An exemplary transformer winding including at least two hollow-cylindrical, axially adjacent winding modules, which are arranged about a common winding axis and have an electrical conductor wound in layers, and a common electrical insulting layer, through which the winding modules are enveloped. The insulating layer has at least one annular, radial depression or annular, radial elevation, which is salient transversely to the winding axis on the radial outer face of said insulating layer.