Rapid and Safe Arc Quench by Using External Magnetic Coil in Power Interruption

Abstract

Low-voltage arc quench is one of the most processes for a successful power interruption in circuit breakers. Typical circuit breakers are designed to switch off the fault current within half a cycle, less than 10 milliseconds, which requires an efficient arc quench and thus poses great challenges in power interruption. Apart from using power electronics, which is very expensive and of low capacity, the classical circuit breakers that uses a stack of steel plates to split the fault-current arc into many sub-arcs are still dominant for both industry and residential installations. Due to the high current, the self-induced magnetic field will drive the arc towards to the steel plates and force the arc being spitted into many sub-arcs, from which the arc-steel plate interfaces generates multiple voltage drops. Once the sum of all voltage drops increases and exceeds the source voltage, the arc will extinguish and quench.  Due to the ferromagnetic effect, the magnetic field increases dramatically during arc splitting by steel plates. However, the self-induced magnetic field have reversed direction on both sides of the steel plates which pushes the sub-arcs to opposite directions and prevents concurrent and even arc splitting. In this report, we report a new technique to compensate the self-induced the magnetic field by using a background magnetic coil, thus, to give an even and simultaneous arc splitting and guarantee the power interruption.