Research on characteristic parameters for multi-factor aging of stator bar insulation of pumped storage generator

The real stator bars of an 18kV pumped storage generator were taken as research objects. The multi-factor sequential aging tests of thermal cycling, electrothermal and vibration were carried out. The dielectric loss angle tangent (tan δ ), capacitance ( C ), Δtan δ , Δ C and maximum partial discharge of the samples at different aging periods were measured. The variation of these parameters with aging time was summarized, and the aging mechanism was analysed. The results show that tan δ , Δtan δ , and Δ C increase overall with aging time, while the capacitance decreases slightly with aging time. The maximum partial discharge decreases gradually at beginning of aging, and then increases after aging of 4 periods. All of tan δ , Δtan δ , Δ C and maximum partial discharge increase obviously in the later stages of aging. They can be used as characteristic parameters for multi-factor aging of stator bars insulation of pumped storage generators, to evaluate the aging state of the insulation with epoxy mica.