Abstract: In a circuit where a power converter (1) that is connected to a motor is also connected at its input terminals (2, 3) to a d.c. power supply system (U.sub.DC) and where at least one condenser (C) is connected in parallel to the power converter (1) connected to the motor and at least one line reactor (L) is connected in series to the condenser (C), a reduction in the harmonic currents fed back into the d.c. power supply system (U.sub.DC) by the power converter (1) connected to the motor above a predetermined minimum frequency is achieved without unnecessarily overdimensioning the condenser (C) and the line reactor (L) due to the fact that the line reactor (L) has at least one tapping point (4) to which at least one RC circuit (5) is connected in parallel to the condenser (C), where the RC circuit (5) has at least one capacitor (C.sub.1) and at least one resistor (R.sub.1) connected in series with it.