Development of generator stator coil with 22kV global VPI insulation

Recently, the demands for generators with large capacity are increasing in the market, and their rated voltage has been heightened accordingly. Therefore, it is required to manufacture high voltage stator windings to improve the quality of the insulation system and to strive for a long-term life. On the grounds of the above, we have evaluated numerous model coils and full-scale coil models by performing the heat cycle test, and established a computing program both for the electric field strength and the taping conditions. As a result of these studies, the development of a global vacuum pressure impregnation (VPI) insulation system for 22 kV has been completed successfully.