Electrical contact phenomena in switching technology - Arc discharges in switching contacts

Arc discharge phenomena upon opening and closure of switching contacts operated in load current ranges up to several tens amps are briefly summarized. Based on the electrical circuit conditions, different types of arc discharges will occur when contacts are opened. Such arc discharges will have certain influences on contact reliability and lifetime through material transfer and erosion, formation and deposition of arc products, and resultant increases in contact resistance. Arc discharges upon contact closure can be basically considered as breakdown, although break arc discharges can be also observed at contact bounces. Moreover, the author´s recent studies indicate that the “minimum arc current value” of contact materials is not actually the lower limit of break arc occurrence and its interpretation should be changed.