Electricity supply assembly with a first and a second power supply device, where the second power supply device is connected to the first power supply device

The power supply arrangement has a transformer that is provided with secondary winding with several taps (3UN,3VN,3WN). The secondary windings of transformer are connected in power supply unit through a power controller. A control input is connected to control terminals of switching portions. The terminals (43-45) of a second power supply unit are connected to taps for a reference potential of the secondary windings through controllable switching portions (41,42) of a second switch group.