Technical Blog

What is a Speed Sensor?

A speed sensor is a type of position sensor which is used to measure rotational speed. They are present in various types of commercial and motorsport vehicles.

Like many devices, a speed sensor is an integral part of onboard systems. They work by providing a voltage measurement corresponding to the magnetic rotational speed. They can be found in applications where contact-free speed measurement is required in areas that can be hard to access.

Different speed sensors use different types of technology, the sensors that we can offer use magnetic or hall effect position sensing technology.

How does a Hall Effect Speed Sensor Work?

A Hall Effect sensor uses a magnetic field dependent semiconductor. The Hall Effect is caused by the Lorentz force, this acts on the moving charge carriers within the magnetic field. 

When an electric current is flowing through any material, the electrons within that current will naturally move in a straight line. The electricity creates its own magnetic field as it becomes electrically charged – known as a semiconductor.

If the semiconductor material is then placed between the two poles of a magnet, instead of moving in a straight line as before, the electrons will be pushed to one side and into a curved line, forming a curved path as they move through the material. This is caused by their own magnetic field reacting to the different fields of the magnet.

As a result of the now curved movement, there are more electrons present on one side of the semiconductor material. Because of this, a potential difference appears across the semiconductor material at right angles to the magnetic field, from both the magnet and the flow of the electric current.

Using this measuring method, the magnetic field difference between these two is calculated with two Hall effect speed sensors mounted on a surface. The constant change between the two hall sensors can be directly related to the speed of the movement.

Hall effect speed sensors are particularly suitable for use on gears. Due to the measuring principle, installing the speed sensors directionally is necessary.

Characteristics of Speed Sensors

Because of the areas in which speed sensors are required, they must be tough and able to stand the harshest environmental conditions. The speed sensor we offer is resistant to changes in pressure, has a wide operating temperature range, is impervious to dust and humidity, and is not hindered by electromagnetic interference.

What is a Speed Sensor Used For?

Speed sensors are used to measure the rotating speed within devices. Many vehicles require speed sensors including; automotive vehicles, aerospace vehicles, off-highway & construction vehicles, railway vehicles, and military vehicles.

Within these vehicles, the specific applications are crankshaft transmission speed, engine speed, dynamometers, fan control, test equipment and engine control.

Speed Sensors from Variohm

We have a range of speed sensors from our sister company Phoenix America. These are magnetic speed sensors using non-contacting technology.

The S series speed sensors are solid-state devices that are magnetically situated making them suitable for use in various applications. This series offers tight magnetic tolerances around a zero gaus level providing a 50% duty cycle over the full operating frequency range.

This series also offers low hysteresis which makes them ideal for applications involving high-density multipole magnet target wheels and large air gaps.

Other features and benefits of the speed sensors we offer are;

  • Reads speeds from 0 to 100kHz
  • Digital output signals
  • Current sinking output
  • 20mA continuous operation
  • 4 to 24VDC operation range
  • Temperature compensated
  • Operating temperature range -40C to 125C

Our range of speed sensors can be seen on our website – take a look here for the full range.

In addition to our sensors from Phoenix, we also have a range of speed sensors suitable for Motorsport. This includes our own Euro-WS gear tooth sensor – take a look at the full range here. Speed Sensors for Motorsport.

For more information on speed sensors please contact us

Article published on: 20/04/2022