Arcing at Electrical Contacts on Closure. Part IV. Activation of Contacts by Organic Vapor

Abstract

The activation of electrical contacts by decomposition products from organic vapors depends upon an adequate surface layer of adsorbed molecules. In earlier work minimum vapor pressures were given for activation by a number of organic compounds. From new experiments reported here the time available for adsorption between successive arcs is equally important, so that the minimum vapor pressure for activation to occur is inversely proportional to the time available for adsorption, or directly proportional to the rate of operation. The effective contact area and the energy are important also and, although quantitative data have not been obtained, it is reasonable to guess that these variables are connected by a relation not far from p/n=KE/A, where n is the minimum rate for activation to occur for the pressure p on the effective contact area A with the available energy E. Quantitative experiments have been made only upon the activation of palladium contacts by vapor of the organic compound known as fluorene, and only the proportionality between p and n has been established.