High-speed AC circuit breaker and high-speed OCR

Abstract

In electrical power systems, especially highly networked and become smart grid recently, faster protection relay and faster circuit breaker are more desirable for system stability at short circuit accidents. Nowadays general interruption time of circuit breaker is 3~5 cycle and trip signal sending time of a protection relay is about 2 cycle for instant operation. Most cases these circuit breaker and protection relay are sufficient for protection of the power systems but some special cases faster circuit breaker and relay are required. We proposed a prototype AC high speed circuit breaker which could interrupt the short circuit current of 12.5kA, 25.8kV within 1 cycle of 60Hz. Also we developed a prototype over current relay(OCR) which can send a trip signal within 1/2 cycle of 60Hz. We carried out a short circuit test these high speed circuit breaker and OCR in combination. At making current of maximum DC components defined in IEC 62271 100 32.5kA peak, 25.8kV, current was sensed and interrupted within 1 cycle. (4 pages)