This part of IEC 60034 which is a technical specification provides a common basis for measuring techniques and instruments, the arrangement of test circuits, normalization and testing procedures, noise reduction, the documentation of test results, the interpretation of test results with respect to partial discharge off-line measurements on the stator winding insulation of rotating electrical machines when tested with alternating voltages up to 400 Hz. This technical specification applies to rotating machines having bars or form wound coils with conductive slot coating. This is usually valid for machines with voltage rating of 6 kV and higher. The measurement methods described in this specification may also be applied to machines without conductive slot coating. However , results may be different and are not covered by this specification.