Förfarande för fasval för enpolig utlösning av högimpediva jordfel i direktjordade kraftnät samt anordning för genomförande av det nämnda förfarandet

摘要

A method and a device for phase selection for single-pole tripping of high-impedance ground faults in direct grounded power networks. Starting from the ratio of the negative-sequence voltage to the zero-sequence current (U2/I0) and the ratio of the negative-sequence voltage to the positive-sequence voltage (U2/U1), two criteria with different conditions are formed, each of which indicating a faulted phase, and if both criteria indicate the same phase as faulted, single-pole tripping can take place.