IEC 61400 12 1 2017 is also available as IEC 61400 12 1 2017 RLV which contains the International Standard and its Redline version showing all changes of the technical content compared to the previous edition IEC 61400 12 1 2017 specifies a procedure for measuring the power performance characteristics of a single wind turbine and applies to the testing of wind turbines of all types and sizes