This part of IEC 60317 forms an element of a series of standards which deals with insulated wires used for windings in electrical equipment. This series consists of three groups describing: 1) Winding wires - Test methods (IEC 60851); 2) Specifications for particular types of winding wires (IEC 60317); 3) Packaging of winding wires (IEC 60264). This part of IEC 60317 deals with the technical specifications for solderable polyurethane enamelled round copper wire, class 155, with a dual coating insulation. The base insulation is based on polyurethane resin, which may be modified providing it retains the essential chemical characteristics of the original resin and meets the requirements of this specification. The top insulation is a bonding layer on the basis of a thermoplastic resin. The range of nominal conductor dimensions covered by this standard is: - grade 1B: 0,020 mm up to and including 0,800 mm; - grade 2B: 0,020 mm up to and including 0,800 mm. The responsible committee is DKE/K 413 "Wickeldrähte" ("Winding wires") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.