Page 878 - Basic Electrical Engineering

Figure 12.2 Basic constructional details of an LVDT transducer

Although the output voltage, E at null position should be zero, it is
0
observed from Fig. 12.3 that a small amount of voltage appears across the

output terminals at this position. This is due to either an incomplete electrical
or magnetic balance between the output voltages at the null position. This

small voltage at null position may also be due to some stray magnetic fields
or temperature effect. The output voltage curve is linear upto a certain range

of displacement beyond which the characteristic start deviating from
linearity.

Advantages and disadvantages of LVDT transducers

The advantages and disadvantages of a LVDT is expressed in terms of certain
performance characteristics like range, sensitivity, resolution, ruggedness,

dynamic response, linearity, etc. Some of these are mentioned as follows:

i. Range of measurement: LVDT can be used for the measurement of high range of
displacement ranging from 1mm to 250 mm.
ii. Frictionless and electrical isolation: There is no physical contact between the windings and
the core. This provides the LVDT a very long life as there is no wear and tear due to friction.
iii. Resolution: A very small movement of the core produces a proportional voltage output. This
makes the resolution of LVDT very high.