Segmented Stator Winding Conductors for Leakage-Resistant Cooling
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Solution Overview
Problem
Large power generators face issues with heat dissipation and insulation failure due to high electrical currents, leading to energy losses and potential catastrophic breakdowns, particularly in hydrogen-cooled machines where leaks can be catastrophic, and existing cooling methods struggle with maintaining tightness and flexibility during conductor bending.
Innovation Solution
The use of C- or E-shaped segments with protrusions and recessed seats to form sealed, flexible hollow conductors that prevent coolant leakage and maintain tightness, allowing for efficient heat transfer and resistance to bending-induced joint failure, combined with friction stir welding or gluing for secure segment joining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If hollow strands with cooling conduits are used to transfer heat away from conductors, then heat dissipation is improved, but the risk of coolant leakage increases
Solution Approach 1:
The hollow strand is divided into multiple segments that are joined together to form a continuous conduit. Each segment is separately manufactured with precise dimensional control, and the joining process creates overlapping regions with multiple seals. This segmentation allows for better quality control of each individual segment while maintaining the integrity of the entire cooling system, thus improving heat dissipation without compromising leakage prevention.
Solution Approach 2:
The sealing elements are pre-installed into grooves within the strand segments before the segments are assembled into the final conductor structure. This preliminary action ensures that seals are properly positioned and secured before the segments are joined together, preventing any potential leakage paths from forming during the assembly process. The seals are also pre-compressed to ensure immediate tightness upon assembly.
2Temperature
If segments are joined together to form hollow strands, then cooling efficiency is improved, but joint tightness and flexibility during bending deteriorate
Solution Approach 1:
The joint design incorporates flexible sealing elements that can deform elastically during bending operations. The sealing lips are designed with appropriate thickness and material properties to accommodate the bending stresses while maintaining their sealing function. This dynamic flexibility allows the joint to bend without compromising tightness, resolving the contradiction between maintaining joint tightness and achieving flexibility during bending.
Solution Approach 2:
The strand segments are constructed using composite structures combining copper conductors with integrated cooling conduits. The joints between segments use composite sealing mechanisms involving rubber or elastomeric materials combined with metal clamps or compression fittings. This composite approach provides both the tightness required to prevent leakage and the flexibility needed to accommodate bending without joint failure.
3Reliability
If groundwall insulation is used to provide electrical insulation, then electrical breakdown prevention is improved, but heat transfer capability deteriorates
Solution Approach 1:
The insulation system is segmented into two distinct functional layers: the groundwall insulation layer for electrical breakdown prevention and the cooling conduit system for heat transfer. This segmentation allows each layer to be optimized independently - the groundwall can use materials with high dielectric strength while the conduit can be designed for maximum thermal conductivity, resolving the contradiction between electrical insulation and heat transfer capabilities.
Solution Approach 2:
The cooling conduit acts as an intermediary heat transfer path that bypasses the thermal limitations of the groundwall insulation. Instead of relying on the insulation material to conduct heat away from the conductor, the coolant flowing through the conduit provides a dedicated high-efficiency heat transfer pathway. This intermediary system maintains the electrical insulation function of the groundwall while independently handling the heat transfer function.
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 solution effectively prevents coolant leakage, enhances joint resilience during bending, and maintains tightness, reducing the risk of insulation failure and energy losses, while ensuring efficient heat dissipation in large power generators.
Implementation Method 1
measures have to be implemented that transfer heat out of the conductor of a winding. The groundwall insulation of a generator is generally no avail, since good electric insulator by their very nature have a low coefficient of thermal conductivity (typically 0.25 - 0.5 W/m·K). To transfer heat away from the conductors of a winding, conduits are arranged inside the conductors.
Implementation Method 2
friction stir welding or gluing for secure segment joining
Data Source
Figure 1
Figure 2
AI summary
Strands of stator or rotor windings of power generators and method for making thereof. A conductor for a winding of a rotating machine, the conductor comprising at least a strand, the at least a strand comprising two segments (8a, 8b), each segment (8a, 8b) providing at least two teeth (9a, 9b) and a groove arranged in between the teeth (9a, 9b), the surfaces of the teeth of the first segment reciprocate the surfaces of the teeth of the second segment, said surfaces of the teeth of the first segment and of the teeth of the second segment are configured to be mated, characterised in that at least one tooth of each segment (8a, 8b) provides at least one protrusion (10a) or at least one recessed seat (10b).