A changeover apparatus for interruption-free changeover between two energy supply systems includes: at least one first outer conductor section and one second outer conductor section; a first mechanical bypass switch arranged in the first outer conductor section; a first semiconductor circuit arrangement connected in parallel with the first mechanical bypass switch; a first measuring device for recording a first voltage and/or a first mains frequency, which first measuring device is connected to the first outer conductor section; a second mechanical bypass switch arranged in the second outer conductor section; a second semiconductor circuit arrangement connected in parallel with the second mechanical bypass switch; and an electronic control unit for actuating, in a predeterminable manner, the first mechanical bypass switch, the first semiconductor circuit arrangement, the second mechanical bypass switch, and the second semiconductor circuit arrangement. The first measuring device is connected for communication with the electronic control unit.