IEC 60317-27:2013 specifies the requirements of paper tape covered rectangular copper winding wires. This covering consists of two or more layers of paper tape, all in the same direction and is primarily intended for winding coils for oil immersed transformers. The range of nominal conductor dimensions covered by this standard is: - width: min. 2,0 mm max. 16,0 mm; - thickness: min. 0,80 mm max. 5,60 mm. The paper tapes covered by this standard are restricted to those specified in IEC 60554-1 having thicknesses in the range 25 μm to 125 μm inclusive. This fourth edition cancels and replaces the third edition published in 1998, Amendment 1:1999. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - new subclause containing general notes on winding wire, formerly a part of the scope; - revision to references to IEC 60317-0-2:2013 to clarify that their application is normative; - new 3.3, Appearance; - modification to 4.4, Increase in dimensions due to paper tape covering; - deletion of Clause 22, High temperature failure; - new Clause 23, Pin hole test. Keywords: requirements of paper tape covered rectangular copper winding wires, winding coils for oil immersed transformers