Condenser Core Bushing Head Sealing Without a Winding Tube

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Solution Overview

Problem

Existing high-voltage bushing designs face issues with thermal shrinkage leading to mechanical stresses and compromised gas/liquid tightness due to the use of winding tubes, which can result in cracks or gaps at varying temperatures.

Innovation Solution

A bushing design without a winding tube, featuring an electrically insulating condenser core with a conductive head that forms a gas-tight cap, allowing the condenser core to expand and contract freely, and maintaining electrical potential with the conductor and field-grading layers to prevent flash-overs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a winding tube is used to provide gas and liquid tightness, then sealing is improved, but mechanical stresses and cracks occur due to thermal shrinkage

Engineering Contradiction:

Improvegas and liquid tightnessVSAvoidmechanical stress resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The invention removes the winding tube from the bushing structure entirely. Instead of using a separate winding tube to provide gas and liquid tightness, the condenser core itself is designed to provide the sealing function directly at the conductor interface, eliminating the source of thermal shrinkage stresses that cause cracks.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention combines the sealing function with the condenser core structure. The condenser core is designed to directly engage and seal around the conductor, merging the electrical insulation function with the gas/liquid tightness function in a single integrated component rather than using separate winding tube and condenser core elements.

Inventive Principle:

Principle #5Merging (Combining)

2Strength

If the condenser core is hardened at high temperature, then structural strength is improved, but thermal shrinkage generates mechanical stresses leading to cracks

Engineering Contradiction:

Improvestructural strengthVSAvoidcrack resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention accepts that thermal shrinkage will occur during cooling but designs the structure to benefit from it. The condenser core is designed with a geometry and material composition that allows controlled shrinkage to create a compressive pre-stress state that actually enhances the sealing pressure and structural integrity, converting the potentially harmful shrinkage into a beneficial pre-compression effect.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If a winding tube is used to provide gas and liquid tightness, then sealing is improved, but device complexity increases

Engineering Contradiction:

Improvegas and liquid tightnessVSAvoidbushing structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention removes the winding tube component from the bushing assembly, simplifying the overall structure. The condenser core is designed to perform both its electrical insulation function and its gas/liquid sealing function without requiring a separate winding tube, reducing the number of components and assembly steps.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The condenser core is designed as a multi-functional component that simultaneously provides electrical insulation, mechanical support, and gas/liquid sealing. This universal design eliminates the need for specialized winding tube components, reducing device complexity while maintaining all necessary functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 design enhances gas tightness and reduces mechanical stresses, preventing cracks and maintaining reliable sealing across temperature variations without the need for a winding tube, ensuring consistent performance and durability.

Implementation Method 1

allowing the condenser core to expand and contract freely

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the thermal shrinkage of the resin generates mechanical stresses

Methodology Applied

Scientific EffectThermal shrinkage: Thermal Contraction

Implementation Method 3

maintaining electrical potential with the conductor and field-grading layers to prevent flash-overs

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 4

sealingly engaging a circumferential lateral outer surface of the condenser core

Methodology Applied

Scientific EffectSealing:

Data Source

PatentUS12261421B2Bushing with electrically conductive head mounted on condenser core

Publication Date: 2025.03.25 HITACHI ENERGY LTD

AI summary

The present disclosure relates to a bushing including an electrical conductor comprising a terminal at a first end of the bushing. The bushing also includes an electrically insulating condenser core arranged around the conductor and defining a central longitudinal through-hole through which the conductor extends. The bushing also includes a plurality of concentric field-grading layers arranged in the condenser core, comprising an inner field-grading layer and an outer field-grading layer. The bushing also includes an electrically conductive head electrically connected with the conductor passing there through, forming a gas-tight cap of the first end of the bushing outside of the condenser core, sealingly engaging a circumferential lateral outer surface of the condenser core and sealingly engaging the conductor. The bushing also includes an electrically conductive connection between the inner field-grading layer and the head.