ABSTRACT
This chapter deals with contamination of arcing contacts. It suggests that the results may be quite different when other electrical and mechanical load conditions from those cited in the specific example are used. The chapter shows that activation can have a different effect on higher-current switching. The amount of organic material that is accumulated on the surface before an arcing operation is dependent on the concentration of the organic vapor, exposure time, and sticking coefficient of the contact metal and vapor combination. Minimum arc voltage increases to well above the minimum arc voltage for the noble metal contact and at a current below the minimum arc current of the contact metal. With exception to very dusty environments and cases where there is no protective housing for the contacts, the effects of atmospheric mineral deposits on arcing contacts are low. One of the most troublesome types of contaminants for arcing contacts consists of silicone compounds.
