Arc Gas Venting in Modular Bucket Switchgear
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Solution Overview
Problem
There is a need for an arc resistant switchgear design that safely directs hot decomposition products away from personnel during an internal arcing fault, while maintaining a minimized section depth and ensuring Type 2B accessibility, as existing designs fail to effectively manage arc gases and pressures in low voltage switchgear.
Innovation Solution
A modular bucket assembly with a box-shaped bucket having vents in the exterior side wall to create an arc gas venting passage, combined with a metal enclosure on the bottom wall that houses direct power connected devices and fuses, configured to withstand arc fault pressures and direct arc gases away from the front, sides, and rear of the switchgear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard auxiliary compartment is used to house direct power connected devices, then the compartment can accommodate the equipment, but the arc blast would exit the front of the switchgear and harm the operator
Solution Approach 1:
The auxiliary compartment is segmented into two distinct parts: a standard auxiliary compartment and a new arc-resistant auxiliary compartment. The arc-resistant compartment is specifically designed with arc gas venting passages to safely channel decomposition products away from personnel, while the standard compartment maintains traditional functionality. This segmentation allows the system to accommodate equipment while protecting operators from arc hazards.
Solution Approach 2:
Arc gas venting passages are introduced as intermediary channels between the arc fault source and the external environment. These passages safely conduct hot decomposition products away from the front, sides, and rear of the switchgear, preventing direct exposure of personnel to harmful arc gases while maintaining normal operational access.
2Ease of operation
If the section depth is minimized for front-connected switchgear, then accessibility from the front is improved, but the ability to effectively manage arc gases and pressures is compromised
Solution Approach 1:
The arc gas venting passages utilize three-dimensional spatial routing to channel arc gases away from personnel in the front accessible area. By designing the passages to extend toward the rear and sides of the switchgear, the system maintains a minimized front section depth while effectively managing arc gases through alternative spatial pathways that do not compromise operator safety.
3Reliability
If vents are added to the exterior bucket side wall, then arc gases can be exhausted safely, but the structural integrity and complexity of the bucket assembly increases
Solution Approach 1:
The bucket assembly is segmented into a standard portion and a vented exterior side wall portion. The vents are strategically located and configured to provide effective arc gas exhaust pathways while minimizing interference with the overall structural integrity of the bucket assembly. This segmented approach allows the addition of safety features without completely redesigning the entire bucket structure.
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 effectively channels arc gases and pressures away from personnel and equipment, ensuring safety during arcing faults and maintaining the shallowest section depth in the industry, thus providing enhanced protection and accessibility in arc resistant switchgear.
Implementation Method 1
Arc temperatures can exceed 20,000 degrees Kelvin, rapidly heating the air and vaporizing metal parts
Implementation Method 2
rapidly heating the air and vaporizing metal parts
Implementation Method 3
the energy resulting from an internal arc in air causes a sudden pressure and temperature increase inside the enclosure
Implementation Method 4
The vents in the exterior bucket side wall define an arc gas venting passage in communication with an interior of the auxiliary compartment for exhausting arc gasses from the auxiliary compartment to an exterior of the switchgear cabinet
Data Source
AI summary
A modular bucket assembly of a low voltage switchgear includes a box shaped bucket having an interior bucket side wall, an exterior bucket side wall with vents in a first periphery, a bucket rear wall, a bucket top wall and a bucket bottom wall. All of the bucket walls define an auxiliary compartment of a switchgear cabinet. The vents in the exterior bucket side wall define an arc gas venting passage in communication with an interior of the auxiliary compartment for exhausting arc gasses to an exterior of the cabinet. The modular bucket assembly further comprises a metal enclosure mounted on the bucket bottom wall. The metal enclosure has a side opening with a second periphery such that the second periphery overlaps the first periphery of the exterior bucket side wall. The metal enclosure is configured to house direct power connected devices and protective fuses and withstand arc fault pressures.