METHOD FOR DETECTING A FAULT OR ALSO THE DIRECTION OF A FAULT IN ELECTRIC LINES AND MEANS FOR EXECUTING THIS METHOD

摘要

A method and an apparatus for detecting a fault and a fault direction in electric lines. The voltage and current is measured simultaneously at at least one location in the electric lines to form a voltage and current step signals (Su, Si) based on the measuring. A Cartesian coordinate system is established defining four quadrants and an origin. The coordinate system has one coordinate corresponding to the voltage step signal Su and another coordinate corresponding to the current step signal Si, wherein each pair of the simultaneously measured signals Su, Si forms a point in the coordinate system and the points define a line of motion progressing from one quadrant to a next adjacent quadrant. Predetermined triggering boundaries are established in each of the quadrants as well as predetermined boundary zones to a predetermined depth from each triggering boundary towards the origin. The progress of the line of motion is monitored relative to the triggering boundaries and the boundary zones. At least a triggering boundary in the next adjacent quadrant is displaced upon a detection and a monitoring step that the line of motion has entered the boundary zone of the one quadrant. A fault is detected upon a detection in the monitoring step that the line of motion has transgressed a triggering boundary and a fault direction is detected based on the quadrants in which a fault detection is made. A triggering signal is generated upon a detection in the monitoring step that the line of motion has transgressed a triggering boundary.