Plastic electromagnetic level sensor

Description

Plastic electromagnetic level sensor gauges use the force of a magnet in the float to change the electrical status of a reed switch.

FIG. 1 shows the components of an plastic electromagnetic level sensor gauge that operates vertically.

FIG. 2 and FIG. 3 show an indicator with a normally-open contact. When the level of fluid increases, the float moves from B towards A. As soon as the magnet in the float reaches point A, the contact closes.

The movement of the float is normally limited by a mechanical stop. If there is no stop, the contact returns to its original position when the magnet passes point B. When the level of fluid drops, the float moves from A towards B, and as soon as the magnet reaches point A1 the contact opens.

The difference between points A and A1 is called the differential, or hysteresis, of the contact.