How Variable Reluctance Speed Sensors Work

//How Variable Reluctance Speed Sensors Work

How Variable Reluctance Speed Sensors Work

How AKA Passive Speed Sensors Work:

Variable Reluctance (Passive Speed Sensor)

  • Magnetic resistance is known as reluctance (variable reluctance = VR).
  • Each tooth positioned in front of the pole decreases reluctance and increases magnetic field density around the coil
  • Each valley increases reluctance and causes the magnetic field to collapse around the coil thereby generating a voltage.
  • Repeating combination of tooth & valley, such as found on a gear, create a sinusoidal electrical output signal.
  • As the rate of change of the magnetic field increases, so does the amplitude

Variable Speed Sensors Features:

  • Senses gears or any ferromagnetic discontinuity
  • No moving parts or contacts
  • Two Wires (No Power Req’d)
  • Harsh environments (pressure or chemical)
  • High ambient Temperatures – (750 F / 400 C max) 

Variable Speed Sensors Benefits:

  • Easy installation
  • No alignment
  • High reliability – mature technology
  • Low Cost

Variable Speed Sensors Limitations:

  • Poor low speed performance (below 100RPM / 15 IPS)
  • Output amplitude dependent on speed and air gap

If you would like more information about the Aitek Speed Sensors or other Aitek Products please contact Forberg Scientific, Inc.
Toll Free: 855-288-5330


Websites: &

By | 2017-05-17T17:13:12+00:00 May 17th, 2017|Uncategorized|0 Comments