Contactless rotary joint with safety function

An inductive rotary joint system has a one phase rectifier for receiving a one phase AC input, generating a comparatively lower DC voltage, and a three phase rectifier for receiving a three phase input, generating a comparatively higher DC voltage. An AC power generator generates an AC signal from the DC voltage, which is coupled by an inductive rotary joint to a load at the rotating side. When being connected to the one phase AC input only, the AC power generator receives a comparatively lower DC voltage and therefore couples a comparatively lower voltage to the load. In the case of being connected to the tree phase AC input, the AC power generator receives a comparatively higher DC voltage and therefore couples a comparatively higher voltage to the load. A control unit located 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. For the case that is a comparatively higher voltage, an x-ray tube is enabled within the load.