Enhanced selectivity and protection via modern current- limiting circuit breakers

Molded-case circuit breakers are the most common protective devices in today's power distribution systems. In recent years, current-limiting molded-case circuit breakers have improved protection by providing significant let-through energy limitation, thus enhancing equipment protection and safety. In addition, current-limiting circuit breakers, when designed as a system, may provide selective behavior over a wide range of fault currents. Several techniques that are available to achieve the fast contact opening required for less than half-cycle interruption are described. The authors describe how, in addition to significantly improved current limitation and protection, selectivity can also be simultaneously achieved