Method and apparatus for adapting earth-fault protection settings in a three-phase electric network

摘要

A method and an apparatus for adapting earth-fault protection settings in a three-phase electric network, the apparatus (10) comprising means for determining a value for a directional phasor quantity at a measuring point in the three-phase electric network after an earth fault has been detected in the three-phase electric network, means for comparing the determined value for the directional phasor quantity with predetermined boundaries on a complex plane, means for determining, on the basis of the comparison, a neutral earthing state of the electric network, and means for adapting one or more earth-fault protection settings on the basis of the determined neutral earthing state of the electric network.