The Measurement of the Transient Power and Energy Dissipated in Closing Switch Contacts

The loss or transfer of metal due to the electrical erosion of contacts used in the telephone system results in reduced life, increased maintenance, or the use of more costly contact metals. All this presents an important economic problem to the Bell System, promoting extensive study of contact phenomena. In the ordinary uses of electrical contacts, the making and breaking of electrical circuits lead to discharges across the contacts, which may last up to the order of 500 microseconds. The behavior of some of these forms of discharge is fairly well understoodf because their long duration and approximately constant voltage permit ready measurement of the effects and an analysis of causes and remedies for the behavior. As a result, these gross effects are under the broad control of the designer, who can allow them when the circuit application permits, but who can reduce them by "protection circuits" at increased cost. The use of sealed * R e c e n t D e v e l o p m e n t s in R e l a y s -- Glass-Enclosed Reed Relay, W. B. Ellwood, E l e c t . Eng., 66, pp. 1104-110G. Nov., 1947. D e v e l o p m e n t of Reed Switches a n d Relays --O. M. H o v g a a r d a n d G. E. P e r r e a u l t , B.S.T.J., 34, pp. 309-333, M a r c h , 1955. f N u m e r o u s p a p e r s by L. H. Germer, M. M. A t a l l a , a n d associates in Bell Telephone L a b o r a t o r i e s . 1191