Principle of Electromagnetic Rotation Detector

External gear type electromagnetic rotation detector

This type can detect rotation signal by approaching closer to the tip of the external detection gear mounted on the rotating shaft. The detector consists of permanent magnet, detection coil and yoke. When the magnetic material comes close to the yoke, the magnetic flux passing the detection coil is changed. And then the detection coil generates the inductive voltage proportional to the frequency variation. The pulsation by the magnetic flux [Frequency f ＝ rotation speed(r/ min)× the number of gears/60 (Hz)] is output as the rotation signal from the detector.
The electromagnetic rotation detector is popularly used in many fields as a reliable measurement method with the following features.

1. Simple structure
2. No power supply required
3. Compact
4. Maintenance free

Built-in gear type electromagnetic rotation detector

This type of detector is used by connecting to the rotating shaft of the machinery side via a coupling, and generates the frequency signal proportional to the rotation speed. The magnetic flux in the magnetic circuit which consists of the permanent magnetic, detection gear and internal gear teeth, is changed by the rotating detection gear mounted on the shaft. And then the detection coil generates the inductive voltage proportional to the frequency variation. The pulsation by the magnetic flux [Frequency: f = rotation speed(r/ min)× the number of gears/60 (Hz)] is output as the rotation signal from the detector.

Revised:2023/12/08