Porous nonmetallic inorganic coatings formed via pulsed microplasma oxidation of A5E aluminum wire used in steel-aluminum wires were developed. The coatings decrease the power losses due to corona discharge from 80 to 20% and increase the voltage of corona discharge during transmission of electricity through high-voltage power wires. The following five most important parameters of these coatings were identified: thickness, porosity, pore diameter, wettability, and dielectric loss tangent. The methodology was developed for rapid assessment of the effectiveness of corona-discharge suppression by coatings based on the dielectric loss tangent.