The invention relates to a manufacturing method of an air-cooled unit capacity hydrogenerator VPI (
Vacuum Pressure Impregnating)
stator coil bar. An inner shielding layer on the surface of a wire canreduce an internal local
discharge probability of the wire. After the coil bar is bound with a VPI main
insulation layer, a straight-
line segment is bound in a half-lapping mode with a layer of low-resistance anti-
corona material, then VPI of
epoxy anhydride resin is carried out, after impregnation is ended, the end part is respectively bound in a half-lapping mode with medium resistance, medium-
high resistance and
high resistance segments, and the surface of an anti-
corona segment of the end part is bound with two
layers of additional insulation
layers; after an anti-
corona layer is processedwell, the coil bar is assembled into a hot-pressing die, pressurization is carried out, and the coil bar is placed into a baking oven to carry out heating, curing and forming; and after the main
insulation layer is cured and formed, a
protection layer is brushed with a high-resistance anti-corona paint and a
surface coating varnish so as to obtain the finished product VPI
stator coil bar. The air-cooled unit capacity hydrogenerator VPI
stator coil bar has the main
technical performance indexes that: (1) a
breakdown voltage of the finished product coil bar is greater than or equal to 5.5UN; and (2) an
electrical aging resistance experiment of the coil bar shows that the service life under a
voltage of 3.0UN is greater than 40H, and the service life under a
voltage of 2.0UN is greater than1,100h.