A system for fixing the inner air deflector on a deflective cover for a rotating electrical machine, wherein this deflector is fixed onto the deflective cover using a fixing element and a nut placed through elongated holes on flaps of the inner deflector and through elongated holes on the deflective cover, so that the tightening of the fixing set is performed from an outer part of the housing of the machine, enabling adjustment of a gap between an outer edge of blades of a fan and an inner surface of the inner air deflector, in order to minimize the effects of formation of counter-flowing air currents near the gap.