New technology yields three ways to overcome coordination constraints on the distribution system

Distribution system overcurrent protection is based upon the gradation of Time-Current Characteristic (TCC) curves to ensure that the proper device operates to isolate a fault on the line. These devices include relayed circuit breakers, reclosers, pulseclosers, and fuses. In the absence of full and proper coordination, protection is not optimized and this results in additional and unnecessary customer outages. This paper discusses how new technologies are expanding the tools that distribution engineers can use to both simplify and improve overcurrent coordination.