Förfarande och anordning för att bestämma den felström som uppstår vid ett fel på kraftlinjer vid kortslutning mellan fas/faser till jord

摘要

A method and a device for determining the fault current IF IF which occurs in case of a fault through a short circuit between phases or from phase/phases to ground. A measure of the fault current IF can be obtained by a linear combination of the sum of measured current samples IR1, IR2, IS1, IS2, IT1, IT2, for each phase at two adjacent points in time and in which each of these sample values is multiplied by a coefficient kR1, kR2, kS1, kS2, kT1, kT2 which is chosen such that the fault current gets into phase with the positive- and negative-sequence current changes.