Consecutive observations of the relationship between eroded contact surfaces and motion of breaking arc at each breaking operation

Contact surfaces and the motion of breaking arc are observed in dc 42V/10A resistive circuit for Ag electrical contacts. Cathode and anode surfaces are observed consecutively with a microscope after each breaking operation. The motion of breaking arc between electrical contacts is also observed from two directions using a high-speed camera and mirrors. As a result, some kinds of different films and eroded regions on the electrical contacts are distinguished. The film and eroded regions on the contact surfaces are generated at different stages of the breaking arc. The range of traces on the cathode surface is determined by the moving range of the cathode spot in the middle stage of the arc duration.