Arc-Free Circuit Protection for Hazardous Location Switching

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Solution Overview

Problem

Conventional circuit protection devices fail to adequately address ignition risks in hazardous locations, such as those with flammable gases or vapors, as they can generate electrical arcing and overheating, necessitating expensive explosion-proof enclosures that increase costs and reduce maintenance efficiency.

Innovation Solution

The development of an ignition-protected switch device with solid state switching elements that operate arc-free, combined with enhanced terminal connections and thermal management features, allowing for safe operation in hazardous environments without the need for separate explosion-proof enclosures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional circuit protection devices are used in hazardous locations, then they can provide basic circuit protection functionality, but they generate electrical arcing and overheating that create ignition risks requiring expensive explosion-proof enclosures

Engineering Contradiction:
Improveignition protectionVSAvoidexplosion-proof enclosure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical switching elements with solid state switching elements that operate without electrical arcing. The solid state switches use semiconductor devices to control circuit interruption, eliminating the mechanical contact separation that causes arcing in conventional devices. This substitution directly addresses the ignition risk while maintaining circuit protection functionality.

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

Solution Approach 2:

The patent changes the operating parameters of the switching elements by using solid state devices that operate at lower temperatures and without arcing. The solid state switches maintain circuit control while operating below temperature thresholds that could ignite hazardous atmospheres, fundamentally changing the thermal and electrical characteristics of the circuit protection device.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If explosion-proof enclosures are used to protect circuit devices in hazardous locations, then ignition risks are contained, but installation costs increase and maintenance efficiency decreases

Engineering Contradiction:
Improveignition protectionVSAvoidmaintenance efficiency
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The patent extracts the ignition protection function from the separate explosion-proof enclosure and integrates it directly into the circuit protection device itself. By incorporating solid state switching elements that inherently operate without arcing and at controlled temperatures, the device achieves ignition protection independently, eliminating the need for additional protective enclosures and simplifying installation and maintenance.

Inventive Principle:
Principle #2Taking out (Extraction)

3Object-affected harmful factors

If solid state switching elements are used to eliminate arcing, then ignition risks are reduced, but device complexity and thermal management requirements increase

Engineering Contradiction:
Improveelectrical arcingVSAvoidthermal management
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent introduces thermal management components as intermediaries between the solid state switching elements and the surrounding environment. These components, including heat sinks and thermal pathways, mediate the heat generated by solid state operation, efficiently conducting and dissipating thermal energy to maintain operating temperatures below ignition thresholds while preserving the arcing-free operation.

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 reduces installation costs, saves space, and enhances maintenance efficiency by eliminating the requirement for explosion-proof enclosures while ensuring compliance with hazardous location standards, thereby preventing ignition sources and ensuring safe operation.

Implementation Method 1

at least one solid state switching element operable in an arc-free manner to connect the load-side terminal to the line-side terminal and disconnect the load-side terminal from the line-side terminal

Methodology Applied
Scientific EffectArc-free switching:

Implementation Method 2

a temperature sensor in the housing; and a controller configured to receive an input from the temperature sensor

Methodology Applied
Scientific EffectTemperature sensing:

Data Source

PatentEP3903330B1Compliant, hazardous environment circuit protection devices, systems and methods
Publication Date: 2024.04.03 EATON INTELLIGENT POWER LTD
  • EP3903330B1 patent drawingFigure 1
  • EP3903330B1 patent drawingFigure 2
  • EP3903330B1 patent drawingFigure 3

AI summary

Solid state and hybrid circuit protection devices include improved arc-less switching capability and overcurrent protection, improved terminal assemblies and improved thermal management features that reduce or eliminate ignition sources for hazardous environments. The solid state and hybrid circuit protection devices are ignition protected and avoid possible explosions and therefore obviate a need for conventional explosion-proof enclosures to ensure safe operation of an electrical power system in hazardous locations.