A transformer may comprise a winding wrapped around a magnetic core, the winding having at least one winding portion extending between the magnetic core and the exterior of the winding in radial direction. The winding may comprise at least a first conductor and at least a second conductor, arranged radially adjacent to each other in each winding portion with the interposition of an insulating layer, wherein the first conductor is arranged radially inwardly with respect to the second conductor for part of each winding portion length, and radially outwardly with respect to the second conductor for another part of each winding portion length.