抄録
Insulation layers of large generator stator coils are molded with heat-press after impregnating resin into porous materials covered with mica paper in VPI (Vacuum Pressure Impregnation) process. While length of coils is about 10 meters, gaps in porous materials are micrometer range. Therefore, the macro-scale analysis model (Porous-Media Model) including flow properties of micro-scale porous materials is needed to analyze impregnation flow into insulation layers of coils. In our study, flow resistance resulting from flowing through porous materials is expressed as the equation by multiplying resin viscosity by section coefficients depending on structure of porous materials. Section coefficients of insulation layers are set for orthogonal three directions considering compressibility and determined from the visualization of macro-scale resin flow in insulation layers and simulation. Using these section coefficients, resin impregnation flow into insulation layer of generator coils was analyzed with changing insulation layer thickness (2-10mm) and resin viscosity (0.1-0.5 Pa・s). From the results, variation in fill time by resin viscosity increased drastically with increase in insulation layer thickness. Therefore, for thicker insulation layer, it is important to control variation in resin viscosity by prediction of it in impregnating.
