Inductive rotary joint system with stationary and rotating sides has a one-phase rectifier for receiving one-phase AC-input to generate low-level DC-voltage, and a three-phase rectifier for receiving three-phase input to generate higher-level DC-voltage. An AC-power generator receives DC-voltage and generates AC-power, which is coupled by an inductive rotary joint to a load at the rotating side. Voltage coupled to the load is comparably higher when the one-phase rectifier is connected and comparably lower when the three-phase rectified is connected. A control unit at the secondary side for controlling at least the load is connected to measure the voltage produced for the secondary side, and to distinguish between a comparatively lower voltage and a comparatively higher voltage. When a presence of a comparatively higher voltage is indicated, an x-ray tube is enabled within the load.
