Abstract: A high-voltage transformer-rectifier device comprising a step-up three-phase transformer with a spatial magnetic circuit made up of three vertical stacks (7) of closed cores (9) insulated from one another and secured in an insulating frame (8), having a common window and carrying the sections (10) of a secondary winding (2). A primary winding (1) comprises three flat rectangular coils (11) whose vertical parts are arranged to lie pairwise along the axis of the common window in each stack (7) of the cores (9). A bridge rectifier section comprises individual bridge rectifiers connected to the sections (10) of the secondary winding (2), and each of the potential screens is formed by ring sections (6 and 20) arranged one on top of another along the stacks (7) of the cores (9).