IEEE Draft Recommended Practice for Thermal Cycle Testing of Form-Wound Stator Bars and Coils for Large Rotating Machines

This procedure is intended for form-wound bars/coils for rotating machines rated 10 kV or more at 50 Hz or 60 Hz that are subjected to many transitions from no-load to full-load current during normal operations, and where rapid load variations are typical. Only the thermal cyclic degradation within the groundwall insulation and/or the conductor package and delamination of the groundwall insulation from the conductor are addressed by this test. The procedure is applicable to indirectly-cooled machine types such as: combustion turbine generators, pumped storage or peaking duty hydrogenerators, synchronous condensers, cyclic duty water pump motors. Various pass fail criteria are presented and the ones that apply in a specific circumstance must be agreed between user and manufacturer prior to commencement of testing.