Title :
Modification in the microstructure of materials with air-break switching at high currents
Author :
Ambier, J. ; Bourda, C. ; Jeannot, D. ; Pinard, J. ; Ramoni, P.
Author_Institution :
Merlin-Gerin, Grenoble, France
Abstract :
An understandable interpretation of eroded contacts is provided by giving a systematic description of the various types of subsurface microstructures encountered and by suggesting mechanisms to explain how they are formed under the influence of an electric arc. Sections and surfaces of disrupted areas are examined by a scanning electron microscope. AgZnO, AgC, AgNi, AgSnO2, and AgCdO are tested for high current separation (2000 A) on a testing apparatus which simulated the operation of a low-voltage circuit-breaker. With respect to AgZnO, the structures after a single separation at 2000 A or after AC4-type electrical life tests are similar and can be reproduced by simulating the thermal effect of an arc on the superficial layer by laser fusion or by melting in a furnace. The results obtained in these tests explain the structural modifications by correlating them to composition, granulometry, and the physical and chemical properties of the material, and thus a better understanding the electrical properties of AgZnO is gained
Keywords :
circuit-breaking arcs; electrical contacts; life testing; scanning electron microscope examination of materials; silver alloys; wear testing; AgC; AgCdO; AgNi; AgSnO2; AgZnO; air-break switching; current separation; electric arc; electrical life tests; eroded contacts; granulometry; laser fusion; low-voltage circuit-breaker; scanning electron microscope; subsurface microstructures; thermal effect; Chemical lasers; Circuit simulation; Circuit testing; Furnaces; Laser fusion; Laser theory; Life testing; Materials testing; Microstructure; Scanning electron microscopy;
Conference_Titel :
Electrical Contacts, 1990. Proceedings of the Thirty-Sixth IEEE Holm Conference on ... and the Fifteenth International Conference on Electrical Contacts
Conference_Location :
Montreal, Que.
DOI :
10.1109/HOLM.1990.113005
