IEC 60034-27-3:2015 provides guidelines for the test procedures and the interpretation of test results for dielectric dissipation factor measurements on the stator winding insulation of rotating electrical machines. These guidelines are valid for rotating electrical machines with conductive slot coatings operating at a rated voltage of 6 kV and higher. This standard applies to individual form-wound stator bars and coils outside a core (uninstalled), individual stator bars and coils installed in a core and complete form-wound stator winding of machines in new or aged condition. This edition includes the following significant technical changes with respect to the previous publication IEC TR 60894:1987: - inclusion of digital measurement of dissipation factor and capacitance; - inclusion of limits for dissipation factor values; - detailed description of measuring techniques; extension of scope to complete windings.