Break arc duration characteristics of AgSnO<inf>2</inf> contacts under magnetic field application with contact opening speeds in the range up to 200mm/s in DC load conditions

Abstract

Break operations of AgSnO 2 contact pairs were conducted in a DC inductive circuit (L=5.7mH) at 14V-11A and in a DC resistive circuit at 14V-13A under different contact opening speeds from 0.5 to 200 mm/s and with/without external magnetic field application in air. Break arc voltage waveforms were observed, and total break arc durations and metallic phase durations were determined based the observed arc voltage waveforms. After the experiments, averages for total arc durations as well as the metallic phase and gaseous phase (when observed) durations were calculated at each condition. The results show that increases in the contact opening speeds lead to reductions in metallic phase durations, while application of external magnetic field causes gaseous phases to become shorter.