This interval allows the upstream relay to have sufficient time to detect and clear the fault if the downstream relay fails to operate. For definite time overcurrent relays, a grading interval of 0. The total interval required depends on the operating speed. The selected protection principle affects the operating speed of the protection, which has a significant im-pact on the harm caused by short circuits. The faster the protection operates, the smaller the resulting ha-zards, damage and the thermal stress will be. In HV (High Voltage) and MV (Medium Voltage) substations, relay protection safeguards critical assets such as transformers, circuit breakers, and lines. Effective relay protection depends on. What is the function of power system protection? For what purpose is IEEE device 52 is used? Why are seal-in and 52a contacts used in the dc control scheme? In a typical feeder OC protection scheme, what does the residual relay measure? Questions? 00000001 00000101 00001001 00100100 10010000 :.