 1
a layer with a hardenable polymeric material is provided between individual layers of conductor strands... when used as intended the line is hardened
Implementation Method 2
This heat treatment is now also used to harden the adhesive. At a temperature of around 100°C to below 140°C, the polymer material initially becomes soft and can therefore easily penetrate between adjacent and bundled strands of a cable strand. The subsequent cooling causes the polymer material (e.g. adhesive) to harden
Implementation Method 3
At a temperature of around 100°C to below 140°C, the polymer material initially becomes soft and can therefore easily penetrate between adjacent and bundled strands of a cable strand
Implementation Method 4
The subsequent cooling causes the polymer material (e.g. adhesive) to harden, as a result of which the individual cores or strands of the cable harness are connected to one another by cohesion
Data Source
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AI summary
A self-supporting electrical cable for an electrical machine, particularly a transformer or inductor, comprising: a plurality of layers (6, 7, 8) of cable strands (2), each consisting of individual wires (3), wherein a layer (4; 5) containing a curable polymeric substance is formed in each case between two adjacent layers (6, 7; 7, 8), and/or the individual wires (3) are coated with said polymeric substance, wherein a self-supporting composite conductor is produced when the polymeric substance has hardened.