Hot spots, i.e. localized areas where higher temperatures can be detected, are among the main causes of failure of electrical equipment housed in cabinets or control panels. So, to correctly dissipate these heat accumulations and correctly manage the temperature inside the electrical panel, cooling must no longer be considered a secondary factor.
How and where hot spots are formed
It’s impossible to say whether and where hot spots could be located inside a cabinet since the layout, the thermal load of the installed electrical equipment, the dimensions of the cabinet and the environmental conditions are unique for each installation.
However, the formation of hot spots is frequent near devices which develop more heat during their activity and those not directly hit by any cooling air flows, due to the internal layout which influences their path.
Hot spots, in fact, can be the result of undercuts or impediments in the path that inhibit cooler air from reaching certain hidden points within the casing. If the cabinet is assumed to be an enclosed space, hot spots are bound to develop near the top, where hot air accumulates, due to heat stratification, and will be further amplified by extreme environmental conditions.
In slightly rarer cases, hot spots could be the result of loose and corroded cables, component failures, and unbalanced loads.
How to spot hot spots
Hot spots inside electrical cabinets can only be identified through advanced techniques, such as thermal imaging, infrared testing, thermal imaging cameras and heat transfer simulations. The simplest solution to identifying hot spots on the surface is to install a thermal imager inside the enclosure and adjust the scale to reveal them. An alternative to identifying potential hot spots in an already built enclosure is to create a design of the existing layout that includes the air inlet and exhaust openings and perform a coupled analysis of air flow and heat transfer, after marking potential sources. Thermal imaging cameras and IR testing are among the latest advances in thermal imaging, providing better results, but they are also more expensive.
Hot spot management solutions
In most cases, the temperature outside the cabinet is low enough to solve everything with a simple forced air exchange, through vented openings such as filters and filter fans, while coolers are an effective solution when there’s the need to control the temperature inside the electrical panel and bring it below the room temperature.
However, even the use of forced convection methods does not absolutely guarantee the risk of hot spot formation if the positioning of the fans in the cabinet is not carefully taken care of. Air vortices and “heat pockets” can make the efforts to ventilate and cool vain.
Here are some tips to avoid hot spots:
- Develop the internal layout before defining the position of the inlet and exhaust openings in the cabinet, taking into account the movement of air and heat transfer within the space.
- Place fans on the panel away from possible airflow restrictions: this allows the airflow to reach an optimal speed which promotes better heat transfer.
- Add air deflectors if necessary to direct airflow to critical areas, thus aiding in the removal of hot spots.
- Install an orientable fan inside the cabinet to ensure the elimination of air pockets, especially in the most critical points.
OF Fandis adjustable fans
The OF series is Fandis’ range of orientable fans, a simple option that guarantees effective results. Often, inside a pre-existing electrical panel, it can be difficult to find enough space to install a fan in the immediate vicinity, oriented in the right position. The OF series, on the other hand, allows you to adjust the direction of the air flow on two axes, in order to concentrate the optimal air flow where necessary, regardless of the installation point.
Fandis orientable fan is available in 230 Vac, 115 Vac versions and 24 Vdc, and all equipped with fixing brackets for uprights with a 25 mm pitch, which is the most widespread standard within electrical panels.