Medium Voltage Bushing Press-Fit Insulation Segmentation
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Solution Overview
Problem
Existing bushings for medium and high voltage face challenges in production complexity and insufficiency in preventing electric discharges due to gas leakage or moisture diffusion, particularly with thin-walled thermoplastic materials.
Innovation Solution
A bushing design featuring a tubular outer shell with a press-fit connection to the voltage-carrying element, filled with an electrically insulating material like polyurethane, which provides enhanced insulation and mechanical strength, and includes a conductive shielding element to suppress electric fields, facilitating efficient production and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick thermosetting resin is used for insulation, then electrical insulation performance is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The insulation system is divided into two segments: a thin thermoplastic outer shell for mechanical protection and moisture barrier, and a separate insulating filler material placed in the space between the conductor and shell. This segmentation allows each material to perform its optimal function without requiring thick thermosetting resin, thereby reducing manufacturing complexity while maintaining insulation performance.
Solution Approach 2:
The invention uses a composite structure combining thermoplastic polymer shell with separate insulating filler material (such as epoxy resin, polyurethane, or other insulators). This composite approach replaces the single thick thermosetting resin structure with a multi-material system that achieves equivalent or superior insulation performance with reduced material thickness and simplified manufacturing.
2Ease of manufacture
If thin-walled thermoplastic bushings are used, then production cost is reduced, but resistance to electric discharges and moisture ingress deteriorates
Solution Approach 1:
The protective function is segmented between the thin thermoplastic shell (providing mechanical strength and moisture barrier) and the insulating filler material (providing electrical discharge protection). This segmentation allows the shell to remain thin and cost-effective while the filler material provides the necessary electrical protection.
Solution Approach 2:
The insulating filler material acts as an intermediary between the conductor and the thin thermoplastic shell, providing the additional electrical insulation and discharge protection that the thin shell alone cannot provide. This intermediary layer enables the use of thin-walled construction without compromising electrical safety.
3Ease of manufacture
If thin-walled thermoplastic bushings are used, then production cost is reduced, but resistance to moisture diffusion deteriorates
Solution Approach 1:
The invention employs a thin thermoplastic shell that, while thin, provides effective moisture barrier protection. The shell's continuous coverage and proper sealing at connection points create an effective barrier against moisture diffusion, demonstrating that thin walls can provide adequate protection when properly designed and sealed.
Solution Approach 2:
The insulating filler material serves as an additional intermediary barrier against moisture, working in conjunction with the thin thermoplastic shell to prevent moisture diffusion to the conductor. This dual-barrier approach enhances moisture protection without requiring the shell itself to be thick.
4Productivity
If press-fit connection is used between outer shell and voltage-carrying element, then assembly efficiency is improved, but connection reliability may deteriorate
Solution Approach 1:
The press-fit connection is designed to be self-aligning and self-securing, where the interference fit between the outer shell and voltage-carrying element automatically provides both mechanical support and electrical insulation. The connection structure itself performs multiple functions without requiring additional components or complex assembly steps, thereby maintaining both efficiency and reliability.
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 offers improved electrical insulation, reduced production costs, and enhanced resistance to electric discharges and moisture ingress, enabling a more efficient and cost-effective bushing for medium and high voltage applications.
Implementation Method 1
the space is filled with a filler of an electrically insulating material other than that of the outer shell, the filler completely filling the space along said section
Implementation Method 2
the connection means are adapted to provide a press-fit between the outer shell and the voltage-carrying element
Data Source
Figure 1~4
AI summary
A device for electric connection to an energy supply conductor (101) for medium and/or high voltage, comprising a voltage-carrying element (106) with an outer periphery (108), and a tubular outer shell (104) with an inner periphery (110), the outer shell (104) being formed by a polymer, and along at least a part of the axial extension of the element (106) the outer shell (104) extends axially with a space (124) between its inner periphery (110) and the outer periphery (108) of the element (106), at least along a section of said part of the axial extension of the element (106) the space (124) is filled with a filler (128) of an electrically insulating material other than that of the outer shell (104). The device is characterized in that the outer shell (104) comprises connection means for connecting the outer shell (104) to the element (106), and in that the connection means are adapted to provide a press-fit between the outer shell (104) and the element (106). An electric installation including the device, and a method for producing the device.