As electrical components become increasingly smaller and are more densely packed into electrical control panels, the amount of heat generated inside cabinets continues to increase. When considering heat dissipation in control panels it’s important to note what electrical equipment manufacturers specify as a maximum allowable operating temperature for their components.
Maintaining a maximum internal control panel air temperature of 95°F (35°C) helps promote higher operating efficiencies and longer electrical component life. It’s easy to overlook the importance heat dissipation plays in control panels and how it can affect electrical equipment reliability.
How Heat Dissipation Works in Sealed Unvented Control Panels
In order to protect against demanding environmental conditions most industrial applications will require sealed unvented control panels such as NEMA Type 12, 4, and 4X cabinets to protect the costly electrical components housed inside. Most applications will require a closed-loop cooling solution due to high ambient temperatures or to protect sensitive electrical components from excess dust and dirt.
While the heat producing electrical components increase the air temperature inside the control panel, the resulting heat is transferred through the walls of the cabinet to the cooler ambient air outside where heat dissipation occurs. If the ambient air were cold enough to maintain temperatures below maximum operating temperature for the electrical components, this would be a natural cost effective cooling solution, but this is rarely a viable option.
The overall cooling capacity needs to match or exceed amount of total heat load generated by the electrical equipment within the control panel when the ambient air temperature is lower than the cabinet air temperature.
How Heat Dissipation Relates to Control Panel Size
Besides ambient temperature, the physical size of a control panel is the primary factor in rate of heat dissipation. Larger control panels will have larger exterior surface areas, resulting in a lower temperature rise from the heat producing electrical components inside. Having an oversized control panel simply to increase the heat dissipation rate doesn’t make economic sense, since larger cabinets are more costly and may require excessive space.
The easiest method to calculate the surface area of the control panel is to use the following equation: Total Surface Area = 2(H x W) + 2(H x D) + 2(W x D), which includes all six sides of the control panel measured in feet. Any surface area not exposed to ambient air, such as wall mounted or free standing cabinet models without legs, must be subtracted from the total value.
Once the total surface area has been determined, the next step is to calculate the heat load produced by the electrical components.
Factoring in Heat Load Produced by the Electrical Components
The total heat load is established by adding together the heat dissipation of all individual components housed inside the control panel. This information can be obtained from the manufacturers of the electrical components and the resulting value is usually given in Watts.
Additional Heat Dissipation Factors to Consider
Although the heat dissipation calculation of a control panel is a simple one, the true impact of external influences can be more difficult to determine. The control panel’s properties such as color, material type and whether it is insulated or not must also be considered. Factors such as maximum ambient temperature, effects of local heat sources and solar heat gain must be included when calculating the control panel’s total heat load. The control panel’s properties such as color, material type and whether it is insulated or not must also be considered.
The combination of these factors, plus the heat dissipation and heat load values all play an important part in determining the associated cooling capacity requirements.
Heat Dissipation and the Enclosure Temperature Management Calculator
Installing the appropriate control panel temperature control solution is important in order to properly protect the valuable electrical equipment housed inside. To help ensure that you select the right cooling solution for your control panel, use the Enclosure Temperature Management (ETM) Calculator.
The ETM calculator will help determine whether the control panel cooling needs will require an air conditioner, an air to air heat exchanger or a filtered fan package. Additionally, results will show which size and type of air conditioner will provide the required cooling capacity offering the most energy and cost efficient operation.
Don’t Ignore Control Panel Temperature Control
Many electrical control equipment failures are caused by overheating due to improper control panel cooling, but could be avoided with proper temperature control planning. An excellent place to start is to download the free Thermal Management Guide: Meeting Control Panel Space Requirements and Avoid Overheating e-book to learn more about how to incorporate enclosure cooling into your design and keep equipment operating safely in a smaller control panel.
For additional help the experts at Thermal Edge are available to help you properly chose the correct control panel cooling system for your application.