Methods to Mitigate Contamination and Moisture Ingress in Switchgear

This paper discusses methods to mitigate contamination and moisture ingress into pad-mounted switchgear. Pad-mounted switchgear is installed and forgotten with little if any maintenance over its life cycle. Site-specific environmental issues may range from mild to severe contamination conditions. Contamination and moisture ingress if severe can lead to premature unit failure. This paper discusses three methods of mitigating contamination and moisture ingress: (1) basic switchgear design concepts, (2) moisture barriers (3) energized cleaning using propelled dry-ice pellets. As a product, the original designs of metal-enclosed switchgear first appeared in the 1930s and, as with every product life cycle, there were initial difficulties to overcome. But, in the case of switchgear, one dual problem has continued over its life cycle. Specifically, the control of contamination and moisture ingress has been critical to long-term survival. This problem became even more difficult as the off-shoot pad-mounted switchgear installed over an open pit became a widely used product in electric utility power distribution systems and has subsequently moved into the commercial and industrial sectors.