Induction in power transmission lines during geomagnetic disturbances

The electric field associated with geomagnetic disturbances gives rise to potential differences at the Earth's surface. Thus, currents are induced in power transmission lines which are earthed at both ends through transformers. The currents vary so slowly with time that they can be considered direct currents. The phenomenon has been studied in Finland for some years, and in connection with this research induced currents have been measured at four places by recording the current from the transformer neutral into the Earth. These measurements are considered in this paper. In addition, theoretical calculation of the potential differences and of the currents is discussed.Paper presented at the Fifth International Wrocaw Symposium on Electromagnetic Compatibility, Wrocaw (Poland), 17–19 September, 1980.