Advantages and disadvantages of LVDT Transducer


What is LVDT?

• LVDT stands for Linear Variable Differential Transformer or Transducer.
• It is passive transducer which measures linear displacement. It produces variable AC voltage which represents physical position of object connected to it.
• In simple form, it uses one primary energized by AC voltage and two secondary coils (having equal number of turns) wound around hollow tube. Movable soft iron core is placed between primary and secondary coils. This is shown in the figure-1.

LVDT Transducer

....about construction ...

Working of LVDT

... • When alternating current is connected to primary coil, magnetic field expands and contracts around the coil.
• When the field is strong and large enough it cuts the secondary coil and induces voltage. Induced Voltage at secondary is in phase with applied voltage at primary coil. • Each secondary coil produces separate voltage.
Refer difference between LVDT vs RVDT >>.

Uses of LVDT


Benefits or advantages of LVDT Transducer

Following are the benefits or advantages of LVDT Transducer:
➨It has high measurement range which is from 1.25 mm to 250 mm.
➨It has low power consumption which is less than about 1 Watt.
➨It is frictionless device.
➨It offers high resolution which is greater than 10 mm.
➨Higher sensitivity of greater than 40 V/mm can be achieved.
➨It is smaller in size.
➨It is less in weight.
➨It has lower hysteresis.
➨It is solid and robust in construction. Hence it is tolerant to shocks and vibrations.
➨It has excellent repeatability.
➨It has very low output impedance.

Drawbacks or disadvantages of LVDT Transducer

Following are the disadvantages of LVDT Transducer:
➨Large displacement is needed for small output.
➨It is affected due to external magnetic field and hence the entire LVDT circuit need to be shielded to achieve desired accuracy.
➨Vibrations due to displacement can affect the performance of the LVDT device.
➨The performance of LVDT is affected due to increase in temperature.
➨In order to get DC output, external demodulator is required.
➨It has limited dynamic response.

Conclusion : ...

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