The Influence of Arc Roots on Current Interruption
Until now it has not been possible to determine a simple relationship between the interruption capability of a circuit breaker and the arc-root behavior. Observation of the roots of a high-current arc on WCu-electrodes in a model circuit breaker reveals a strong vaporization of electrode material. Since contamination of the quenching medium by several percent of metal vapor increases its electrical conductivity at low temperatures (2000–6000 K) by at least an order of magnitude, this metal vapor should decrease the quenching ability. It is also observed that frequent separation of the arc and the jet of electrode vapor occurs, accompanied by removal of the arc roots from the ignition point by the vapor. Accordingly mixing of the arc plasma and the vapor does not take place. To clarify this behavior, spectroscopic measurements were made of the plasma- and vapor temperature in front of the graphite cathode of a high-current dc-arc. The measurements show that in the case of strong vaporization, the electrode vapor in the vicinity of the electrode is much colder than the arc plasma. By using an appropriate electrode material, it is possible to avoid the contamination of the quenching medium and uncontrolled movement of the arc roots.
KeywordsMetal Vapor Circuit Breaker Copper Vapor Strong Vaporization Current Zero
Unable to display preview. Download preview PDF.
- 1.H. Edels, Properties of the high pressure ultra-high-current arc, in Proc. XI Int Conf. Ion. Gases, Invited papers Prague (1973)Google Scholar
- 2.D. R. Airy, R. E. Kinsinger, P. H. Richards and H. D. Swift, IEEE Trans. PAS 95 (1976) 1Google Scholar
- 3.P. J. Shayler and M. T. C. Fang, The transport and thermodynamic properties of a copper-nitrogen mixture. Report ULAP-T 45 of the University of Liverpool, Department of Electrical Engineering and Electronics (December 1976)Google Scholar
- 4.J. Ruffer, Siemens AG, Forschungslaboratorien Erlangen, Germany, private communicationGoogle Scholar
- 5.W. Hermann, U. Kogelschatz, L. Niemeyer, K. Ragaller and E. Schade, IEEE Trans. PAS 95 (1976) 1165Google Scholar
- 6.D. W. Branston and J. Mentel, XIII Int. Conf. Phen. Ionized Gases, Berlin (1977)Google Scholar
- 7.W. Hermann and K. Ragaller, IEEE Trans. PAS 96 (1977) 1546Google Scholar
- 11.J. Mentel, Appl. Phys., in pressGoogle Scholar