So you need to cool down an electrical enclosure filled with heat-producing electronics? There are many products on the market designed specifically for this purpose, but finding what you need can be difficult if you do not know what you need or do not understand the common industry slang. This article is for the uninitiated — often called newbies — or those needing a refresher course on the topic of enclosure climate control.
Manufacturers of cooling solutions for electrical enclosures will often promote their own product while finding flaws in the types of products they do not produce. In truth, all of the common enclosure cooling solutions have a place in the market, but what is preferable for one application, may not be optimal for another.
Some factors to take into account when deciding on an enclosure cooling solution are:
- The height, width and depth of the enclosure.
- The desired temperature inside the enclosure. This will usually be based upon what temperature the electronics contained inside the enclosure can withstand.
- The temperature in the area where the enclosure is located, which is referred to as ambient temperature.
- The heat load produced by components inside the enclosure. This information generally can be located on the labels for each component and is measured in watts.
- Location of the enclosure. This will determine the National Electrical Manufacturers Association (NEMA) rating required for both the enclosure and cooling solution. NEMA ratings may not be available on certain enclosure cooling products.
There are many NEMA ratings, but the most common are:
- NEMA 12. Enclosure is suitable for indoor use and provides some protection against dust, lint and dripping water.
- NEMA 4. Enclosure is designed to shield internal components from outdoor weather conditions such as ice, sleet and snow, in addition to everything covered by NEMA 12.
- NEMA 4X. Similar to NEMA 4, but the enclosure is also resistant to corrosive effects.
Once the enclosure requirements have been determined based on these factors and you know how many BTUs are required (which is generally determined based on these factors via a calculator available from most manufacturers), you can begin selecting an enclosure cooling solution from some of the options below.
Industrial air conditioners utilize technology similar to air conditioners used in many common, everyday cooling applications. The air conditioner pushes cool air into an enclosure without exposing the enclosure contents to the outside environment. Sealing the enclosure in this manner is known as being closed-loop and is a key requirement in applications where there are contaminants in the environment. These are generally mounted on the side of an enclosure, although there are some manufacturers that offer top-mounted models. Most manufacturers produce air conditioners within a range of 1,000 to 20,000 BTUs of cooling capacity, and the equipment can be customized to the requirements of a specific application.
Ideal Use. Air conditioners are the most common enclosure cooling solution due to their wide range of cooling capacities, energy efficiency and customizable options. Other closed-looped enclosure cooling solutions generally cannot effectively cool anything requiring more than 5,000 BTUs. For anything 6,000 to 20,000 BTUs, an air conditioner is going to be the most effective and realistic option.
Vortex coolers separate compressed air into streams of hot and cold air with the cold air being used to cool the enclosure. The lack of moving parts and Freon make these units a low-maintenance option for busy plant personnel. Vortex coolers will function in environments up to 175°F (79°C), which is a much higher maximum temperature than most other cooling solutions.
Ideal Use. Vortex products are a low-priced solution for a cooling enclosure that will last for a long time. However, they will use precious compressed air to do so. These are typically mounted on top of an enclosure and are generally available from 500 to 5,000 BTUs.
Filtered fans pull air from the outside environment into the enclosure. Filtered fans are not closed-loop systems, so outside contaminants can penetrate the enclosure. Some manufacturers will not produce these for high end NEMA ratings (e.g., NEMA 12, 4 or 4X).
Ideal Use. Filtered fans are a great solution for budget-conscience customers who have enclosures that are in clean, indoor applications and not in harsh environments where the desired temperature inside the enclosure is not lower than the ambient temperature.
Heat exchangers are cooling systems that employ the heat pipe principle to exchange heated air from an electrical enclosure for cooler air from the outside environment. This simple design requires few moving components to operate, which minimizes maintenance requirements. Unlike filtered fans, these are closed-loop systems and are usually available in NEMA 12, 4 or 4X.
Ideal Use. Heat exchangers are often used in the same types of environments as filtered fans, meaning where the desired temperature inside the enclosure is not lower than the ambient temperature. However, the extra protection they provide by being closed-loop makes them a more reliable, yet more expensive, solution.
Thermoelectric Air Conditioners
Unlike traditional air conditioners, these units use a series of heat sinks to produce cold air for the enclosure. This technology incorporates far fewer moving parts than other air conditioners and requires less maintenance. These units usually have a cooling capacity of 200 to 4,000 BTUs and can be mounted vertically, horizontally or at an angle.
Ideal Use. The superior reliability of these units makes them an ideal solution for environments where critical processes have low BTU cooling requirements. This increased reliability makes them useful in military or petrochemical applications. However, the dependability of these units comes at a premium and makes thermoelectric air conditioners the most expensive enclosure cooling option on the market.
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