Description 3090A Honeywell Speed Sensor DESCRIPTION Hazardous Location VRS sensors are designed for use in locations where explosion-proof or intrinsically safe sensors are required. Passive VRS (Variable Reluctance Speed) Magnetic Speed sensors are simple, rugged devices that do not require an external voltage source for operation. A permanent magnet in the sensor establishes a fixed magnetic field. The approach and passing of a ferrous metal target near the sensor’s pole piece (sensing area) changes the flux of the magnetic field, dynamically changing its strength. This change in magnetic field strength induces a current into a coil winding which is attached to the output terminals.
