A study on Low-Voltage DC circuit breakers

Recently, DC distribution systems become hot issues since DC type loads increase rapidly according to the expansion of IT equipment such as computers, servers, and digital devices; DC type loads will cover 50% for all electricity loads in 2020 which was mere 10% in 2000 [1,2]. DC distribution systems are also accelerated by the expansion of renewable power systems since they are easy to be interfaced with DC grids rather than AC grids. However, removing the fault current in DC grids is comparably difficult since the DC current has non zero-crossing point like in AC current [3]. Thus, developing dedicated DC circuit breakers for DC grids is necessary to get safety for human and electrical facilities[4]. Magnet arc extinguishing method is proper to small size DC circuit breakers [5,6]. However, simple magnet arc extinguishing method is not enough to break inductive fault currents. This paper proposed a novel DC circuit breaker against inductive fault current defined by IEEE C37.14-2004 Standard for Low-Voltage DC Power Circuit Breakers Used in Enclosures. The performance of the proposed DC circuit breaker was verified by an experimental circuit breaker test system built in this research.