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
Email: processsales@forberg.com
Websites: www.forberg.com & www.autoctrls.com