METHOD FOR IMPREGNATING ELECTRICAL-MACHINE WOUND STATOR STACK Russian patent published in 2001 - IPC

FIELD: electrical engineering. SUBSTANCE: method involves pre-drying of stacks, vacuum evaporation, treatment with impregnating material, mainly with varnish, followed by drying in two stages; during first stage solvent is removed and during second one, impregnating material film is baked, allowed to cool down, and then excess material is removed. Novelty is that for pre-drying stator is heated to 70-100 C for 45-60 min and vacuum evaporation is effected before dipping it in impregnating-material tank while bringing pressure to residual value of (4-7)•10⁴ Pa and holding stator under these conditions for at least 60 s; impregnating material is thinned with solvent until its viscosity is brought to 25-50 s whereupon pressure of (20-25)•10⁴ Pa is built up within impregnation tank. Stator is held under these conditions in impregnating tank for 300-600 s and then impregnating material is pumped out, pressure is reduced to residual value of (6•10⁴-3•10³) Pa, and impregnating material is allowed to run off external surfaces of stator and its winding; after that stator is dried out for 1.9-2.1 h during first stage at 122-135 C and for 2.4-2.6 h during second stage at 135-155 C. EFFECT: improved quality of impregnated stack, enhanced reliability and service life of machine. 9 cl