Product Description
MEVS speed sensor is also named as variable-reluctance sensor. It is preferred for industrial and automotive environments, because they sustain mechanical vibration and higher temperature operatin. In most applications, they sense a steel target that is part of a rotating assembly. Because the unprocessed signal amplitude is proportional to the target speed, a sensor whose signal-processing circuitry is designed for high speed ceases to function at some lower rate of rotation.
MEVS speed sensor often refers to a passive magnetic sensor because it does not need to be powered. MEVS speed sensor is self generating.
Principle: MEVS speed sensor is basically a permanent magnet with wire wrapped aroung it. The interal construction of the speed sensor consists of a magnet, pole piece and coil. A magnetic field extends from the magnet, through the pole piece and coil out into the air space at the end of the sensor. The return path of the magnetic field is from the air space to other end of the magnet. As a ferrous toothed ring on the wheel padded the tip of the pole piece, the magnetic field increases and then decreases as the object moves away from the pole piece. The snap or the rapid change in the magnetic field induces an AC voltage signal in the coil. With an ideal target and matching sensor, the induced voltage is in the shape of a sine wave.