The invention relates to an electric circuit arrangement (20) for the functional testing of a monitoring device (4) for a power supply system (2), the electric circuit arrangement (20) having a test resistance (Rf1, Rf2) which is switched between an active conductor (L1, L2) of the power supply system (2) and ground (PE) and has a settable actual resistance value (Rx). In this context, a bidirectional cascade (12) consisting of field-effect transistors as test resistances (Rf1, Rf2) and an analog control (10) for the continuous-value setting of the actual resistance value (Rx) to a predefined target resistance value (R0) are provided.
Furthermore, the invention relates to a modular circuit arrangement (60) consisting of several electric circuit arrangements (20) according to the invention, each of the electric circuit arrangements (20) being assigned a different active conductor (L1, L2) of the electric power supply system (2), and a central control unit (50) being implemented for controlling and monitoring the electric circuit arrangements (20).