Sealed On-Load Tap Changer Switch for Arc Suppression

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Solution Overview

Problem

On-load tap changers experience arcing issues during switch position changes, leading to wear and contamination of electrical switches and surrounding components, which reduces their lifetime and increases maintenance needs.

Innovation Solution

A hermetically sealed electrical switch with a movable switch means and arc suppression gas or vacuum inside the housing, routing conductors from the inside to the outside to minimize arcing and contain contaminants, allowing for reduced wear and easy replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electrical switch is operated in air or insulating oil environment, then the switch can perform make-before-break or break-before-make operations, but arcing occurs causing wear and contamination of the electrical switch and surrounding components

Engineering Contradiction:
Improveswitch operation reliabilityVSAvoidarcing and contamination
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent divides the electrical switch into a sealed housing unit that contains the electrical contacts and switch means, separating them from the surrounding insulating oil environment. This segmentation allows the switch to operate in a controlled atmosphere (vacuum or inert gas) while maintaining connectivity to the external electrical system through sealed conductors, thus preventing arcing-induced contamination of surrounding components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates an inert environment by sealing the electrical contacts and switch means in a housing filled with vacuum or inert gas (such as nitrogen or sulfur hexafluoride). This inert atmosphere suppresses arcing during switch operation, significantly reducing wear and contamination of the electrical contacts while maintaining reliable make-before-break or break-before-make functionality.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

2Duration of action of stationary object

If a hermetically sealed housing with vacuum or arc suppression gas is provided, then arcing is reduced and lifetime is extended, but the device complexity increases

Engineering Contradiction:
Improveelectrical switch lifetimeVSAvoidhousing and sealing structure
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent combines the electrical switch components (contacts, switch means) with the protective housing into a single integrated unit. The housing serves multiple functions: structural support, environmental sealing, and arc suppression containment. This merging reduces the need for additional protective components and simplifies installation while extending electrical switch lifetime through reduced arcing.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the electrical switch operation from the harmful external environment (insulating oil) by enclosing it in a separate sealed housing. This extraction isolates the arcing phenomenon within the housing where it can be controlled through vacuum or inert gas filling, preventing contamination of surrounding components while extending switch lifetime.

Inventive Principle:
Principle #2Taking out (Extraction)

3Object-generated harmful factors

If the electrical switch is designed to contain contaminants, then surrounding components are protected from contamination, but the ease of repair decreases

Engineering Contradiction:
Improvecontamination spreadVSAvoidelectrical switch replacement
Core Design Contradiction:
Object-generated harmful factorsVSEase of repair

Solution Approach 1:

The patent designs the electrical switch as a modular sealed unit that can be replaced as a complete assembly. This segmentation allows the contained contaminants to remain isolated within the housing during replacement, protecting surrounding components while enabling straightforward swap-out of the entire switch unit without complex disassembly or contamination control procedures.

Inventive Principle:
Principle #1Segmentation

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 significantly extends the lifetime of on-load tap changers by minimizing arcing and containment of contaminants within the housing, reducing maintenance needs and maintaining the insulating properties of surrounding components.

Implementation Method 1

the inner space is under vacuum or is filled with an arc suppression gas

Methodology Applied
Scientific EffectVacuum: Vacuum

Implementation Method 2

the electrical contacts and the switch means will be subjected to less arcing upon operation of the electrical switch

Methodology Applied
Scientific EffectArc suppression: Electric Arc

Data Source

PatentEP4333009A1An electrical switch for an on-load tap changer
Publication Date: 2024.03.06 HITACHI ENERGY LTD
  • EP4333009A1 patent drawingFigure 1
  • EP4333009A1 patent drawingFigure 2a~3b
  • EP4333009A1 patent drawingFigure 4a~5b

AI summary

An electrical switch (1) for an on-load tap changer (2), said electrical switch (1) comprising: at least three electrical contacts (3a, 3b, 3c) connected to a respective electrical conductor (4a, 4b, 4c), a switch means (5) configured to be movable between a plurality of positions (P1, P2), wherein the switch means (5) in each respective position (P1, P2) physically contacts a respective combination (C1, C2) of said electrical contacts (3a, 3b, 3c) to provide electrical contact between the electrical contacts in each respective combination (C1, C2) of electrical contacts (3a, 3b, 3c), a hermetically sealed housing (6) providing an inner space (7) enclosing the electrical contacts (3a, 3b, 3c) and the switch means (5), said electrical conductors (4a, 4b, 4c) extending from the electrical contacts (3a, 3b, 3c) inside the inner space (7) of the housing (6) to an outside of the housing (6), and a control means (10) configured to control movement of the switch means (5). The inner space (7) is under vacuum or is filled with an arc suppression gas.