Eddy current displacement sensors combine several advantages. They provide high precision and resolution on a wear-free, noncontact basis. They are resistant to external influences such as dirt, pressure and fluctuating temperatures and therefore are ideally suited to harsh industrial environments.
The eddy current principle occupies a unique position amongst inductive measuring methods. Measuring via eddy current is based on the extraction of energy from an oscillating circuit. This energy is needed for the induction of eddy currents in electrically-conductive materials. Here, a coil is supplied with alternating current whereby a magnetic field forms around the coil. If an electrically conducting object is placed in this magnetic field, eddy currents are induced which form a field according to Faraday’s induction law. This field acts against the field of the coil, which also causes a change in the impedance of the coil. This impedance can be calculated by the controller by looking at the change in the amplitude and phase position of the sensor coil.