Role of Sensors & Transducers in Instrumentation

In this tutorial, We will learn all basic to advance detail about sensors and Transducer, what is sensors and why it is used in industry and use in our day to day life, the definition of sensors and Transducer, construction, working, classification, principal operation, advantages, and application 

Measurement of any physical quantity in the real world is essential because with the help of physical quantity value we can find out the various condition for any phase, in our day to day life or Industry we have to find out or calibrate multiple physical parameters like temperature, pressure, flow, humidity, speed and many more, so how to find out this physical quantity in numerical or electrical form so let's understand what is the mechanism behind this

Definition of sensor and Transducers
Sensors and Transducers are widely used electronic devices in any industry to measure any physical quantity, so sensor and transducer both perform their different task but we use this together so that they can perform their function batter manner so "sensor is a device which senses or detect any physical  changes in the environment ", in actual we observe many physical changes in our daily life like change in pressure, change in temperature, flow, and speed so these physical changes measure or detect by the sensor

Now we will talk about Transducer, in our electronic devices like mobiles, computers, laptops and many automated systems. we always either voltage or current signal form for processing and working to the device, but our all physical changes are always present in non-electric signal so how to convert it into the electric form so here we use transducer.

"Transducer is a device which converts non-electric a physical quantity into electrical quantity " in simple word " sensor and Transducer is a device which senses or detect physical parameter and convert it into an electrical signal so that we can use this electrical signal for further use in our electrical device like computer laptop, and many more her we can take the various example of sensors and transducers like thermocouple, LVDT, RTD, etc.

" Transducer can be a Sensor but sensor can not have a Transducers " meant transducer can also sense or detect changes in any physical quantity and convert it into electrical signal but sensor only sense or detect the physical changes but can not convert it into electrical form.

Classification of Sensor and Transducers
Here we can divide the sensor and Transducer based on their principle of operation. so let's see how many types so sensor and transducer and or on which bases we can categorize it.

  1. Based on basic electric principal or devices like Resistor, Capacitor & Inductance

    • Resistive Transducers: In this Transducer here change in any physical parameter or quantity causes the change in a resistor of device or sensor and after some appropriate electrical arrangement, we can measure the change in resistance, for example, resistive transducer Potentiometer, strain Gauge, etc.

    • Capacitive Transducers: In a Capacitive transducer here change in a physical quantity, causes a change in the capacitance of the circuit, here change in capacitance can occur due to a change in distance or length between a plate of the capacitor and a change in the dielectric medium of a capacitor. we can measure the capacitance of the circuit, transducer, and device with the help of various electrical bridges.

    • Inductive Transducers: The inductive transducer work on farad electromagnetic low, in this transducer the magnetic field, self-inductance, or mutual inductance varies as per change in physical changes like change in displacement either linear or Angular displacement, force, pressure velocity, in the inductive transducer we measure electrical signal in the form of voltage example of the inductive transducer is LVDT.

  2. Based on power require an active or passive  transducer

    • Active transducer: In an active transducer, we do not require to give an external power source or supply to work the transducer they are self generate their power supply by a change in quantity like piezoelectric transducer they do not require an external power supply.

    • Passive Transducer: in a passive transducer, here we need to give some external power supply or source to perform their operation, normally we need to give 5 volts and 20mA current to the circuit for operation there are some examples of Passive transducers like Resistive and capacitive and Inductive based transducer they all require an external power supply.

  3. Primary & Secondary Type Transducers

    • Primary Transducers: The primary transducer is all those mechanical devices that convert physical quantity into non-electrical or another measurable quantity like pressure can convert unto displacement through the burden tube and bellows and many more.

    • Secondary Transducer: secondary transducer output cause the change in the secondary transducer parameter and this parameter converts into electrical form with the help of the secondary transducer so in simple word we can say that the secondary transducer converts the mechanical signal into a corresponding electrical signal

  4. Analog and Digital Transducer

    • Analog transducer: A Transducer that detects the physical changes and gives an output signal in the analog form, so such transducer is called an analog transducer

    • Digital Transducer: Those sensors which give their output signal corresponding to change in input variable in the digital form are called  Digital Transducer

  5. Transducer and Inverse - Transducers

    • Transducer Device: A transducer device can convert only physical change into electrical form. but can not perform its reverse function which means that it can not convert electrical quantity into non - electrical or physical quantity like LVDT. Strain Gauge etc.

    • Inverse - Transducer devices: A Inverse transducer device those are which can perform a reverse function means it can convert electrical energy into mechanical form AC Motor can convert electrical energy into mechanical form, similarly, piezoelectric transducers can convert force or displacement into an electrical form or its reverse.