A module assembly for the application-specific construction of power factor correction, filter, and absorption circuit systems in selectively non-choked, choked, protective or thyristor-connected design, comprising a busbar system, fuse holders, switch components, at least one choke, and power capacitors. A first module unit has a first section for receiving busbars, fuse holders, fuses, a busbar cover as protection against accidental contact with the busbar, and a second, trough-like section for receiving switch components that can be mechanically fixed and electrically contacted. A second module unit is designed to receive switchable capacitor winding blocks, enclosing the at least one winding block, insulating the same. The first and the second module unit each have a base region, wherein mechanical and/or electrical connections are led via apertures in the base regions, such that either a back-to-back assembly with direct docking of the first and second module units can be affected.