Relationships between Break Arc Behaviors of AgSnO₂ Contacts and Lorentz Force to be Applied by an External Magnetic Force in a DC Inductive Load Circuit Up to 20V-17A

Abstract

When AgSnO₂ contacts were operated to break an inductive DC load current of 14V-12A, 20V-7A or 20V-17A at a contact opening speed of 10mm/sec or slower, application of an external magnetic field resulted in reductions in break arc durations even without magnetic blowing. Simple estimation of Lorentz force to be applied onto arc column revealed that a certain minimum magnitude of Lorentz force seems to be required for initiating arc blowing. Certain relationships between the Lorentz force magnitude and the timing of metallic-to-gaseous phase transition were also found to exist.