Module unit, composite and method for monitoring an energy supply network

will be explained in a module unit (DS1), comprising: - a first connecting device (A1) - a second connecting device (A2), - a switched between the first terminal device and the second terminal apparatus switching unit (S1a), - a detection unit (E1a) - a control unit (SE1), the output side with the switching unit (S1a) and the input side to the detecting unit (E1a) is connected, - a receiving unit (E1), which is coupled on the output side with the control unit (SE1), and containing - either a further grasping unit (E2a) which, based on a third connecting device (A3) for a consuming unit (V1) detects an electric current or electric power, or a storage unit (M1) in which a value of electric current or electric power for a consuming unit (V1) is stored.