Wet tests on naturally polluted glass and composite insulators
The study examines what type of bird excrement contamination will lead to insulator's flashovers on the Estonian 110 kV overhead power lines. Wet tests made in laboratory with naturally contaminated glass and composite insulators show that traditional (insulator's surface) contamination will not lead to flashovers and therefore most likely the flashovers are caused by highly conductive bird excrement streamers. The tests also show that using corona rings at composite insulator's line end fittings, affects the occurring probability of partial discharge extent on wetted insulator.
The study about indefinite fault causes in Estonian 110 kV power grid
The study examines the cause of indefinite flashovers in the Estonian 110 kV power grid. The number of indefinite flashovers has increased significantly in last years causing a lot of problems to the TSO. Concluding the study one can argue that most of indefinite faults in power grid are in high probability caused by the wildlife, more specifically birds. Main “cause” could in high probability be migrating bird called White Stork.
Geomagnetic micropulsations due to the motion of ocean waves
When sea waves move in the magnetic field of the earth, electric currents are generated in the water volume. These currents give rise to a small magnetic field which perturbs the earth's field. For plane trochoidal waves, this perturbing field decays exponentially with altitude and lies in a vertical plane which is oriented in the direction of wave propagation. The magnitude of the perturbing field also depends upon the magnitude and dip angle of the earth's field, and upon the height, wavelength, and propagation direction of the sea waves. For north-south waves, sea state 5, and an altitude of 100 feet, the perturbation is of the order of 0.1 gamma.