Basics of Thermal Management in Enclosures


To prevent the premature failure of equipment within an electrical enclosure, thermal management is key. There are two ways of cooling an enclosure; by natural convection and forced convection.

Natural convection

Natural convection used for an enclosure means that cool air will naturally flow through the bottom making the heat rise and then flow out of the top. This is a very slow and gradual process and cannot be controlled. This is a risky choice for the components inside.

Forced convection

Forced convection uses the same principle but with help from a fan filter unit to help draw cool air in and blow hot air out (as well as cooling the air within). By using a fan filter unit, you are also protecting your equipment against splashes and dust. An air conditioner can also be used depending on the equipment’s cooling needs.

To establish what fan you need you must know the maximum ambient temperature, the temperature that the equipment needs to be kept below and heat loss figures. This information is usually stated by the manufacturer and is easy to find.  The following equation can then be used to determine the airflow:


V=    F   x Kw                                                                    V = Volume Required

ΔT                                                                       kW =Watts Dissipation / Heat Loss

ΔT=Allowable Temperature increase inside the cabinet

F= (m³ °C/Wh)

V = 3.1 x 1200


Example: –3.1m³ x (1200W / 15°C) = 248m³/h required airflow.

Note that altitude should be considered in the equation as it affects the air density, without adjusting for this the results will be skewed.

As discussed above, a controlled approach is the most beneficial. One product that is essential to the approach is a thermometer. By using a thermometer you can know at all times what temperature the enclosure it at making sure it doesn’t get too cold or too hot, then taking the appropriate action for the equipment. Another useful accessory is an anti-condensation heater. It doesn’t need to be cold for condensation to form, it only takes a slight change in temperature. By using an anti-condensation heater this can be prevented. Condensation can make the equipment behave erratically or worse, damage it.

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