Abstract: A waste-heat recovery system for a waste-heat source, made up of an ORC (Organic-Rankine Cycle) postconnected thereto. The waste-heat source is connected with the heating device of the ORC as well as an expansion machine, coupled to a generator, for steam expansion in the ORC, which has magnetic bearings with an associated control device and a power supply via a direct current intermediate circuit of a generator frequency converter. The design and safe operating behavior of a waste-heat recovery system made up of an ORC post-connected to a waste-heat source are optimized. In a power supply failure, the electric energy that a down-running generator continues to generate is used to supply the magnetic bearings with the associated control device in order to ensure a safe operation in the event of a power supply failure.