Three-phase electric power systems can transmit large amounts of power, typically in the range of 2000 MVA with a voltage of 765 kV. Under such extreme conditions, the air surrounding the transmission lines is ionized, which significantly increases the conductivity. The present contribution proposes a simple model which allows one to estimate the ionization and the electric conductivity of the air as a function of the power density flowing in the power line system. Near the transmission lines, it is shown that the air conductivity is increased by several orders of magnitude relative to normal conditions. In this scenario, the dielectric breakdown is favored by avalanche processes and lightning stroke probability is significantly increased.
air ionization; transmission lines; lightning
