inductive transducer

inductive torque transducer working principle

What is a transducer?

The device is used for the conversion of physical quantities into proportional electrical quantities such as in voltage or electric current. It plays an important role in the instrumentation system. Inductive torque sensor is use for measurement of torque of motor’s shaft. Inductive torque transducer working principle is simple just to getting a electrical signal from transducer sensor. It can measure physical quantities like displacement, temperature, motion, level, pressure, etc. The output which is obtained from the transducer is in the electric form and its equivalent to the measured quantity. There are numerous types of transducer but in this, we will discuss inductive transducer only.

What is Inductive transducer?

It is an electrical device used to convert physical motion into modifying inductance within. It is a self-generating type. Like it uses the principle of fundamental electric generator which means when a motion among a conductor as well as magnetic field induces a voltage within the conductor.

inductive torque transducer

Self-inductance change:

It can be derived by


N= no. Of twists of coil

R= magnetic circuit reluctance


It primarily consists of the two-part of the coil, the first one is the movable magnetic core, the element that senses pressure. Not only this has the inductance of the coil changed as the AC voltage is applied to that. Moreover, there is a direct relationship with the inductance increase and the current decrease with the help of the coil. 


  • If there is a significant change in the quantity to be measured, then there is a significant change in the inductance.
  • The electromagnetic induction’s principle is applicable here, which is primarily used to measure or to detect the things.
  • The foremost fundamentals are the Famous law of Faraday
  • The principle of a fundamental electrical generator is applicable here. 


A magnetic field develops when a current is flowing through the active inductive transducer then instantly the current flow by the circuit that contains an effective inductor when the magnetic field changes through it. This effect is primarily used to indicate all the metallic jobs that usually associates with the field of the magnetic. 

However, the objects that are non-metallic like liquid or some different type’s dirt that won’t react with the field of the magnetic, this is the reason that the inductive sensor could effectively perform in any of the dirt conditions.

There are two types of inductive transducers available such as simple inductance & two-coil mutual inductance. The best example of an inductive transducer is LVDT (Linear variable differential transformer).

  • Simple inductance

A single simple coil that is used as a transducer can be termed as the mechanical element whose displacement has to be evaluated, after that it will change the path of the flux permanence that is originated from the circuit. The final equivalent output is the modified version of the inductance circuit. Moreover, the output of the circuit can be adjusted corresponding to the value of the input. Hence this is the foremost reason that this value could be calculated. 

  • Two-coil mutual inductance

This is the second most fundamental and the different types of coils that are arranged in it. With the help of the external source of power, this primary coil will be generated. However, the focused output could be attained. Moreover, the input of the mechanical and the output are proportional to each other. 

Advantages and disadvantages of inductive transducer

  • It is used for measuring the displacement, for which we use one of its types known as Linear Variable Differential Transformer (LVDT) to measure displacement in terms of the voltage difference between two secondary voltage.
  • It also used to detect the motion of the equipment, for which we the device we use known as a proximity sensor. It also measures position, touchpads.
  • It is used for the detection of metals, to find out the missing parts otherwise count the objects.


  • It will reduce load effects.
  • Higher the responsivity of transducers.
  • Strong against ecological quantities.


  • Due to the side effects, the operating range will be reduced.
  • Sensitive to the magnetic field.
  • The working temperature should lie under the cutie temperature.
Industrial Application of inductive Transducer

The application of inductive transducers finds in proximity sensors also to measure position, touchpads, dynamic motion, etc.

Inductive torque transducer works to measure torque of motors and moving machines

In industries this device is used as a traffic light sensor.  It is also used as metal detector. As the device is able to detect metal under the ground.  They are very useful in industries as this device as a proximity sensor is able to detect the presence and absence of an object other than its position. 

So, in this, we have discussed the inductive transducer and its applications. We go through its structure, the principle of working, where it applies, its advantages and disadvantages of uses and its working phenomenon. As we know any electronic device has some good as well as a bad impact also but besides this, it has numerous applications which are helpful for us in any sort of way. In a modern era, this device is helpful in maintaining the motion, metals, temperature, and pressure of the object by detecting them with the help of a magnetic field. It has two coils one is simple and the other one is a mutual two coil. Both have different working phenomenon and has different techniques to be work on.inductive torque transducer working

Proximity Sensor types & their applications in industries

Proximity Sensor Types and Uses in Industries

To detect the presence of an object without being into physical contact with the object, proximity sensors are used. The proximity sensor works on different principles to sense different objects. Different types of sensors are used in for different scenarios where the detection of the objects is required through non-physical contact. For example, inductive type proximity sensor used for metallic objects and capacitive type sensor for non metallic objects.

Mainly there are two types like inductive and capacitive. But proximity sensors are further classified into several types depending on the principles that are used for the detection of an object without any physical contact. They are also classified according to the type of material they sense.

Here is the list of some basic types of the proximity sensor.

Inductive Proximity Sensor:

The inductive sensor is the type of proximity sensor used to detect metallic objects without being in physical contact with the object. The principle under which the inductive proximity sensor is the electrical principle of inductance. The target object is detected when an electromagnetic force is induced in the object due to the fluctuation of the current.

The inductive sensor makes use of an oscillator circuit for the generation of the high frequency of the electromagnetic field. When an object comes in touch with the field, then at the surface of the object an eddy current will be produced. The eddy current absorbs radiated energy from the sensor, this will result in the loss of energy and also the strength of the oscillator will be changed.

inductive proximity sensor working

The changes in the strength of the magnetic field will be detected by the sensor detection section of the sensor, it will then trigger a solid-state output level if the strength of the magnetic field starts decreasing.


  • The accuracy rate is high
  • Switching rate is also very high 
  • Harsh environmental condition is not a limitation for this type of proximity sensor.


  • Only suitable for the detection of metallic objects
  • Range limitation

Capacitive Proximity Sensor:

Capacitive sensors are almost similar to inductive proximity sensors, the only difference between these two types of proximity sensors is that the capacitive inductor produces electrostatic instead of the electromagnetic field. 

The formation of the sensing surface is made using two metal electrodes, the oscillator produces the electrostatic field between two plates. Whenever a metallic or non-metallic object meets the electrostatic field, the capacitance of the oscillator changes. 

capacitive proximity sensor working

The oscillator circuit begins to oscillate and changes the state of the output of the proximity sensor as a result when it reaches a certain value of amplitude.


  • Detection of metal and non-metal object is possible with the help of capacitive sensors
  • Very high speed of detecting an object
  • Very good stability
  • Power usage is efficient 
  • The cost is very low


  • Temperature and humidity effects the performance of the sensor
  • The accuracy level is less as compared to the inductive sensor
  • Designing very difficult.
Photoelectric Proximity Sensor:

This sensor works on the principle of light for the detection of objects without any physical contact with the object. There are 2 basic types of photoelectric sensors 

  1. Reflective sensor
  2. Through-beam sensor

The reflective sensor works by the emission of a beam of light that hits the object and reflected the sensor, usually in the same physical house as beam emitter.

The through-beam sensor, on the other hand, comprises two parts, one is an emitter, also known as a source of light and the other is a detector or separate receiver. Whenever an object breaks the beam of light, the detector will register this break.


  • It is also known as an all-purpose sensor because it has the capability of sensing all types of material.
  • The life span is longer
  • The sensing range is good 
  • It is very reliable 
  • The response time is very fast
  • The cost is very low


  • Lens gets contaminated 
  • Two separate components are required.

All the different proximity sensors types and their application in industries are well described and their comparison you can see in following image

Proximity sensor types

If you want to learn about working principles for all above sensors you can check this link

All images credit goes to machinedesign