Coaxial Earthing Contact in Three Position Switchgear

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

State-of-the-art three position switches in medium or high voltage switchgear are large, require large gas compartments, and do not support short current paths, which limits their efficiency and design capabilities, especially in Gas Insulated Switchgear (GIS) applications.

Innovation Solution

A three position switch with a tube-shaped conductor and a coaxial earthing contact, where a piston moves axially to enable current flow, isolation, or earthing, providing a short current path and reducing the size of the switchgear compartment by aligning the switches with busbars, and using a ceramic layer for thermal management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional three position switch with piston and tulip contacts is used, then the switch can realise connected, isolated and earthed positions, but the switch becomes relatively large and requires relatively large gas compartments

Engineering Contradiction:

Improveswitch functionalityVSAvoidgas compartment size

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The earthing contact is positioned inside the tube-shaped conductor, creating a nested configuration where the earthing contact is coaxially arranged within the conductor. This nesting allows the earthing function to be integrated within the existing conductor volume, eliminating the need for separate external earthing structures and reducing the overall gas compartment size while maintaining all three switch positions.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If traditional three position switches are used, then the switch can provide isolation and earthing functions, but the current path inside the switchgear panel becomes long

Engineering Contradiction:

Improveisolation and earthing functionVSAvoidcurrent path length

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

Instead of having the earthing contact outside the conductor, the design inverts the traditional arrangement by placing the earthing contact inside the tube-shaped conductor. This inversion creates a direct radial current path from the conductor through the piston to the earthing contact, significantly shortening the current path length compared to traditional external earthing configurations.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If larger gas compartments are used to accommodate traditional three position switches, then the switch can operate reliably, but the overall switchgear size increases

Engineering Contradiction:

Improveswitch operationVSAvoidswitchgear compartment size

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The design merges the earthing contact with the internal space of the tube-shaped conductor, combining two functional elements (conductor and earthing contact) into a compact integrated structure. This merging eliminates the need for separate external earthing components and reduces the overall switchgear compartment volume while ensuring reliable operation of all switch positions.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP3671789B1Medium or high voltage switchgear with a three position switch

Publication Date: 2021.06.23 ABB (SCHWEIZ) AG

Figure 1
Figure 2~3
Figure 4

AI summary

The present invention relates to a medium or high voltage switchgear (1) with a three position switch. The three position switch comprises a tube shaped conductor (91) for connection of a cable and the three position switch comprises an earthing contact (100). The earthing contact is arranged inside of and coaxial to the tube shaped conductor.