Switchgear Air Intake Shutter Layout for Internal Arc Containment

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Solution Overview

Problem

Conventional metal enclosed switchgear with large current ratings face issues where high temperature and high pressure gases generated during internal short circuits can escape through air intake openings due to the failure of check valve type shutters to block the flow, leading to reliability concerns and increased switchgear dimensions.

Innovation Solution

Incorporating a ground fault partition body or frame between the check valve type shutter and conductive portions to redirect stray arcs and prevent the check valve type shutter from opening, ensuring the air intake opening remains closed during internal short circuits, thus preventing high temperature and high pressure gas from escaping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a check valve type shutter is provided on an air intake opening to block high temperature and high pressure gas during faults, then safety is improved, but the shutter may be opened by electromagnetic force during ground faults causing reliability to deteriorate

Engineering Contradiction:
Improvehigh temperature and high pressure gas escapeVSAvoidshutter operation reliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

A ground fault partition body is introduced as an intermediary component between the air intake opening and conductive portions. This partition body redirects stray arcs away from the check valve type shutter, preventing the shutter from being opened during ground faults while still allowing it to function as a safety barrier against high temperature and high pressure gas escape.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the switchgear dimensions are increased to accommodate safety margins from charged portions to the shutter, then safety is improved, but device complexity and size increase

Engineering Contradiction:
Improvearc impact on shutterVSAvoidswitchgear dimensions
Core Design Contradiction:
Object-affected harmful factorsVSLength of stationary object

Solution Approach 1:

The ground fault partition body serves as a protective intermediary that redirects stray arcs before they can reach the check valve type shutter. This allows the shutter to be positioned closer to charged portions without compromising safety, thereby reducing the overall dimensions of the switchgear while maintaining adequate safety margins.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution enhances the reliability of the check valve type shutter operation, preventing gas escape and allowing for a more compact switchgear design by ensuring the check valve type shutter effectively blocks high temperature and high pressure gases during faults.

Implementation Method 1

a check valve type shutter 33...blocks the air intake opening 32 in the occurrence of an internal short circuit fault

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

Incorporating a ground fault partition body or frame between the check valve type shutter and conductive portions to redirect stray arcs

Methodology Applied
Scientific EffectArc redirection: Electric Arc

Implementation Method 3

the air around the switchgear is taken in to lower internal air temperature by convection in the inside of the switchgear

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3200295B1switchgear
Publication Date: 2023.08.30 MITSUBISHI ELECTRIC CORP
  • EP3200295B1 patent drawingFigure 1
  • EP3200295B1 patent drawingFigure 2
  • EP3200295B1 patent drawingFigure 3

AI summary

A switchgear according to the present invention comprises: an air intake mechanism attachment body (31) arranged on an air intake portion (30) provided on a housing (1); an air intake opening (32) provided in the air intake mechanism attachment body (31); a check valve type shutter (33) which is arranged on the inner side of the air intake opening on the housing (1), performs an air intake from the outside of the housing (1), and blocks the air intake opening (32) in the occurrence of an internal short circuit fault; and a ground fault partition body (35) arranged between the check valve type shutter (33) and a conductive portion in the housing (1).