Cap for Electrical Bushing with Integrated Conductive Protrusion

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Solution Overview

Problem

Existing caps for closing electrical bushings in switchgears face issues with unclear fixing mechanisms, high resistivity, and poor electrical contact, leading to potential partial discharges and reduced device lifetime.

Innovation Solution

A cap with a conductive stiffening means and a flexible insulating part, featuring a tubular spring and internal extension for easy assembly and low-resistance electrical contact, ensuring proper electric field distribution and dielectric strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate contacting part made of semiconductor material is used to achieve electrical contact between the switchgear plug and the metallic socket, then electrical contact is provided, but the assembly becomes complex and the electrical resistance increases

Engineering Contradiction:
Improveelectrical contact reliabilityVSAvoidcap structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the contacting function directly into the metallic socket by forming an integrally formed protrusion that extends from the socket wall. This eliminates the need for a separate contacting part, simplifying the cap structure while ensuring reliable electrical contact between the switchgear plug and the metallic socket through the integrated conductive path

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If a separate contacting part made of semiconductor material is used to achieve electrical contact, then electrical contact is provided, but the electrical resistance becomes high

Engineering Contradiction:
Improveelectrical contact reliabilityVSAvoidelectrical resistance
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The contacting function is merged into the metallic socket itself, which is made of conductive material. The integrally formed protrusion creates a direct conductive path from the socket wall to the contact point, eliminating the high-resistance semiconductor material interface and reducing overall electrical resistance while maintaining reliable electrical contact

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If the hole in the metallic socket has larger dimensions than the contacting part, then assembly is easier, but poor electrical contact and high resistance occur

Engineering Contradiction:
Improveassembly easeVSAvoidelectrical contact quality
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The metallic socket with its integrally formed protrusion is designed as a single piece, eliminating the need for separate contacting parts that would require precise hole dimensioning. The protrusion naturally fits with the switchgear plug while ensuring optimal electrical contact area, combining assembly ease with reliable electrical contact without high resistance

Inventive Principle:
Principle #5Merging (Combining)

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 cap provides a robust, easy-to-assemble solution with reliable and low-resistance electrical contact, reducing the risk of partial discharges and extending the device's lifespan by ensuring efficient electric field distribution.

Implementation Method 1

a conductive cap stiffening means located inside the non-through hole, mechanically coupled to the insulating part, and comprising a tubular part for receiving a switchgear plug of the electrical bushing

Methodology Applied
Scientific EffectElectrical Conduction: Conduction (electrical)

Implementation Method 2

the cap stiffening means comprises an extension: electrically and mechanically coupled to the tubular part, located at least partially inside a geometrical contour defined by an infinitely long cylinder extending the tubular part, arranged to electrically contact said switchgear plug

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3343712B1Cap for closing an electrical bushing
Publication Date: 2019.02.13 HET VEER
  • EP3343712B1 patent drawingFigure 1
  • EP3343712B1 patent drawingFigure 2~3
  • EP3343712B1 patent drawingFigure 4~5

AI summary

The present invention relates to a cap (7; 170) for closing an electrical bushings of an external connecting device (104). The cap (7; 170) comprises a flexible insulating part (71) configured to be at least partially received in said electrical bushing and comprising a non-through hole (73). The cap (7; 170) also comprises a conductive cap stiffening means (72; 172) located inside the non-through hole (73) and comprising a tubular part (75) for receiving a switchgear plug (22) of the electrical bushing and an extension (74) arranged to electrically contact said switchgear plug (22). The extension (74) is a contacting part creating an electrical contact between the switchgear plug (22) and the tubular part (75).