AN APPARATUS AND METHOD FOR DETERMINING A FAULTED PHASE OF A THREE-PHASE UNGROUNDED POWER SYSTEM

摘要

Provided is an apparatus (24) and method for determining a faulted phase resulting from a fault in a three-phase ungrounded power system (10). The method includes comparing a phase angle of an operating phasor to a phase angle of a fixed reference phasor The operating phasor is derived from a digitized signal sample of a plurality of measured signals of the power system(l?) The method also includes comparing a phase angle difference between the operating phasor and the fixed reference phasor to at least one threshold to determine the faulted phase. The fixed reference phasor may be a phase-to- phase voltage or a positive sequence voltage of the plurality of measured signals of the power system (10) The operating phasor may be a zero sequence current, a zero sequence voltage or a combination of a zero sequence current and a zero sequence voltage of the plurality of measured signals of the power system(l0).