A differential transmission (4) for an energy generating installation, in particular for a wind power installation, has three input or output drives wherein a first input drive is connected to an input drive shaft (2) of the energy generating installation, an output drive is connected to a generator (13) which can be connected to a power supply system (9), and a second input drive is connected to an electrical machine (14, 8) as a differential drive (14). At least two machine-side frequency converter output stages (22) are connected to the electrical machine (14, 18). The electrical machine (14, 18) can therefore prevent the second input drive from rotating at an excessively high rotation speed in the event of failure of a machine-side frequency converter output stage (22), by electrical braking with the aid of at least one further machine-side frequency converter output stage (22).