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How Magnetostrictive Sensor works

Magnetostriction is a property of ferromagnetic materials such as iron, nickel, cobalt and their alloys to expand or contract when placed in magnetic field.
Initially when these ferromagnetic materials are not magnetised the magnetic domains of the ferromagnetic material are randomly distributed. But when they are placed in magnetic field the magnetic domains undergo changes and are arranged in parallel.
A magnetostrictive sensor is used to measure linear position. It basically senses the position of the permanent magnet(position magnet) to determine the distance between the permanent magnet and the sensor head.
The main components of the magnetostrictive sensor are
  • Waveguide
  • Position magnet
  • Electronics
  • Strain pulse detection system
  • Damping module

MTS Magnetostrictive Sensor Principle

The basic part of the magnetostrictive sensor is the sensing element called the waveguide. The waveguide is made of ferromagnetic materials such as iron, nickel, cobalt and their alloys. The position magnet which is round in shape moves around this waveguide.

Initially when position has to be determined the sensor electronics sends a current pulse called the interrogation pulse through the waveguide and starts the timer. So a magnetic field is created around the waveguide. When the magnetic field of the position magnet interacts with the magnetic file around the waveguide a strain pulse is generated which travels at the speed of sound on both sides. On one side this strain pulse is detected by the strain pulse detection system and then processed by the electronics and converted into electrical pulse. The position is determined based on the time the strain pulse takes to reach the strain pulse detection system. The un useful pulse which travels opposite to the electronics is damped by damping module to prevent any interference by reflections from the waveguide tip.

Advantages of Magnetostrictive sensor: since it is non contact( the position magnet does not touch waveguide) there is no wear and friction. So there is no limitation on the number of operating cycles and is not affected by vibrations.
Linear measurement

Disadvantages of Magnetostrictive sensor: Dead band on both side of the sensor.( Some manufacturers can reduce the dead bands based on your requirement but cannot make it to zero)

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This Blog is made so that the students and engineers get the basic knowledge on the various types of sensor technologies available. This blog contains information on the working of various kinds of sensors, their advantages, disadvantages, common applications and links of best manufacturers.

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