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-Degradation of power contacts in corrosive atmosphere leads to significant increase of the contact resistance and consequently to a rise in temperature, and eventually to the failure. In electrical apparatus, both base metal copper and silver plating heavily corrode in environment containing sulfuric gases. In addition, expansive growth of silver filaments (whiskers) has been often found on primary current conductors of circuit breakers. This paper describes extensive whisker growth found in switchgear at paper recycling mill. The major environmental factor to initiate the growth is relatively low concentration of Hydrogen Sulfide (H 2 S). As soon as a thick enough layer of silver sulfide has been formed, metal filaments start to grow virtually everywhere but most intensely in locations usually having elevated temperature while electrical units are energized. Though hazardous phenomenon has been seen from 1920s and caused a number of violent failures, but it was practically neither studied nor understood. Just in two months after previous cleaning, we found the filaments up to several inches (6-8 cm) long and up to 0.04 in (1 mm) thick. Using SEM/EDS analysis we have determined chemical composition and morphology of the whiskers. Most of the whiskers are made of silver with 1-3 % of copper. The surface of the whiskers long exposed to atmosphere is contaminated with silver sulfide. After thoroughly investigating the factors that initiate and accelerate whiskers' growth we have determined effective means eliminating extremely hazardous phenomenon For more information, contact:

The paper presents a review of research data published during last 40-year period in the field of electrical contact lubrication. The paper examines the role of lubrication in corrosion protection as a barrier between contact surfaces and atmospheric pollutants. For effective long-term corrosion protection, it is important to properly choose and thoroughly qualify a lubrication product for a specific contact material and a specific combination of environmental variables. Another use of lubricants is to protect contacts from mechanical wear and/or friction, and from degradation due to fretting. Conversely, use of inappropriate lubricants may induce a significant risk by producing degradation, collecting particulate matter, and developing a high electrical resistance of the contact surfaces. It is very important to carefully choose the lubricants to maintain a stable contact resistance and preserve the physical integrity of the contact surface. This paper also analyzes the effect of chemical composition and consistency (fluids, greases, solid lubricants) on the durability of lubricants in regards to various types of contact material, design and load.

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