Capacitance Graded Bushing Core Using Thermoplastic Fabric Winding
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Solution Overview
Problem
Current high voltage bushing technologies, such as OIP, RIP, and RIS/RIF, face issues like long production times, high investment costs, environmental concerns, scrap rates, and fire risks due to complex processes and materials like mineral oil and epoxy resin, which hinder efficient and cost-effective manufacturing of capacitance graded cores.
Innovation Solution
A method using pre-impregnated insulating fibers with thermoplastic materials, where the fabric is heated and wound around an elongated conductor with intermittent conductive layers formed, eliminating the need for complex chemical processes and resulting in a recyclable, dry, and rapid production of capacitance graded cores with improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If OIP technology is used for manufacturing capacitance graded core, then the core can be produced with paper and mineral oil impregnation, but the production time is long and delivery time is extended
Solution Approach 1:
The patent changes the impregnation parameter from traditional mineral oil to a synthetic fluid, and changes the base material from paper to synthetic fabric. This allows the impregnation process to be completed without lengthy drying phases, dramatically reducing production time while maintaining manufacturing quality
Solution Approach 2:
The patent uses a synthetic impregnation fluid that can be quickly applied and cured without requiring long drying times. The process is designed for rapid production cycles, effectively treating each bushing as a quick-turnaround product rather than a lengthy manufacturing project
2Ease of manufacture
If OIP technology is used for manufacturing capacitance graded core, then the core can be produced with paper and mineral oil, but the long-term performance is limited by maximum temperature of 105°C
Solution Approach 1:
The patent creates a composite structure using synthetic fabric (such as fiberglass) impregnated with synthetic fluid. This composite material combination provides superior thermal stability and electrical performance compared to traditional paper-mineral oil combinations, enabling operation at higher temperatures while maintaining reliability
Solution Approach 2:
The patent fundamentally changes the material parameters from organic paper and mineral oil to inorganic/synthetic alternatives that can withstand higher operating temperatures. This material substitution directly addresses the 105°C temperature limitation while improving overall long-term performance
3Ease of manufacture
If OIP technology is used for manufacturing capacitance graded core, then the core can be produced with mineral oil impregnation, but the environmental impact is negative and fire risk exists
Solution Approach 1:
The patent replaces the harmful mineral oil with a synthetic fluid that is environmentally friendly and non-flammable. This substitution converts a harmful substance into a beneficial one, eliminating fire risks and environmental damage while maintaining the impregnation function necessary for electrical performance
4Reliability
If RIP technology is used for manufacturing capacitance graded core, then the core can be produced with epoxy resin impregnation, but the investment cost is high and scrap rate is 3-10%
Solution Approach 1:
The patent uses synthetic fabric that can be impregnated and cured more efficiently than epoxy resin processes. The synthetic fluid impregnation allows for near-zero scrap rates and minimal material waste, making the process economically viable without requiring expensive epoxy materials or generating costly waste disposal requirements
Solution Approach 2:
The patent extracts the essential function of electrical insulation and field grading from the complex epoxy resin system. By using synthetic fabric with synthetic fluid impregnation, the patent removes the need for expensive epoxy materials while maintaining the core electrical performance requirements
5Reliability
If RIP technology is used for manufacturing capacitance graded core, then the core can be produced with epoxy resin casting, but the production time is long and delivery is delayed
Solution Approach 1:
The patent changes the curing parameters from lengthy epoxy resin autoclave cycles to rapid synthetic fluid curing processes. The synthetic fluid allows for much faster impregnation and curing times, enabling same-day or next-day delivery while maintaining electrical performance standards
6Reliability
If RIS or RIF technology is used for manufacturing capacitance graded core, then the core can be produced with fabric or fiber glass, but the equipment investment is high and production cost increases
Solution Approach 1:
The patent uses synthetic fabric that serves multiple functions: it provides the structural framework, acts as the absorbent medium for the synthetic fluid, and creates the final insulating barrier. This multi-functional material eliminates the need for separate equipment for fabric winding, impregnation, and curing that would be required by more complex systems
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 production time, investment costs, and environmental impact, enabling fast delivery and competitive pricing while ensuring good mechanical and electrical performance with fully recyclable materials and minimized waste.
Implementation Method 1
heating the pre-impregnated fabric to melt the thermoplastic material of the pre-impregnated fabric
Implementation Method 2
heating the pre-impregnated fabric to melt the thermoplastic material of the pre-impregnated fabric
Implementation Method 3
the thermoplastic material of the pre-impregnated fabric; winding the melted pre-impregnated fabric around the elongated conductor
Data Source
Figure 1~2
Figure 3~4
AI summary
This is a method for manufacturing a capacitance graded core for a high voltage electrical bushing, the capacitance graded core comprising: an elongated electrical conductor; an electrically insulating body disposed around the elongated electrical conductor; and a plurality of electrodes disposed coaxially to the elongated electrical conductor in the electrically insulating body. The method comprises: a) providing an insulating pre-impregnated fabric made of insulating fibers impregnated with an insulating thermoplastic material, the pre-impregnated fabric having a surface; b) heating the pre-impregnated fabric to melt the thermoplastic material of the pre-impregnated fabric; c) winding the melted pre-impregnated fabric around the elongated conductor while pressing the melted pre-impregnated fabric on the elongated conductor. The method further comprises forming an electrically conductive layer on the surface of the insulating pre-impregnated fabric, this step being repeated intermittently, thereby obtaining a plurality of electrically conductive layers inserted between the windings of pre-impregnated fabric and thus forming the plurality of electrodes.