“..the higher the humidity within an enclosure, the shorter the life expectancy of the components inside.”

Heat inside electronic enclosures is a hazard for production and functional safety that is often underestimated. Today’s powerful electronic assemblies and components inside modern machinery and systems are constantly exposed to the rigors of increasingly higher temperatures.

In order to ensure a constant level of operational reliability and a long service life for electronic systems under difficult ambient conditions, it is absolutely essential to know about the decisive factors involved in air conditioning electronic enclosures.

Preliminary View

Many control systems in modern electronic equipment are based on semi-conductor components and computer technology. These components are being packed in higher density resulting in higher rates of heat dissipation and less natural dissipation through the enclosure surface area. Studies have shown that as the temperature stress increases on these components their life expectancy will decrease significantly.

Humidity Inside Enclosures

Another deadly enemy of electronic equipment is humidity. You will always find a certain amount of water dissolved in ambient air. The higher the level of humidity within an enclosure, the shorter you can expect the life expectancy to be of the components inside.

An air conditioner can exert its influence on this by reducing the level of humidity. The operating principle of an air conditioner is to convert warm air into the cold air, thereby encouraging the accumulation of condensation inside the air conditioner and dehumidifying the air inside the electronic enclosure, therefore, reducing the level of humidity.

Proper Temperature Settings

A special physical effect is caused by a high degree of fluctuation in ambient temperature. Condensation has been known to accumulate on the inside surface of the electronic enclosure.

If the temperature drops below the dewpoint, humidity condenses on the inside surface of the switchboard. The dewpoint is a term used to express the precipitation of water from relative humidity.

 This is one of the reasons the temperature setting inside the electronic enclosure is still set relatively high at ~35° C. (i.e. typical plant temperature ~35° vs office room temperature ~24° C). Electronics do not need to be cooled down to human comfort levels but kept below a temperature that prevents the degrading of the components.

Important Project Considerations

Early on, during the project-planning phase for your equipment, you should always pay due consideration to the location of your air conditioning system. In the case of equipment with a high packing density, it is important to ensure satisfactory airflow in each of the designed enclosure compartments.

Correctly sizing an air conditioner requires precise information on the installed power component’s heat dissipation. It’s important to know how the components are mounted and what type of enclosure is to be used in the installation. Not to be forgotten in this context are the ambient conditions, such as electronic enclosure installation site, dust or emission content in the ambient air, relative humidity, and fluctuations in ambient temperatures.

Check that air intake and extraction in the external circuit of the air conditioner are satisfactory to ensure that the thermal energy can be abducted into the atmosphere in an optimum manner.

To make it easy Pfannenberg has made their PSS sizing software available to those that want recommendations on products for every unique application. It cleverly takes into account environmental conditions, specifications, heat loads & target conditions.

If the airflow volume of components with large-sized built-in fans is greater than that of the cooling system, or if the airflow circuits counteract each other during operation, the refrigeration capacity is considerably reduced, and heat pockets can form.

The Future of Cooling Units

In the future, cooling will play a more significant role in machine design because it is now more important than ever for machine builders to think of air conditioning early on in the design process preventing expensive re-works and premature component breakdowns.