Development of a new topology of dc hybrid circuit breaker

A new topology of dc hybrid circuit breaker based on fast switch and liquid metal fault current limiters(LMFCL) is proposed for medium voltage dc system in this paper. The voltage generated by LMFCL can commutate the fault current into the parallel thyristors and make arcless open of fast switch contacts. The thyristors are forced off due to the parallel LC reverse pulse discharge circuit. The influences of bulkhead aperture diameter, current rising rate and voltage on LMFCL at the initial commutation moment on the arcless current commutation are analyzed. Finally, the breaking based on arcless commutation is accomplished with short circuit fault simulated using synthetic circuit.