High Output VRS sensors are designed for use in applications where higher output voltages are needed. They perform best at low to medium speeds with medium to high impedance loads. Front-End Sealed versions are available for use where the sensor is exposed to fluids, lubricants or adverse environmental conditions. 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 lines 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 (

The KJT-EX34H-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 EX34H is specifically designed for use in explosive atmospheres.