Application of switchgear in unusual environments

With an increased emphasis on reducing the size of installations, switchgear designers are faced with the diametrically opposed requirements of increasing short-circuit withstand and continuous current ratings while reducing space for the air that provide both primary insulation and cooling for the energized parts. Using modern material science, compact integrated dielectric systems can be developed without compromising the essential features for achieving higher short-circuit withstand and continuous current ratings. As this trend continues, it is increasingly important for the user of the equipment to fully understand the implications of the operating environment. Humidity and contamination become increased risk factors for initiating partial discharge and tracking failures across the solid insulation system; reducing the mean time between failures and shortening the required maintenance cycles to unexpected levels. IEEE Standards define Usual Service Conditions for proper equipment installation and also offer application guidelines for Unusual Service Conditions. This paper will discuss these guidelines and define the owner and manufacturers' responsibilities to assure system reliability by examining a specific installation and issues experienced.