Arc Flash Resistant Enclosure Segregated Cooling Paths
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Solution Overview
Problem
Electrical enclosures face challenges in withstanding mechanical and thermal effects of internal arcing faults, which can cause damage and pose hazards, and in providing effective cooling and environmental protection against dust and moisture.
Innovation Solution
The enclosure design features segregated cooling paths and enhanced arc flash resistance, with a blower directing air from both compartments out of the enclosure, and arc flash paths that increase the arc's travel length and force it to change direction, reducing arc energy by 75% before exit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air cooled enclosures have intake vents and exhaust vents for cooling, then cooling effectiveness is improved, but arc plasma can escape through these vents during arc faults
Solution Approach 1:
The enclosure is divided into multiple compartments (first compartment for power conversion equipment, second compartment for other equipment) with separate cooling paths. Each compartment has its own intake vents and exhaust vents, preventing arc plasma from propagating through the entire enclosure while maintaining cooling effectiveness in each zone.
Solution Approach 2:
A partition wall with fire-resistant material acts as an intermediary between compartments, and arc shields are positioned at strategic locations to block and redirect arc plasma away from vents and personnel areas, allowing cooling air flow while preventing harmful arc plasma escape.
2Productivity
If arc flash paths are shortened for efficient heat dissipation, then cooling efficiency is improved, but arc energy reduction is insufficient
Solution Approach 1:
The arc flash path is configured to extend in multiple dimensions within the enclosure, utilizing vertical and horizontal pathways rather than direct straight-line paths. The arc flash path extends from lower vents upward and then outward through upper exhaust vents, increasing path length and forcing arc energy dissipation through extended travel distance while still maintaining effective heat removal.
3Ease of operation
If operator controls are placed on the front door for ease of operation, then ease of operation is improved, but personnel are exposed to arc flash hazards
Solution Approach 1:
Operator controls are extracted from the front door and relocated to a safe position outside the enclosure or on a protected panel. This removes the hazard of arc flash exposure to operators while maintaining ease of operation, as controls remain accessible but are no longer in the direct path of potential arc plasma escape.
Solution Approach 2:
The design uses the enclosure structure and partitioning to redirect arc plasma away from personnel areas. The arc shields and compartmentalized design convert the potential harmful direct arc path into a controlled path that dissipates energy safely within the enclosure, allowing controls to remain accessible while protecting personnel.
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 design enhances safety by effectively dissipating arc energy, maintaining component reliability, and providing protection against dust and moisture, while reducing personnel exposure to arc flashes.
Implementation Method 1
a blower to direct air from both the first and second compartments out of the enclosure. The ambient air drawn into the first compartment flows along a first cooling path extending from the first intake vent to the blower
Implementation Method 2
a first arc flash path of the first compartment extends between the first intake vent and the blower (exhaust outlet), the arc flash path making at least two 90 degree turns prior to the blower
Data Source
Figure 1~3
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AI summary
Disclosed examples include enclosures with segregated or divided cooling paths and improved arc flash resistance. In one example, a TYPE 12, 50 DEGREE C ambient common bus power conversion enclosure design provides enhanced arc flash protection & segregated cooling for high reliability of imbedded electronics. Example enclosures and systems can be used in association with AC/DC converters for motor drives or motor control centers, and/or for electroplating or painting systems with modular anode control (MAC) systems to implement an anodic DC electroplating for workpieces and other end use applications.