How does heat transfer and how does it affect the reliability of the electrical components of a panel?

The electrical and electronic components of an enclosure can withstand variable heat variations, beyond which the reliability of their operation is compromised. For this reason, it’s important to know how temperature affects their operation and which thermal conditions they can withstand, inquiring when designing the panel.

But that’s not all: the electrical activity of the components itself absorbs energy, which is partly transformed into thermal energy (Joule effect). This heat builds up in the through environment of the enclosure, moving from one point to another, and possibly becoming trapped in areas critical for the components that occupy them.

How does heat move in the electrical cabinet?

Going into detail, there are three different ways of transferring heat: conduction, convection and radiation.

• Conduction: thermal energy is transmitted by direct contact between a body with a higher temperature and a colder one, until a thermal equilibrium is reached.
• Convection: the passage of thermal energy occurs thanks to the movement of air which, as it becomes hotter, decreases in density and rises to the top. When the transmission of heat occurs with only the air currents that are formed due to differences in density, we speak of natural convection. If, on the other hand, the movement is induced and faster, thanks for example to the use of a fan, then the convection is called forced.
• Radiation: with heat exchange by radiation, we mean the transport of thermal energy through electromagnetic waves, regardless of the presence of an interposed transmission medium, as is the case for conduction (surface) or convection (air). To irradiate means “to emit radiation”. All bodies emit and absorb electromagnetic radiations and, since these radiations carry energy, when they strike a body and are absorbed, they cause an increase in the kinetic energy of the molecules and therefore a consequent rise in temperature. An example common to all: the sun! 

  

Outdoor applications

In outdoor applications, even the environment outside the electrical panel can represent a danger for the transferring of heat. Solar radiation can cause an increase in the average temperature inside the cabinet, as well as in a cold and windy area there could be a subtraction of heat by convection.

The stratification of heat

Considering the dynamics of heat transmission and all the potential sources we have inside and outside the cabinet, it is finally necessary to consider the phenomenon of stratification. In the absence of controlled ventilation, the hotter and drier air tends to accumulate at the top, while the cold and humid one below. A good dimensioning of the climatic control must therefore consider both the average level of temperature and humidity, and the working conditions of the individual devices, so as not to subsequently run into problems of reliability of the latter.

Fandis offers multiple solutions for correct ventilation and cooling of the panel, as well as for temperature and humidity regulation, up to the control of climatic parameters for preventive diagnostics.

To find out more, visit our website fandis.com read our articles about ventilation, and discover our products for electrical panels, or leave a comment on this article. One of our technicians will answer you as soon as possible.