FIELD: electrical engineering.
SUBSTANCE: according to the method for determination of a damaged feeder on the bus section of a three-phase grid win an insulated neutral in case of single-phase earth faults, for power grids wherein transformers are installed on feeders with only two phases (usually - Phases A and C) one obtains the magnitudes and angles of zero-sequence pseudocurrents by way of digital conversion of analogue signals of two phase currents of each feeder prior to and after damage, their difference yielding the zero-sequence current in every feeder. Then one compares the zero-sequence currents complex magnitudes taking into account the facts that the zero-sequence current in the damaged feeder is the maximum among all the section feeders currents and that the angle of zero-sequence current in the damaged feeder differs from the angles of zero-sequence currents in the undamaged feeders by approximately 180 degrees.
EFFECT: reliability improvement.
