Operation experience with a new fault location system for MV networks

The first part of this paper contains a short review on pr oblems related to distribution system operators' (DSOs) curr ent pr actice regarding earth fault location and sustained faulty operation of compensated networ ks. A new device and method ar e then pr esented that have been implemented recently at Hungarian DSOs. This technique uses curr ent injection par allel to the Petersen coil for fault location, and the same device is further used to decr ease the har monics in the residual fault curr ent during sustained earth-fault oper ation. First field test results are presented. It is also shown that the CTs installed along with the pr oposed device1eliminate the need for the additional resistor that was necessary to select the faulted feeder.