Patent ID: 7728600
Filing Date: 2010-06-01
Classification: G01R

Abstract:
1. A method for determining a distance of a phase-to-earth fault on a three-phase electric line of an electric network, the method comprising: monitoring current and voltage quantities of the three-phase electric line at a measuring point; detecting a phase-to-earth fault on the three-phase electric line and a faulted phase of the three-phase electric line; determining a first estimate value for a distance between the measuring point and a point of fault on the basis of values of the monitored current and voltage quantities and a first equation which relates the current and voltage quantities to the distance and is based on a fault loop model of the electric line, in which model the load of the electric line is located between the measuring point and the point of fault; determining a second estimate value for the distance between the measuring point and the point of fault on the basis of values of the monitored current and voltage quantities and a second equation which relates the current and voltage quantities to the distance and is based on a fault loop model of the electric line, in which model the point of fault is located between the measuring point and load of the electric line; and selecting according to predetermined criteria one of the determined two estimate values as the distance between the measuring point and the point of fault.