Light Sensitive Marker for Arc Fault Localization in Fluid Insulated Switchgear

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Solution Overview

Problem

Current methods for detecting internal arc faults in fluid insulated switchgear are often expensive, time-consuming, unreliable, or prone to electromagnetic interference, and require complex installations or short time windows for gas sampling.

Innovation Solution

A light sensitive marker is integrated into the switchgear, which changes color when exposed to light from an internal arc, allowing for simple, inexpensive, and interference-free localization of the affected compartment by visual inspection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical fibers and detectors are used to detect internal arcs, then detection reliability is improved, but device complexity and installation cost increase

Engineering Contradiction:
Improvedetection reliabilityVSAvoidinstallation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the detection function from complex electronic systems and implements it through a simple light-sensitive marker that passively changes color when exposed to arc light. This eliminates the need for optical fibers, detectors, and electronic data acquisition systems, resolving the contradiction between detection reliability and installation complexity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The light-sensitive marker is a simple, inexpensive, single-use component that can be easily attached to switchgear compartments. Once it has indicated an arc event through color change, it serves its purpose and can be replaced, providing reliable detection without the complexity and cost of reusable electronic systems

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Reliability

If gas sampling is performed to detect arc-related SF6 decomposition by-products, then detection capability is improved, but time window for sampling is reduced

Engineering Contradiction:
Improvedetection capabilityVSAvoidsampling time window
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The light-sensitive marker is pre-installed on the switchgear compartments before any arc event occurs. It is positioned to be exposed to the interior where arcs may happen, so it is ready to immediately record any arc event without requiring post-event gas sampling or analysis

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If pressure sensors with high time resolution are installed to detect sudden pressure rise, then detection precision is improved, but device complexity and electromagnetic interference risk increase

Engineering Contradiction:
Improvepressure measurement precisionVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/electronic pressure sensing system with a passive optical indicator system. Instead of measuring pressure changes electronically, the light-sensitive marker directly responds to the physical presence of arc light, eliminating the need for pressure sensors, data acquisition systems, and electronic signal transmission that are susceptible to electromagnetic interference

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If burst disk is used to locate arc faults, then localization is improved, but indication is only available when burst disk opens

Engineering Contradiction:
Improvearc fault localizationVSAvoidindication availability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The light-sensitive marker is pre-positioned on or near the burst disk and other critical components before any arc event. This ensures that even if the burst disk does not open, the marker will have been exposed to arc light and will change color, providing reliable indication of the arc location regardless of burst disk behavior

Inventive Principle:
Principle #10Preliminary action

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

Enables rapid and reliable detection of internal arc faults without the need for complex installations or high-resolution pressure measurements, reducing downtime and maintenance costs by using a color-changing marker that can be easily attached to the switchgear.

Implementation Method 1

a light sensitive marker with a light sensitive substance that changes color when exposed to light

Methodology Applied
Scientific EffectPhotochromism: Photochromism

Data Source

PatentEP3807909B1Light indicator for location of internal arcs in fluid insulated switchgear
Publication Date: 2022.08.24 HITACHI ENERGY SWITZERLAND AG
  • EP3807909B1 patent drawingFigure 1~2B
  • EP3807909B1 patent drawingFigure 3~4

AI summary

A fluid insulated switchgear (10) comprises a fluid compartment (12) filled with an electrically insulating fluid (14); an electrical conductor (18) inside the fluid compartment (12) and electrically insulated by the electrically insulating fluid (14); and a light sensitive marker (26) with a light sensitive substance (34), which changes color, when exposed to light; wherein the light sensitive marker (26) is arranged at a position exposed to light generated by an internal arc.