Variable Reluctance Speed Sensors

Variable reluctance speed sensors are like coils or solenoids wrapped around a magnet and pole piece. They don’t need external power and have two leads: power and ground. The sensor generates voltage when a gear tooth moves near it. The rotating target’s frequency can then be used to determine the speed of the application. Factors like the diameter of the target wheel and the dimensions of each tooth affect the calculation. So, VR sensors are a simple yet effective way to measure speed in a variety of applications.

A variable reluctance sensor (commonly called a VR sensor) sducer that measures changes in magnetic reluctance. When combined with basic electronic circuitry, the sensor detects the change in presence or proximity of ferrous objects.

With more complex circuitry and the addition of software and specific mechanical hardware, a VR sensor can also provide measurements of linear velocity, angular velocity, position, and torque.

VR sensors, also known as passive or electromagnetic sensors, do not require an external supply.

 

Image of a speed sensor produced by Magnetic Sensors Corp, featuring a compact and durable design with no external power supply required. The sensor boasts a simple 2-wire installation, no moving parts or contacts, and can operate in temperatures ranging from -40°C to +230°C. The sensor comes in a wide variety of styles and sizes, with pole pieces ranging from .040" to 311". It also offers spade, conical, round, or blind pole pieces and can be customized to fit various configurations.

Features

  • No external power supply required
  • High reliability. Long life
  • Robust 2- wire installation
  • No moving parts or contacts
  • Operating Temp -40 °C to + 185 °C
  • Wide speed rage
  • Pole piece from .040″ to 311″
  • Spade, conical, round, or blind pole pieces available
  • Customized versions available
  • Adapts to various configurations

Sizes Available
Tubular .150″ to .500″ inch diameter
UNF Thread 1/4-28 to 3/4-16 inch
Metric Thread M12X1.25 TO M22X1.5

 

Other VR sensors in this category

 

Close-up photo of the MSC 007 variable reluctance speed sensor, a cylindrical metallic device with wires protruding from one end with 3/4-24 Threaded end and a length of 2.70 inches. The device is used to measure high speeds on engine driven generators and is available in metric versions with or without a Deutsch connector. It is known for its durability and versatility and is commonly used in agriculture, electric power generation, and industrial applications.

MSC 401007-00

Description:  VR Speed Sensor

Thread:  3/8-24

Thread Length:  2.70 in

Lead Wire Length: 7.75 in

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A photo of the Magnetic Pick Up Sensor PN 401029-20, featuring a cylindrical metallic body with a 5/8-18 threaded end and a length of 5.16 inches. This analog variable reluctance passive sensor generates a sine wave output without requiring an external power source, and its voltage is determined by the target speed and air gap. It is configurable for most environments, and customized versions are also available. This sensor is adaptable to various configurations and is commonly used in diesel engine generators, engine ignition systems, pumps and flow meters, as well as turbines and power generation applications.

MSC 401029-20

Description: VR Speed Sensor

Thread : 5/8-18 in UNF-2A

Thread Length: 4.90 in

Lead Wire Length : 5.60 in

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A photo of the Magnetic Pick Up Sensor PN 401029-30, featuring a cylindrical metallic body with a 5/8-18 UNF-2A threaded end and a length of 3.60 inches. This analog variable reluctance passive sensor generates a sine wave output without requiring an external power source, and its voltage is determined by the target speed and air gap. It is commonly used in various applications such as governors, rail actuators, agricultural equipment, and manufacturing control systems.

MSC 401029-30

Description: VR Speed Sensor

Thread: 5/8-18 in UNF-2A

Thread Length: 5.49 in

Lead Wire Length: 3.59 in

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A photo of the Magnetic Pick Up Sensor PN 401072-90, featuring a cylindrical metallic body with an M15x1.5 thread and a length of 4.25 inches. This analog variable reluctance passive sensor generates a sine wave output without requiring an external power source, and its voltage is determined by the target speed and air gap. It is configurable for most environments, and customized versions are also available. This sensor is adaptable to various configurations and is commonly used in governors, rail actuators, agricultural equipment, and manufacturing control systems, as well as diesel engine generators, engine ignition systems, pumps and flow meters, and turbines and power generation applications.

MSC 401072-90

Description: VR Speed Sensor

Thread:  M16 x 1.5 |

Thread Length: 3.13 in

Lead Wire Length: 4.25 in

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A photo of the Magnetic Pick Up built by Magnetic Sensors Corporation with Sensor PN 401092-80. The pick-up is made of 303 stainless steel material and has a thread size of 3/4-16 UNF-2A, with an overall length of 6.50 in. It has an operating temperature range of -40°F to 250°F and an inductance of 90 mH NOM and resistance of 565 OHMS NOM. This analog variable reluctance passive sensor generates a sine wave output without the need for an external power source. The voltage is determined by the target speed and air gap. This sensor is commonly used in applications such as governors, rail actuators, agricultural equipment, and manufacturing control systems. It is used by one of Magnetic Sensors Corporation's customers, Emerson."

MSC 401092-80

Description:  VR Speed Sensor

Thread: 3/4-16 in

Thread Length: 2.57 in

Lead Wire Length: 3.50 in

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A photo of a Magnetic Pick Up built by Magnetic Sensors Corporation, featuring Sensor PN 401070-70, made of 303 Stainless Steel material with thread size 5/8-18 UNF-2A, and measuring 2.62 inches in overall length. This sensor has an operating temperature range of -65° F to 225° F and is an analog variable reluctance passive sensor that generates a sine wave output without requiring an external power source. The voltage is determined by the target speed and air gap. It is commonly used in applications such as governors, rail actuators, agricultural equipment, and manufacturing control systems. This particular sensor is used by one of our customers, EMERSON.

MSC 401070-70

Description:  VR Speed Sensor

Thread: 5/8-18 in UNF-2A

Thread Length: 1.48 in

Lead Wire Length: 2.62 in

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Functions and Applications for MSC’s Variable Reluctance Sensors

   Variable reluctance sensors have a variety of functions and applications, as seen below :

SENSOR TYPE
Active Digital Output
Variable Reluctance Speed Sensor with Digital Output
Passive Analog Output
Variable Reluctance Speed Sensor
Variable Reluctance Speed Sensor W/ Complimentary Outputs

 

INDUSTRY APPLICATIONS
Aviation/ Aerospace Brake Controls, Jet Engines, Fuel Pump Monitor, APU, Turbochargers, Steering Mirror Actuator, Valve Actuator
Biotech Centrifuge Speed Measurement, Proximity Switches
Exercise Equipment Speed Control, Distance Measurement
Military Bradley Fighting Machine, F8 Crusader, AAV7 Amphibious Assault Vehicle, Unmanned Aerial Vehicles
Railroad Engine Controls, Turbines, Valve Position