Resin Impregnated Paper Condenser Core Thermal Expansion
Solution Overview
Problem
The mismatch in thermal expansion coefficients between resin impregnated paper (RIP) condenser cores and metal winding tubes leads to delamination or high mechanical stress, making it difficult to remove the mandrel after winding and potentially damaging the winding tube.
Innovation Solution
Using a winding tube made from an electrically insulating material with a thermal expansion coefficient similar to that of the RIP, such as resin impregnated paper or fibre composite materials, and providing an electrical connection through the tube for conductor insertion, allowing the conductor to be inserted after the core is formed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a metal winding tube (aluminium or copper) is used to form the longitudinal through hole in the condenser core, then it is easy to establish a potential connection between the conductor and the innermost foil, but the mismatch in thermal expansion coefficients causes delamination or high mechanical stress in the winding tube
Solution Approach 1:
The patent changes the material parameter (thermal expansion coefficient) of the winding tube from metal (aluminium or copper) to resin impregnated paper (RIP), which has a thermal expansion coefficient matching that of the condenser core. This parameter change eliminates the thermal expansion mismatch that causes delamination and mechanical stress, while the RIP material is still conductive enough to provide the necessary potential connection.
2Adaptability or versatility
If a mandrel is used to wind the condenser core and then removed to provide a longitudinal through hole, then the conductor can be exchanged freely, but it is difficult to remove the mandrel after winding due to shrinkage of the core during manufacture
Solution Approach 1:
The patent extracts the function of forming the longitudinal through hole from the mandrel process. Instead of using a mandrel that must be removed, the winding tube itself is designed to provide the through hole during and after the winding process. The winding tube is inserted through the core after winding, eliminating the mandrel removal step entirely.
3Ease of manufacture
If the condenser core is wound directly on the conductor, then the potential connection is simplified, but the conductor cannot be exchanged between copper and aluminium
Solution Approach 1:
The patent segments the condenser core into two independent parts: the core itself and the winding tube. The core is wound separately on a mandrel, and the winding tube is inserted through the core afterward. This segmentation allows the conductor to be chosen independently of the core manufacturing process, enabling flexibility in conductor material selection while maintaining simple potential connection through the winding tube.
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 reduces the risk of thermal expansion-related issues, enabling a stable and secure condenser core assembly with reduced mechanical stress and ease of conductor insertion, while maintaining electrical insulation and potential connection.
Implementation Method 1
The mismatch in thermal expansion coefficients between resin impregnated paper (RIP) condenser cores and metal winding tubes leads to delamination or high mechanical stress
Data Source
Figure 1
AI summary
The present disclosure relates to a resin impregnated paper (RIP) condenser core 1 configured for being positioned around an electrical conductor 6. The condenser core comprises a winding tube 3 forming a longitudinal through hole through the condenser core, configured for allowing an electrical conductor to be inserted there through; an electrically insulating RIP body 2 wound onto and around the winding tube; and at least one electrically conducting foil 4 coaxially encircling the winding tube and being surrounded by the RIP body insulating each of the at least one foil from any other of the at least one foil. The winding tube is of an electrically insulating material which has been chosen from a group consisting of materials having a volumetric thermal expansion coefficient within the range of 50% to 200% of the volumetric thermal expansion coefficient of the RIP body.