DC-arc blowing under pulsed magnetic field

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

“…After a certain period of time when Lorentz force prevails the sticking force, the arc starts its motion for magnetic blowing. Thus, the Lorentz force level required for prevailing the sticking force level in [7] may correspond to the above-mentioned critical level of Lorentz force required for magnetic blowing (about 0.1mT in this study).…”

“…As further consideration with respect to the threshold level of Lorentz force to be required for realizing magnetic blowing, Vassa et al [7] describe that even with the applied external magnetic force, a certain period of time is necessary before the magnetic field becomes actually effective for initiating magnetic blowing. As the explanation, a certain level of sticking force between an arc and a cathode surface is considered.…”

“…As the explanation, a certain level of sticking force between an arc and a cathode surface is considered. More specifically, until Lorentz force (described as Laplace force in [7]) induced by the applied external magnetic field becomes dominant over the sticking force, the arc remains stuck to the spot where it is formed. After a certain period of time when Lorentz force prevails the sticking force, the arc starts its motion for magnetic blowing.…”

“…The sticking force in [7] is expressed as determined by several factors including a friction coefficient of a contact surface, a plasma pressure to be applied onto the contact surface, a thermal conductivity coefficient, and a temperature gradient at the contact surface. Some of those factors are difficult to be actually determined and/or calculated, and no specific value of the critical sticking force level is presented there.…”

“…In order to realize longer lifetime and/or better performances, reductions in break arc durations are strongly required. For such a purpose, increases in contact opening speeds as well as application of external magnetic field are often employed [1]- [7]. However, the authors' previous research results revealed that complicated phenomena can be observed and further research work is needed [8]- [14].…”