Effect of Magnetic Field on Different Opening Processes of Multi-Break Vacuum Gaps

Vacuum gap saturation of single break can be solved by multiple breaks in series. In different breaking processes, the unbalanced energy and charges injected into the breaks lead to unbalanced voltage distribution. The purpose of this paper was to compare the voltage distribution under the regulation of magnetic field in different opening process. The magnetic fields with 3 ms width were applied at the point 3 ms before current through zero. Comparing with no axial magnetic field, the voltage distribution unbalances deceased both in synchronous and asynchronous opening processes. Under the condition that the arcing time of high-voltage break remained at 6.6 ms and the magnitude of axial magnetic fields was 60 mT, voltage distributions of high-voltage break were approximately proportional to the arcing times of the low-voltage break from 3.4 ms to 6.6 ms. It demonstrated that axial magnetic fields could effectively improve the voltage distribution of multi-break vacuum circuit breakers in synchronous and asynchronous opening processes.