HV Bushing with Conductive Field Guiding Element
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Solution Overview
Problem
Existing bushings for medium and high voltage face challenges in production complexity and cost, with insulating gas alone being insufficient to prevent electric discharges and susceptible to leakage, and thermoplastic bushings may allow moisture diffusion.
Innovation Solution
A bushing design featuring a tubular outer shell made of polymer with a conductive guiding element placed in the space between the shell and the voltage-carrying element, filled with an electrically insulating material like polyurethane, which provides efficient shielding and prevents air pockets, allowing for flexible material selection and easier assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If insulating gas is used to fill the space between the conductor and the outer shell, then the production cost is reduced and the structure is simplified, but the prevention of electric discharges becomes insufficient and the system becomes susceptible to gas leakage
Solution Approach 1:
The insulating space is segmented into two distinct zones: an inner region filled with insulating liquid (oil or resin) directly surrounding the conductor for reliable discharge prevention, and an outer region filled with insulating gas for cost-effective volume filling. This segmentation allows each material to perform its optimal function while combining the benefits of both approaches.
Solution Approach 2:
Different insulating materials are applied to different regions based on their specific requirements: the high-dielectric-strength insulating liquid is placed where electric field stress is highest (near the conductor surface), while the lower-cost insulating gas is used in regions where mechanical filling is easier and electric stress is lower.
2Ease of manufacture
If thermoplastic material is used for the outer shell, then the production cost is reduced compared to thermosetting resin, but moisture diffusion into the container becomes possible
Solution Approach 1:
The insulating liquid (particularly resin-based materials) serves as an intermediary barrier between the external environment and the container interior. This liquid layer, in conjunction with the thermoplastic outer shell, creates a dual-protection system that maintains the moisture barrier function traditionally provided by thermosetting materials while allowing the use of cost-effective thermoplastic shells.
3Reliability
If thick solid bodies of thermosetting material are used for insulation, then satisfactory electrical insulation and discharge prevention are achieved, but the production process becomes costly and complex
Solution Approach 1:
The patent utilizes liquid-filled cavities (insulating oil or resin) to provide electrical insulation instead of relying on thick solid thermosetting material. The liquid filler is introduced into the mold cavity after the shell and conductor are in place, allowing for thinner shell walls and simplified molding processes while achieving the required insulation performance through the liquid dielectric medium.
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 reduces production complexity and costs, enhances electrical insulation, prevents electric discharges, and shields against moisture, resulting in a reliable and efficient bushing for medium and high voltage applications.
Implementation Method 1
filling said space with a filler in a liquid state and permitting the filler to solidify
Implementation Method 2
at least one guiding element for guiding the electric field produced by the voltage-carrying element, the guiding element being at least partly conductive
Data Source
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 further comprises at least one guiding element (136, 502, 602) for guiding the electric field produced by the voltage-carrying element (106), the guiding element (136, 502, 602) being at least partly conductive, and the guiding element (136, 502, 602) is provided in said space (124). An electric installation including the device, and a method for producing the device.