DETECTION OF A METAL OT MAGNETIC OBJECT

摘要

The invention relates to a measuring device for detecting a metal object, comprising an emission coil for producing a magnetic field and a compensation network which is connected to the emission coil, a differential voltage being applied between the emission coil and the compensation network. Said measuring device also comprises a control device for supplying the emission coil and the compensation network with alternating voltages such that the value of an alternating voltage component of the differential voltage, which is time synchronised with the alternating voltage, is minimised. Said control device is configured to detect the metal object when the ratio of the alternating voltages does not correspond to the ratio of the flows flowing through the emission coils and the compensation network.