Merits:
1. LVDT has infinite resolution as it gives stepless output and it has got no mechanical element to change output in discrete steps. Nowadays transducers are available with the resolution up to 1 micron.
2. LVDT has almost linear characteristics within its prescribed range.Linearity upto +25 or -25% can be achieved in commercially available LVDTs.
3. LVDT has high sensitivity.It usually varies from 10mV / mm to 40 V/mm.
4.Its output is very high which,even in some cases,eliminates the need for amplification devices.
5.These devices consume very less power (less than 1 watt).
6. LVDT can be used on high frequencies up to 20 kHz.
7.Output impedance of LVDT remains constant which in case of potentiometer varies with displacement.
8.Absence of sliding contact makes LVDT a more reliable device.
9.LVDT has very low hysteresis so a good repeat ability can be achieved with it.
10.LVDT is very rugged devices in construction so it can tolerate shocks and variations without any adverse effect.
11.It is a very stable and easy to align and maintain due to simplicity of construction,small size and light weight.
Demerit:
1.These devices are sensitive to stray magnetic fields but its problem is overcome by using magnetic shields.
2.Relatively large displacements are required for appreciable differential output.
3.Sometimes,the transducer performance is affected by vibrations.
Applications:
LVDTs are suitable for use in applications where the displacements are too large for strain gauges to handle,for example,LDVTs can be employed for measurement of displacements that range from a fraction of a mm to a few cm. If LVDT is to be employed for measurement of mechanical displacement greater than 25mm, an appropriate mechanical ratioing(gearing) must be used.
Since the LVDTs can also be connected to other transducers,whose outputs are mechanical displacements,these are often employed together with other transducers for measurement of force,weight,pressure etc.
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