Post-Arc Current After High-Current Interruption in Vacuum

Detailed measurements of post-arc current in a vacuum were made. This investigation was particularly characterized by conducting post-arc current measurements following high arc currents (36 kA rms maximum). Postarc current increases with main arc current, and shows a sharp increase when the main arc current reaches certain value. The magnitude of post-arc current for each contact material differed; the descending order is Cu-Bi > Cu > Cu-W > Ag-W. Shield current was also measured to clarify the characteristics of the ion current. Cu-Bi > Cu > Cu-W > Ag-W was the descending order of measured shield current. The characteristics of post-arc current are explained by referring to those results.