A system for a machine, in particular an automated production machine, has a large number of proximity sensors. Each proximity sensor has at least one secondary winding that is suitable for drawing power from a medium-frequency magnetic field. At least one primary winding, which is fed from a medium-frequency oscillator, is provided for supplying the proximity sensors with electrical power without using wires. Each proximity sensor is equipped with a transmitting device that emits radio signals, which contain sensor information of interest, to a central receiving device that is connected to a process computer for the machine. A proximity sensor and a primary winding for this purpose are also proposed.