Abstract: The invention relates to a supply device (13) which feeds a consumer (7) with power by means of a supply network (12). Said supply device (13) fulfils both the function of a power supply and the function of a network filter, an optimum working point to be adjustable in terms of the operating modes as supplier/active filter, according to the required energy reserves. This is achieved by means of an active phase effect filter, a harmonic wave detection means (3) determining a compensating power dependent on the network harmonic wave power, and a control device component (5) whose action is adapted to the compensating power requirement being provided for the determination of an amplification factor (6). The compensating power is supplied to the current inverter according to the utilisation of the current inverter (1) and the amplification factor (6).