The WDA4 is a non-contacting high-power, extended range magnetic proximity sensor, not affected by dust or material build up, used to detect moving ferrous material up to 75mm away from the sensor.
This sensor is a great choice for measuring speed and alignment on bucket elevators and on other applications such as using the WDA switch as broken/slack chain detector on drag chain conveyors or as a non-contact speed switch for screw conveyors.