Leon Foucault was a French physicist and inventor. The eddy current was discovered by Leon Foucault in 185 1 year. It is caused by the intersection of moving magnetic field and metal conductor, or the vertical intersection of moving metal conductor and magnetic field. In short, it is caused by electromagnetic induction effect. This action produces an electric current in the conductor. Because Leon Foucault discovered the eddy current phenomenon, he called it Foucault current.

In the same year, it also found that the induction cooker can heat food. Not only that, but also the rotation of the pendulum plane proves that the earth has rotation. This simple pendulum demonstrating the rotation of the earth is also called Foucault pendulum.

Classification of eddy current sensors:

1, classified according to the waveform and number of excitation sources. There are sine wave, pulse wave and square wave.

2. According to the different classification of the output signal of the detection coil. There are two kinds: parameter coil and transformer coil. The output signal of parametric coil is the change of coil impedance, which is generally not only the coil that generates excitation magnetic field, but also the coil that picks up eddy current signal of workpiece, so it is also called self-induction coil. Transformer coil, which outputs the induced voltage signal on the coil, generally consists of two groups of coils, one for exciting the alternating magnetic field and the other for picking up the eddy current signal.

3. Classification of the relative positions of the detection coil and the workpiece. There are three types of coils: external penetrating coil, internal penetrating coil and placing coil.

Reference to the above content: Baidu Encyclopedia Foucault