A straightforward way of obtaining selective protection is to use time grading. The principle is to grade the operating times of the relays in such a way that the relay closest to the fault spot operates first. Time-graded protection is implemented using overcurrent relays with either definite time. Accelerated protection is a critical component in modern power systems, designed to swiftly detect and isolate electrical faults to prevent widespread damage and ensure operational continuity. It is commonly implemented through protection relays, which monitor parameters like current and voltage to. Protective relays and devices have been developed over 100 years ago to provide “last line” of defense for the electrical systems. ## What Are Advanced. Use this Protection Relay Setting Calculator to calculate pickup current, time multiplier settings (TMS), operating time, coordination time interval (CTI), and plug setting multiplier (PSM) using fault current, CT ratio, and IEC 60255 curve parameters. These calculations are critical in industrial.