Enclosure air conditioners remove the heat generated by electronic devices from the inside of cabinets or enclosures. They typically use refrigerants and include thermostatic controls to maintain programmed environmental conditions. Some devices automatically evaporate condensate, eliminating the need for draining. Others include an air flow sensor that monitors the temperature of the condenser and ensures that blockage or contamination does not compromise cooling efficiency. Enclosure air conditioners use either single-phase or three-phase power and vary in terms of cooling efficiency, which is often expressed in kilowatts, tons of refrigeration, or British thermal units (BTU) per hour. Devices that use direct current (DC) voltages operate at 12 or 24 VDC. Devices that use alternating current (AC) voltages operate at 115, 230, 380/400 or 460 VAC. For AC devices, frequencies include 50, 60, and 400 Hz. Typically, 400 Hz devices are used in aerospace applications.
Physical specifications for enclosure air conditioners include mounting style, NEMA rating, and IP rating. Some air conditioners mount on enclosure side walls in a standard cabinet rack. Others mount in recessed pockets or cavities. Top-mount devices are used in enclosures that do not provide adequate clearance for side mounting. Bottom-mount devices fit the enclosure base or bottom and are usually rack-mounted. The National Electrical Manufacturers Association (NEMA), a non-profit trade organization, rates enclosures for electrical equipment. Enclosure air conditioners with NEMA 3R, NEMA 4, and NEMA 4X ratings are suitable for indoor or outdoor use and provide protection against dirt, rain, sleet, and snow. Ingress protection (IP) 34, a European standard, sets criteria for preventing the ingress of particles larger than 2.5 mm. IP 54 sets standards for protection against shock, vibration, dust and rain. In terms of outdoor use, IP 54 is nominally equivalent to the NEMA 3 rating.
Enclosure air conditioners are available with a variety of special features. For example, some devices place electrical or electronic filters on the incoming power line to suppress noise caused by electromagnetic interference (EMI) or radio frequency interference (RFI). Others include interlocks, alarms, or signals to alert users to faults or system failures. Short cycle detection is a feature that monitors compressor on/off cycles for length and efficiency. Enclosure air conditioners that use refrigerants without chlorofluorocarbons (CFCs), a chemical compound believed to be responsible for depleting the Earth’s ozone layer, are increasingly popular.
Many safety agencies rate or certify enclosure air conditioners. For example, the International Engineering Consortium (IEC) publishes and maintains standards for electrical product conformity. In Europe, electrical and electronic equipment must bear the CE Mark to indicate compliance with product safety and electromagnetic compatibility directives. In North America, the Canadian Standards Association (CSA) Mark may appear alone or with indicators. Products that bear the CSA Mark alone are certified only for the Canadian market. Products that appear with the indicators "C and US" or "NRTL/C” are certified for both the U.S. and Canadian markets. Underwriters Laboratories (UL) approves both component parts and complete assemblies.
Other Topics You Might Be Interested In
-
Selecting Air Conditioners for Industrial Enclosures (.pdf)
enclosures including internal heat loads, the various methods used to rate the cooling capacity. of enclosure air conditioners, the impact of humidity and other ambient conditions, and energy. efficiency. Understanding air conditioner performance diagrams and sizing tools in relation to application...
-
Enclosure Cooling - Local or Remote? (.pdf)
"Cooling from a Distance" based off a paper written by Chiller Product Manager Howard Kielar, was featured in Process Cooling. The article highlights how remote enclosure cooling offers a viable alternative to local packaged air conditioners for challenging industrial applications, and the type...
-
APPLY SOLAR SHIELDING TO LESSEN HEAT LOAD, PROTECT ENCLOSURE COMPONENTS
The temperature rise inside an enclosure above outdoor ambient is caused by internal equipment heat dissipation and solar energy absorption. Some common thermal management solutions for enclosures include air conditioners, heat exchangers, ventilation and color when evaluating solar loading...
