A measurement on electromagnetic noise and change of surface in arcing electric contacts

The authors have observed the relationship between waveform of electromagnetic noise and change of surface for opening Ag-Pd electric contacts. In case of Ag-Pd electrodes, continuous noise is observed in the whole period of arc discharge in both current polarities. Fluctuations of arc voltage and noise are large in the middle part of arc discharge duration. The noise has a tendency to decrease in the later half. The authors proposed that noise waveforms and changes of electrode surface at various circuit conditions are classified into three categories. As these results, the authors showed the correlation between pattern of noise waveform and the change of electrode surface.