Paddle switch is designed to detect high or low levels of free-flowing dry Solids, such as powders and granules. It is mounted through the wall of a vessel such that the paddle protrudes inside the vessel.
A small electric motor drives the paddle, which rotates freely in the absence of material. Impeded by material the motor will be turned within the housing while loading a spring and triggering two switches. One of them is a dry electric contact for control and alarm functions while the other cuts the power to the motor. When the material level drops, the loaded stretched tension spring returns the motor to its original position and the unit is reactivated.