LVDT Advantages And Disadvantages | Pros and Cons of Linear Variable Differential Transformer (LVDT), Benefits and Drawbacks

LVDT Advantages And Disadvantages: LVDT or Linear variable differential transformer is a type of sensor positioned to measure the linear displacement. It is an electromechanical passive inductive transducer. It can convert the rectilinear motion into a corresponding electrical signal. The sensors of LVDT are readily functional to measure say a few millionths of an inch up to several inches. LVDT depends on Faraday’s principle of the law of electromagnetic induction that states ” the net induced emf in the circuit is directly proportional to the rate of change of magnetic flux across the circuit and the magnetic flux of the coil wounded with wires can be changed by moving a bar magnet through the coil.” It is an inductive transducer that measures the speed and position of the object.

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What is LVDT? Advantages and disadvantages of Linear Variable Differential Transformer 2022

LVDT is an electromechanical sensor used to produce the AC voltage output. They can perform under high shock and vibration when used in a drastic environment. An output voltage is zero when voltage output is opposite and equal in polarity at that time the magnetic core is central in position or null position.LVDT output characteristics require amplitude and frequency of AC which is different from standard power lines to operate. They are designed to operate at a temperature of 650°C( 1200 F).

As it is an AC-controlled device therefore it doesn’t have any electrical device inside it. It has a high accuracy level and is used widely. Its electric output is obtained because of the difference in voltage produced which is why it is known as a differential transformer.

Applications of LVDT

Linear variable differential transformers (LVDT) are mostly used to measure physical quantities like pressure, force, tension, etc. Firstly these quantities are converted into displacement by using the transducers and then convert the displacement into an electrical voltage signal. It’s also used in automation, aircraft, satellites, and many industries. It is used as a servomechanism.

Advantages of LVDT (Linear variable differential transformer)

Listed are a few advantages of linear variable differential transformers.

Let us briefly go through the advantages of linear variable differential transformers.

  1. Frictional loss reduced: Since the iron core does not have contact with the transformer coil there is no friction between them and the chances of frictional losses are reduced which makes LVDT the best device. If there will be no friction then there will also be no wear and tear in the object.
  2. Power consumption is low: During operation, there are many times when the power required to operate the machine is low as LVDT uses only 1W power to operate. Therefore the power consumption is low.
  3. Uneven operational shock: It can tolerate a high proportion of shock and vibration especially when a core is loaded with a spring. This makes LVDT the best transducer. Because of their small size and lightweight, they are stable and aligned.
  4. Hysteresis losses are low: Hysteresis losses don’t allow repeating the process thus it becomes necessary that hysteresis losses must be less; this will help in repetition and also be excellent in all conditions.
  5. Conversion is directly into electrical signals: LVDT converts the measure of linear displacement into an electrical signal which helps in processing easily. This boosts up the working of various mechanical equipment.
  6. Dynamic response: As friction is low there can be manipulation at ease in the process. Because of this nature of LVDT, the dynamic response becomes very fast to change in the core position.
  7. Smooth operation: LVDT works smoothly and has a wide range of measurements ranging from 1.25 mm to 250mm. This is advantageous to many heavy industries, automation, aircraft, satellite, turbines, hydraulics, etc.
  8. Higher sensitivity: The sensitivity recorded of LVDT is 40V/mm. LVDT gives high output therefore there will be no need for an amplifier or amplifying process. It is sensitive to stray magnetic fields.

There are a few other advantages too like

  • It offers a high resolution of 10 nm or more
  • It is compact
  • It is not affected due to external environmental
  • It has a lower output impedance

Disadvantages of LVDT (Linear variable differential transformer)

Let us briefly go through the disadvantages of linear variable differential transformers.

  1. Need for extra setup: As LVDT is sensitive to stray magnetic fields therefore extra setup is required to protect it from the stray magnetic field. Therefore it becomes a little expensive.
  2. Affected by various factors: Vibration, variation, and temperature are a few factors that affect the working of LVDT. As it is an electromagnetic device it has to be affected by these factors.
  3. Large displacement for small output: LVDT has to measure a large number of displacements to provide a small output that is one of the demerits of LVDT.
  4. Use of demodulator: since LVDT is an AC signal thus we have to use a demodulator network to obtain DC output. This is again one of the demerits of LVDT.

Although it has a few disadvantages, the advantages of LVDT are more, therefore, people opt for it as it gives the best result.

LVDT Advantages And Disadvantages

Comparison Table for Advantages and Disadvantages of LVDT (Linear Variable Differential Transformer)

Below is the comparison table for the advantages and disadvantages of linear variable differential transformers.

Advantages of LVDTDisadvantages of LVDT
Frictional loss reduced and Conversion is directly into electrical signalsNeed for extra set up
Power consumption is low and Dynamic responseAffected by various factors
Uneven operational shock and Smooth operationLarge displacement for small output
Hysteresis losses are low and Higher sensitivityUse of demodulator

FAQs on Pros and Cons of Linear Variables Differential Transformers

Question 1.
What is LVDT?

LVDT or Linear variable differential transformer is a device used for the measurement of displacement. It works by converting the mechanical movement into an electrical signal. It can measure even the smallest displacement of 0.1 mm.

Question 2.
What do you mean by displacement?

Displacement refers to a vector quantity in which length or distance is measured, say the shortest distance from the initial position and final position undergoing motion. Mathematically Displacement is termed as the shortest distance between the starting and end position of an object.

Question 3.
What is LVDT used for?

LVDT is an electromagnetic sensor used to transform mechanical motion into variable electrical signals and is used for measuring displacement. It is used to measure the displacement or position of the object.

Question 4.
What is Residual voltage?

When we say the output voltage is at the null position it means it should be equal to zero but in actual practice, there is still a small amount of voltage which is known as null or residual voltage. This may be due to the presence of harmonics produced in output voltage due to the use of the iron core.

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