Sensored Bushing Mesh Electrode to Prevent Partial Discharge
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Solution Overview
Problem
Existing sensored bushings in medium-voltage or high-voltage power distribution networks face issues with electrical discharges due to voids and delamination in the insulating material, leading to reduced reliability and increased manufacturing costs.
Innovation Solution
A bushing design with a low-voltage electrode having a circumferential wall made of a mesh of conductive wires, allowing the casting material to flow through apertures and form bridges during solidification, reducing voids and delamination, and enhancing mechanical stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solidified casting material is used to embed capacitors in the bushing body, then mechanical rigidity and electrical insulation are improved, but voids and delamination occur leading to partial discharges
Solution Approach 1:
The low-voltage electrode is constructed as a mesh structure with intentional apertures, creating a porous configuration that allows casting material to penetrate through and form mechanical bridges. This porous design enables the casting material to flow through the electrode structure during manufacturing, establishing strong mechanical interconnections that prevent delamination and void formation, thereby eliminating partial discharge risks while maintaining mechanical rigidity.
2Manufacturing precision
If the casting material is made highly viscous to reduce void formation, then filling completeness is improved, but flow into cavity through apertures is hindered
Solution Approach 1:
The low-voltage electrode is designed as a three-dimensional mesh structure with apertures distributed throughout its volume, rather than a solid two-dimensional barrier. This dimensional transformation allows the casting material to flow through the electrode structure in multiple directions, ensuring complete cavity filling even with highly viscous materials, while the mesh geometry facilitates penetration and bridge formation.
3Reliability
If a mesh of conductive wires is used for the low-voltage electrode, then conductivity and mechanical stability are improved, but structural complexity increases
Solution Approach 1:
The mesh structure of the low-voltage electrode simultaneously fulfills multiple functions: it provides electrical conductivity through the conductive wire network, enables mechanical interconnection with the casting material through aperture bridges, allows casting material flow through its structure, and maintains structural stability. This multi-functionality eliminates the need for separate components for each function, reducing overall device complexity despite the mesh configuration.
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 design ensures reliable voltage sensing with reduced discharges and lower manufacturing costs by minimizing voids and delamination, improving mechanical stability and conductivity.
Implementation Method 1
the apertures allow the casting material radially outside the circumferential wall to be mechanically connected with the casting material in the cavity
Implementation Method 2
The dielectric is formed by a portion of the casting material arranged in the cavity
Data Source
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AI summary
Bushing (1) for connecting a separable connector to a switchgear or to a transformer in a national grid for distributing electrical power at medium or high voltages. The bushing comprises a) a bushing body (141) of a solidified, electrically insulating casting material; b) a bushing conductor (560), embedded in the casting material, for conducting power at medium or high voltages into the switchgear or the transformer, and c) an integrated primary capacitor (150), operable in a high-voltage portion of a voltage divider for sensing a voltage of the bushing conductor. The primary capacitor comprises a low-voltage electrode (170), a high-voltage electrode (160) and a dielectric. The high-voltage electrode is a section of the bushing conductor. The low-voltage electrode is embedded in the casting material and comprises a circumferential wall (173) surrounding the bushing conductor and forming a cavity (177). The dielectric is formed by a portion (181) of the casting material arranged in the cavity. The circumferential wall comprises a mesh of conductive wires forming a plurality of apertures between the conductive wires to allow the casting material radially outside the circumferential wall to be mechanically connected with the casting material in the cavity.