RF Eddy Current Speed Sensors
These RF sensors can sense ferrous steel and aluminum targets at large distances and low speeds. They cannot sense through ferrous steel and aluminum but can sense through thick walls of non-magnetic stainless steel and other non-magnetic materials. A digital output (square wave signal) is produced at the same rate as targets passing by. Typical usage is speed sensing of flowmeter turbine blades.
A driver circuit is required for the sensor to operate. Sensors can be provided as a sensing coil with a remote driver circuit or with the circuit integrated into the sensor housing.
Intrinsically Safe and Explosion/Flame Proof versions are also available for Hazardous Locations. In some applications this sensor type can be replaced by an Amplified Variable Reluctance Speed Sensor or Hall Effect Zero Speed Sensor.