Abstract: Conductor bundles for the concentric coils of a dry inductor having no iron core. The coils define cooling air gaps therebetween, adjacent ones of the coils being electrically connected in parallel and each coil being comprised of turns of a conductor bundle of the same rectangular cross section, the coils having different numbers of said turns. The conductor bundles form the turns of the coils and comprise a plurality of conductors electrically insulated from each other and twisted together, the conductor bundles of all coils are structurally identical with respect to the number and cross-sectional dimension of the conductors, and the rectangular cross sections of the conductor bundles forming respective coils have different cross-sectional dimensions in the axial direction of the respective coil whereby the coils have the same dimension in said axial direction while the number of the turns of the coils differs.