Study on the effect of different internal corona protection on electrical properties of generator stator bar

Dielectric loss factor (tandelta), largest repeatedly occurring PD magnitude and breakdown voltage of large generator stator bars with different internal corona protection were studied in this paper. It was found the electric properties which, the increment of tandelta, breakdown voltage and partial discharge magnitude etc. of the bars with internal corona protection were excelled than the bars without the structure. The loss factor of the bars fully shielded was smaller than those with partial shield layer. The dielectric loss factors of the fully shield bars were similarly but the partial discharge magnitude and breakdown voltage are very different depending on different structure of internal corona protection. These parameters could effectively characterize the electrical properties of large generator stator bars. The study had important reference for designing internal corona protection structure of large generator stator bars.