400 V class high-speed current limiting circuit breaker for electric power system

In Japan, a new network distribution system with advanced protective and operational functions designed to meet the needs of today's information society is being studied. For this new distribution system, the authors have developed high-speed current limiting equipment using gate turn-off thyristors (GTOs), to lower the breaking capacity of switches and to suppress instantaneous voltage drops. The main components of this equipment are a high-speed vacuum switch and a GTO switch connected in parallel. The usual load current is carried by the vacuum switch. In the case of a system fault, the fault current is commutated to and interrupted by the GTO switch by opening the vacuum switch. The time from fault occurrence to current interruption is less than 1 ms. This response time is about 100 times as fast as that of mechanical breakers. This equipment dose not require a large cooling system and is compact compared with conventional solid-state equipment.<
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