ENCLOSURES PRODUCTS CALCULATING THERMAL DISSIPATION
Thermal dissipation occurs when the heat of an object is transferred to its environment, or onto nearby colder objects. The thermal dissipation of an electrical enclosure is one of the most important elements to consider before installing the cabinet itself. The thermal balance for an electrical cabinet is the optimal condition
to preserve the life of the installed components, but requires a careful evaluation of all the thermal powers acting on it: it is valid if the total of the thermal powers sum is zero. In order to obtain the thermal balance of an electrical cabinet, the
design conditions must be defined. A good rule of thumb is to set 35˚C for the ideal internal temperature – to avoid overheating the electrical components whilst ensuring the risk of condensation is very low. The thermal power, for example, the amount of thermal energy
transmitted through the walls of the electrical cabinet, is just one of the factors that guarantee the thermal balance. This depends on: temperature of the cabinet’s environment; construction material and surface area of the electrical cabinet; and location of the electrical cabinet. By knowing these three factors, the designer can
calculate the thermal dissipation of an electrical cabinet using the Thermal Dissipation Formula: Qdiss=U*A*ΔT [W]. Whereby: U [W/m2
K] is the thermal transmittance of the
walls of the electrical cabinet A [m²] is the total heat exchange area ΔT [K] is the temperature difference between the cabinet exterior and interior (Tenvironment
-Tcabinet ). In most cases, electrical enclosures need to be cooled
so a combination of fan filter units and exhaust inlets should be employed. When cabinets are installed in an environment which is colder than the required internal temperature, thermostats and heaters are needed to avoid condensation.
Axair Fans
www.axaironline.co.uk
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