Abstract: A fault protection system is configured to detect a fault in an electric power system. The fault protection system obtains a differential measurement signal. The differential measurement signal may, for example, indicate, as a function of time, the difference between currents or voltages measured at two or more terminals or boundaries of a fault protection zone of the electric power system. Regardless, the fault protection system generates a fault detection signal by cross-correlating the differential measurement signal with a reference signal. The reference signal may for instance be the differential measurement signal that is expected upon occurrence of a fault. The fault protection system performs fault detection, for detecting a fault internal to the fault protection zone, as a function of the fault detection signal.

Abstract: A fault protection system is configured to detect a fault in an electric power system. The fault protection system obtains a differential measurement signal. The differential measurement signal may, for example, indicate, as a function of time, the difference between currents or voltages measured at two or more terminals or boundaries of a fault protection zone of the electric power system. Regardless, the fault protection system generates a fault detection signal by cross-correlating the differential measurement signal with a reference signal. The reference signal may for instance be the differential measurement signal that is expected upon occurrence of a fault. The fault protection system performs fault detection, for detecting a fault internal to the fault protection zone, as a function of the fault detection signal.

Abstract: A protective relaying system includes a local protective relay operatively coupled to a protected line segment at a first location, and a remote protective relay operatively coupled to the protected line segment at a second location. The remote protective relay generates a signal (PILOT RECEIVE) to indicate the detection of a fault. This signal is communicated to the local protective relay and employed therein to supervise single-pole trip operations.

Abstract: Disclosed is a protective relaying system that trips a local circuit breaker (BL) connected to a transmission line by providing a trip signal ("TRIP.sub.-- BL") to the circuit breaker. The system comprises a local filter operatively coupled to the transmission line, and a local relay operatively coupled to the filter. The local filter receives inputs indicative of phase currents on the transmission line and provides an output ("VFL.sub.k ") derived from the inputs. The local relay (1) receives the output (VFL.sub.k) of the local filter, (2) receives an output ("VFR1.sub.k ", "VFR2.sub.k ") of at least one remote filter, and (3) generates the trip signal. The local filter and relay preferably employ substantially all digital electronic circuitry to generate the trip signal.