Enclosure Thermal Management

The internal temperature of an electrical enclosure must be closely monitored and controlled in order to protect sensitive equipment housed inside. The changing temperature outside of an enclosure can require heating or cooling applications for the inside of an enclosure to prevent components from freezing or overheating and to prevent condensation from forming. 

Enclosure air conditioners use chemical refrigerants, compressors, evaporators, condensers and fans to cool the inside of an enclosure. They create a closed loop system for cooling, which circulates the air inside the enclosure without mixing with outside air. Thermoelectric coolers have a cold side that is placed inside the enclosure and a hot side placed outside the enclosure with fans that circulate the cool air throughout the enclosure.

Enclosure fans draw filtered, ambient air into the enclosure at the same time as internal, heated air is blown out as exhaust. An exhaust filter can be used with a filter fan to aid in pressurization of the enclosure, reducing the chance of unfiltered air entering back into the enclosure. A filter fan should be located in the bottom third of the enclosure and the filtered exhaust grill placed as high as possible on the opposite side of the fan.

Enclosure heaters are necessary when an outdoor enclosure is located where temperatures dip well below freezing and heating is required to keep the internal temperature of the enclosure within an optimal operating range for the electrical components. Heaters also help to reduce condensation, with relative humidity inside the enclosure ideally kept below 65 percent. A heater should be placed near the bottom of the enclosure to allow natural convection of heat distribution, but some larger enclosures could require a fan to distribute heat.