Causes of Indefinite Faults in Estonian 110 kV Overhead Power Grid

The study considers causes of indefinite faults in the 110 kV overhead power grid in Estonia. The number of indefinite faults (flashovers on overhead line insulators) has increased significantly in the last years, causing a lot of problems to the transmission system operator (TSO). The study claims wildlife, more specifically migrating birds white storks, to be responsible for most of the indefinite faults in the power grid (excremental contamination).