Improving selectivity & arc-flash protection through optimized instantaneous protection settings

In today´s power distribution systems, existing protection methods do not provide full selectivity and instantaneous fault clearing for expected fault current, including lower magnitude arcing currents simultaneously. This paper will discuss two methods that may change that. The first method is a selectivity analytical technique useful with many circuit breaker trips currently available in the industry. The second method is a new circuit breaker trip technology. Both methods allow switchgear Circuit Breakers (CB) to use sensitive instantaneous settings and maintain selectivity when used upstream current-limiting molded case circuit breakers, current-limiting motor circuit protectors or current-limiting fuses in downstream equipment such as motor control centers.