Electric power generator system using ring-shaped generators and essentially being formed by turbines and generators and optionally converging-diverging nozzles. The turbines optionally have an open centre and curved and/or hinged vanes, and are optionally axial turbines or open-centred reel-shaped turbines, cycloidal turbines optionally with a circular cog wheel, or impellers, or the like. The generators can have permanent magnets or variable reluctance, unsealed and optionally independent. The exciter can be made of a ring (of magnets or areas alternately having high and low magnetic permeability) around the vanes, and the armature (winding magnets or magnets having a high-permeability core) forms an arc or ring fitted in the housing or the nozzle and/or the stationary inner cylinder or ring (or braced ring system) in the case of open-centred turbines.