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. The output signal of a VRS sensor is an ac voltage that varies in amplitude and wave frequency as the speed of the monitored device changes, and is usually expressed in peak to peak voltage (Vp-p). One complete waveform (cycle) occurs as each target passes the sensor's pole piece. If a standard gear were used as a target, this output signal would resemble a sine wave if viewed on

The KJT-EX58AM40-LY series Variable Reluctance Speed (VRS) sensors consist of an iron core, an inductive coil and a permanent magnet. A ferrous pole wheel passing the sensor face changes the magnetic field strength, resulting in an AC Voltage being induced in the coil. The frequency of the output signal is proportional to the speed of the moving target. The amplitude of the signal depends on speed, air gap, geometry of the target, magnetic properties of the target material and the electrical load. VRS sensors, also known as passive or electromagnetic sensors, do not require an external supply. The EX58AM40 is specifically designed for use in explosive atmospheres.