Erosion of Electrical Contacts by Arcing at Closure in Telephone Switching Systems

Tsuneo KANAI  Yasutaka IMORI  Kunio OHNO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E76-C   No.2   pp.308-317
Publication Date: 1993/02/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Components
Keyword: 
contact,  erosion,  arcing,  closure,  

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Summary: 
The erosion of contact metal, which determines the life of contacts in the telephone switching system, is proportional to the arc energy. The equations for arc voltage, arc current, arc duration time and number of arcs are expressed explicitly in terms of circuit parameters and contact properties, and the expression is derived for arc energy that accompanies a single operation of contact closure. Contact erosion is consistent with the calculated arc energy. The erosion rate at closure is estimated based on the measured contact-erosion volume and the calculated arc energy. Arc energy at contact closure becomes as large as that at contact break if the cable is long or the supply voltage is high. This expression in combination with the expression for contact break enabled us to perform contact life design, which is indispensable for maintenance administration of telephone switching systems.