An apparatus including a fixed part, a rotary support configured to be driven in rotation relative to the fixed part, at least one item of electrical equipment carried by the rotary support, and a power supply device configured to supply electrical energy to the electrical equipment. The power supply device includes an asynchronous machine including a stator fixed to the fixed part and a rotor carried by the rotary support, and an excitation device. The stator includes an electrical circuit including at least one switch configured to switch between an open state in which the electrical circuit is open and a closed state in which the electrical circuit is closed. The rotor includes at least one winding connected to the electrical equipment. The excitation device is configured to provide a reactive current to the electrical circuit of the stator or to the winding of the rotor.