Energy Management/Energy Efficiency

Passive Thermal Solutions: Remember, Air is Still Free

Increasingly, panel builders must do more. That’s because facility demands are greater. Facilities – and the panels or cabinets within them – must withstand increasingly severe environmental conditions. That’s true both in terms of temperature and amount of pollution exposure.

However, experience has shown me that not all projects are equal and neither are all demands. What’s more, not everything should be resolved with a high degree of protection and a powerful thermal solution. Don’t fall into the trap of thinking that everything is a nail because all you have is a hammer – or an air conditioning unit. If you do, you or a facility manager will pay for it with greater energy consumption and larger energy bills.

An analogy would be to that arcade and video game classic (and recent screen star): Pac-Man. A thermal solution is like a big Pac-Man, with the balls being eaten the calories coming off the electrical and electronic equipment. The goal is to turn Pac-Man from bright yellow to something greener and more environmentally friendly.

So, how is that done? Well, there are certain rules of the art. Following these can overcome many thermal challenges or complications and optimize costs.

  • First, chose cabinet dimensions carefully. Usually, the size of a control cabinet is determined by the dimensions of electrical equipment. Typically, the decisive dimension is depth. Often, however, we forget that the air must circulate inside the cabinets. So, keep this in mind so that you end up with a robust thermal architecture
  • Second, avoid unnecessary mixing. If possible, do not put power equipment and control equipment in the same cabinet. Control equipment, such as PLCs and switches, are often full of temperature sensitive electronics. Such electronics will be impacted by what is being dissipated by power equipment, such as variable speed drives.
  • Third, arrange things properly. As an example, many cabinet makers install variable speed drives near the roof of the enclosure. That concentrates heat and may mean the temperature difference between the top of the cabinet and the bottom, a distance of only two meters or so, may be up to 20° C. For the same reason, a fan near the air inlet of an inverter or other heat producing piece of equipment can be very beneficial.
  • Fourth, keep cabinet color in mind. A light color is helpful if heat exchange by radiation is important. That’s because light colors reflect light while dark ones absorb it, with all that implies with regard to heat absorption.

The accompanying two diagrams illustrate these principles. The resulting energy savings are substantial, up to 52%.

Diagram 1: Rules to Be Observed

Diagram 2

Diagram 2: Power Load Arrangement

If you want to win at this game and make your Pac-Man greener, keep these principles in mind. For a more complete discussion, see “How to reduce damage to components through effective thermal management”. You can also make use of our ProClima software to take into account all the variables in your installation and fine tune these general principles.


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