Foerfarande Foer lokalisering av ett jordslutningsfel av stor resistans i ett eldistributionsnaet pao basis av stroemmaetning

摘要

The invention concerns a method for locating a high-resistance earth fault in a power distribution system on the basis of current measurements. In the method, variations of the zero sequence voltage U0 and the zero sequence current I0f of the line or line section with their phase angles are measured. The variations are calculated as compared to a more long-term average (e.g. covering a period of 10 minutes). The influence of current through the zero sequence impedance Z0f of the healthy state of the line is deducted from the measured variations in the zero sequence current. Among current measurements compensated in this manner, the one is selected as corresponding to the faulty line or line section which has the greatest absolute value of the current and which simultaneously exceeds a predetermined threshold.