Effective Shortening of Break Arc Duration s of Ag and Several Ag-based Contacts in DC Load Conditions with Increased Contact Opening Speeds and External Magnetic Field

Abstract

Break operations of Ag, AgSnO 2 , and AgC contact pairs were conducted in a DC inductive (L=5.7mH) load circuit with 14V-12A, 20V-7A and 20V-17A at different contact opening speeds from 1 to 200 mm/s and with/without external magnetic field application of about 120 mT in air. Break arc voltage waveforms were observed, and total break arc durations and metallic phase durations were determined based on the observed arc voltage waveforms. After the experiments, averages for the total arc durations as well as the metallic phase and gaseous phase (when observed) durations were calculated at each condition. Faster contact opening speeds caused reductions in total break arc durations in all of tested conditions, and realized almost inversely-proportional reductions for metallic phase durations. External magnetic field application showed no influences on metallic phase duration, while leading to shorter gaseous phases in certain conditions.