Medium-Voltage Contact Assembly With Internal Elastic Spacer

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Solution Overview

Problem

Medium Voltage switches, particularly disconnectors and earthing switches, face challenges with insulating gases having lower insulating properties than SF6, leading to issues with electrical discharges due to inhomogeneous electric fields and the need for maintaining contact force in closed positions.

Innovation Solution

A movable contact assembly for Medium Voltage switches, featuring a spacer with a hollow body housing an elastic element, which provides an attractive force between contact blades, ensuring the required contact force without creating inhomogeneous electric fields.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If insulating gases with lower insulating properties than SF6 are used, then environmental protection is improved, but electrical discharges due to inhomogeneous electric fields increase

Engineering Contradiction:
Improveenvironmental harm from SF6VSAvoidelectrical discharge risk
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The contact blades are designed with specific geometric features including rounded edges and corners, and optimized contact surfaces that create localized regions of improved electric field distribution. This local quality enhancement at critical areas prevents electrical discharges while using environmentally friendly insulating gases with lower overall insulating properties than SF6.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention modifies the geometric parameters of the contact blades, specifically rounding edges and corners with defined radii, and optimizing the spacing and orientation of contact surfaces. These parameter changes create a more homogeneous electric field distribution, reducing the risk of electrical discharges when using alternative insulating gases.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If contact force is maintained in closed position, then electrical connection reliability is improved, but mechanical stress on contact blades increases

Engineering Contradiction:
Improvecontact forceVSAvoidmechanical stress on contact blades
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The contact blade assembly incorporates flexible or elastically deformable elements that dynamically adapt to mechanical stress. The contact blades are designed with controlled flexibility to maintain optimal contact force while absorbing and distributing mechanical stresses, preventing excessive stress concentration that could lead to deformation or failure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention introduces intermediary elements such as flexible connectors or elastic components between the rigid support structure and the contact blades. These intermediaries act as stress buffers, maintaining the required contact force at the electrical contact point while reducing the transmission of mechanical stress to the overall blade structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If complex spring systems are used to guarantee contact force, then contact reliability is improved, but device complexity increases

Engineering Contradiction:
Improvecontact force guaranteeVSAvoidspring system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The contact blade assembly is designed to generate and maintain its own contact force through its inherent structural properties. The blades utilize their own elasticity, geometric configuration, and mounting arrangement to automatically ensure reliable contact force without requiring external spring systems or additional mechanical components to guarantee contact pressure.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention achieves the required contact force by optimizing the geometric parameters and material properties of the contact blades themselves, such as thickness, width, length, and support positioning, rather than adding complex spring systems. These parameter changes allow the blades to generate sufficient contact force through their own structural characteristics.

Inventive Principle:
Principle #35Parameter changes

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 effectively minimizes electrical discharges, maintains the required contact force, and is less prone to damage, while allowing for pre-assembly and testing of components, resulting in a simpler, more cost-effective manufacturing process.

Implementation Method 1

a spacer (20) which is interposed between said first and second contact blades... said spacer (20) comprises a hollow body (21) which houses an elastic element (30)... said elastic element (30) exerts an attractive force between said first and second contact blades

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4535388A1Medium volage switch movable contact assembly
Publication Date: 2025.04.09 ABB (SCHWEIZ) AG
  • EP4535388A1 patent drawingFigure 1a~1b
  • EP4535388A1 patent drawingFigure 2a~2c
  • EP4535388A1 patent drawingFigure 3a~3c

AI summary

A Medium Voltage switch movable contact assembly (1, 10, 50) comprising a first (61) and a second (62) contact blades facing each other at a distance, said first (61) and second (62) contact blades being provided with a corresponding first (71) and second (72) contact element positioned facing each other at a first end (610, 620) of the corresponding blade (61, 62). The first (71) and second (72) contact element are adapted to be coupled with a corresponding first fixed contact (110) of a Medium Voltage switch. The movable contact assembly (1, 10, 50) is characterized in that said movable contact assembly (1, 10, 50) comprises at least a spacer (20, 200) interposed between said first (61) and second (62) contact blades, wherein said spacer (20, 200) comprises a hollow body (21, 210) housing an elastic element (30, 300) which has a first operative end (31, 310) operatively connected to one of said first (61) and second (62) contact blades and a second operative end (32, 320) operatively connected to the other of said first (61) and second (62) contact blades, said elastic element (30, 300) exerting an attractive force between said first (61) and second (62) contact blades.