Patent ID: 8791704

Claim:
A system for identifying a fault type in an electric power delivery system from a calculated total zero-sequence current and a calculated total negative-sequence current, calculated from a first plurality of currents associated with a first location of the electric power delivery system and a second plurality of currents associated with a second location of the electric power delivery system, comprising: a first intelligent electronic device (IED) configured to obtain the first plurality of currents; the first IED configured to: calculate an angular difference between the total zero-sequence current and the total negative-sequence current; determine which of a plurality of predetermined angular difference sectors includes the angular difference; compare a phase-to-phase current magnitude and a predetermined threshold; and, identify the fault type based on the determined angular difference sector and the comparison of the phase-to-phase current magnitude and the predetermined threshold; wherein the fault is identified as a second-phase-to-third-phase-to-ground fault when: a magnitude of a second-phase-to-third-phase current is greater than the predetermined threshold; and, the determined sector is one selected from the group consisting of: a sector associated with a second-phase-to-third-phase-to-ground fault or a first-phase-to-third-phase-to-ground fault; and a sector associated with a second-phase-to-third-phase-to-ground fault or a first-phase-to-second-phase-to-ground fault.