Abstract: To supply various loads connected to a uninterruptible bus, a power supply system N is connected (when functioning normally) by means of a mechanical switch, keeping an energy storage unit charged by means of a static converter which also functions preferrably as a phase shifter to stabilize the supply voltage. In the event of a power system malfunction, the storage unit is discharged by means of the static converter arrangement, and the mechanical switch is opened. The opening of this switch is not critical since between the switch and uninterruptible bus there is an inductance arrangement and an auxiliary switch. In case of a power system malfunction (auxiliary switch open), a large inductance and its large corresponding impedance of the inductive impedance arrangement becomes effective which during proper operation of the power system is shunted.