7-Enclosure temperature control.pdf - Enclosure Temperature Control Overview Enclosure Temperature Rise(DT Electrical and electronic components are

# 7-Enclosure temperature control.pdf - Enclosure Temperature...

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AttaBox Industrial Enclosures | AttaBox.com | 500 Maple Street, Belding, MI 48809 | P 616.794.0700 | A ROBROY ENCLOSURES™ BRAND 131 Overview Electrical and electronic components are continually being reduced in size allowing designers to place more equipment in a smaller space. This concentration of equipment generates higher internal temperatures and makes heat dissipation very important. Overheating causes electrical insulation to deteriorate and shortens the life of electrical and electronic components. As a rule of thumb, for every 18°F (10°C) above room temperature (72°F or 22°C) an electronic device operates, its life expectancy is reduced by 50% Enclosure Materials The following information applies to gasketed and unventilated enclosures. Exterior surface finishes significantly influence temperature rise. Fiberglass, polycarbonate, and painted steel enclosures dissipate heat better than unfinished aluminum or stainless steel enclosures because the fiberglass, polycarbonate, and painted steel surfaces are more efficient thermal radiators than the unfinished surfaces. In outdoor applications light colored enclosures such as white have a high reflectance which minimizes solar heat gain compared to dark colored enclosures. Enclosure Surface Area The total surface area of the enclosure directly influences heat dissipation. The larger the total surface area the lower the temperature rise will be. To calculate the total internal surface area in sqft use the following equation: Surface Area = 2[(AxB)+(AxC)+(BxC)] / 144 where the specific enclosure inside dimensions are A x B x C. This equation uses all six (6) sides of an enclosure. If any particular side is not available for transferring heat (example the back is mounted against a cement wall) that surface area should be subtracted from the total surface area available. Also note, enclosure volume cannot be substituted for enclosure area. Enclosure Heat Input The heat generated in an enclosure varies and depends on the equipment mounted in the enclosure and the application. In order to calculate Temperature Rise, this heat input or power input must be known. This information can be obtained from the component manufacturers of components to be installed in the enclosure. Enclosure Temperature Rise (DT) Enclosure temperature rise is the temperature difference between the air inside a non-ventilated or cooled enclosure and the ambient air outside the enclosure. The enclosure temperature rise is independent of the ambient temperature; it is dependent on the heat generated within the enclosure and the actions taken to dissipate that heat. To establish the maximum service temperature, the temperature rise value from the graph in Figure 1, must be added to the maximum ambient temperature surrounding the enclosure.

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