Arc Resistant Enclosure Flame Arresting Duct System
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Solution Overview
Problem
Underground mining environments pose a risk due to the proximity of high power electrical equipment to flammable materials and explosive gases, as existing arc-resistant enclosures are inadequate in preventing flames from escaping and extinguishing them before release into the environment.
Innovation Solution
An arc-resistant electrical enclosure with a duct system featuring pressure relief chambers and flame arresting ventilation partitions creates a torturous mechanical maze to redirect and extinguish internal flames before they exit, using arc chutes and flaps to manage pressure and oxygen consumption, and segregating circuit breaker panels to isolate potential fires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solid sheet-metal enclosure is used to protect electrical components, then protection from dust, water, and physical damage is improved, but the ability to safely manage and extinguish internal flames during arcing faults deteriorates
Solution Approach 1:
The enclosure is segmented into multiple compartments including a flame arrestor chamber, pressure relief chamber, and main equipment chamber. This segmentation allows the system to contain and manage flames locally within the flame arrestor chamber while protecting the main equipment, resolving the contradiction between solid enclosure protection and flame management capability
Solution Approach 2:
A flame arrestor is introduced as an intermediary component between the internal electrical equipment and the external mining environment. This flame arrestor acts as a mediator that allows heat dissipation while blocking flame propagation, enabling the solid enclosure to maintain its protective function while preventing flame escape
2Stress or pressure
If arc resistant enclosures are designed to withstand and direct gasses out of the roof, then pressure relief is improved, but flame escape risk increases in mining environments with flammable ceilings and coal dust
Solution Approach 1:
Instead of directing flames and hot gases upward through the roof as in conventional arc resistant enclosures, this design inverts the approach by directing them laterally through side walls equipped with flame arrestors. This inversion prevents flame escape into the mining environment while still achieving pressure relief, resolving the contradiction between pressure management and flame containment
3Object-affected harmful factors
If a torturous mechanical maze duct system is implemented to extinguish flames, then flame extinction capability is improved, but device complexity increases
Solution Approach 1:
The duct system is segmented into a series of chambers (flame arrestor chamber, pressure relief chamber, transition chamber) rather than using a complex tortuous maze. Each chamber performs a specific function: flame arrestment, pressure relief, and flow transition. This segmentation achieves flame extinction through a simpler, more maintainable structure
Solution Approach 2:
The flame arrestment function is extracted as a separate, dedicated chamber rather than being integrated into a complex duct maze. This extracted flame arrestor chamber uses a simple grid structure to achieve flame extinction, reducing overall system complexity while maintaining effectiveness
4Object-affected harmful factors
If circuit breaker panels are segregated into separate compartments, then flame isolation between panels is improved, but enclosure complexity increases
Solution Approach 1:
The enclosure is segmented into distinct compartments for different circuit breaker panels, with each compartment separated by fire-resistant walls. This segmentation allows flames to be contained within a single panel compartment while isolating other panels, achieving flame isolation through a straightforward compartmentalized structure rather than a complex system
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
Effectively prevents the escape of flames and gases from the enclosure, ensuring safety by extinguishing internal hot flames within the enclosure before release, thereby reducing the risk of igniting flammable materials and explosive gases.
Implementation Method 1
flame arresting ventilation partitions between each flame arresting compartment and ventilation panels within the compartment to force a change in direction of an arc or flames while consuming oxygen to extinguish the flame
Implementation Method 2
duct system that provides a torturous mechanical maze with pressure relief and flame arresting ventilation partitions to release pressure of expelled gasses
Data Source
AI summary
Methods, systems, apparatus and devices for an arc resistant electrical enclosure that includes a duct system of adjacent pressure relief chambers separated by flame arresting ventilation partitions to provide a torturous mechanical maze to relieve internal pressure and extinguish internal hot flames within the flame arresting duct system prior to exiting the enclosure expelling gasses into the external environment. The adjacent partitioned pressure relief chambers for routing pressure and or flames through the duct system with ninety degree turns from one pressure relief chamber into the next adjacent pressure relief chamber. In an embodiment, a set of ventilation panels is located within one or more of the adjacent pressure relief chambers and each next pressure relief chamber can have a volume that is less than the volume in the preceding chamber.